25 days after the tsunami

Unfortunately we haven't had time to update the blog today so here is a quick and dirty update.

JAIF's latest update can be found here, NISA's latest here. A quick glance shows that the pressure within the number 1 reactor pressure vessel continues to climb, but the containment pressure is unchanged and the feedwater nozzle temperature is going down. The pressure in the pressure vessel is still very much lower than normal operating pressure so its not a problem as long as the integrity of the vessel is sound. The spent fuel pools seems to be nice and cool in all 4 reactors.

Dose rates within all the containments are going down, likely due to the constantly decaying levels of I-131(3 half lifes have passed which mean only one eight of the original inventory is still there, in another eight days only one 16th will be left and so on). Flow rates have been somewhat lowered.

Cs-137 has been detected in fish, 526 Bq per kg to be specific. The limit is 500 Bq so the fish isn't unsafe to eat. But it's not a nice trend. Of course with time the Cs-137 should dilute into insignificance so its unlikely to pose much of a long term problem either.

NHK and Kyodo reports that the injection of sodium silicate into the pit with the leak to the ocean has been somewhat successful in lowering the leakage rate. It has to be emphasized though that this is in no means a permanent solution, it just means the water will have to take another path and will eventually end up in the ocean anyway. Any delay is good though since it allows more I-131 to decay before it gets spread. But to permanently fix the issue TEPCO needs to restore internal circulation inside reactor number 2, as long as water is put into the core, then steam blown into the leaking wet well radioactive water will continue to be spread.

Dealing with the radioactive water in the turbine halls seems to be exceptionally slow work and even when the water is removed it will likely take some time before one gets the pumps repaired or replaced. If the summary by Murray Mills is correct (link) its going to be a lot of work to get the control rooms and equipment running again.

TEPCO has given a new overview of the plant, monitoring positions etc(hats of to atomic power review) that I have attached below.

The Guardian The unpalatable truth is that the anti-nuclear lobby has misled us all
Reuters WRAPUP 1-Japan nuclear plant operator says may have slowed radioactive leak

Depleted Cranium Numbers of Fukushima-Daiichi “Victims”
NEI Nuclear Notes Lessons from Fukushima
Atomic power review Good overhead view of Fukushima Daiichi / update

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