Japanese officials believe a faulty thermometer signalled a spike in temperature at reactor two at the stricken Fukushima plant last week.
Plant operator the Tokyo Electric Power Company (Tepco) said the thermometer may be faulty and did not agree with other readings taken within the reactor.
Concerns were raised early this month when temperatures rose inside reactor two to a high of 93.3°C, almost reaching the temperature at which the nuclear reactor would no longer be in cold-shutdown. This was achieved in December when the temperature was reduced to 95°C. Engineers at the site had been pumping extra water and boric acid into the reactor to bring the temperature down.
Tepco said that temperatures in the reactor are now falling. The Fukushima nuclear power plant in Japan was devastated by last March’s magnitude nine earthquake and subsequent tsunami.