ML18101A382
| ML18101A382 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 12/08/1994 |
| From: | Labruna S Public Service Enterprise Group |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NLR-N94211, NUDOCS 9412130203 | |
| Download: ML18101A382 (3) | |
Text
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- , Public Service Electric and Gas Company I
Stanley LaBruna Public Service Electric and Gas 1Company P.O. Box 236, Hancocks Bridge, NJ 08038 609-339-1700 Vice President - Nuclear Engineering DECO 8 1994
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NLR-N94211 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:
SIGNIFICANT PEAK FUEL CLAD TEMPERATURE CHANGES SALEM GENERATING STATION UNIT NOS. 1 AND 2 FACILITY OPERATING LICENSES DPR-70 AND DPR-75 DOCKET NOS. 50-272 AND 50-311 In accordance with the requirements of 10CFR50.46(a) (3) (ii),
Public Service Electric and Gas Company (PSE&G) hereby reports changes of greater than fifty degrees F to the calculated Peak Clad Temperature (PCT) for the Salem Unit Nos. 1 and 2 Small Break Loss of Coolant Accident (SBLOCA) analyses.
These changes are the result of corrections to errors identified in the Westinghouse 1985 SBLOCA Evaluation Model using NOTRUMP.
The changes are not the result of any plant design or operational issues, and are considered permanent allocations of margin to the 10CFR50.46 PCT limit of 2200 degrees F.
0 By letter dated July 27, 1994, PSE&G reported a Salem SBLOCA PCT of 1551 degrees F.
The PCT changes identified below result in a revised calculated SBLOCA PCT of 1660 degrees F.
The reported changes do not affect Large Break LOCA analyses.
SBLOCTA Axial Nodalization and Rod Internal Pressure Model Revision Westinghouse has reevaluated the SBLOCTA code, which is part of the NOTRUMP evaluation model used for Salem SBLOCA analyses.
The standard model developed in the 1970's has 19 axial nodes with a finer distribution in the top elevations of the fuel.
A series of calculations were performed using finer nodalizations.
It was concluded that a finer nodalization would result in more conservative results (i.e., higher calculated PCT).
Further investigation into the SBLOCTA code resulted in the ___________ _
identification and correction of-*nodaliz-a:ticii1-ancf-overall fluid conservation errors~-
Westinghouse has established a revised standard for rod nodaJ.*i.?.ation which specifies a o. 25 ft nodalization for all elevations which are predicted to become uncovered during the transient.
Another issue affecting the SBLOCTA code applies to the model 9412130203 941208 PDR ADOCK 05000272 P
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, **--c o s 1994 used for calculating transient fuel rod internal pressure.
Fuel rod pressure is used to determine clad creep, burst and blockage behavior for SBLOCA transients.
Westinghouse has revised the rod internal pressure model, as described in their letter to NRC NTD-NRC-94-4253, dated August 9, 1994.
The SBLOCTA calculation has been rerun for the limiting SBLOCA case to determine the combined effects of the axial nodalization and rod internal pressure errors.
The combined effect of these errors results in a permanent PCT margin allocation of +85 degrees F.
Boiling Heat Transfer correlation A closely related set of errors dealing with how mixture velocity is defined for use in boiling heat transfer regime correlations has been corrected.
This affects the NOTRUMP calculations of heat transfer coefficent, and results in a permanent PCT margin allocation of -6 degrees F.
steam Line Isolation Logic Two errors affecting the steam line isolation logic in the.SBLOCA evaluation model have been discovered and evaluated.
The logic resulted in the isolation functions occurring at a slightly later time than when the appropriate signal was generated.
Calculations to account for these analysis errors result in a permanent PCT margin allocation of +30 degrees F.
conclusions In order to account for the errors described above, the SBLOCA PCT is changing from the previously reported value 1551 degrees F to 1660 degrees F.
The criteria of 10CFR50.46, including the PCT limit of 2200 degrees F, continue to be met.
The reported PCT changes are considered to be permanent margin allocations, as they are associated with corrections to the SBLOCA evaluation model.
No additional corrective actions are necessary to demonstrate compliance with 10CFR50.46.
If there are any questions regarding this transmittal, please contact us.
Sincerely,
- _J:
95-4933
Document control Desk NLR-N94211 C
Mr. T. T. Martin, Administrator - Region I U. s. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Mr. L. N. Olshan, Licensing Project Manager -
Salem U. S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Rockville, MD 20852 Mr. c. Marschall (809)
USNRC Senior Resident Inspector Mr. K. Tosch, Manager, IV NJ Department of Environmental Protection Division of Environmental Quality Bureau of Nuclear Engineering CN 415 Trenton, NJ 08625 DEC 081994 95-4933