ML20205S555

Safety Evaluation Accepting Response to GL 96-06, Assurance of Equipment Operability & Containment Integrity During Design Basis Accident Conditions

ML20205S555
Person / Time
Site:	Catawba
Issue date:	04/21/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20205S553	List: ML20205S549 ML20205S555
References
GL-96-06, GL-96-6, NUDOCS 9904260256
Download: ML20205S555 (2)

Text

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• * * * *,o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION CATAWBA NUCLEAR STATION. UNITS 1 AND 2 RESPONSE TO GENERIC LETTER 96-06 DOCKET NOS. 50-413 AND 50-414

1.0 INTRODUCTION

Generic i.etter (GL) 96-06, " Assurance of Equipment Operability and Containment Integrity During Design Basis Accident Conditions," requested each licensee to determine the plant's susceptibility to three phenomena: (1) waterhammer in containment air cooling water systems during accident conditions, (2) two-phase flow in containment air cooling water systems during accident conditions, and (3) overpressurization of piping systems that penetrate containment due to heat up and expansion of fluid during both normal operation and accident conditions.

Duke Energy Corporation (the licensee) responded by letters dated October 29,1996, and January 28,1997. The staff requested additional information on items (1) and (2) by a letter dated March 19,1998. The licensee responded by letter dated June 24,1998. The staff requested additional information on item (3) by letter dated July 30,1998. The licensee responded by letter dated December 14,1998.

The staff completed its review of the licensee's information conveyed by the above correspondence. The staff's review findings are set forth below.

2.0 EVALUATION By letters dated January 28,1997, and June 24,1998, the licensee informed the staff that the containment fan coolers are not restored to service following the event scenarios that are of concern. The staff accepts the licensee's information and agrees that items (1) and (2) are not applicable to the Catawba units.

In the response dated January 28,1997, the licensee identified three penetrations in each Catawba unit which were vulnerable to a water-solid volume that would be subjected to an increase in pressure due to heating of trapped fluid. The licensee stated that these segments are isolated by soft seated plug valves and that sufficient overpressure protection existed due to expected leakage through the valves. These three penetrations are identified as penetrations numbered M-337, M-216, and M-358. In the letter dated December 14,1998, the licensee further clarified that the penetration M-358 actually contains compressible gases rather than water; therefore, it is not susceptible to thermally-induced pressurization. For penetrations M-337 and M-216, the licensee stated that thermally-induced pressurization would be limited to acceptable values by the isolation valve leakage, and the licensee provided the results of actual leakage test data of spare valves to demonstrated that licensing criteria are met. The 9904260256 990421 PDR ADOCK 05000413 P

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uatien determined that all other piping segments penetrating containment were not susceptiole to thermally-induced pressurization.

The staff finds that the licensee's response provides an acceptable resolution for item (3), the issue of thermally-induced pressurization of piping segments penetrating the containment.

3.0 CONCLUSION

As discussed above, the licensee has addressed the three issues requested by GL 96-06, and the staff found the licensee's response acceptable. This completes the staff's actions on the licensee's response.

Principal Contributors: James Tatum Gary Hammer Date: April 21,1999 i