ML20033C385
| ML20033C385 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/28/1980 |
| From: | Kelber C NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Mark C Advisory Committee on Reactor Safeguards |
| Shared Package | |
| ML20030A300 | List: |
| References | |
| FOIA-81-320 NUDOCS 8112030073 | |
| Download: ML20033C385 (2) | |
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.o MEMORANDUM FOR: Carson Mark, ACRS Charles Kelber, ARSR FROM:
SUBJECT:
CONCERNS ABOUT SEQUOYAH I regret I didn't have time to discuss ice-condenser plants with you more There are some problems that concern me, and, I suspect, others fully.
that you might want to pursue further.
It appears that ice-condenser plants like Sequoyah are peculiarly vulnerable The ice to small break accidents (S2) with long depressurization times.
melts while the core is still in the process of being uncovered, so a principle source of cooling is used up by tSe time severe failures start.
Moreover, the functioning of a safety system, the Air Return Fans, apparently ensures the flammability of the containment atmosphere in the event of TMI Now the question is whether controlled burning can, by itself, type failures.
limit the potential for containment failure.
Brie fly, I have had two sets of very limited conversations on this topic.
the Containment Branch personnel in NRR appear to feel that controlled burning may be okay on the basis of the actions of containment vafety systems and on a judgment that MARCH may be overly conservative.
The PAS staff and most notably the draft SANDIA report on SEQUOYAH, appear to calculate, using MARCH, containment failure either from sudden hydrogen burning or from a combination of prolonged hydrogen burning and steam over-pressure.
It may well be that one group is right for some accident sequences, the I judge it vital that this apparent other for different sequences.
difference be made explicit.
As you know, we have I can add just a small amount to this discussion.It appears to be conservative in made an independent evaluation of MARCH.
its treatment of those processes that take place at a very high rate-~The code i
momentum is not rigorously conserved.
mass; since most processes in the containment are relatively slow, I doubt We are, MARCH is greatly conservative except for some very special cases.
for example, looking closely into the issue of the " steam spike," both So far, we do not see a reason to suppose analytically and experimentally.
MARCH exaggerates steam production rates by factors as large as two.
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. JUL 2 81980 Carson, Mark So far as I can see, SEQUOYAH may well need to include a filtered vented containment system with a capacity of about 100,000 cfm for burning to make sense for a range of scenarios.
I don't want to judge whether the reactor should get a full-power license. But if the judgment-that it should get such a license depends on installation of hydrogen ignition systens, an FVCS should also be considered.
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s, Charles N. Kelber, Assistant Director Advanced Reactor Safety Research Division of Reactor Safety Research 4
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