A scare over temperatures rising near the danger level in a reactor at Fukushima Dai-ichi nuclear power plant, where workers are battling to prevent a resurgence of the radiation crisis, could be a false alarm, the plant operator said yesterday. Instruments showed the temperature inside the plant’s No. 2 reactor topped 90oC yesterday, double what it was a month ago and close to boiling point, in which water cooling nuclear fuel in the reactor could evaporate and start a new meltdown.
However, a faulty thermometer was likely giving false readings, said Tokyo Electric Power Co (TEPCO), operator of the plant 240km northeast of Tokyo.
The Fukushima plant’s cooling system was wrecked by the earthquake and tsunami on March 11 last year, triggering reactor meltdowns and a radiation crisis that has caused widespread contamination and mass evacuations.
TEPCO said it was able to bring the temperature down at two other places in the reactor to about 33oC from over 40oC a week ago by pumping more water into it.
“Following our cooling efforts, temperatures at the two other locations are declining steadily, while that at the location in question keeps rising. This leads us to think that the thermometer at the location in question is not functioning properly, rather than the actual temperature rising,” TEPCO general manager Junichi Matsumoto told reporters yesterday.
Matsumoto said there was little sign of steam, which would be produced when water is at such a high temperature, and TEPCO believes the reactor is still in cold shutdown, meaning temperatures are stable below boiling point.
The government announced on Dec. 16 that the plant’s reactors had reached a state of cold shutdown, a milestone in cleanup efforts and a precondition for allowing about 80,000 residents evacuated from a 20km radius of the plant to return home.
Japanese Minister of the Environment Goshi Hosono said he believed the plant was still in cold shutdown, but warned against complacency.
“The instruments are showing readings that are difficult to understand, but I believe we don’t have to change our view that the plant is in cold shutdown,” Hosono said in parliament. “Nevertheless, we continue to assess the situation ready for all possibilities.”