ML19274E072
| ML19274E072 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 02/07/1979 |
| From: | Check P Office of Nuclear Reactor Regulation |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7903080427 | |
| Download: ML19274E072 (2) | |
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s MEMORANDUM FOR: Robert W. Reid, Chief, Operating Reactors Branch f4, Division of Operating Reactors FRON:
Paul S. Check, Chief, Reactor. Safety Branch, Division of Operating Reactors
SUBJECT:
TOLED0' EDISON COMPANY'S REQUEST TO REMOVE LICENSE
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CONDITION 2.C.(3(1) FROM DAVIS BESSE - 1 LICENSE The Reactor Safety Branch has completed it's review of the licensee's request to remove the subject license condition. This license condition requires Toledo E81 son Company (the licensee) to provide reactor coolant flow data within 30 days-following 2 weeks of sustained power operation at a power level of 90". or greater of rated thermal power. This flow data is used to determine and document the reactor coolant system total pressure doops. After reviewing the background information (explained below) pertaining to the plant while in the licensing stage, and since the licensee fulfilled the requirement of the license condition we find the licensee's request acceptable.
The original evaluation of Davis-Besse Unit il (DB-1) LOCA analysis was based on the review of the B8W topical report BAU.10105. Subsequent to that evaluation Toledo Edison Company informed the NRC that an erroneous
. input value of the cold leg nozzle friction factor has used in the LORA analysis. Consequently, the licensee (then aoplicant) submitted a reanalysis of DB-1 LOCA based on the correcited cold leg nozzle model and the corresponding revised reactor system pressure distribution. The LOCA reanalysis resulted in. lower peak clad temperatures (PCTs) for the worst break analysis. The reason for the reduction In PCTs compared to those reported in BAW-10105 was due to the decreased flow resistance (corrected values) and the corresponding enhanced reflooding rate in the core following a LOCA.
The LOCA reanalysis was found acceptable by the staff. However a condition was added to the license for the licensee to provide operating reactor coolant flow data which would be used to verify the reactor coolant system
Contact:
S. Diab, RS/ DOR 28285 7903080 42.I
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total pressure drops. The licensee provided the ' required operating reactor flow data. However, it the time the licensee reported the 00-1 flow-data he started removing the BPRAs and the ORAs from the core.
Since the BPRA and ORA removal resultdd in new core flow characteristics -
(higher core bypass-flow) the licensee agredd to provide the reactor coolant flow data again, after BPRA and ORA removal.
In Reference 1 the licensee provides the reactor coolant flows and the corresponding system total pressure drops before and after BPRA dnd ORA removal. The system total pressure drops determined by the measured reactor coolant flows (Reference 1)' are less than the system total pressure drops used in the last LOCA analysis submitted by the licensee and accepted by the staff. Therefore, we conclude that the -decreased reactor core flow resistance will result in increased reflooding rate in the core following a LOCA - that is, enhancing the ECCS performance.
Given the above conclusion, we find the licensee's request to remove license condition 2.C.(3)(1) acceptable.
Original Signed by Paul S. Check i
Paul S. Check, Chief i
Reactor Safety Branch Division of Operating Reactors i
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cc:
V. Stello Jr./D. Eisenhut R. Vollmer W. Russell C. Berlinger l
F. Coffman i
S.~ Weiss DISTRIBUTION:
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G. Vissing Central File S. Diab RS Rdg.
G. Mazetis SDiab Rdg.
A. Ignatonis PCheck
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Section C, RS/ DOR NRR File Reference 1: Letter from L. E. Roe, Tolec:o Edision Company to the Director of Nuclear Reactor Regulation, USNRC, dated January 16, 1979.
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