Tokyo Electric Power Co. said the temperature in one of the damaged reactors at its Fukushima nuclear station rose to levels above safety limits even as it injected increased amounts of cooling water.
One of three thermometers indicated the temperature at the bottom of the No. 2 reactor pressure vessel rose to 93.7 degrees Celsius (200.7 Fahrenheit) today, higher than the 80 degrees limit, Ai Tanaka, a spokeswoman for the utility known as Tepco, said by phone today.
There are no signs of isotopes that would suggest the reactor has gone critical and there’s been no increase in radiation around the site, the company said in a statement. The other two thermometers at the bottom of the vessel showed temperatures of 32.8 degrees and 33.1 degrees earlier today, spokesman Naohiro Omura said. The thermometers have a margin of error of as much as 20 degrees.
“We think the thermometer may be faulty,” Omura said. The other two gauges indicate temperatures are falling, he said.
It’s also possible that unstable water flow into the unit may have kept the coolant from reaching parts of the melted fuel, he said.
The utility increased the rate of coolant flow to 17.4 cubic meters per hour from 14.1 cubic meters per hour as of 3:30 p.m. yesterday, it said in a statement.
Tepco and Japan’s government announced on Dec. 16 they succeeded in bringing the reactors into a safe state known as cold shutdown nine months after the March 11 earthquake and ensuing tsunami caused the worst release of radiation since the Chernobyl accident in 1986.