Fukushima Daiichi Nuclear Plant Weekly Review

A faulty thermometer in unit 2, radioactive gravel and a frank mea culpa from a Japanese nuclear safety chief highlighted the news from Tokyo Electric Power Co.’s Fukushima Daiichi nuclear plant last week.

Recent developments surrounding the tsunami-damaged reactors include:

Fukushima unit 4 spent fuel pool. Source: TEPCOTEPCO: Bad Thermometer Showed High Unit 2 Temps

Since Feb. 2, a thermometer in unit 2 showed a disconcerting temperature increase at the bottom of the reactor pressure vessel. Crews increased the volume of water cooling the unit and added boric acid as a precaution against recriticality. On Monday afternoon the temperature reached 93.3 C, well above an 80 C government threshold, yet telltale fission products were absent and other temperature readings around the unit remained normal. Later that day TEPCO tested the electrical circuit in the thermometer and confirmed it was damaged, according to a company release, likely because of a broken wire.

Safety Panel Chief Says Nuclear Regulations Lax

The head of a body that advises the Japanese government on nuclear safety apologized before a Parliament-convened panel Wednesday, offering blunt criticism of Japan’s regulations and safety culture before the March earthquake. Haruki Madarame said non-binding safety guidelines for utilities did not account for devastating tsunamis or station blackouts, Voice of America reported. He also accused regulators of being too friendly with industry and of becoming complacent about evolving international safety standards they failed to meet. The government has since reorganized its agencies that oversee nuclear power.

Cesium Found at Quarry and in Buildings Using Its Gravel

Testing by the Fukushima prefectural government turned up readings of up to 214,200 becquerels of cesium per kilogram of gravel at a quarry in Namie, the Mainichi Daily News reported Thursday. The samples were taken in late January after elevated radiation doses were detected in apartments and other structures built using the gravel. About 1,100 buildings contain material from the quarry, of which 150 have been tested.

(Photo: Image taken Feb. 10 during remote filming inside the unit 4 spent fuel pool. Source: TEPCO)

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