Showing posts with label radioactive iodine. Show all posts
Showing posts with label radioactive iodine. Show all posts
Monday, May 2, 2011
Monday, April 25, 2011
25/04 汚染水濃度、１か月前の２５０倍…４号機地下
福島第一原子力発電所の４号機タービン建屋地下の汚染水について、東京電力は２５日、約１か月前に比べ、放射性セシウムで２５０倍の高濃度になっていることを、事故対策統合本部の記者会見で公表した。
３号機タービン建屋から流入している可能性がある。水位も上昇しつつあり、原子炉の安定冷却に向けた工程に影響を及ぼす恐れがある。
東電は２１日に、４号機タービン建屋地下の汚染水を採取し、放射性物質の濃度を測定した。通常運転時の炉水の１０倍の濃度の放射性ヨウ素や、ヨウ素濃度を上回る放射性セシウムなどを検出。３月２４日に同じ場所で採取した汚染水と比べると、長期にわたり高い放射線を出すセシウム１３４が７８００ベクレル、同１３７も８１００ベクレルで、それぞれ約２５０倍に濃度が上昇していた。また放射性ヨウ素１３１も約１２倍だった。
建屋地下の水位は徐々に上昇しており、４月２５日午前１１時で、床から最大１・１５メートルの水深が計測されるなど、前日に比べて５センチ上昇。１週間前に比べて１５センチも増えるなど、水量全体も増加しつつあるという。
また、３号機タービン建屋地下の高濃度汚染水についても、改めて２か所で濃度を調べ直したところ、１か月前に比べて１・５～２倍以上になっていた。
（2011年4月25日20時57分 読売新聞）
３号機タービン建屋から流入している可能性がある。水位も上昇しつつあり、原子炉の安定冷却に向けた工程に影響を及ぼす恐れがある。
東電は２１日に、４号機タービン建屋地下の汚染水を採取し、放射性物質の濃度を測定した。通常運転時の炉水の１０倍の濃度の放射性ヨウ素や、ヨウ素濃度を上回る放射性セシウムなどを検出。３月２４日に同じ場所で採取した汚染水と比べると、長期にわたり高い放射線を出すセシウム１３４が７８００ベクレル、同１３７も８１００ベクレルで、それぞれ約２５０倍に濃度が上昇していた。また放射性ヨウ素１３１も約１２倍だった。
建屋地下の水位は徐々に上昇しており、４月２５日午前１１時で、床から最大１・１５メートルの水深が計測されるなど、前日に比べて５センチ上昇。１週間前に比べて１５センチも増えるなど、水量全体も増加しつつあるという。
また、３号機タービン建屋地下の高濃度汚染水についても、改めて２か所で濃度を調べ直したところ、１か月前に比べて１・５～２倍以上になっていた。
（2011年4月25日20時57分 読売新聞）
Tuesday, April 19, 2011
19/04 Evacuation subsidy limited / System's narrow scope penalizes families by separating them
Shingo Hashitani / Yomiuri Shimbun Staff Writer
FUKUSHIMA--"Why can't I evacuate with my two daughters?"
Akiko Sato, 24, a resident of Iitatemura in Fukushima Prefecture, was complaining to a community administrative assistant who had come to her house to explain the village's subsidy system for evacuees leaving due to radiation leaks from the crippled Fukushima No. 1 nuclear power plant.
The village is designated by the central government as being within the planned evacuation area.
The Iitatemura village government is subsidizing residents' evacuation costs in light of the high concentration of radioactive substances detected in the local water and soil.
However, the subsidy system's inconvenient conditions have prompted criticism from the villagers because those most eager to utilize it--such as families with babies--are effectively prevented from benefiting.
Under the system, the village pays an accommodation fee of 5,000 yen a night (including three meals) to Iitatemura residents who evacuate to outside hotels and ryokan inns that contracted with the village. The subsidies are paid from prefectural coffers.
Those who qualify fall into two categories. One is pregnant women. The other is children under 3 years old accompanied by just one guardian.
Sato, a part-time worker, was angry as the system would separate her family of four--Sato, her husband, 30, and daughters Hina, 5, and Aoi, 2.
If Sato elected to receive the subsidy to evacuate with Aoi, Hina would have to stay home alone when her husband is at work. The system does not cover lodging expenses for her husband and Hina. The subsidy is appealing, she said, but unacceptable because she cannot allow her family to be separated.
Late last month, high levels of radioactive iodine-131 were detected in the village's tap water. The Satos evacuated to her parents' home located outside the village. At that time, the families of Sato's brother and sister also evacuated to the home. "We couldn't stay there too long, and it was stressful for my daughters," Sato said.
Consequently, the Satos returned to their home in the village after a week.
She said her family has decided to remain in their house for the time being.
"We're scared of radiation, but it's important that our family lives together. The nuclear plant has affected everything that was part of normal life," Sato said.
Five months pregnant, Misuzu Abe, 21, shares the same problem as Sato. Abe cannot go outside with her 1-year-old Raiki, for fear of radiation risk to the boy and her unborn baby.
After thinking it through, Abe decided to evacuate with Raiki while leaving her husband alone in the village, and then applied to the village government on April 9. However, she thought twice and retracted the application as she "was worried to be without her spouse especially when pregnant."
The Abes rented an apartment outside the village and moved there with Raiki. But the move has rendered the family ineligible for the Iitatemura evacuation subsidy.
The Fukushima prefectural government set up a subsidy system without any conditions on the age or number of people residing together for all cities, towns and villages located within a 30-kilometer radius of the nuclear plant. However, the system does not cover most of the areas in Iitatemura, which lies only partially within the 30-kilometer limit. As a result, of the 125 qualified villagers, only 37 applied for the subsidy before the April 11 deadline. Like Abe, some submitted but then withdrew their applications, and in the end, only 28 residents actually had evacuated the village as of Sunday.
(Apr. 19, 2011)
FUKUSHIMA--"Why can't I evacuate with my two daughters?"
Akiko Sato, 24, a resident of Iitatemura in Fukushima Prefecture, was complaining to a community administrative assistant who had come to her house to explain the village's subsidy system for evacuees leaving due to radiation leaks from the crippled Fukushima No. 1 nuclear power plant.
The village is designated by the central government as being within the planned evacuation area.
The Iitatemura village government is subsidizing residents' evacuation costs in light of the high concentration of radioactive substances detected in the local water and soil.
However, the subsidy system's inconvenient conditions have prompted criticism from the villagers because those most eager to utilize it--such as families with babies--are effectively prevented from benefiting.
Under the system, the village pays an accommodation fee of 5,000 yen a night (including three meals) to Iitatemura residents who evacuate to outside hotels and ryokan inns that contracted with the village. The subsidies are paid from prefectural coffers.
Those who qualify fall into two categories. One is pregnant women. The other is children under 3 years old accompanied by just one guardian.
Sato, a part-time worker, was angry as the system would separate her family of four--Sato, her husband, 30, and daughters Hina, 5, and Aoi, 2.
If Sato elected to receive the subsidy to evacuate with Aoi, Hina would have to stay home alone when her husband is at work. The system does not cover lodging expenses for her husband and Hina. The subsidy is appealing, she said, but unacceptable because she cannot allow her family to be separated.
Late last month, high levels of radioactive iodine-131 were detected in the village's tap water. The Satos evacuated to her parents' home located outside the village. At that time, the families of Sato's brother and sister also evacuated to the home. "We couldn't stay there too long, and it was stressful for my daughters," Sato said.
Consequently, the Satos returned to their home in the village after a week.
She said her family has decided to remain in their house for the time being.
"We're scared of radiation, but it's important that our family lives together. The nuclear plant has affected everything that was part of normal life," Sato said.
Five months pregnant, Misuzu Abe, 21, shares the same problem as Sato. Abe cannot go outside with her 1-year-old Raiki, for fear of radiation risk to the boy and her unborn baby.
After thinking it through, Abe decided to evacuate with Raiki while leaving her husband alone in the village, and then applied to the village government on April 9. However, she thought twice and retracted the application as she "was worried to be without her spouse especially when pregnant."
The Abes rented an apartment outside the village and moved there with Raiki. But the move has rendered the family ineligible for the Iitatemura evacuation subsidy.
The Fukushima prefectural government set up a subsidy system without any conditions on the age or number of people residing together for all cities, towns and villages located within a 30-kilometer radius of the nuclear plant. However, the system does not cover most of the areas in Iitatemura, which lies only partially within the 30-kilometer limit. As a result, of the 125 qualified villagers, only 37 applied for the subsidy before the April 11 deadline. Like Abe, some submitted but then withdrew their applications, and in the end, only 28 residents actually had evacuated the village as of Sunday.
(Apr. 19, 2011)
Sunday, April 17, 2011
16/04 福島第１原発：ヨウ素、セシウム過去最高 ３０キロの海水
文部科学省は１６日、１５日に採水した福島第１原発の東約３０キロ地点の海水から、１リットル当たり１６１ベクレルの放射性ヨウ素と、同１８６ベクレルの放射性セシウムを検出したと発表した。３月２３日から付近の海域で断続的に調査しているが、今回は過去最高の数値だった。
原発から放出する場合の濃度限度はヨウ素が１リットル当たり４０ベクレル、セシウムが同９０ベクレル。今回はそれぞれ４倍、２倍の高い数値が出た。
毎日新聞 2011年4月16日 23時41分
Saturday, April 16, 2011
29/03 枝野官房長官の会見全文〈２９日午前９時５０分〉
2011年3月29日13時25分
枝野幸男官房長官の午前９時５０分からの記者会見の内容は次の通り。
【冒頭発言】
原子力発電所事故への対応などについて総理に対して情報提供や助言を行うため、本日付で、多摩大学大学院教授の田坂広志氏を内閣官房参与に任命することとし、先ほど総理より辞令交付した。田坂氏は、原子力工学の分野においてすぐれた知見を有しているので、安全対策に関して助言などを行う。
【原発事故】
――福島第一原発について。敷地内から微量のプルトニウムが検出された。危険性と、過去の水素爆発などで敷地外に拡散した可能性は。
「東電の報告では、土壌５検体、５カ所から採ったものについて、プルトニウムが確認された。検出されたプルトニウムの濃度は、環境中に存在するフォールアウト、大気圏内核実験による放射性降下物の影響と思われる程度と同程度、濃度は同程度だ。ただし、そのプルトニウムの種類は、フォールアウトと異なるものが入っている。そういう濃度比率になっている」
「今回の事故の影響が考えられる。引き続きこの事故の影響によって、高い濃度のプルトニウムが検出されるということになると、それは対応が必要になるので、引き続き継続的にモニタリングを続けていく」
――これまでも広範囲でモニタリング検査してきたが、プルトニウムについても広範囲で強化するか。
「ここは専門家のみなさんの助言を頂きながら進めないとならない。ここまでのところは、プルトニウムは相対的に重いので、周辺地域のモニタリングをしっかりと行っていくことで、広範な地域でのモニタリングの必要性についての一定の判断はできるという種類の説明は受けている。実際に、濃度としては高いものではないが、原子力発電所に由来するプルトニウムが出ていると考えられる状況なので、さらに専門家のみなさんに助言を仰いで、どうした地域でモニタリングを行うべきかということは、常にチェックして参りたい」
――建屋外側から高濃度の汚染水。注水すればするほど汚染水が出る。原子力安全委員会の班目（まだらめ）委員長は「どう処理できるか知識を持ち合わせてない」と発言した。現状は手詰まりなのではないか。
「原子力安全委の委員の先生も、原子力関連の専門家の皆さんといってもそれぞれ分野があるわけで、班目委員長の専門はそういった分野ではないと思う。なので、委員長としての認識ではないと思う、個人として。今、安全委員会の助言を頂きながら、原子力安全・保安院と東電中心に、出てきている水をどうやって安全に排出するか、それをキープ、確保するかについてはさまざまな検討作業を進めている。現時点で、こういうやり方をしますと確定的なことを報告する段階ではないが、様々な検討、手段についての精査が行われている現状だ」
――様々な方法を模索ということだが、注水と排水のバランスが困難ではないか。作業を開始するメドは。
「注水については原子炉、あるいは燃料棒の温度が高熱になって空だきになるのは避けないとならない。この冷却は優先して進めないとならないと思う。一方で、水についてはできるだけ早いほうがいいということで、検討と作業を進めている状況だ。本当に可能な限り早くというのが今の状況だ」
――排水が必要だからといって、注水を止めることはないということか。
「少なくとも両方の状況を見ながら、注水の方を必要あればやらざるを得ないだろうとみている」
――やらざるを得ないとは。
「つまり、注水を止めることで燃料棒が高熱になる、空だきになるような状況は、これは全体の状況からみれば優先的に阻止しないとならない状況だろうと思う。ただ、できるだけ注水量が少ないなかで、燃料棒の温度が上がらない状況をキープするというための努力は進めている。ただ、やはり抜本的には水を抜いていくということを、できるだけ早く進めていかないとならない状況だというのは間違いない」
――プルトニウムが出たということは、核燃料の損傷が進んでいるのではないか。
「核燃料に由来すると思われる濃度比率のものが検出されている。燃料棒から出ている可能性が高いというか、ほぼ間違いないだろうという状況だろう。これは、周辺のたまり水の濃度が非常に高いこととあわせて、燃料棒が一定程度溶融したと思われることを裏付けるものである。このこと自体は大変深刻な事態だが、そのことによる周辺部への影響をいかに阻止し、収束させるかということに、いま全力を挙げている」
【首相の情報発信】
――震災前には毎日、首相発言があった。震災後は数回しかない。国民には違和感がある。危機的状況が長期化、日常化していくなかで、今後首相は日々どうメッセージを発信し、リーダーシップをとるのか。
「ここは震災に対する対応、原子力発電所に対する対応、最高責任者としてしっかりとその対応に万全を期しないとならないという、これが最優先課題だと思う。と同時に、内閣総理大臣として国民の皆さんにしっかりとしたメッセージを発信していくということも、それに次いで重要な役割があることは間違いないと思う。できるだけ、国民の皆さんへの発信については、関係大臣、あるいは私が代われるところは、この間代わって、そのことで最高指揮官としての総理の業務をできるだけ優先できるようにとやってきているところだが、いまご指摘のように、長期にわたっているという状況のなかで、どう総理としての国民へのメッセージというものの時間というかエネルギーを確保するかは、この間も検討してきているところだ。いまの指揮官としての判断、指揮との兼ね合いのなかで、ある程度の時間とエネルギーを国民へのメッセージに注がなければならない必要性は、日々高まっているとは認識している」
――国際社会からの支援やメッセージに対し、首相としてメッセージを発信する必要があるのではないか。
「この間も、オバマ米大統領はじめ、幾つかの国の首脳とは電話会談などで、直接、支援への感謝などを含め、コミュニケーションをとっているが、さらに外務大臣と役割分担しながら、国際社会とのコミュニケーションをしっかりとっていかなければならない」
【東京電力】
――一部の報道で東京電力の国有化を政府が検討とあるが、事実関係は。
「現時点で、そういった検討を政府の機関で行っていることはないと認識している。まずは東京電力として事故の収束に全力をあげ、その上で事故の影響を受けている皆さんに対する対応をしっかり行って頂く、まずはそのことに全力を尽くして頂くということについて、政府としてしっかり指示をする段階だ」
【田坂広志内閣官房参与】
――内閣官房参与になった田坂氏だが、大学で原子力の講義をされていないが、なぜ選ばれたのか。参与はどういう基準で、誰が選んでいるのか。
「原子力工学の分野に識見を持たれた上で、様々なリスクコントロールなどについての知見をお持ちであるという総合的なところでお願いをしたと聞いている。原子力に関する分野は専門性が分かれていて幅広いから、炉の専門家とか放射線の専門家とか、様々な分野の専門家とそれを横断的に一定の知見を持っている方、両面が必要だと私も思っている」
「どなたをどうお願いするかという基準は、なかなかひと言で抽象的に申しあげるのは難しいが、民間の方を含めて、様々な方にこの間、意見、助言は頂いているが、政府の立場をしっかりと持って頂くことで、公務員としての様々な責任と同時に公務員だからできる部分があるので、そういう身分を持って頂いたほうが、助言を頂く上でプラスであるという状況ならば、そうした参与などの立場を持って頂いた上で、助言を頂くと。それ以外の立場の皆さんからも、純粋に民間の方からも、助言はたくさん頂いている、そういうところに違いがある」
【被災者の被害認定】
――被災者の被害認定の基準。被災地で半壊にとどまっている世帯が避難所に入れず、ガス、水道もない自宅での居住を強いられているケースがある。半壊世帯をどうするべきか。被害認定基準の弾力的な運用をどう考えているか。
「被害認定基準がそもそも直接避難所で受け入れてサポートする、しない、できる、できないということとダイレクトにつながっているとは私は認識していないが、家屋の損壊による事実上の補償のような話があるが、そういうところは全壊と半壊で、従来から制度があるが、それについての全壊の認定については、昨日申しあげたが、かなり柔軟にやっていこうという措置はとっている」
「避難所に避難頂くうんぬんについては、その全壊か半壊が直接の基準ではなっていないと理解しているが、その点が現場の市町村で誤解、徹底がされていない、あるいはこの間の、色々と大きな動きがある中で、もしどこかの部局から誤った指示がなされているとすればいけないので、それは確認して、全壊半壊にかかわらず、当面の避難のことについては事実上、それぞれの自宅で生活できないという事情に基づいて、対応すべきであると思うので、確認をした上で徹底したい」
――現場では、ヒアリングの段階で、被災状況をみて重い方を優先するという運用がされているようだ。
「それはそれぞれの地域ごとの避難所のキャパシティーとの問題で、現場の判断でそういったことはあり得るだろうと思う。ただ、それについては避難所のキャパシティーそのものについて、国の支援でより広範に、必要な方が受けられるように、こういう支援はさらに強化しなければいけないだろうと思う」
【池田経済産業副大臣の発言】
――池田経産副大臣が原発事故の行方について、「神のみぞ知る」と発言したことについて。
「私はとにかく菅総理を先頭に全力を挙げて、これ以上悪化させないための努力を最大限努めていくのが、政府の役割だと思っている」
./.
枝野幸男官房長官の午前９時５０分からの記者会見の内容は次の通り。
【冒頭発言】
原子力発電所事故への対応などについて総理に対して情報提供や助言を行うため、本日付で、多摩大学大学院教授の田坂広志氏を内閣官房参与に任命することとし、先ほど総理より辞令交付した。田坂氏は、原子力工学の分野においてすぐれた知見を有しているので、安全対策に関して助言などを行う。
【原発事故】
――福島第一原発について。敷地内から微量のプルトニウムが検出された。危険性と、過去の水素爆発などで敷地外に拡散した可能性は。
「東電の報告では、土壌５検体、５カ所から採ったものについて、プルトニウムが確認された。検出されたプルトニウムの濃度は、環境中に存在するフォールアウト、大気圏内核実験による放射性降下物の影響と思われる程度と同程度、濃度は同程度だ。ただし、そのプルトニウムの種類は、フォールアウトと異なるものが入っている。そういう濃度比率になっている」
「今回の事故の影響が考えられる。引き続きこの事故の影響によって、高い濃度のプルトニウムが検出されるということになると、それは対応が必要になるので、引き続き継続的にモニタリングを続けていく」
――これまでも広範囲でモニタリング検査してきたが、プルトニウムについても広範囲で強化するか。
「ここは専門家のみなさんの助言を頂きながら進めないとならない。ここまでのところは、プルトニウムは相対的に重いので、周辺地域のモニタリングをしっかりと行っていくことで、広範な地域でのモニタリングの必要性についての一定の判断はできるという種類の説明は受けている。実際に、濃度としては高いものではないが、原子力発電所に由来するプルトニウムが出ていると考えられる状況なので、さらに専門家のみなさんに助言を仰いで、どうした地域でモニタリングを行うべきかということは、常にチェックして参りたい」
――建屋外側から高濃度の汚染水。注水すればするほど汚染水が出る。原子力安全委員会の班目（まだらめ）委員長は「どう処理できるか知識を持ち合わせてない」と発言した。現状は手詰まりなのではないか。
「原子力安全委の委員の先生も、原子力関連の専門家の皆さんといってもそれぞれ分野があるわけで、班目委員長の専門はそういった分野ではないと思う。なので、委員長としての認識ではないと思う、個人として。今、安全委員会の助言を頂きながら、原子力安全・保安院と東電中心に、出てきている水をどうやって安全に排出するか、それをキープ、確保するかについてはさまざまな検討作業を進めている。現時点で、こういうやり方をしますと確定的なことを報告する段階ではないが、様々な検討、手段についての精査が行われている現状だ」
――様々な方法を模索ということだが、注水と排水のバランスが困難ではないか。作業を開始するメドは。
「注水については原子炉、あるいは燃料棒の温度が高熱になって空だきになるのは避けないとならない。この冷却は優先して進めないとならないと思う。一方で、水についてはできるだけ早いほうがいいということで、検討と作業を進めている状況だ。本当に可能な限り早くというのが今の状況だ」
――排水が必要だからといって、注水を止めることはないということか。
「少なくとも両方の状況を見ながら、注水の方を必要あればやらざるを得ないだろうとみている」
――やらざるを得ないとは。
「つまり、注水を止めることで燃料棒が高熱になる、空だきになるような状況は、これは全体の状況からみれば優先的に阻止しないとならない状況だろうと思う。ただ、できるだけ注水量が少ないなかで、燃料棒の温度が上がらない状況をキープするというための努力は進めている。ただ、やはり抜本的には水を抜いていくということを、できるだけ早く進めていかないとならない状況だというのは間違いない」
――プルトニウムが出たということは、核燃料の損傷が進んでいるのではないか。
「核燃料に由来すると思われる濃度比率のものが検出されている。燃料棒から出ている可能性が高いというか、ほぼ間違いないだろうという状況だろう。これは、周辺のたまり水の濃度が非常に高いこととあわせて、燃料棒が一定程度溶融したと思われることを裏付けるものである。このこと自体は大変深刻な事態だが、そのことによる周辺部への影響をいかに阻止し、収束させるかということに、いま全力を挙げている」
【首相の情報発信】
――震災前には毎日、首相発言があった。震災後は数回しかない。国民には違和感がある。危機的状況が長期化、日常化していくなかで、今後首相は日々どうメッセージを発信し、リーダーシップをとるのか。
「ここは震災に対する対応、原子力発電所に対する対応、最高責任者としてしっかりとその対応に万全を期しないとならないという、これが最優先課題だと思う。と同時に、内閣総理大臣として国民の皆さんにしっかりとしたメッセージを発信していくということも、それに次いで重要な役割があることは間違いないと思う。できるだけ、国民の皆さんへの発信については、関係大臣、あるいは私が代われるところは、この間代わって、そのことで最高指揮官としての総理の業務をできるだけ優先できるようにとやってきているところだが、いまご指摘のように、長期にわたっているという状況のなかで、どう総理としての国民へのメッセージというものの時間というかエネルギーを確保するかは、この間も検討してきているところだ。いまの指揮官としての判断、指揮との兼ね合いのなかで、ある程度の時間とエネルギーを国民へのメッセージに注がなければならない必要性は、日々高まっているとは認識している」
――国際社会からの支援やメッセージに対し、首相としてメッセージを発信する必要があるのではないか。
「この間も、オバマ米大統領はじめ、幾つかの国の首脳とは電話会談などで、直接、支援への感謝などを含め、コミュニケーションをとっているが、さらに外務大臣と役割分担しながら、国際社会とのコミュニケーションをしっかりとっていかなければならない」
【東京電力】
――一部の報道で東京電力の国有化を政府が検討とあるが、事実関係は。
「現時点で、そういった検討を政府の機関で行っていることはないと認識している。まずは東京電力として事故の収束に全力をあげ、その上で事故の影響を受けている皆さんに対する対応をしっかり行って頂く、まずはそのことに全力を尽くして頂くということについて、政府としてしっかり指示をする段階だ」
【田坂広志内閣官房参与】
――内閣官房参与になった田坂氏だが、大学で原子力の講義をされていないが、なぜ選ばれたのか。参与はどういう基準で、誰が選んでいるのか。
「原子力工学の分野に識見を持たれた上で、様々なリスクコントロールなどについての知見をお持ちであるという総合的なところでお願いをしたと聞いている。原子力に関する分野は専門性が分かれていて幅広いから、炉の専門家とか放射線の専門家とか、様々な分野の専門家とそれを横断的に一定の知見を持っている方、両面が必要だと私も思っている」
「どなたをどうお願いするかという基準は、なかなかひと言で抽象的に申しあげるのは難しいが、民間の方を含めて、様々な方にこの間、意見、助言は頂いているが、政府の立場をしっかりと持って頂くことで、公務員としての様々な責任と同時に公務員だからできる部分があるので、そういう身分を持って頂いたほうが、助言を頂く上でプラスであるという状況ならば、そうした参与などの立場を持って頂いた上で、助言を頂くと。それ以外の立場の皆さんからも、純粋に民間の方からも、助言はたくさん頂いている、そういうところに違いがある」
【被災者の被害認定】
――被災者の被害認定の基準。被災地で半壊にとどまっている世帯が避難所に入れず、ガス、水道もない自宅での居住を強いられているケースがある。半壊世帯をどうするべきか。被害認定基準の弾力的な運用をどう考えているか。
「被害認定基準がそもそも直接避難所で受け入れてサポートする、しない、できる、できないということとダイレクトにつながっているとは私は認識していないが、家屋の損壊による事実上の補償のような話があるが、そういうところは全壊と半壊で、従来から制度があるが、それについての全壊の認定については、昨日申しあげたが、かなり柔軟にやっていこうという措置はとっている」
「避難所に避難頂くうんぬんについては、その全壊か半壊が直接の基準ではなっていないと理解しているが、その点が現場の市町村で誤解、徹底がされていない、あるいはこの間の、色々と大きな動きがある中で、もしどこかの部局から誤った指示がなされているとすればいけないので、それは確認して、全壊半壊にかかわらず、当面の避難のことについては事実上、それぞれの自宅で生活できないという事情に基づいて、対応すべきであると思うので、確認をした上で徹底したい」
――現場では、ヒアリングの段階で、被災状況をみて重い方を優先するという運用がされているようだ。
「それはそれぞれの地域ごとの避難所のキャパシティーとの問題で、現場の判断でそういったことはあり得るだろうと思う。ただ、それについては避難所のキャパシティーそのものについて、国の支援でより広範に、必要な方が受けられるように、こういう支援はさらに強化しなければいけないだろうと思う」
【池田経済産業副大臣の発言】
――池田経産副大臣が原発事故の行方について、「神のみぞ知る」と発言したことについて。
「私はとにかく菅総理を先頭に全力を挙げて、これ以上悪化させないための努力を最大限努めていくのが、政府の役割だと思っている」
./.
Thursday, April 14, 2011
14/04 Huge radiation release led to severity hike
The Yomiuri Shimbun
The government upgraded the severity of the crisis at the Fukushima No. 1 nuclear power plant to Level 7. But what exactly does this rating mean? And was the decision made too slowly?
The Economy, Trade and Industry Ministry's Nuclear and Industrial Safety Agency raised its provisional evaluation of the seriousness of the accident to the maximum of Level 7 in the International Nuclear Event Scale (INES) because of the large quantity of radioactive substances that have been discharged from the plant's damaged reactors.
INES is designed to show how serious a nuclear accident is in an easily understandable way.
The scale was introduced in 1992 by the International Atomic Energy Agency and the Organization for Economic Cooperation and Development in the wake of the 1979 accident at the Three Mile Island nuclear plant and the 1986 Chernobyl disaster.
The scale is from zero to seven and takes into account three factors:
-- Degree of damage to functions that contain radioactive material.
-- Effects inside nuclear facilities, such as workers exposed to radiation.
-- Amount of radioactive material discharged into the atmosphere.
In accidents Level 5 or higher, the amount of radioactive material released plays a major role in the evaluation process. In a Level 7 accident, the quantity is at least several tens of thousands of terabecquerels.
The IAEA defines Level 7 as a "major accident" that is a "major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures."
Level 6, classified as a "serious accident," involves a "significant release of radioactive material likely to require implementation of planned countermeasures." Level 5 is an accident with wide consequences and is a "limited release of radioactive material likely to require implementation of some planned countermeasures" with "several deaths from radiation."
The seriousness, therefore, of a Level 7 accident is incredibly high.
The nuclear safety agency said the amount of radioactive material released from the Fukushima plant is about 10 percent of that discharged during the Chernobyl accident in the former Soviet Union, which is the only other nuclear accident to be rated Level 7.
But the quantity of radiation released in the Chernobyl accident took place in the 10 days it took for the radiation leak to be contained.
According to the Cabinet Office's Nuclear Safety Commission, about one terabecquerel per hour of radiation is currently being discharged into the air. If this situation continues for months, thousands of terabecquerels will be released, putting the Fukushima crisis on par with the world's only other major nuclear accident.
Junichi Matsumoto, acting head of Tokyo Electric Power Co.'s Nuclear Power & Plant Siting Division, acknowledged the seriousness of the Fukushima accident at a press conference Tuesday. "Although the details of the [Chernobyl and Fukushima] accidents are different, from the standpoint of how much radiation has been released, [Fukushima] is equal to or more serious than Chernobyl."
Taichi Maki, guest professor of climatic environmental studies at the University of Tsukuba, said, "It's significant the discharge is still going on. As long as the reactors are unstable, we have to worry about an increase in the quantity of radiation released. I assume the increase to Level 7 took that into consideration."
The nuclear safety agency and the Nuclear Safety Commission on Tuesday announced separately their calculations of how much radioactive material has been released from the Fukushima plant.
The commission, which is in charge of measuring radiation, made its calculations based on air measurements taken at 33 locations near the plant and data from the System for Prediction of Environmental Emergency Dose Information, which forecasts the spread of radioactive material. The commission concluded the total amount released was 630,000 terabecquerels of iodine-131 and cesium-137, which was converted into iodine-131 to make the calculations.
The agency, which monitors nuclear reactors, calculated the total quantity of radioactive material that was in the Nos. 1-3 reactors when the crisis began and how much leaked when steam in the containment vessels was released into the air. The agency concluded that 370,000 terabecquerels of radioactive iodine and cesium have been released.
According to TEPCO, at the time of the March 11 earthquake, 660 million terabecquerels of radioactive material was in the Nos. 1-4 reactors.
Comparing this figure with the calculation made by the nuclear safety commission and agency, about one-500th of the reactors' radioactive material has been released. This means most of the radioactive material likely is still in the reactors.
But where did the discharged radioactive substances go?
Atsushi Kasai, former senior official of the Japan Atomic Energy Research Institute, said the material has three major destinations--air, soil and seawater.
Of the radioactive material discharged into the atmosphere, including the large quantity released at the beginning of the accident, Kasai said more than half was probably still floating around in the air.
"Though these substances don't pose a hazard to human health in the short term, if radioactive material keeps being discharged, the likelihood of it entering people's bodies through the food chain will increase," Kasai said.
===
Was the nuclear crisis deliberately downplayed?
The government may have been trying to downplay the crisis at the Fukushima No. 1 nuclear power plant by setting its initial severity rating at Level 4 on an international scale, according to specialists.
The initial assessment was made immediately after the emergency erupted on March 12. A week later, the rating was raised to Level 5--and eventually to Level 7 on Tuesday, more than 20 days after the second assessment.
According to the Cabinet Office's Nuclear Safety Commission (NSC), most of the radioactive substances released from the nuclear complex had escaped by around March 15 after a series of hydrogen explosions and fires at the Nos. 1-4 reactors.
The amount of radioactive materials being emitted into the air skyrocketed on March 15 and 16. The NSC believes the increase was due to a massive discharge of radioactivity after the pressure suppression chamber at the No. 2 reactor was damaged.
In mid-March, the French Nuclear Safety Authority rated the Fukushima crisis as Level 6, while the U.S.-based Institute for Science and International Security (ISIS) said it was Level 6 or 7. But the Nuclear and Industrial Safety Agency left its rating unchanged, saying, "The crisis will not harm people's health."
But the agency hiked the crisis to Level 5 on March 18, seeming to cave to international opinion. According to agency spokesman Hidehiko Nishiyama, "It was difficult to make an evaluation because the pressure and temperature [in the reactors] was changing drastically."
Up until Tuesday, Nishiyama insisted it was "too early to raise it to Level 6."
The agency announced radiation forecasts by the System for Prediction of Environmental Emergency Dose Information (SPEEDI) only once on March 23. These results serve as the basis for severity assessments. The data showed 30,000 to 1,100,000 terabecquerels of radiation were emitted over the 12 days immediately following the disaster.
In a press conference Tuesday, NSC member Seiji Shiroya distanced himself from the decision to raise the severity level. "I thought it might've been a Level 7 at the time, but it's the agency that makes the call," he said.
Hirotada Hirose, a disaster expert and former professor at Tokyo Woman's Christian University, said, "I wonder if the government treated the [nuclear crisis] as a political matter just to try to prevent causing panic and further problems. It's possible political considerations drove them to downplay the situation in the early stages."
"The government might've wanted to ease people into the harshness of the reality. But if reassuring information is the main priority, people won't be able to properly prepare for a disaster and distrust in the government will grow," he said.
(Apr. 14, 2011)
The government upgraded the severity of the crisis at the Fukushima No. 1 nuclear power plant to Level 7. But what exactly does this rating mean? And was the decision made too slowly?
The Economy, Trade and Industry Ministry's Nuclear and Industrial Safety Agency raised its provisional evaluation of the seriousness of the accident to the maximum of Level 7 in the International Nuclear Event Scale (INES) because of the large quantity of radioactive substances that have been discharged from the plant's damaged reactors.
INES is designed to show how serious a nuclear accident is in an easily understandable way.
The scale was introduced in 1992 by the International Atomic Energy Agency and the Organization for Economic Cooperation and Development in the wake of the 1979 accident at the Three Mile Island nuclear plant and the 1986 Chernobyl disaster.
The scale is from zero to seven and takes into account three factors:
-- Degree of damage to functions that contain radioactive material.
-- Effects inside nuclear facilities, such as workers exposed to radiation.
-- Amount of radioactive material discharged into the atmosphere.
In accidents Level 5 or higher, the amount of radioactive material released plays a major role in the evaluation process. In a Level 7 accident, the quantity is at least several tens of thousands of terabecquerels.
The IAEA defines Level 7 as a "major accident" that is a "major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures."
Level 6, classified as a "serious accident," involves a "significant release of radioactive material likely to require implementation of planned countermeasures." Level 5 is an accident with wide consequences and is a "limited release of radioactive material likely to require implementation of some planned countermeasures" with "several deaths from radiation."
The seriousness, therefore, of a Level 7 accident is incredibly high.
The nuclear safety agency said the amount of radioactive material released from the Fukushima plant is about 10 percent of that discharged during the Chernobyl accident in the former Soviet Union, which is the only other nuclear accident to be rated Level 7.
But the quantity of radiation released in the Chernobyl accident took place in the 10 days it took for the radiation leak to be contained.
According to the Cabinet Office's Nuclear Safety Commission, about one terabecquerel per hour of radiation is currently being discharged into the air. If this situation continues for months, thousands of terabecquerels will be released, putting the Fukushima crisis on par with the world's only other major nuclear accident.
Junichi Matsumoto, acting head of Tokyo Electric Power Co.'s Nuclear Power & Plant Siting Division, acknowledged the seriousness of the Fukushima accident at a press conference Tuesday. "Although the details of the [Chernobyl and Fukushima] accidents are different, from the standpoint of how much radiation has been released, [Fukushima] is equal to or more serious than Chernobyl."
Taichi Maki, guest professor of climatic environmental studies at the University of Tsukuba, said, "It's significant the discharge is still going on. As long as the reactors are unstable, we have to worry about an increase in the quantity of radiation released. I assume the increase to Level 7 took that into consideration."
The nuclear safety agency and the Nuclear Safety Commission on Tuesday announced separately their calculations of how much radioactive material has been released from the Fukushima plant.
The commission, which is in charge of measuring radiation, made its calculations based on air measurements taken at 33 locations near the plant and data from the System for Prediction of Environmental Emergency Dose Information, which forecasts the spread of radioactive material. The commission concluded the total amount released was 630,000 terabecquerels of iodine-131 and cesium-137, which was converted into iodine-131 to make the calculations.
The agency, which monitors nuclear reactors, calculated the total quantity of radioactive material that was in the Nos. 1-3 reactors when the crisis began and how much leaked when steam in the containment vessels was released into the air. The agency concluded that 370,000 terabecquerels of radioactive iodine and cesium have been released.
According to TEPCO, at the time of the March 11 earthquake, 660 million terabecquerels of radioactive material was in the Nos. 1-4 reactors.
Comparing this figure with the calculation made by the nuclear safety commission and agency, about one-500th of the reactors' radioactive material has been released. This means most of the radioactive material likely is still in the reactors.
But where did the discharged radioactive substances go?
Atsushi Kasai, former senior official of the Japan Atomic Energy Research Institute, said the material has three major destinations--air, soil and seawater.
Of the radioactive material discharged into the atmosphere, including the large quantity released at the beginning of the accident, Kasai said more than half was probably still floating around in the air.
"Though these substances don't pose a hazard to human health in the short term, if radioactive material keeps being discharged, the likelihood of it entering people's bodies through the food chain will increase," Kasai said.
===
Was the nuclear crisis deliberately downplayed?
The government may have been trying to downplay the crisis at the Fukushima No. 1 nuclear power plant by setting its initial severity rating at Level 4 on an international scale, according to specialists.
The initial assessment was made immediately after the emergency erupted on March 12. A week later, the rating was raised to Level 5--and eventually to Level 7 on Tuesday, more than 20 days after the second assessment.
According to the Cabinet Office's Nuclear Safety Commission (NSC), most of the radioactive substances released from the nuclear complex had escaped by around March 15 after a series of hydrogen explosions and fires at the Nos. 1-4 reactors.
The amount of radioactive materials being emitted into the air skyrocketed on March 15 and 16. The NSC believes the increase was due to a massive discharge of radioactivity after the pressure suppression chamber at the No. 2 reactor was damaged.
In mid-March, the French Nuclear Safety Authority rated the Fukushima crisis as Level 6, while the U.S.-based Institute for Science and International Security (ISIS) said it was Level 6 or 7. But the Nuclear and Industrial Safety Agency left its rating unchanged, saying, "The crisis will not harm people's health."
But the agency hiked the crisis to Level 5 on March 18, seeming to cave to international opinion. According to agency spokesman Hidehiko Nishiyama, "It was difficult to make an evaluation because the pressure and temperature [in the reactors] was changing drastically."
Up until Tuesday, Nishiyama insisted it was "too early to raise it to Level 6."
The agency announced radiation forecasts by the System for Prediction of Environmental Emergency Dose Information (SPEEDI) only once on March 23. These results serve as the basis for severity assessments. The data showed 30,000 to 1,100,000 terabecquerels of radiation were emitted over the 12 days immediately following the disaster.
In a press conference Tuesday, NSC member Seiji Shiroya distanced himself from the decision to raise the severity level. "I thought it might've been a Level 7 at the time, but it's the agency that makes the call," he said.
Hirotada Hirose, a disaster expert and former professor at Tokyo Woman's Christian University, said, "I wonder if the government treated the [nuclear crisis] as a political matter just to try to prevent causing panic and further problems. It's possible political considerations drove them to downplay the situation in the early stages."
"The government might've wanted to ease people into the harshness of the reality. But if reassuring information is the main priority, people won't be able to properly prepare for a disaster and distrust in the government will grow," he said.
(Apr. 14, 2011)
14/04 ４号機プール「燃料損傷は部分的」 水分析結果を公表
2011年4月14日0時58分
東京電力は１３日、福島第一原発４号機の核燃料貯蔵プールから初めて採取した水の分析結果を公表した。放射性物質の濃度は運転時の原子炉内の水より高いが、燃料は溶融を疑わせるほどではなく、破損があっても部分的と東電はみている。また、プールの水位は燃料棒の上端から約２メートル上の位置まであって燃料は水につかっており、１３日未明からの放水で水位はさらに１メートルほど上がったという。
４号機は地震時に定期検査中で炉内の燃料がすべてプールに移されていた。爆発で建屋が壊れたことから、燃料が大きく損傷した可能性が指摘されていた。 東電は１２日、コンクリートポンプ車で４号機の燃料貯蔵プールの水約４００ｃｃを採取して放射能を分析した。ヨウ素１３１は１ｃｃあたり２２０ベクレル、セシウム１３４は８８ベクレル、セシウム１３７は９３ベクレル含まれていた。いずれも通常は検出限界以下か１ベクレル未満という。
ただ、数百万単位の値が出ているタービン建屋などの汚染水に比べれば低く、東電は「燃料の一部は破損しているが、大部分は健全」とみている。爆発による落下物で燃料が損傷したり、周辺に漂っていた放射性物質が取り込まれたりした可能性もあるという。
一方、２号機タービン建屋の外にある坑道にたまった汚染水を建屋内の復水器に移し替える作業は１３日午後、合計６６０トンを移し、予定の作業を終えた。坑道のたて坑の水位は午後６時現在で６センチ下がった状態になった。タービン建屋地下にたまった水の水位も下がり、両者がつながっている可能性が高まった。
坑道には６千トン近い汚染水があるとみられ、残りを復水器に移すか、受け入れに向け点検が進む集中廃棄物処理施設（容量約３万トン）に移すかを検討する。
また、東電は１～３号機の事故から１３日まで炉内に注入した水の総量を明らかにした。１号機が５７２４トン、２号機が１万２８４２トン、３号機が８１６９トン。原子炉圧力容器に入る量は２５０～３００トンで、多くが水蒸気になったり格納容器の下部にたまったりし、容器外に漏れ出した分もあるとみられる。
東京電力は１３日、福島第一原発４号機の核燃料貯蔵プールから初めて採取した水の分析結果を公表した。放射性物質の濃度は運転時の原子炉内の水より高いが、燃料は溶融を疑わせるほどではなく、破損があっても部分的と東電はみている。また、プールの水位は燃料棒の上端から約２メートル上の位置まであって燃料は水につかっており、１３日未明からの放水で水位はさらに１メートルほど上がったという。
４号機は地震時に定期検査中で炉内の燃料がすべてプールに移されていた。爆発で建屋が壊れたことから、燃料が大きく損傷した可能性が指摘されていた。 東電は１２日、コンクリートポンプ車で４号機の燃料貯蔵プールの水約４００ｃｃを採取して放射能を分析した。ヨウ素１３１は１ｃｃあたり２２０ベクレル、セシウム１３４は８８ベクレル、セシウム１３７は９３ベクレル含まれていた。いずれも通常は検出限界以下か１ベクレル未満という。
ただ、数百万単位の値が出ているタービン建屋などの汚染水に比べれば低く、東電は「燃料の一部は破損しているが、大部分は健全」とみている。爆発による落下物で燃料が損傷したり、周辺に漂っていた放射性物質が取り込まれたりした可能性もあるという。
一方、２号機タービン建屋の外にある坑道にたまった汚染水を建屋内の復水器に移し替える作業は１３日午後、合計６６０トンを移し、予定の作業を終えた。坑道のたて坑の水位は午後６時現在で６センチ下がった状態になった。タービン建屋地下にたまった水の水位も下がり、両者がつながっている可能性が高まった。
坑道には６千トン近い汚染水があるとみられ、残りを復水器に移すか、受け入れに向け点検が進む集中廃棄物処理施設（容量約３万トン）に移すかを検討する。
また、東電は１～３号機の事故から１３日まで炉内に注入した水の総量を明らかにした。１号機が５７２４トン、２号機が１万２８４２トン、３号機が８１６９トン。原子炉圧力容器に入る量は２５０～３００トンで、多くが水蒸気になったり格納容器の下部にたまったりし、容器外に漏れ出した分もあるとみられる。
Wednesday, April 13, 2011
13/04 N-crisis upgraded to '7' / Fukushima accident boosted to top level of global scale
The Yomiuri Shimbun
The Nuclear and Industrial Safety Agency raised the provisional severity level of the crisis at the Fukushima No. 1 nuclear power plant on Tuesday to the worst rating of seven on an international scale, equivalent to that of the 1986 Chernobyl crisis.
The agency had previously rated the accident as a five.
The agency, under the Economy, Trade and Industry Ministry, said the amount of radioactive material, calculated based on the reactors' estimated condition, reached "more than several tens of thousands of terabecquerels."
A terabecquerel equals 1 trillion becquerels.
The level is defined as a "major accident" under the International Nuclear and Radiological Event Scale (INES), or the highest level on its scale from zero to seven.
According to the agency, the total amount of iodine-131 and cesium-137 emitted between March 11 and at 11 a.m. Tuesday reached 370,000 terabecquerels according to the reactors' estimated condition. Within this assessment, cesium levels were converted to their equivalent in iodine-131 levels.
Cabinet Office's Nuclear Safety Commission, meanwhile, announced Tuesday that the total amount of iodine and cesium emitted between March 11 and April 5 was 630,000 terabecquerels (again, with cesium levels converted to the iodine equivalent), calculated according to the amount of radiation observed around the facility.
"The total amount of radioactive materials emitted thus far is equal to about 10 percent of that released in the Chernobyl accident. The amount of radiation exposure is small," said Agency spokesman Hidehiko Nishiyama.
According to the commission, the current volume of radioactivity being emitted is about one-ten thousandth of that monitored at its peak.
The agency decided to raise the INES level not only because of the calculated radiative material released into the atmosphere but also because of the widespread ramifications of the accident.
===
Effect on health, environment
By Kyoichi Sasazawa / Yomiuri Shimbun Staff Writer
For an incident to be rated on the International Nuclear and Radiological Event Scale (INES), it is assessed by the nuclear supervisory authorities in the nation where it occurred and is then reported to the International Atomic Energy Agency (IAEA).
In Japan, the Nuclear and Industrial Safety Agency is in charge of the assessment.
Last month, the nuclear safety agency provisionally rated the Fukushima crisis at level 5. However, domestic and international experts argued the provisional level should be 6 or higher based on the facts that high levels of radiation were measured around the facility and significant amounts of radioactive material had escaped.
In the Chernobyl crisis, about 5.2 million terabecquerels of radioactive material was emitted into the air in the space of 10 days.
The amount of radioactive material aerially emitted from the Fukushima No. 1 plant right after the accident was about 10 percent of that of Chernobyl. But the scale of the Fukushima accident still stands out among other nuclear power accidents that have happened around the world.
Also, a large volume of radioactive material has been dumped into the sea in the current incident. Since work to bring the situation under control has run into one complication after another, an end to the crisis could be months or even a year away, with the amount of nuclear leakage increasing.
The assessed INES level reflects negative impacts on health and the environment. It will be important to carefully monitor the incidence of leukemia and cancer as well as soil contamination. The crisis also could strongly affect the international image of Japan.
(Apr. 13, 2011)
The Nuclear and Industrial Safety Agency raised the provisional severity level of the crisis at the Fukushima No. 1 nuclear power plant on Tuesday to the worst rating of seven on an international scale, equivalent to that of the 1986 Chernobyl crisis.
The agency had previously rated the accident as a five.
The agency, under the Economy, Trade and Industry Ministry, said the amount of radioactive material, calculated based on the reactors' estimated condition, reached "more than several tens of thousands of terabecquerels."
A terabecquerel equals 1 trillion becquerels.
The level is defined as a "major accident" under the International Nuclear and Radiological Event Scale (INES), or the highest level on its scale from zero to seven.
According to the agency, the total amount of iodine-131 and cesium-137 emitted between March 11 and at 11 a.m. Tuesday reached 370,000 terabecquerels according to the reactors' estimated condition. Within this assessment, cesium levels were converted to their equivalent in iodine-131 levels.
Cabinet Office's Nuclear Safety Commission, meanwhile, announced Tuesday that the total amount of iodine and cesium emitted between March 11 and April 5 was 630,000 terabecquerels (again, with cesium levels converted to the iodine equivalent), calculated according to the amount of radiation observed around the facility.
"The total amount of radioactive materials emitted thus far is equal to about 10 percent of that released in the Chernobyl accident. The amount of radiation exposure is small," said Agency spokesman Hidehiko Nishiyama.
According to the commission, the current volume of radioactivity being emitted is about one-ten thousandth of that monitored at its peak.
The agency decided to raise the INES level not only because of the calculated radiative material released into the atmosphere but also because of the widespread ramifications of the accident.
===
Effect on health, environment
By Kyoichi Sasazawa / Yomiuri Shimbun Staff Writer
For an incident to be rated on the International Nuclear and Radiological Event Scale (INES), it is assessed by the nuclear supervisory authorities in the nation where it occurred and is then reported to the International Atomic Energy Agency (IAEA).
In Japan, the Nuclear and Industrial Safety Agency is in charge of the assessment.
Last month, the nuclear safety agency provisionally rated the Fukushima crisis at level 5. However, domestic and international experts argued the provisional level should be 6 or higher based on the facts that high levels of radiation were measured around the facility and significant amounts of radioactive material had escaped.
In the Chernobyl crisis, about 5.2 million terabecquerels of radioactive material was emitted into the air in the space of 10 days.
The amount of radioactive material aerially emitted from the Fukushima No. 1 plant right after the accident was about 10 percent of that of Chernobyl. But the scale of the Fukushima accident still stands out among other nuclear power accidents that have happened around the world.
Also, a large volume of radioactive material has been dumped into the sea in the current incident. Since work to bring the situation under control has run into one complication after another, an end to the crisis could be months or even a year away, with the amount of nuclear leakage increasing.
The assessed INES level reflects negative impacts on health and the environment. It will be important to carefully monitor the incidence of leukemia and cancer as well as soil contamination. The crisis also could strongly affect the international image of Japan.
(Apr. 13, 2011)
13/04 Fukushima accident raised to same level as Chernobyl
2011/04/13
An aerial view of the Fukushima No. 1 nuclear power plant (Provided by Air Photo Service)
Editor's note: We will update our earthquake news as frequently as possible on AJW's Facebook page: http://www.facebook.com/AJW.Asahi. Please check the latest developments in this disaster. From Toshio Jo, managing editor, International Division, The Asahi Shimbun.
* * *
Japan raised the severity rating of the crisis at the Fukushima No. 1 nuclear power plant on Tuesday to the same level as the Chernobyl disaster, weeks after it was criticized for downplaying the seriousness.
Pointing to the large amount and wide dispersion of radioactive material from the stricken facility, the Nuclear and Industrial Safety Agency (NISA) and the Nuclear Safety Commission of Japan raised their accident assessment to level 7, defined as a "major accident" on the International Nuclear and Radiological Event Scale.
While the quantity of radioactive material leaked so far from Fukushima is only about 10 percent of that released by the 1986 Chernobyl fire, officials are concerned that multiple reactors are still out of control.
Junichi Matsumoto, an official with the plant's operator Tokyo Electric Power Co., said: "Discharge (of radioactive materials) has not been completely stopped and there are concerns that the amount released could equal or exceed that for Chernobyl."
Immediately after the March 11 earthquake, NISA rated the situation at Fukushima as a level 4 accident, meaning that radioactive materials had been released outside of the Fukushima nuclear plant.
On March 18, the assessment was raised to level 5, the same as the 1979 accident at the Three Mile Island nuclear plant in the United States.
One standard used for a level 5 accident is the emission of radiation levels equivalent to several hundreds to several thousands of terabecquerels of radioactive iodine. One terabecquerel is a trillion becquerels.
Subsequent estimates of the total amount of radioactive materials released had levels of iodine between 370,000 and 630,000 terabecquerels. That is above the standard of several tens of thousands of terabecquerels that is used to define a level 7 accident on the International Nuclear and Radiological Event Scale.
The explosions and fire at the Chernobyl plant spread about 5.2 million terabecquerels across several countries.
Keiji Miyazaki, professor emeritus of nuclear reactor engineering at Osaka University, said: "At Chernobyl, (radiation) was spread out over a wide area due to an updraft caused by the fire and high temperatures. While Fukushima has not reached that level, a major contributing factor is the damage to fuel rods at several reactors and in storage pools for spent fuel rods."
At Fukushima, radioactive material has been released into the environment in a series of separate incidents. Radioactive steam was initially deliberately vented into the atmosphere to reduce pressure within the core containment vessels. Subsequent hydrogen explosions at the buildings housing the No. 1 and No. 3 reactors blew away part of the ceilings and dispersed radiation.
An explosion near the suppression pool for the No. 2 reactor and a fire at a storage pool for spent fuel rods at the No. 4 reactor are also believed to have released radioactive material.
The absence of any revision in the accident assessment after March 18 led to criticism abroad that the Japanese government was underestimating the severity of the situation.
The new assessment has been reported to the International Atomic Energy Agency, but it may not be enough to eliminate international concern that the Japanese government has not released all relevant information.
Keiji Kobayashi, a former lecturer of nuclear engineering at Kyoto University's Research Reactor Institute, said: "From the time when a dry boil at the reactor core and hydrogen explosions occurred, it became difficult to stop the discharge of radiation. It was clear the accident was more than a level 6. There are also elements not found in the Chernobyl accident such as the release of radioactive materials into the ocean."
An aerial view of the Fukushima No. 1 nuclear power plant (Provided by Air Photo Service)
Editor's note: We will update our earthquake news as frequently as possible on AJW's Facebook page: http://www.facebook.com/AJW.Asahi. Please check the latest developments in this disaster. From Toshio Jo, managing editor, International Division, The Asahi Shimbun.
* * *
Japan raised the severity rating of the crisis at the Fukushima No. 1 nuclear power plant on Tuesday to the same level as the Chernobyl disaster, weeks after it was criticized for downplaying the seriousness.
Pointing to the large amount and wide dispersion of radioactive material from the stricken facility, the Nuclear and Industrial Safety Agency (NISA) and the Nuclear Safety Commission of Japan raised their accident assessment to level 7, defined as a "major accident" on the International Nuclear and Radiological Event Scale.
While the quantity of radioactive material leaked so far from Fukushima is only about 10 percent of that released by the 1986 Chernobyl fire, officials are concerned that multiple reactors are still out of control.
Junichi Matsumoto, an official with the plant's operator Tokyo Electric Power Co., said: "Discharge (of radioactive materials) has not been completely stopped and there are concerns that the amount released could equal or exceed that for Chernobyl."
Immediately after the March 11 earthquake, NISA rated the situation at Fukushima as a level 4 accident, meaning that radioactive materials had been released outside of the Fukushima nuclear plant.
On March 18, the assessment was raised to level 5, the same as the 1979 accident at the Three Mile Island nuclear plant in the United States.
One standard used for a level 5 accident is the emission of radiation levels equivalent to several hundreds to several thousands of terabecquerels of radioactive iodine. One terabecquerel is a trillion becquerels.
Subsequent estimates of the total amount of radioactive materials released had levels of iodine between 370,000 and 630,000 terabecquerels. That is above the standard of several tens of thousands of terabecquerels that is used to define a level 7 accident on the International Nuclear and Radiological Event Scale.
The explosions and fire at the Chernobyl plant spread about 5.2 million terabecquerels across several countries.
Keiji Miyazaki, professor emeritus of nuclear reactor engineering at Osaka University, said: "At Chernobyl, (radiation) was spread out over a wide area due to an updraft caused by the fire and high temperatures. While Fukushima has not reached that level, a major contributing factor is the damage to fuel rods at several reactors and in storage pools for spent fuel rods."
At Fukushima, radioactive material has been released into the environment in a series of separate incidents. Radioactive steam was initially deliberately vented into the atmosphere to reduce pressure within the core containment vessels. Subsequent hydrogen explosions at the buildings housing the No. 1 and No. 3 reactors blew away part of the ceilings and dispersed radiation.
An explosion near the suppression pool for the No. 2 reactor and a fire at a storage pool for spent fuel rods at the No. 4 reactor are also believed to have released radioactive material.
The absence of any revision in the accident assessment after March 18 led to criticism abroad that the Japanese government was underestimating the severity of the situation.
The new assessment has been reported to the International Atomic Energy Agency, but it may not be enough to eliminate international concern that the Japanese government has not released all relevant information.
Keiji Kobayashi, a former lecturer of nuclear engineering at Kyoto University's Research Reactor Institute, said: "From the time when a dry boil at the reactor core and hydrogen explosions occurred, it became difficult to stop the discharge of radiation. It was clear the accident was more than a level 6. There are also elements not found in the Chernobyl accident such as the release of radioactive materials into the ocean."
13/04 N-crisis upgraded to '7' / Fukushima accident boosted to top level of global scale
The Yomiuri Shimbun
The Nuclear and Industrial Safety Agency raised the provisional severity level of the crisis at the Fukushima No. 1 nuclear power plant on Tuesday to the worst rating of seven on an international scale, equivalent to that of the 1986 Chernobyl crisis.
The agency had previously rated the accident as a five.
The agency, under the Economy, Trade and Industry Ministry, said the amount of radioactive material, calculated based on the reactors' estimated condition, reached "more than several tens of thousands of terabecquerels."
A terabecquerel equals 1 trillion becquerels.
The level is defined as a "major accident" under the International Nuclear and Radiological Event Scale (INES), or the highest level on its scale from zero to seven.
According to the agency, the total amount of iodine-131 and cesium-137 emitted between March 11 and at 11 a.m. Tuesday reached 370,000 terabecquerels according to the reactors' estimated condition. Within this assessment, cesium levels were converted to their equivalent in iodine-131 levels.
Cabinet Office's Nuclear Safety Commission, meanwhile, announced Tuesday that the total amount of iodine and cesium emitted between March 11 and April 5 was 630,000 terabecquerels (again, with cesium levels converted to the iodine equivalent), calculated according to the amount of radiation observed around the facility.
"The total amount of radioactive materials emitted thus far is equal to about 10 percent of that released in the Chernobyl accident. The amount of radiation exposure is small," said Agency spokesman Hidehiko Nishiyama.
According to the commission, the current volume of radioactivity being emitted is about one-ten thousandth of that monitored at its peak.
The agency decided to raise the INES level not only because of the calculated radiative material released into the atmosphere but also because of the widespread ramifications of the accident.
===
Effect on health, environment
By Kyoichi Sasazawa / Yomiuri Shimbun Staff Writer
For an incident to be rated on the International Nuclear and Radiological Event Scale (INES), it is assessed by the nuclear supervisory authorities in the nation where it occurred and is then reported to the International Atomic Energy Agency (IAEA).
In Japan, the Nuclear and Industrial Safety Agency is in charge of the assessment.
Last month, the nuclear safety agency provisionally rated the Fukushima crisis at level 5. However, domestic and international experts argued the provisional level should be 6 or higher based on the facts that high levels of radiation were measured around the facility and significant amounts of radioactive material had escaped.
In the Chernobyl crisis, about 5.2 million terabecquerels of radioactive material was emitted into the air in the space of 10 days.
The amount of radioactive material aerially emitted from the Fukushima No. 1 plant right after the accident was about 10 percent of that of Chernobyl. But the scale of the Fukushima accident still stands out among other nuclear power accidents that have happened around the world.
Also, a large volume of radioactive material has been dumped into the sea in the current incident. Since work to bring the situation under control has run into one complication after another, an end to the crisis could be months or even a year away, with the amount of nuclear leakage increasing.
The assessed INES level reflects negative impacts on health and the environment. It will be important to carefully monitor the incidence of leukemia and cancer as well as soil contamination. The crisis also could strongly affect the international image of Japan.
(Apr. 13, 2011)
The Nuclear and Industrial Safety Agency raised the provisional severity level of the crisis at the Fukushima No. 1 nuclear power plant on Tuesday to the worst rating of seven on an international scale, equivalent to that of the 1986 Chernobyl crisis.
The agency had previously rated the accident as a five.
The agency, under the Economy, Trade and Industry Ministry, said the amount of radioactive material, calculated based on the reactors' estimated condition, reached "more than several tens of thousands of terabecquerels."
A terabecquerel equals 1 trillion becquerels.
The level is defined as a "major accident" under the International Nuclear and Radiological Event Scale (INES), or the highest level on its scale from zero to seven.
According to the agency, the total amount of iodine-131 and cesium-137 emitted between March 11 and at 11 a.m. Tuesday reached 370,000 terabecquerels according to the reactors' estimated condition. Within this assessment, cesium levels were converted to their equivalent in iodine-131 levels.
Cabinet Office's Nuclear Safety Commission, meanwhile, announced Tuesday that the total amount of iodine and cesium emitted between March 11 and April 5 was 630,000 terabecquerels (again, with cesium levels converted to the iodine equivalent), calculated according to the amount of radiation observed around the facility.
"The total amount of radioactive materials emitted thus far is equal to about 10 percent of that released in the Chernobyl accident. The amount of radiation exposure is small," said Agency spokesman Hidehiko Nishiyama.
According to the commission, the current volume of radioactivity being emitted is about one-ten thousandth of that monitored at its peak.
The agency decided to raise the INES level not only because of the calculated radiative material released into the atmosphere but also because of the widespread ramifications of the accident.
===
Effect on health, environment
By Kyoichi Sasazawa / Yomiuri Shimbun Staff Writer
For an incident to be rated on the International Nuclear and Radiological Event Scale (INES), it is assessed by the nuclear supervisory authorities in the nation where it occurred and is then reported to the International Atomic Energy Agency (IAEA).
In Japan, the Nuclear and Industrial Safety Agency is in charge of the assessment.
Last month, the nuclear safety agency provisionally rated the Fukushima crisis at level 5. However, domestic and international experts argued the provisional level should be 6 or higher based on the facts that high levels of radiation were measured around the facility and significant amounts of radioactive material had escaped.
In the Chernobyl crisis, about 5.2 million terabecquerels of radioactive material was emitted into the air in the space of 10 days.
The amount of radioactive material aerially emitted from the Fukushima No. 1 plant right after the accident was about 10 percent of that of Chernobyl. But the scale of the Fukushima accident still stands out among other nuclear power accidents that have happened around the world.
Also, a large volume of radioactive material has been dumped into the sea in the current incident. Since work to bring the situation under control has run into one complication after another, an end to the crisis could be months or even a year away, with the amount of nuclear leakage increasing.
The assessed INES level reflects negative impacts on health and the environment. It will be important to carefully monitor the incidence of leukemia and cancer as well as soil contamination. The crisis also could strongly affect the international image of Japan.
(Apr. 13, 2011)
Sunday, April 10, 2011
10/04 Excessive radioactive cesium found in fish sampled off Fukushima
TOKYO (Kyodo) -- Radioactive cesium above the legal limit for consumption was detected Saturday in young sand lance caught off Fukushima Prefecture, as the prefecture took samples amid a voluntary ban on fishing there in the wake of the ongoing nuclear crisis.
One of the four sample fish had a level of cesium of 570 becquerels per kilogram on Thursday about 1 kilometer off the city of Iwaki, and the other three measured 480 to 500 becquerels. The limit is 500 becquerels under the Food Sanitation Law.
The samples were taken after the species was found contaminated off Ibaraki Prefecture, although fishermen have voluntarily refrained from fishing off Fukushima due to the crisis at the Fukushima Daiichi Nuclear Power Station.
Radioactive iodine measured 1,100 to 1,700 becquerels in the samples against the legal limit of 2,000 becquerels.
The move came as food makers and restaurant operators in Japan have increasingly begun to check levels of radioactive substances in food coming from the Kanto region, where Fukushima is not included.
A guild of tobacco growers in Fukushima said, meanwhile, it has decided not to plant leaf tobacco this year although the prefecture ranked seventh last year in output among Japan's 47 prefectures.
Agriculture, Forestry and Fisheries Minister Michihiko Kano visited the prefecture the same day to coordinate with local authorities to keep farmers from planting rice near the nuclear complex, saying he expects the size of the banned area to be decided on in about mid-April.
Up to 26 becquerels of iodine and 8 becquerels of cesium were found in two flatfish species caught Friday off the Ibaraki city of Hitachinaka, according to the latest test results released by Ibaraki Prefecture.
The radioactive levels were also below the limits or none in strawberries and other farm produce in Fukushima, while no levels were found in spinach and three other types of produce tested in Niigata Prefecture.
(Mainichi Japan) April 10, 2011
One of the four sample fish had a level of cesium of 570 becquerels per kilogram on Thursday about 1 kilometer off the city of Iwaki, and the other three measured 480 to 500 becquerels. The limit is 500 becquerels under the Food Sanitation Law.
The samples were taken after the species was found contaminated off Ibaraki Prefecture, although fishermen have voluntarily refrained from fishing off Fukushima due to the crisis at the Fukushima Daiichi Nuclear Power Station.
Radioactive iodine measured 1,100 to 1,700 becquerels in the samples against the legal limit of 2,000 becquerels.
The move came as food makers and restaurant operators in Japan have increasingly begun to check levels of radioactive substances in food coming from the Kanto region, where Fukushima is not included.
A guild of tobacco growers in Fukushima said, meanwhile, it has decided not to plant leaf tobacco this year although the prefecture ranked seventh last year in output among Japan's 47 prefectures.
Agriculture, Forestry and Fisheries Minister Michihiko Kano visited the prefecture the same day to coordinate with local authorities to keep farmers from planting rice near the nuclear complex, saying he expects the size of the banned area to be decided on in about mid-April.
Up to 26 becquerels of iodine and 8 becquerels of cesium were found in two flatfish species caught Friday off the Ibaraki city of Hitachinaka, according to the latest test results released by Ibaraki Prefecture.
The radioactive levels were also below the limits or none in strawberries and other farm produce in Fukushima, while no levels were found in spinach and three other types of produce tested in Niigata Prefecture.
(Mainichi Japan) April 10, 2011
万能薬ではないヨウ素剤、服用タイミングも重要
安定ヨウ素剤の服用は、避難時に放射性物質にさらされる恐れがある住民を守る予防策だ。
ヨウ素は甲状腺ホルモンを合成するのに必須の元素で、甲状腺はふだんから体内に取り込んだヨウ素を蓄積している。このため、原発から出た放射性ヨウ素が空気や食べ物などと一緒に体内に入ると、甲状腺内に蓄積して放射線を出し続け、がんになりやすい。
これを避けるため、放射線を出さないヨウ素を製剤化した安定ヨウ素剤を服用し、あらかじめ甲状腺を安定ヨウ素で満たしておく。その結果、放射性ヨウ素が体内に入り込んでも、甲状腺には蓄積せずに体外に排出されやすい。
服用の効果を上げるには、服用のタイミングが重要だ。服用後に効果が続く時間は約２４時間とされており、早くから服用しても効果はない。放射性ヨウ素が体内に取り込まれた後でも約８時間までなら、服用により甲状腺への取り込み量を４０％近く減らせる。
原子力安全委員会の指針では、服用対象者は４０歳未満。４０歳以上は
忘れてはいけないのは、安定ヨウ素剤は被曝の万能薬ではないことだ。セシウムなど、ヨウ素以外の放射性物質による体への影響は防げない。ヨウ素過敏症など、服用できない人もいる。吐き気や下痢などの副作用も報告されており、避難時に１回のみ服用することになっている。
ヨウ素の入ったうがい薬や消毒薬に予防効果があると誤解されているが、効果がないばかりか、飲むと体に有害な成分が含まれている恐れもある。ワカメや昆布にもヨウ素は含まれているが、含有量が一定ではなく、十分な効果は得られない。（吉田昌史、本間雅江）
（2011年3月22日 読売新聞）
原発キーワード 半減期
放射性物質は、原子を構成する陽子と中性子のバランスが不安定で、エネルギーを放出しながら、一定の割合で崩壊し、別の安定性の高い原子に変化していく。この際、放出されるのが放射線だ。
放射線を出す能力（放射能）は時間の経過とともに弱まっていき、この放射能が半分になるまでの期間のことを、半減期という。半減期は、放射性物質によって異なり、不安定なものほど多くの放射線を放出して崩壊が速く進むので短い。
福島第一原発の事故後、近隣地域の農産物から暫定規制値以上のレベルで検出された放射性ヨウ素１３１の半減期は８日、放射性セシウム１３７では３０年。ヨウ素よりもセシウムの方が土壌にも残りやすいことになる。長いものでは、プルトニウム２３９の２万４０００年、ウラン２３８の４５億年などがある。
（2011年3月24日 読売新聞）
放射線を出す能力（放射能）は時間の経過とともに弱まっていき、この放射能が半分になるまでの期間のことを、半減期という。半減期は、放射性物質によって異なり、不安定なものほど多くの放射線を放出して崩壊が速く進むので短い。
福島第一原発の事故後、近隣地域の農産物から暫定規制値以上のレベルで検出された放射性ヨウ素１３１の半減期は８日、放射性セシウム１３７では３０年。ヨウ素よりもセシウムの方が土壌にも残りやすいことになる。長いものでは、プルトニウム２３９の２万４０００年、ウラン２３８の４５億年などがある。
（2011年3月24日 読売新聞）
Sunday, April 3, 2011
01/04 As Fukushima fallout circles the globe, nuclear sleuths sift it for clues
By Brian Vastag, Friday, April 1, 11:50 AM
Three weeks into the nuclear crisis in Japan, minute traces of radioactive dust have circled the globe, even arriving in Maryland and Virginia.
Fallout from the Fukushima Daiichi nuclear plant has landed on 30 exquisitely sensitive detectors on desolate Arctic islands, on the tops of tall buildings and in other windy locales across the Northern Hemisphere, according to the Comprehensive Test Ban Treaty Organization, which maintains those sensors. Sniffing the air like silent sentinels, the 63 shack-like stations (with 17 more planned) are capturing tiny radioactive particles in filters much like those on a home furnace.
Analysis of that dust is a key step in an intricate process of nuclear sleuthing: The dust’s distinctive chemical signature can show scientists whether the particles blew into the air from a bomb, a damaged nuclear reactor or used uranium fuel. It can even point to the extent of damage suffered by a fission reactor. Tracing global wind patterns back then pinpoints where the emissions originated.
“It’s nuclear forensics,” said Kai Vetter, a professor of nuclear engineering at the University of California at Berkeley, who built his own radiation detector atop a campus building after the Fukushima crisis began.
“You can learn quite a lot from the pattern of radioactive isotopes,” said Hamish Robertson, a physicist at the University of Washington in Seattle.
In the United States, another network of more than 100 stations maintained by the Environmental Protection Agency is also gathering radioactivity from Japan. State health departments maintain their own monitoring systems, which is how Maryland detected tiny traces in the air and water March 24.
Super-sensitive detection
After the March 11 earthquake and tsunami damaged Fukushima, the global sensor network began to light up for the first time since nuclear detonations in North Korea in 2006 and 2009.
On March 14, a station on the Kamchatka Peninsula in Russia sniffed out unusual radioactive elements. That cloud then split, drifting southward and eastward, with one arm arriving two days later in Sacramento, and three days after that in Charlottesville. On March 20, the ultra-thin broth of radioactive particles blew over Iceland. And it reached all the way to Kuwait City on March 25, two weeks after the first emissions from Fukushima.
The reporting of even these minuscule amounts of unusual radiation has caused alarm, driving a run on potassium iodide pills and Geiger counters. But officials at the EPA and the Centers for Disease Control and Prevention and independent experts have repeatedly stressed that the amount of radioactivity detected outside Japan is far too low to affect human health.
Modern radiation detection systems are simply astoundingly sensitive, they explain, designed to pick up traces of nuclear explosions anywhere in the world. The detector atop the CTBTO’s headquarters in Vienna, Austria, still catches vestiges of the Chernobyl disaster that occurred 25 years ago, said Lassina Zerbo, director of the group’s international data center.
Vetter’s detector at Berkeley even catches radioactivity on the wind from treatments received by thyroid cancer patients passing by six stories below.
Taking radioactive fingerprints
Natural radiation — mostly from airborne radon — “drowns out” the radiation from Fukushima spotted in the United States, said Michael Miller, a University of Washington physicist who, along with Robertson, helped construct a radiation detector in a campus building’s air intake duct.
So a sensor that simply measured the total amount of radiation from airbone particles would be useless in nuclear forensics. Modern detectors do much more. They outline the dust’s distinctive radioactive fingerprint by measuring precise concentrations of five or more radioactive elements, or isotopes.
Each atom of these isotopes is unstable, shedding excess energy — via radiation — in a process called decay. By measuring the form and intensity of this energy, the radiation detectives can identify the isotopes in play and deduce from them what might have happened.
Radioactive iodine-131 and cesium-137 are key to this process. They don’t exist in nature, so their appearance signals a nuclear event — either a bomb or a reactor in trouble. Both can cause health problems in large amounts. But iodine-131 decays relatively rapidly: After eight days, half the original amount is gone. Its presence means that the event that created it occurred just weeks beforehand. Cesium-137 takes much longer to decay, with a half-life of 30 years. Traces of cesium-137 from Chernobyl still waft on Earth’s great jetstreams.
Clues in the air
It was detective work of this kind that alerted the world to the world’s worst nuclear disaster 25 years ago. In April 1986, nuclear power plant workers in Sweden detected a spike in iodine-131 and cesium-137, which — after a check of wind patterns — revealed the unfolding disaster at Chernobyl, which the Soviet Union had not disclosed.
Because both isotopes can come from a bomb or a reactor, nuclear sleuths also search for another isotope that originates only in reactors: cesium-134. It is produced during the slow-boil nuclear fission inside reactors, but not the flash-bang of a nuclear explosion. The ad-hoc sensors built by academics on the West Coast have picked up cesium-134 from Fukushima, as have the permanent CTBTO stations.
Nuclear detectives can dive deeper still, sorting out whether radioactive emissions emanate from a dangerously active and still-fissioning reactor core, from burning fuel rods, or from used fuel sitting in pools.
When the active core of Chernobyl exploded, it sent dozens of different radioactive elements into the atmosphere, including isotopes of strontium, yttrium, and rhodium — all produced only by active reactor cores or burning fuel rods.
The University of Washington team say they have not seen any of these isotopes, indicating that the fuel rods at Fukushima have not caught on fire.
And the lack of other short-lived isotopes — especially iodine-133 — indicates that the primary safety systems at Fukushima kicked in as planned during the earthquake and shut down fission in the reactors. Halting fission starts an atomic clock of sorts in which quickly decaying isotopes vanish within hours or days. Andreas Knecht of the University of Washington team said their Seattle detector can sense iodine-133 up to seven days after a reactor produces it, but has found none.
The detection of still another isotope, tellurium-132, offers a further clue about the source of radioactive emissions from Fukushima. Fuel rods sit in pools for months or years, releasing fewer and fewer different isotopes over time, and — unlike hotter fuel rods — they don’t produce tellurium-132. Spotting that isotope, as the detectors have, points to a damaged reactor core.
By putting these radioactive puzzle pieces together, the Seattle team was able to conclude in a paper published March 28 that fission in Fukushima’s three active cores was halted during the earthquake, and that the reactor cores launched radioactive debris into the air on clouds of steam shortly thereafter.
Fallout from the Fukushima Daiichi nuclear plant has landed on 30 exquisitely sensitive detectors on desolate Arctic islands, on the tops of tall buildings and in other windy locales across the Northern Hemisphere, according to the Comprehensive Test Ban Treaty Organization, which maintains those sensors. Sniffing the air like silent sentinels, the 63 shack-like stations (with 17 more planned) are capturing tiny radioactive particles in filters much like those on a home furnace.
Analysis of that dust is a key step in an intricate process of nuclear sleuthing: The dust’s distinctive chemical signature can show scientists whether the particles blew into the air from a bomb, a damaged nuclear reactor or used uranium fuel. It can even point to the extent of damage suffered by a fission reactor. Tracing global wind patterns back then pinpoints where the emissions originated.
“It’s nuclear forensics,” said Kai Vetter, a professor of nuclear engineering at the University of California at Berkeley, who built his own radiation detector atop a campus building after the Fukushima crisis began.
“You can learn quite a lot from the pattern of radioactive isotopes,” said Hamish Robertson, a physicist at the University of Washington in Seattle.
In the United States, another network of more than 100 stations maintained by the Environmental Protection Agency is also gathering radioactivity from Japan. State health departments maintain their own monitoring systems, which is how Maryland detected tiny traces in the air and water March 24.
Super-sensitive detection
After the March 11 earthquake and tsunami damaged Fukushima, the global sensor network began to light up for the first time since nuclear detonations in North Korea in 2006 and 2009.
On March 14, a station on the Kamchatka Peninsula in Russia sniffed out unusual radioactive elements. That cloud then split, drifting southward and eastward, with one arm arriving two days later in Sacramento, and three days after that in Charlottesville. On March 20, the ultra-thin broth of radioactive particles blew over Iceland. And it reached all the way to Kuwait City on March 25, two weeks after the first emissions from Fukushima.
The reporting of even these minuscule amounts of unusual radiation has caused alarm, driving a run on potassium iodide pills and Geiger counters. But officials at the EPA and the Centers for Disease Control and Prevention and independent experts have repeatedly stressed that the amount of radioactivity detected outside Japan is far too low to affect human health.
Modern radiation detection systems are simply astoundingly sensitive, they explain, designed to pick up traces of nuclear explosions anywhere in the world. The detector atop the CTBTO’s headquarters in Vienna, Austria, still catches vestiges of the Chernobyl disaster that occurred 25 years ago, said Lassina Zerbo, director of the group’s international data center.
Vetter’s detector at Berkeley even catches radioactivity on the wind from treatments received by thyroid cancer patients passing by six stories below.
Taking radioactive fingerprints
Natural radiation — mostly from airborne radon — “drowns out” the radiation from Fukushima spotted in the United States, said Michael Miller, a University of Washington physicist who, along with Robertson, helped construct a radiation detector in a campus building’s air intake duct.
So a sensor that simply measured the total amount of radiation from airbone particles would be useless in nuclear forensics. Modern detectors do much more. They outline the dust’s distinctive radioactive fingerprint by measuring precise concentrations of five or more radioactive elements, or isotopes.
Each atom of these isotopes is unstable, shedding excess energy — via radiation — in a process called decay. By measuring the form and intensity of this energy, the radiation detectives can identify the isotopes in play and deduce from them what might have happened.
Radioactive iodine-131 and cesium-137 are key to this process. They don’t exist in nature, so their appearance signals a nuclear event — either a bomb or a reactor in trouble. Both can cause health problems in large amounts. But iodine-131 decays relatively rapidly: After eight days, half the original amount is gone. Its presence means that the event that created it occurred just weeks beforehand. Cesium-137 takes much longer to decay, with a half-life of 30 years. Traces of cesium-137 from Chernobyl still waft on Earth’s great jetstreams.
Clues in the air
It was detective work of this kind that alerted the world to the world’s worst nuclear disaster 25 years ago. In April 1986, nuclear power plant workers in Sweden detected a spike in iodine-131 and cesium-137, which — after a check of wind patterns — revealed the unfolding disaster at Chernobyl, which the Soviet Union had not disclosed.
Because both isotopes can come from a bomb or a reactor, nuclear sleuths also search for another isotope that originates only in reactors: cesium-134. It is produced during the slow-boil nuclear fission inside reactors, but not the flash-bang of a nuclear explosion. The ad-hoc sensors built by academics on the West Coast have picked up cesium-134 from Fukushima, as have the permanent CTBTO stations.
Nuclear detectives can dive deeper still, sorting out whether radioactive emissions emanate from a dangerously active and still-fissioning reactor core, from burning fuel rods, or from used fuel sitting in pools.
When the active core of Chernobyl exploded, it sent dozens of different radioactive elements into the atmosphere, including isotopes of strontium, yttrium, and rhodium — all produced only by active reactor cores or burning fuel rods.
The University of Washington team say they have not seen any of these isotopes, indicating that the fuel rods at Fukushima have not caught on fire.
And the lack of other short-lived isotopes — especially iodine-133 — indicates that the primary safety systems at Fukushima kicked in as planned during the earthquake and shut down fission in the reactors. Halting fission starts an atomic clock of sorts in which quickly decaying isotopes vanish within hours or days. Andreas Knecht of the University of Washington team said their Seattle detector can sense iodine-133 up to seven days after a reactor produces it, but has found none.
The detection of still another isotope, tellurium-132, offers a further clue about the source of radioactive emissions from Fukushima. Fuel rods sit in pools for months or years, releasing fewer and fewer different isotopes over time, and — unlike hotter fuel rods — they don’t produce tellurium-132. Spotting that isotope, as the detectors have, points to a damaged reactor core.
By putting these radioactive puzzle pieces together, the Seattle team was able to conclude in a paper published March 28 that fission in Fukushima’s three active cores was halted during the earthquake, and that the reactor cores launched radioactive debris into the air on clouds of steam shortly thereafter.
Saturday, April 2, 2011
02/04 Contaminated groundwater detected for first time near Fukushima plant
2011/04/02
Groundwater near the crippled Fukushima No. 1 nuclear power plant was confirmed contaminated with radiation for the first time.
Officials of Tokyo Electric Power Co., the plant operator, said Thursday that water taken from a groundwater discharge facility near the building housing the No. 1 reactor contained iodine-131 about 10,000 times the acceptable levels.
Referring to the detection of contaminated groundwater, Chief Cabinet Secretary Yukio Edano said on Friday, "We will have to conduct proper monitoring of the effects on seawater and the surrounding regions."
Government officials were also planning to strengthen checks for radiation contamination of groundwater and the ocean.
Highly contaminated water believed to have leaked from the reactor cores has already been detected in concrete trenches within the plant grounds.
While a connection is still not clear, the detection of contaminated groundwater could mean that highly radioactive water from the reactor cores has leaked outside of the plant site.
TEPCO officials said the contaminated water was taken from a facility that discharges water to a ditch after groundwater has been pumped up from a depth of about 15 meters.
The pumps are located around the reactor building and designed to prevent the building from moving due to the buoyancy of the groundwater.
A water sample taken Wednesday from the discharge facility detected iodine-131 with a radiation level of 430 becquerels per cubic centimeter.
Officials of the Nuclear and Industrial Safety Agency asked TEPCO to check into the type and amount of radioactive material found in the water. TEPCO is now reanalyzing the water samples.
TEPCO officials did not deny the possibility of a connection between the groundwater and the contaminated water found in the basements of the turbine buildings of the reactors.
However, it is possible that radioactive substances emitted from the Fukushima plant dispersed into the atmosphere and returned to the ground as rainfall.
After the March 11 Great East Japan Earthquake, the pumps removing groundwater stopped operating so groundwater has not been flowing directly into the ocean through the discharge ditch.
Sources said the possibility was low that the groundwater would leak into the ocean and raise radiation levels in seawater to the level detected Thursday.
Seawater near the Fukushima No. 1 nuclear plant has been found contaminated with iodine-131 at 4,385 times greater than the acceptable levels.
The science ministry has expanded measurement points to up to about 30 kilometers off the coast from the Fukushima No. 1 plant and continues to check the water at the surface and seabed.
On March 23, surface water was found to have iodine-131 about twice the acceptable levels at a point about 30 km off the coast. On Wednesday afternoon, water from about 10 km off the coast was also found to have iodine-131 at twice the acceptable levels.
While iodine-131 is normally not found near the seabed, levels about one-fourth the acceptable standards have been detected.
Meanwhile, TEPCO officials on Friday began spraying synthetic resins using a sprinkler truck within the Fukushima plant grounds to prevent the spread of dust containing radioactive materials. The water-soluble resin is used in civil engineering work and creates a film when it dries.
Officials said the resin could contain the dust for between six months to a year.
Work also began on Friday to pump in fresh water to tanks within the Fukushima plant from U.S. military ships.
Officials of Tokyo Electric Power Co., the plant operator, said Thursday that water taken from a groundwater discharge facility near the building housing the No. 1 reactor contained iodine-131 about 10,000 times the acceptable levels.
Referring to the detection of contaminated groundwater, Chief Cabinet Secretary Yukio Edano said on Friday, "We will have to conduct proper monitoring of the effects on seawater and the surrounding regions."
Government officials were also planning to strengthen checks for radiation contamination of groundwater and the ocean.
Highly contaminated water believed to have leaked from the reactor cores has already been detected in concrete trenches within the plant grounds.
While a connection is still not clear, the detection of contaminated groundwater could mean that highly radioactive water from the reactor cores has leaked outside of the plant site.
TEPCO officials said the contaminated water was taken from a facility that discharges water to a ditch after groundwater has been pumped up from a depth of about 15 meters.
The pumps are located around the reactor building and designed to prevent the building from moving due to the buoyancy of the groundwater.
A water sample taken Wednesday from the discharge facility detected iodine-131 with a radiation level of 430 becquerels per cubic centimeter.
Officials of the Nuclear and Industrial Safety Agency asked TEPCO to check into the type and amount of radioactive material found in the water. TEPCO is now reanalyzing the water samples.
TEPCO officials did not deny the possibility of a connection between the groundwater and the contaminated water found in the basements of the turbine buildings of the reactors.
However, it is possible that radioactive substances emitted from the Fukushima plant dispersed into the atmosphere and returned to the ground as rainfall.
After the March 11 Great East Japan Earthquake, the pumps removing groundwater stopped operating so groundwater has not been flowing directly into the ocean through the discharge ditch.
Sources said the possibility was low that the groundwater would leak into the ocean and raise radiation levels in seawater to the level detected Thursday.
Seawater near the Fukushima No. 1 nuclear plant has been found contaminated with iodine-131 at 4,385 times greater than the acceptable levels.
The science ministry has expanded measurement points to up to about 30 kilometers off the coast from the Fukushima No. 1 plant and continues to check the water at the surface and seabed.
On March 23, surface water was found to have iodine-131 about twice the acceptable levels at a point about 30 km off the coast. On Wednesday afternoon, water from about 10 km off the coast was also found to have iodine-131 at twice the acceptable levels.
While iodine-131 is normally not found near the seabed, levels about one-fourth the acceptable standards have been detected.
Meanwhile, TEPCO officials on Friday began spraying synthetic resins using a sprinkler truck within the Fukushima plant grounds to prevent the spread of dust containing radioactive materials. The water-soluble resin is used in civil engineering work and creates a film when it dries.
Officials said the resin could contain the dust for between six months to a year.
Work also began on Friday to pump in fresh water to tanks within the Fukushima plant from U.S. military ships.
01/04 Iodine-131 4,385 times limit found near N-plant
The Yomiuri Shimbun
Radioactive iodine-131 at a level 4,385 times the government-set limit has been detected in the sea adjacent to Tokyo Electric Power Co.'s Fukushima No. 1 nuclear power plant, the government's nuclear safety agency said Thursday.
The seawater was sampled from a spot just south of drain outlets for the plant Wednesday afternoon, according to the Nuclear and Industrial Safety Agency.
On the previous day, the agency had announced a seawater iodine level of 3,355 times the limit in a water sample taken Tuesday afternoon. The agency said it is unclear where the iodine came from. The level dropped to 800 times the limit in the Wednesday morning sample before rising again in the afternoon.
Meanwhile, work to move water from an outdoor makeup water storage tank for the No. 3 reactor to another tank was finished, completing a step in the process of removing radioactive water from the turbine buildings of the Nos. 2 and 3 reactors.
As the process is consuming a considerable amount of time, TEPCO has started studying ways to shorten it, TEPCO officials said. The work at the No. 2 reactor was scheduled to be completed on Friday or later, TEPCO said.
The contaminated water within the turbine buildings was to be removed and stored in condensers in the buildings, but the condensers were filled to their capacities. Thus, TEPCO now plans to move the water in the condensers to the outside tanks.
In a related action, TEPCO postponed the start of an operation to spray synthetic resin to prevent the dispersal of radioactive substances from the debris and soil on the grounds of the plant near the Nos. 4, 5 and 6 reactors due to rain.
(Apr. 1, 2011)
Radioactive iodine-131 at a level 4,385 times the government-set limit has been detected in the sea adjacent to Tokyo Electric Power Co.'s Fukushima No. 1 nuclear power plant, the government's nuclear safety agency said Thursday.
The seawater was sampled from a spot just south of drain outlets for the plant Wednesday afternoon, according to the Nuclear and Industrial Safety Agency.
On the previous day, the agency had announced a seawater iodine level of 3,355 times the limit in a water sample taken Tuesday afternoon. The agency said it is unclear where the iodine came from. The level dropped to 800 times the limit in the Wednesday morning sample before rising again in the afternoon.
Meanwhile, work to move water from an outdoor makeup water storage tank for the No. 3 reactor to another tank was finished, completing a step in the process of removing radioactive water from the turbine buildings of the Nos. 2 and 3 reactors.
As the process is consuming a considerable amount of time, TEPCO has started studying ways to shorten it, TEPCO officials said. The work at the No. 2 reactor was scheduled to be completed on Friday or later, TEPCO said.
The contaminated water within the turbine buildings was to be removed and stored in condensers in the buildings, but the condensers were filled to their capacities. Thus, TEPCO now plans to move the water in the condensers to the outside tanks.
In a related action, TEPCO postponed the start of an operation to spray synthetic resin to prevent the dispersal of radioactive substances from the debris and soil on the grounds of the plant near the Nos. 4, 5 and 6 reactors due to rain.
(Apr. 1, 2011)
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Thursday, March 31, 2011
30/03 Low Levels of Radiation Found in American Milk
March 30, 2011
By MATTHEW L. WALD
By MATTHEW L. WALD
Tests of milk samples taken last week in Spokane, Wash., indicate the presence of radioactive iodine from the troubled Fukushima Daiichi nuclear plant in Japan, but at levels far below those at which action would have to be taken, the Environmental Protection Agency said on Wednesday.
Radioactive materials in liquids are measured in pico-curies per liter, and the sample, taken March 25, showed a reading of 0.8 pico-curies, the agency said. Those numbers, it said, would have to be 5,000 times higher to reach the “intervention level” set by the Food and Drug Administration.
“These types of findings are to be expected in the coming days and are far below levels of public health concern, including for infants and children,” the environmental agency said.
Levels of iodine 131 entering the air can be very diluted, but if the iodine is deposited on grass eaten by cows, the cows will reconcentrate it in their milk by a factor of 1,000. This is mainly a concern with fresh milk, not for dairy products that are stored before consumption.
Iodine 131 has a half-life of eight days, meaning that every eight days it loses half its strength. Since production of iodine 131 stopped when the Fukushima reactors shut down on March 11, it has already been through two half-lives and could easily be halved once or twice more again before the milk is consumed as cheese or yogurt.
Iodine 131 emits beta particles, which resemble electrons. They are not considered a major hazard outside the human body, although in large doses, they can damage the cornea of the eye.
The problem arises when materials that emit beta particles are ingested or inhaled. Iodine 131 is chemically identical to normal, nonradioactive iodine and thus is absorbed into the body just as normal iodine is, mainly in the thyroid gland, where it delivers a concentrated dose to that small organ and can cause cancer.
In the Chernobyl nuclear accident of 1986, the biggest health effect was cases of thyroid cancer, especially in children living near the nuclear plant in Ukraine.
Radioactive materials in liquids are measured in pico-curies per liter, and the sample, taken March 25, showed a reading of 0.8 pico-curies, the agency said. Those numbers, it said, would have to be 5,000 times higher to reach the “intervention level” set by the Food and Drug Administration.
“These types of findings are to be expected in the coming days and are far below levels of public health concern, including for infants and children,” the environmental agency said.
Levels of iodine 131 entering the air can be very diluted, but if the iodine is deposited on grass eaten by cows, the cows will reconcentrate it in their milk by a factor of 1,000. This is mainly a concern with fresh milk, not for dairy products that are stored before consumption.
Iodine 131 has a half-life of eight days, meaning that every eight days it loses half its strength. Since production of iodine 131 stopped when the Fukushima reactors shut down on March 11, it has already been through two half-lives and could easily be halved once or twice more again before the milk is consumed as cheese or yogurt.
Iodine 131 emits beta particles, which resemble electrons. They are not considered a major hazard outside the human body, although in large doses, they can damage the cornea of the eye.
The problem arises when materials that emit beta particles are ingested or inhaled. Iodine 131 is chemically identical to normal, nonradioactive iodine and thus is absorbed into the body just as normal iodine is, mainly in the thyroid gland, where it delivers a concentrated dose to that small organ and can cause cancer.
In the Chernobyl nuclear accident of 1986, the biggest health effect was cases of thyroid cancer, especially in children living near the nuclear plant in Ukraine.
Wednesday, March 30, 2011
24/03 Gov't should clearly explain health risks of radioactive contamination
Gov't should clearly explain health risks of radioactive contamination
In this photo released by Tokyo Electric Power Co. (TEPCO), gray smoke rises from Unit 3 of the tsunami-stricken Fukushima Dai-ichi nuclear power plant in Okumamachi, Fukushima Prefecture, Japan, Monday, March 21, 2011. Official says the TEPCO temporarily evacuated its workers from the site. At left is Unit 2 and at right is Unit 4. (AP Photo/Tokyo Electric Power Co. )
The effects of radioactive contamination of food and drinking water are spreading as workers struggle to handle a nuclear power plant crisis in Fukushima Prefecture.
Following warnings in parts of Fukushima Prefecture, the Tokyo Metropolitan Government recommended that infants in Tokyo should not drink tap water. The government has halted shipments of unprocessed milk and some vegetables produced in Fukushima Prefecture, among other areas, and is asking people not to consume these products.
The government message that has accompanied such warnings is: "These products won't harm your health. But just in case, we don't want you to eat or drink them."
Just how should we receive this seemingly contradictory message? Food and water form the foundation of people's existence. Naturally, the government should boost the monitoring of products to accurately grasp the state of contamination, but that alone won't solve the problems that have emerged.
In areas damaged by the March 11 earthquake and tsunami, food and other materials are still in short supply. The government should consider the circumstances in these areas and improve its risk management and communication.
If there are going to be restrictions on the intake of water and some food products, then the government must prepare a system to deliver replacement products to disaster-hit areas. People have been left wondering what they should do if they can't obtain replacement products, and what risks infants and pregnant women face. The government must carefully address such concerns.
If officials want people to reach calm decisions -- not just about the safety of food and water but also about the radiation in the air -- then they must do more than occasionally dishing out figures and their interpretations of them.
How much radiation have the people living in affected areas been exposed to in total? When officials say there is no health risk if people are exposed to radiation for a long time, exactly how long is a "long time"? And what does the term "health effects" actually mean? If the government wants people to remain calm then it must answer such questions in clearer terms.
Officials should also clearly state whether radiation around the nuclear power plant is declining or not and how the situation is expected to develop. Information regarding the transition of radiation levels in Fukushima Prefecture would be helpful in determining the outlook for Tokyo, too.
Understandably, it is difficult to accurately measure the physical effects of exposure to low levels of radiation. Still, the threat of damage to DNA, resulting in cancer, is worrying. The human body is equipped to repair such damage, but when the level of damage is high, the long-term risks cannot be ignored.
After the Chernobyl nuclear power plant disaster, thyroid cancer emerged among children who continued to drink milk contaminated with radioactive iodine. Surely a priority for the Japanese government is to come up with ways to protect children, while explaining that the situation in Japan is different. If people over a certain age are not at risk, then the government should clearly say so.
In handling the situation, the government must ensure residents stay well even if radioactive contamination continues. It must not let people move about in confusion trying to get their hands on uncontaminated food and water.
(Mainichi Japan) March 24, 2011
Tuesday, March 29, 2011
về potassium idodide với 2 chất Iod 131 và Cs 137,134
Sông Hồng nói:
18/03/2011 lúc 8:42 chiều |
nguồn: trang blog của Nguyễn Đình Đăng
18/03/2011 lúc 8:42 chiều |
Kính gởi TS Nguyễn Đình Đăng, thật cám ơn bài viết có tính trung thực và dễ hiểu của bác về các tình hình lẫn quá trình xảy ra ở NHDNT Fukushima. Cháu chỉ xin có một thắc mắc, đó là chất potassium iodide theo 1 số nguồn tin khoa học, cho rằng, chất này không có tác dụng ngăn được phóng xạ? Ngoài ra, viec sử dụng không có hướng dẫn và trong tình trạng đồn thổi ồ ạt kéo nhau sử dụng ở nhiều nơi vậy có an toàn cho sức khỏe không ạ? Mong được bác giúp đỡ giải thích thêm về tác động của potassium idodide với 2 chất Iod 131 và Cs 137,134 , cháu xin chân thành cám ơn bác!
Nguyễn Đình Đăng nói:
20/03/2011 lúc 1:03 chiều |Potassium iodide (KI) là muối của iodine bền vững I-127 (không phóng xạ). Cơ thể cần I-127 để tạo nên hormones tuyến giáp (thyroid hormones).
Sự cố tại lò phản ứng hạt nhân làm iodine phóng xạ I-131 thoát ra ngoài không khí, thâm nhập cơ thể người qua đường hô hấp (thở hít), tiêu hoá (ăn, uống). Khi đó tuyến giáp hấp thụ I-131, và sẽ bị tổn thương, có thể bị ung thư. I-131 có thời gian bán hủy (half-life) tương đối ngắn (khoảng 8 ngày). Vì thế không còn nhiều I-131 trong các thanh nhiên liệu đã qua sử dụng và đã được làm lạnh (cooled spent fuel).
Tuyến giáp hấp thụ, không phân biệt, cả I-127 và I-131. Potassium iodide (KI) có tác dụng cản không cho I-131 không thâm nhập vào tuyến giáp theo cơ chế đơn giản như sau. Khi uống một liều lượng potassium iodide (KI) đủ lớn, I-127 trong KI được tuyến giáp hấp thụ. Vì I-127 là nguyên tố bền vững, tuyến giáp trở nên “no” iodine, không thể hấp thụ iodine được nữa trong vòng 24 giờ, bất kể đó là iodine bền vững hay iodine phóng xạ.
Thực ra muối ăn chứa iodine (iodized table salt) của chúng ta cũng có chứa một lượng iodine đủ cho sức khoẻ chúng ta trong điều kiện bình thường, nhưng không đủ nhiều iodine đế cản iodine phóng xạ.
Potassium iodide (KI) chỉ cản không cho I-131 xâm nhập tuyến giáp (thyroid gland), chứ không bảo vệ được các bộ phận khác và cũng không chống được tác hại của các nguyên tố phóng xạ khác.
Chú ý:
1 – Chỉ được uống potassium iodine (KI) theo chỉ dẫn của bác sĩ và KI chỉ có tác dụng trong trường hợp bị nhiễm phóng xạ độ cao. Uống KI khi không cần thiết có thể gây hại cho sức khoẻ.2 – Chỉ những người dưới 40 tuổi mới có nhiều nguy cơ bị ung thư tuyến giáp vì nhiễm iodine 131, đặc biệt đối với trẻ nhỏ. Nguy cơ này ở những người trên 40 tuổi là rất nhỏ.
(Xem chi tiết tại http://www.nirs.go.jp/data/pdf/iodine.pdf)
nguồn: trang blog của Nguyễn Đình Đăng
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