March 17th 2011- All the Troublesome Reactor Venting and How to Prevent It

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From: ,t-armer, Mitchell T. [[email protected]]
Sent: Thursday, March 17, 2011 9:15 AM
To: Tinkler, Charles; Basu, Sudhamay; Lee, Richard; Gavrilas, Mirela
Cc: ‘[email protected]
Subject: RE: Assessement of cooling requirements for Fukushima units 1-3

Hi everyone,

I want to make two final sugestions that I thought of this morning and I’m sending it to you in hopes that it can be factored into the accident management at the site ASAP.

My hand calculations below indicated that at the fire pumping rate of 30 T/hour through the cores (?) outlet core temp on unit 1 should go subcooled today.

However, it’s going to be another week at least for units 2-3.

I’ve also heard about salt crystalization concerns, and that may be detrimental to flow passages through the core/core debris.

So, if they are getting more equipment on site, it would be very beneficial to double the pumping capacity for units 2/3 to try to get those subcooled ASAP.

This would: 1) decrease crystalization rate of salt and 2) really reduce source term from the cores.

Then, the only steaming you should be able to see from the plants would be the spent fuel pools which they are attacking now.

This would help clarify some of the aerial data from units 2-3 iof the only steam source were the pools.

Second, I don’t know if the drywell plugs are still in place, but if you flood the drywell to the extent that it fills out the top, then some of the water spilling onto the deck would make it into the SFP??

This is my last direct contact, we now have to go through DOE, but I want to get info out as fast as possible so that it can help if viable.

Praying for the Japanese,

er, Mitchell T.
,y, March 14, 2011 1:22 PM
. Christopher; Khalil, Hussein S.; Peters, Mark T.; Sattelberger, Alfred P.
[email protected]’; Seidensticker, Ralph W.
Assessement of cooling requirements for Fukushima units 1-3


I did a few back of the envelope calculations to scope out what the cooling requirements will be at Fukushima units 1-3 in the event that they are not able to reestablish power to the site and, thereby, normal cooling functions at these plants.

The limited information I have suggests that they are supplying 30 MT/hour of seawater to unit 1, and so I’ll assume that the same is currently going to units 2 and 3. To put this in perspective, that amount of cooling flow can remove 2.8 MW while remaining subcooled at atmospheric conditions, and up to 21.7 MW if this amount of water is completely boiled off.

[quote]Ideally, you would like to get to subcooled outlet core conditions so you’ll stop forming steam and then you can stop the venting that is causing concern right now.

That amount of heat removal needs to be compared to the decay heat levels in these reactors to determine when subcooled conditions can be reached. Unit 1 was 460 Mwe and Units 2- 3 were 784 Mwe per Chris’s previous email.

Thus, I estimate the thermal power levels of these reactors to be 1200 MWt and 2000 MWt, respectively. After three days (or currently), the power level for a U core would fall to about 0.4 % assuming that the reactors had operated for 200 fullpower days before the earthquake (a little higher for the MOX core but I don’t have data to assess that).

Thus, decay heat in Unit 1 is now about 4.8 MW and for Units 2/3 it’s about 8 MWt.

Thus, I suspect they’re still venting steam at all three units. I then looked at the times when the decay heat will fall below the level at which subcooling can be achieved (ie 2.8 MWt core decay heat level) and for unit 1 that is 6 days total (ie 3 days from now) and for units 2 and 3 it will be about 16 days (ie 13 more days).

This is a worst case scenario that assumes they can’t get electricit back to the site and establish normal cooling function; ie they have to rely on sea water injection. Also, I assumed 200 full power days; the power level could be less or a little more if I overestimated/understimated operation times.

As far as coolability of the degraded cores, my opinion is that units 1 and 3 are in coolable configurations; it’s been 3 days now and if the configuraiton was not coolable the material most likely would have failed the reactor pressure vessel. I guess the jury is still out on Unit 2; I think the entire core has gone dry at least once. The good news is that the decay heat is way down from what it was a few hours after the accident was initiated.



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