ML20154J721
| ML20154J721 | |
| Person / Time | |
|---|---|
| Issue date: | 01/10/1986 |
| From: | Catton I Advisory Committee on Reactor Safeguards |
| To: | Boehnert P Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-CT-1829, NUDOCS 8603110028 | |
| Download: ML20154J721 (2) | |
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ADVISORY COMMIT. TEE ON REACTOR SAFE 2UARDS CASHINGTON, C. C. M PRELIMINARY COMMENTS January 10, 1986 9MD n
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MEMORANDUM FOR:
Paul Boehnert, ACRS FROM:
Ivar Catton, ACRS Consultant
SUBJECT:
REVIEW OF " COORDINATION OF SUPPORT PROJECT FOR THE B&W INTEGRAL SYSTEM TEST PROGRAM " BY J-P SURSOCK AND M. W. YOUNG I reviewed the information sent in the December 11, 1985 package. The report on scaling by Larson seems to miss the point. We all know exact similitude is impossible.
Rather than looking for it, he should be trying to make sure that parameter variations are sufficient to " prove" the codes.
The approach being taken by the IST program is unique. This is the first NRC major research program that has integrated several facilities of different scales and separate effects in a sensible way.
I would, however, like to see a shift in emphasis from explaining individual system atypicalities to demonstrating understanding of the differences using our computational tool.
It would be of value to see what MIST type atypicalities would do to estimated plant behavior using TRAC or RELAP-5. This would, I believe, be of more value than the tests outlined in the report. With the analysis in hand, one could probably better select tests to be run and possibly eliminate those that will yield meaningless plant behavior.
The tall skinny SG may be too tall and skinny to act like a full size SG. The AFW heat transfer process is multi-dimensional at the tube sheets. The single T/C per tube sheet will not yield enough information about the multi-dimensionality to be worthwhile. This would also help estimate metal stored energy. One T/C is not enough. This area is important because code SG modeling is inadequate except in the crudest s en s.e,.
The SRI-2 and UMCP are scaled a bit differently.
Even so, they are still too tall and skinny to avoid a host of atypicalities. They will, however, be very helpful in code prediction verification.
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Paul Boehnert, ACRS January 10, 1986 What does not come across clearly in the report is how the different systems will be used to demonstrate that our advanced codes can predict the behpvior of a full scale PWR.
For example, one needs to lay out a plan for demonstrating that all behavior in all three HLUBs is predicted well enough. A series of tests could be selected from the three systems's test matrices.. One would have to be sure that the tests have proper detail for the code analysts to test their codes. Tests run in the three systems at the same pressure could be used to assess the codes ability to model geometric. effects.
Varying pressure in regions of overlap will give us confidence in our ability to reproduce certain thermodynamic processes. A serious effort is needed to select an appropriate minimum ~ set of tests for such a study. Scaling is the single most important issue if we are to scale to full size PWRs.
Scaling data from each facility up to a full size plant implies knowl-edge we may not have.
I think it would be better to model each facility with the basic code and then analyze differences between data and calculation.
In doing the analysis one might develop scaling principles for certain parts of the system that will be of value. The IST program presents us with an opportunity to "do it right." We should try to do so.
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