A thermocouple device in the pressure vessel of reactor 2 at Tokyo Electric Power Co.'s Fukushima No. 1 power plant read over 285 degrees Monday but Tepco dismissed the reading, claiming the device is faulty.
Two similar reactor 2 thermometers at the same height — about 3 meters from the bottom of the pressure vessel — as the apparent faulty one gave readings of about 31 to 33 degrees Monday. The problematic one read over 90 degrees in the morning but hit 285.4 at 3 p.m. after Tepco checked its status by gauging its electrical resistance.
The resistance was about 1.7 times more than the average, so some cables are probably partially disconnected and causing the malfunction, Tepco said, adding the temperature readings tend to show higher numbers when cables are disconnected.