05/04 TEPCO had to dump radioactive water in ocean due to shortage of storage space

TEPCO had to dump radioactive water in ocean due to shortage of storage space

In this photo taken on Thursday, March 31, 2011 by Japan Maritime Self-Defense Force and released by Japan Defense Ministry Friday, April 1, a U.S. military barge carrying pure water arrives to the quay near Unit 1 of the tsunami-stricken Fukushima Dai-ichi nuclear complex in Okumamachi, Fukushima Prefecture, northeastern Japan, after being towed by a JMSDF tugboat, not shown. (AP Photo/Japan Defense Ministry)

The Tokyo Electric Power Co. (TEPCO) had no option but to dump some 10,000 metric tons of low-level radioactive water into the Pacific Ocean, as it failed to secure room for the contaminated water elsewhere.

TEPCO, the operator of the crisis-hit Fukushima No. 1 Nuclear Power Plant, had been pumping low-level radioactive water into the first and second basements of a turbine building at the plant's No. 4 nuclear reactor. But it stopped doing so when it found out that the level of water containing high concentrations of radioactive materials in an underground shaft outside the turbine building of the neighboring No. 3 reactor was only about one meter below ground level.

The water in the shaft has a high concentration of radioactive materials -- 200 becquerels of iodine-131 per cubic centimeter. This water could overflow in about a week if more of it were poured into the shaft, so it had to be shifted into the basements instead, leaving no room for the low-level radioactive water.

"We can't use the basements of the No. 4 reactor (for the low-level radioactive water). It is an unavoidable measure," Hidehiko Nishiyama, a spokesman for the Nuclear and Industrial Safety Agency, said at a news conference on March 4. Apart from the No. 2 reactor, the No. 3 reactor also threatened to leak contaminated water.

In this Saturday, April 2, 2011 photo released by Tokyo Electric Power Co. (TEPCO), leaking radioactive contaminated water drain through crack of a maintenance pit, right, into the sea, near the Unit 2 reactor of Fukushima Dai-ichi nuclear nuclear power plant in Okumamachi, Fukushima Prefecture, northeastern Japan.(AP Photo/Tokyo Electric Power Co.)

Dumping contaminated water in the sea is rare and is likely to spark a backlash among the local residents. A TEPCO spokesman apologized over the unprecedented move at a news conference in Fukushima, saying, "We are sorry for causing you more trouble."

Click here for the original Japanese story

(Mainichi Japan) April 5, 2011

東日本大震災：福島第１原発事故　低濃度汚染水、海に放出　高濃度、４号機移送失敗

　◇４号機移送「失敗」

　東京電力が低レベルの放射性物質を含んだ汚染水を海に放出した背景には、「玉突き作戦」の貯蔵先として当初見込んでいた４号機のタービン建屋地下への移送が事実上失敗し、海に垂れ流しになっている高濃度汚染水の貯蔵にめどがつかない事態に追い込まれたことがある。

　「４号機地下を（移送先に）使うことをふさがれてしまった。やむを得ない措置だ」。４日会見した経済産業省原子力安全・保安院の西山英彦審議官は肩を落とした。

　東電は当初、４号機のタービン建屋地下１、２階を「タンク」として使うことを想定。集中環境施設にたまっている低レベル汚染水約１万トンの移送作業を２日から始めた。

　だが保安院によると、汚染水約１０００トンを移送した４日の時点で、隣接する３号機タービン建屋の外にある立て坑の水位が約１５センチ上昇していることが判明。立て坑の水位は地上から約１メートルまで迫り、移送を続ければ約１週間であふれてしまう計算だ。３号機の立て坑の水は、ヨウ素１３１が１立方センチ当たり２００ベクレルと高濃度の放射性物質を含む。２号機に加え３号機でも汚染水の流出が始まる危険があった。

　東電によると、集中環境施設は、原発構内で使った衣類の洗濯水や、配管や機器の点検に使った水などを蒸留して処理し、残った放射性物質を固めて貯蔵している。今回は、この中に津波による海水が大量に入りこみ、放射性物質が溶け出しているとみられる。

　事業者自ら汚染水を海中に放出するのは異例で、地元の反発も予想される。福島県で会見した東電の白井功・技術・広報担当は「地元の皆様に一段のご苦労をおかけし、非常に申し訳ない」と言葉を詰まらせた。【酒造唯、平野光芳】