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Sunday, May 15, 2011

Further Fukushima Daiichi updates 5/15

Be sure to see the previous post on this blog regarding the apparent total derangement of the reactor core at Fukushima Daiichi No. 1 plant. The following updates are in addition to that important information.

-NHK is carrying the line that TEPCO believes that hydrogen entered the No. 4 reactor building after No. 3 was vented, through a common discharge stack or vent. Apparently the hydrogen partially did exit to atmosphere but also essentially backed into the No. 4 building. It will be important for all plants everywhere to disassociate common vents such as this to prevent a repeat occurrence of any sort.

-NHK is also reporting that TEPCO will revise or scrap its cooling plan for the No. 1 plant, and perhaps the others, given the apparent inability of the primary containments to hold water. We again wonder why the primary containments are structurally unsound. Possible contributors: 1. Earthquake damage. 2. Direct core melt contact. 3. Hydrogen explosion damage. 4. Salt induced corrosion acceleration, if corrosion were already present. 5. Poor or improper welds or pipe penetrations.

-TEPCO is now feeding water to No. 3 reactor through two sources; the firefighting line, which we think is going to the core top flood ports, and the feed system through the normal feed sparger ring. Temperature at No. 3 plant has been rising steadily lately. The actual dynamics of the events at all three plants differ, and while we are getting much clearer data on No. 1 plant the last 48 hours it is beginning to appear as if No. 3 plant is becoming more, not less, unstable.

-There are still various news sources reporting that TEPCO still does not have the reactors under control, or that they are not shut down. "Shut down" means that the fission process is stopped, which it most surely is. "Under control" in terms of an operating reactor means steady state control of power, temperature and pressure which in the case of shut down but heavily damaged reactors doesn't really apply. This is most probably simple error or carelessness of word choice, but we know that the desire to exaggerate to get sales is all too real in the press.

-TEPCO is going to fully analyze the reactor conditions at No. 2 and No. 3 plants which should lead to a flood of information about those plants just like that seen here for No. 1 plant. We expect all that within 48 to 72 hours.

The situation at Fukushima Daiichi is both evolving faster than it had for a while right now and becoming clearer in terms of what has already happened and what is happening minute by minute. I will endeavor to report all of this information as it becomes available on this site as soon as possible.

9:55 PM Eastern Sunday 5/15
ATOMIC POWER REVIEW

2 comments:

  1. Now that we have the rate of fall of the water level, can we work out if that matches 1)standard boiling away rate or 2)draining through broken pipes due to earthquake damage?
    I've done a back of the envelope and to me it seems the water level went down faster than one would expect through just boiling. All the way down to the recirculating water outlet nozzle level when it stabilised for a while until the corium started falling into the bottom of the RPV?

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  2. @zytheran: We should wait a few days until the entire early operational history of the reactor plant is translated into English to make this sort of estimate... I already know that operators were performing some manual actions such as plant pressure relief, and of course there is some very brief cooldown and thus water shrink due to that cooldown as well. The point is that there are other actions being taken that would prevent us from making an easy determination of simple boil-off, or simple leakage. I suspect that the recirc pump seals may have been damaged when the earthquake hit, but we don't know that for sure... and the condition of each and every individual pump seal at each plant is likely to differ. We are likely to see these details soon.

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