Fukushima no.2 "torus" OK

March 15, 2012

No cracks or strains seen in suppression chamber of No. 2 reactor at Fukushima plant

http://mdn.mainichi.jp/mdnnews/news/20120315p2a00m0na009000c.html

This photo provided by TEPCO shows the interior of the "torus" pressure pool in the reactor building of the No. 2 reactor at the Fukushima No. 1 Nuclear Power Plant.

Tokyo Electric Power Co. (TEPCO) took and released photographs on March 14 of the pressure suppression chamber of the No. 2 reactor at the crippled Fukushima No. 1 Nuclear Power Plant and the utility said there were apparently no cracks in the chamber or no changes in the shape of the device.

It is the first time TEPCO, the operator of the troubled nuclear power station, has taken photographs of the interior of a pressure control chamber at the troubled Fukushima nuclear plant since the outbreak there of the ongoing crisis. "Apparently, there were no cracks in the suppression chamber and there were no changes in the shape."

The pressure suppression chamber is designed to turn steam in the reactor into water to be used for cooling. In order to identify places to which coolant water leaked from the reactor or underground water flowed to, TEPCO planned to check the inside of a doughnut-shaped pressure suppression pool called "the torus," which houses the pressure suppression chamber. TEPCO took the photographs of the pressure control chamber as part of its preliminary survey for the plan.

TEPCO employees entered the basement mezzanine of the reactor building at the No. 2 reactor on March 14 and confirmed that the doors to the "torus" could be opened. The maximum level of mid-space radiation in the "torus" was 160 millisierverts per hour. There was contaminated water about 60 centimeters beneath the basement mezzanine, and the level of radiation on the surface of the tainted water was the same as that of the mid-space radiation in the chamber. Part of the reddish brown paint seemed to have come off inside the pressure suppression chamber, and TEPCO said, "That could be because dust piled up, or the color may have changed due to the accident."

Meanwhile, other TEPCO employees walked down to the basement mezzanine of the No. 3 reactor and confirmed that the doors to the "torus" were deformed and could not be opened. That's apparently due to a hydrogen explosion. The level of mid-space radiation in front of the chamber was up to 75 millisieverts per hour. As was the case with the No. 2 reactor, there was contaminated water about 60 centimeters beneath the mezzanine, and the radiation level on the surface of the tainted water was 140 millisieverts per hour.

The TEPCO employees were exposed to up to 2.87 millisievets of radiation during their missions. That was below the 10 millisiervets per hour of radiation the utility had assumed they would be exposed to.

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