Fukushima units near cold shutdown

29 September 2011

The temperatures at the bottom of the reactor pressure vessels (RPVs) of the damaged Fukushima Daiichi units 1, 2 and 3 have all been recorded as being below 100°C for the first time since the accident triggered by the March 11 earthquake and tsunami, according to Tokyo Electric Power Company (Tepco). At 5.00pm on 28 September, the temperature of the bottom of the RPV of unit 2 was 99.4°C. The temperature of unit 1 has been below 100°C - the boiling point of water - since late July, while that of unit 3 dropped below 100°C in early September. The temperatures of units 1 and 3 are currently around 78°C and 79°C, respectively. Cold shutdown at all three reactors - when the heat from radioactive decay has been removed effectively enough for coolant water to be below 100ºC - is the goal of the second phase of Tepco's roadmap for stabilisation. It aims to achieve this by the end of 2011. However, Tepco spokesman Junichi Matsumoto said "Although the temperature (of unit 2) has been showing a falling tendency overall, the temperature of the bottom of the pressure vessel has gone up and down, so it is still too early to (make a definitive conclusion)."

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