Loss of coolant at Fukushima Daiichi 2
FIRST PUBLISHED: 6.14pm
UPDATE 1: 8.04pm Information from Tepco television appearance
Serious damage to the reactor core of Fukushima Daiichi 2 seems likely after coolant was apparently lost for a period. Seawater is again being injected, but coolant level is unknown.
A spokesman for Tokyo Electric Power Company has appeard on national broadcaster NHK to explain the company's efforts to control unit 2's reactor core after its isolation cooling system failed following an increase in containment pressure to some 700 kPa.
Having shut down on 12 March, the amount of decay heat produced by nuclear fuel in the reactor core will have dropped exponentially to less than a few percent of its value on shutdown, but this still must be removed by the passage of water.
The company prepared to inject seawater into the reactor system, but this was only started "after the water level reached the top of the fuel." Gauges indicated that water levels continued to drop despite the injection process and after some time injection became impossible due to high pressure.
Opening the relief valve made injection possible again, but after a time pressure relief was again required. Injection has continued since that second venting operation but gauges still do not indicate that water levels are rising.
The Japan Atomic Industry Forum reported back statements from the Nuclear and Industrial Safety Agency (NISA) saying that Tepco made a notification at 8.50pm that some fuel rods were presumed broken, based on radiation detected.
Researched and written
by World Nuclear News
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