ML19281A872

Reviews Re ECCS Evaluation Model.Requests Addl Info Re Heat Transfer & Flow Redistribution of Revised Model

ML19281A872
Person / Time
Issue date:	03/21/1979
From:	Tedesco R Office of Nuclear Reactor Regulation
To:	Scherer A ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY
References
NUDOCS 7904160061
Download: ML19281A872 (2)

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~9 Mr. A.E. Scherer

, Licensing Manager Combustion Engineering Inc.

1000 Prospect Hill Road

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Windsor, Connecticut' 06095

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Dear Mr. Scherer:

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Subject:

Evaluation of Corbustion Engineering Flow Blockage Model

References:

1., !!RC Letter from D.F. Ross to A.E. Scherer, dated liarch 22, 1978.

2.

CE Letter from A.E. Scherer to D.F. Ross, Jr.,

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LD-78-069, dated Septerrbe(18,1978.

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The Combustion' Engineering flow-blockage mo' del incohorated in your

' [ 'I ECCS evaluation model'has been under review by the~ staff. You were U

t informed in Reference 1 of our conclusion that the predictions of LOCA-induced cladding strain and resultant assembly flow blockage were, in general, nonconservative.. In addition, you were requested to provide us with the technical justification for your conclusion

_ that. the present CE ECCS evaluation model continues to be acceptable or can be acceptably modified to take into account the staff's con-.

'cerns Your response to this request was provided in Reference 2 '

V and contained an evaluation which demonstrated that the current model -

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1s' conservative with' respect _to a' revised model....This model incor

% 4 4. C porated a' revised rupture-strain ~model an'd'an. improved steam' cooling

'y '(M heat transfer model. You concluded thit the CE flow blockage bodel '" -

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>,E ' We have resiewed the information you prese'nted in, Reference 2 and have

some additional" questions about the heat transfer and, flow redistri-

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bution' aspects of the revised model described in Reference 2.

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With respect to Figure 3-13, what is the range of Reynolds~-

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' numbers for System 80 plants?.

3!. Provide 'a' comp 3rison of the new and old model for 60% blockage as was done for 20% blockage i.n. Figure '3-12.' i ~ '

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In the revised calculation, how far down stream of the rupture does the peak cladding temperature and peat local oxidation occur (see page 3-16 of Reference 2)? -

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Provide ~a' sample calculation for Kij as used in Appendix A.

Reference 2.:

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Provide in more detail the solution methodology for HCROSS as described in Appendix A.

We have comunicated these questions verbally to Mr. Longo and received some informal answers. However, it is important to receive documentat. ion of all the answers. In the near future we vill be communicating further s

with you about the rupture-strain part of the model.

If yourhave any questions please contact Mr. Paul Norf an of the Analysis Branch. He maybereachedon(301)492-7911.

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Sincerely, Orl:: Inst signea by J

Thomas M. N0T*k RobertL.Tedesed,AssistantDirector for Reactor Safety Division of Systems Safety

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Office of Nuclear Reactor Regulation

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