According to WNN, Unit 3 cold shutdown appears to have gone exactly as expected, with no systems damaged. The reactor went from power production to cold shutdown – where coolant water is at less than 100ºC – in about 34 hours.
Damage to the emergency core cooling systems (ECCS) of units 1, 2 and 4 led to TEPCO declaring emergency status. The reactors used the make up water condensate system to maintain coolant levels above the reactor core.
An additional emergency notice was declared for Unit 1 because the temperature of a suppression chamber reached 100ºC.
The Fukushima Daini plant then continued in a relatively steady state throughout 12 March, with coolant levels and pressures contantly monitored by engineers. Units 1, 2 and 4 were prepared for potential venting, but this was not required.
In the last 48 hours, TEPCO has carried out repairs to the emergency core coolant systems (ECCS) of Units 1, 2 and 4. Unit 1 announced cold shutdown at 1.24 am today and Unit 2 followed at 3.52 am.
TEPCO has completed repairs to the ECCS of Unit 4 and gradual temperature reduction started at 3.42pm.
In contract to Fukushima Daiichi, Fukushima Daini apparently has had off-site power at least since March 12.
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