The Yomiuri Shimbun
The lights finally came on in the central control room of the No. 3 reactor at the Fukushima No. 1 nuclear power plant Tuesday night after the electricity supply was restored.
On Wednesday morning, workers began trying to activate additional pumps to help flood storage pools for spent fuel rod at the Nos. 3 and 4 reactors with fresh water.
Tokyo Electric Power Co., operator of the nuclear plant which was devastated by the massive March 11 earthquake and tsunami, said supplying power to some meters and gauges in the central control room of the No. 1 reactor showed the temperature inside the reactor was 100 C higher than its design allowed for.
TEPCO said electricity reached the No. 3 reactor Tuesday night, enabling the utility to turn on lights and some instruments and collect various data.
The firm said a temporary pump sending seawater into the No. 3 reactor core would be replaced by a different pump, which would send in fresh water, by Thursday.
On Wednesday morning, workers suspended some of their efforts at the No. 2 reactor because of high radiation levels at the turbine building, where they had planned to try to connect an external power cable, TEPCO said.
TEPCO is also looking into whether a temporary pump could be powered with external electricity to pour water directly into a spent fuel rod pool at the No. 4 reactor, which has also been cooled down with sprayed water.
TEPCO is exploring the feasibility of using the central control room of the Nos. 3 and 4 reactors as a base for workers to repair and maintain a battery charger room in the facility's basement that provides power to the reactor's control system.
TEPCO would cover the room's walls with lead plates to shield the interiors from high amounts of radiation.
The central control room of the Nos. 3 and 4 reactors is located on the second floor of the central control building, between the reactors' turbine buildings. Precise details of its location are not disclosed, as a security measure against terrorism.
The workers would also check pumps and electrical systems at the reactor buildings, located just west of the turbine buildings.
Under normal circumstances, each control room is staffed around the clock by 11 workers on a two-shift system.
TEPCO said it succeeded between Tuesday night and early Wednesday in supplying electricity to meters and gauges at the Nos. 1, 3 and 4 reactors to collect various data.
Consequently, they found the internal temperature of the No. 1 reactor was rising sharply. To cool it down, they increased the amount of water poured into the reactor to 18 tons per hour.
At 6 a.m. Wednesday, the internal temperature of the No. 1 reactor was in excess of 400 C, much higher than the 302 C intended by its design, but it declined slowly to reach 390 C as of 10 a.m.
The company said fuel rods' temperature had apparently risen after being exposed to the air after the water level in the reactor fell.
Workers had difficulty restoring power at the No. 2 reactor, which was damaged extensively by tsunami following the massive earthquake.
TEPCO said two workers were slightly injured when they tried to set up a temporary switchboard at a common fuel rod storage pool between Tuesday night and early Wednesday.
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Pumping operations expand
The utility firm started spraying water around 10 a.m. Wednesday into a spent fuel rod storage pool at the No. 4 reactor with a German-made squeeze pump. On Tuesday, TEPCO sprayed 150 tons of water into the pool with the same machine.
TEPCO has borrowed two more squeeze pumps of a different model but with the same capabilities. The company is considering introducing the two additional pumps to the dousing operation at the nuclear power plant as soon as possible.
The Self-Defense Forces dispatched a CH-47 helicopter to fly over the nuclear plant and measure temperatures at the nuclear reactors shortly before 9 a.m.
A RF-4 reconnaissance plane was dispatched shortly after 9 a.m. to take photos of the damaged reactors with a high-performance camera.
(Mar. 24, 2011)
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