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Monday, March 21, 2011

Fukushima Daiichi: SITREP 3/21

The wires are sort of quiet at the moment, since it's the middle of the night in Japan. We're expecting some big news in the next 48 hours or so and are continuing the all-hours coverage, but while it's quiet for the moment it might be a good time to step back a bit and look at what the overall timeline ahead looks like.

For the very long term, it's probably safe to say that the planned ABWR plants that would have been on this site as Fukushima Daiichi No. 7 and No. 8 will never be built.

In the nearer term, it's seeming likely that No. 5 and No. 6 will not restart and go on the grid any time soon; it's hard to imagine trying to operate these plants and getting constant shift changes in and out while a massive radioactively contaminated site immediately by these plants is being cleaned up. In point of fact, the entire site may never see any nuclear power generation ever again.

Those are very long term suppositions .. now let's look at the situation right at hand. TEPCO has two immediate and serious problems: Three nuclear reactors with varied degrees of core damage, and four spent fuel pools in the reactor buildings with varying degrees of damage.

TEPCO's most pressing problems are thus: 1. Stabilize condition of reactor cores installed in No. 1, No. 2 and No. 3 plants. 2. Stabilize condition of spent fuel in all four plants.

Following this, TEPCO will have to begin to make preparations at a later date for removal of the damaged reactor cores for disposal. This will have to be preceded of course by the clearing of all wreckage on top of the reactor buildings and most probably the total removal of all spent fuel to some other facility. An on site facility would be best in the short term; there are some site joint spent fuel assets but a new facility might be better.

Removal of the debris around the buildings will have to precede this step and is actually being planned now - tanks will be used, along with modified construction equipment. Demolition of the areas on top of the reactor buildings will be far more hazardous and complicated, but will need to be done eventually at some point to obtain access to the reactor shield plugs, the drywell domes and finally the reactor vessel heads for removal of the reactor cores themselves.... This will probably have to be preceded by serious flushing of the reactor cores. CUNO corporation used to make large in-line filters used for break-in of reactor plants to achieve reactor grade coolant water quality, and perhaps some special clean-up filters can be fitted to allow the coolant to be filtered and for loose material to be collected prior to actually opening the reactor vessels.

When will this happen? Well, that is really up in the air. TEPCO and the government would like to achieve, I'm sure, complete decommissioning of the site to the point where you could picnic on it (don't laugh, it's been done many times and I'll show this later today) but that's not going to happen because of the amount of ground contamination I expect they'll find under and around the plants. The best mid-term time frame solutions are to either set the containments up for what we might call SAFSTOR or else ENTOMB status -- you seal them up to allow for time to decay high rad levels, with a set date of opening them later for complete dismantling and site clearing. We'll put more of that type of information on the blog in the days and weeks to come as TEPCO, NISA and JAIF work together to get some credible solutions to the site management problem after the actual nuclear accident phase is over... which it's not.

That should be about the best idea we can have at the moment of where this is all going. Keep watching here for frequent updates.

3:10 PM Eastern Monday 3/12

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