ML20126E414
| ML20126E414 | |
| Person / Time | |
|---|---|
| Issue date: | 06/06/1985 |
| From: | Thomas C Office of Nuclear Reactor Regulation |
| To: | Taylor J BABCOCK & WILCOX CO. |
| References | |
| NUDOCS 8506170072 | |
| Download: ML20126E414 (2) | |
Text
June 6, 1985' Mr. J. H. Taylor Licensing Services Babcock and Wilcox
'3315 Old Forest Poad Post Office Box 10935 Lynchburg, Virginia 24506-0935-
Dear Mr. Taylor:
SUBJECT:
REQUEST NUMBER TWO FOR ADDIYIONAL INFORMATION ON BAV-10156 We:are_ currently reviewing the Babcock and Wilcox Licensing Topical Report, RAW-10156, entitled "LYNXT-Core Transient Thermal-Fydraulic Progran."
The initial review reveals the need for the additional information indicated in the enclosure.
In order to complete this review within the currently scheduled time, responses to all questions should be received by NRC by June 24, 1985.
Please advise D. H. Moran at (301) 492-9409 ff you cannot meet this date.
The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OBM clearance is not required under P.L.96-511.
Sincerely, Original signed by/
Cecil 0. Thomas, Chief Standardization & Special Projects Branch Division of Licensing
Enclosure:
As stated DISTRIBUTION:
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O ENCLOSURE QUESTION ON LYNXT APPLICATION The staff evaluation of the LYNXT code has concluded that calculational models in LYNXT are acceptable for both steady state and transient analyses of the core thermal hydraulics. However, since both BAW-2 and BWC critical heat flux correlations and their respective DNBR limits were developed with steady state CHF test data and steady state thermal hydraulic codes, it is questionable as to whether these DNBR limits in connection with the LYNXT transient solution provide the required protection against departure from nucleate boiling at a 95/95 probability / confidence level. Therefore, until such proof can be made of the adequacy of the steady state DNBR limits using the transient LYNXT solution, we find that only the steady state solution of LYNXT is acceptable for DNBR analysis. For those transients which are DNBR limited, a quasi-steady state approach can be used in which the reactor coolant system analysis provides the time dependent boundary conditions to the core and the steady state solution of LYNXT is used for the core thermal hydraulic and DNBR calculations. Since you have expressed in a meeting with the staff that B&W intends to use the transient solution of LYNXT for the analyses of some transients which are not DNBR limited, please provide a list of these transients and your justifications as to why these analyses are, acceptable.
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