ML20195D204
| ML20195D204 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 11/01/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20195D201 | List: |
| References | |
| NUDOCS 8811040262 | |
| Download: ML20195D204 (2) | |
Text
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UNITED STATES 3
8 j
NUCLEAR REGULATORY COMMISSION E
WASHINGTON, D. C. 20555 L
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION NORTING SCHEDUL AR EXEMPTION FROM 10 CFR 50.46(a )(1)(1)
PUBLIC SERVICE ELECTRIC AND GA5 COMPANY PHIL ADELPHI A__ELECTR IC C0_M_P ANY DELMARVA POWER AND LIGHT COMPANY ATLANTIC CITY ELECTRIC COMPANY SALEM UNIT 2 DOCKET NO. 50-311
1.0 INTRODUCTION
During the Salem Unit 2 fourth refueling outage, defective tubes were discovered in two steam generators.
The licensee decided to plug the row 1 tubes in all four Salem Unit 2 steam generators as a precautionary measure. As a result of this decision, 2.7% of the Salem Unit 2 steam generator tubes have been plugged. Also, during refueling operations, a burnable poison rodlet assembly hold down nut, a locking weld pin and a hand held gamma measurement probe with cable connector were inadvertently dropped into the reactor cavity of Salem Unit 2.
Subsequent efforts to retrieve these items were unsuccessful.
As a result, a decision was made by the licensee to evaluate these objects as loose parts within the reactor cooling system (RCS). These changes in plant configuration affect the peak cladding temperature (PCT) during a large break loss-of-coolant-accident (LOCA).
For plants licensed based on the 1978 Westinghouse large break LOCA model, NRC generic letter 86-16 requires subsequent plant changes which affect the results of the model, to be reevaluated against the updated, approved model and submitted in accordance with 10 CFR 50.46(a)(1)(1).
Based on this requirement, the licensee is required to perform a formal reanalysis to confirm that Salem Unit 2 meets the applicable criteria of 10 CFR 50.46(b) based on the current plant configuration.
By letters dated October 21, 1988 and October 24, 1988, the licensee states that the required formal reanalysis with the new ECCS model cannot be completed for approximately 5 months and because Salem Unit 2 is scheduled to enter mode 2 on November 1, 1988, the licensee requests a one-time, temporary exemption from 10 CFR 50.46(a)(1)(1) based on its specific circumstances.
The licensee provided a safety evaluation of large break LOCA for both steam generator tube plugging and unrecovered loose parts in RCS to support its request for esemption.
The licensee has committed to submit its formal reanalysis by March 31, 1989.
2.0 EVALUATION The licensee in attachments 2 and 3 to its letter dated October 21, 1988, provided the results of its safety evaluation of large break LOCA for both steam generator tube plugging and unrecovered loose parts in RCS, h
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4 Based on the licensee's large break LOCA sensitivity study, a conservative estimate of the penalty would be 28"F associated with 3.5?, tube plugging and 22*F associated with loose parts in RCS of Salem Unit 2.
However, the licensee indicated that the licensing basis large break LOCA analysis for Salem was performed using fuel performance parameters which are now overly conservative.
Accounting for the lower rod internal back fill oressure of the fuel currently in Salem Unit 2, results in a peak clad temperature (PCT) benefit larger than the combined penalty of approximately 50*F due to the steam generator tube plugging and the loose parts in the RCS. Thus, the net effect will result in no increase to the current calculated PCT of 2130*F for large break LOCA. This PCT is low enough that there are no concerns from meeting other criteria for a larae break LOCA. The staff considers that the licensee evaluation is reasonable and conservative.
3.0 CONCLUSION
Based on the information presented in the licensee's letter dated October 21, 1988, the staff has concluded the following; 1.
Granting a one time temporary exemption from 10 CFR 50.46(a)(1)(1) for Salem Unit 2 in order to return to power operation is acceptable. The licensee will submit its formal reanalysis by March 31, 1989.
2.
The licensee has made a good faith effort to comply with the regulation and the licensee's request for exemption meets the criteria in 10 CFR 50.12(a)(2) in that special circumstances are present which warrant approval.
S.
The licensee has provided the results of its safety evaluation regarding the steam generator tube plugging and loose parts in RCS.
The staff considers that these changes in plant configuration will not significantly affect the safety margin of Salem Unit 2.
Dated:
November 1, 1988