ML19309B173

Describes Review of Primary Coolant Sys Pressure Isolation Valves in Response to NRC 800223 Ltr Re Potential for Loca. Forwards Sketches of Penetrations Exhibiting Event 5 Valve Configuration for Each Unit

ML19309B173
Person / Time
Site:	Hatch
Issue date:	03/31/1980
From:	Widner W GEORGIA POWER CO.
To:	Office of Nuclear Reactor Regulation
References
TAC-12900, TAC-12901, NUDOCS 8004030227
Download: ML19309B173 (8)

Text

,

, GeorgM Power Company 230 Peach!rce Street Pott Omce Dox 4545 Atlanta, Georgia 30302 Telephone 404 522-0000 L

Power Generation Department March 31, 1980 Georgia Power U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D. C. 20555 NRC DOCKETS 50-321, 50-366 OPERATING LICENSES DPR-57, NPF-5 EDWIN I. HATCH NUCLEAR PLANT UNITS 1, 2 PRIMARY COOLANT SYSTEM PRESSURE ISOLATION VALVES Centlemen:

In response to your letter of February 23, 1980, regarding the poten-tial for an overpressurization and rupture of low pressure piping which could result in a LOCA which bypasses containment, Georgia Power Company has reviewed the valve configurations for all Class 1 system boundary piping, specifically examining high pressure to low pressure system inter-faces. This review was limited to component integrity and functionality as a pressure isolation barrier.

Within the Class 1 system boundary, we found three penetrations which exhibit an Event V valve configuration for each unit - (Penetrations 9A and 9B, which connect to Feedwater, HPCI, RCIC, Reactor Water Cleanup and Control Rod Drive systems as shown in sketches SK-4 and SK-5, and the Standby Liquid Control (SLC) system penetration as shown in SK-6). However, the next valves in the SLC system beyond the Class 1 boundary are valves which cannot pass flow until punctured by an explosive charge. In addition the SLC isolation valves are leak tested at intervals not greater than two years. We therefore believe the reliability of the SLC isolation scheme is sufficiently established.

Penetration 9A provides a pathway for one Feedwater line and HPCI injection as shown in SK-4 and SK-5. Although the Class 1 boundary ends after the first motor operated valve in the HPCI line, high pressurr.

piping extends back to the HPCI pump and includes another motor operated valve as shown. Leak rate tests are performed on the boundary valves at i intervals not exceeding two years. The Feedwater system connected to penetration 9A has high pressure piping which extends back to the reactor feed pumps, encompassing cdditional motor operated valves. The boundary valves are leak rate tested at intervals not greater than two years. We therefore conclude that the rnliability of the isolation valves for pene-tration 9A is sufficiently established.

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8004030 2A i

GeorgiaPower A U. S. Nucicar Regulatory Commission Office of Nuclear Reactor Regulation Washington, D. C. 20555 An identical situation exists for penetration 9B Feedwater and RCIC systems. In addition, Reactor Water Cleanup and Control Rod Drive return lines feed into the line entering penetration 9B as shown in sketches SK-4 and SK-5. The piping for the entire Reactor Water Cleanup system is designed for a high pressure environment. This feature provides additional assurance beyond that provided by the periodic leak-rate testing of the boundary valves. The Control Rod Drive return line feeds into the Reactor Water Cleanup return line outside the Class 1 boundary. The piping in this system is designed for high pressure back to the control rod drive pumps, encompassing additional motor operated valves. These design features provide additional protection beyond that provided by the periodic leak-rate testing of the penetration boundary valves.

In sumary, six penetrarions contain Event V configurations. The Noundary valves for each of the six penetrations are periodically leakage ite tested in accordance with existing Technical Specifications. In addi-

, ton, high pressure piping extends beyond the containment boundary valves  ;

atd, in every case, contains additional motor operated valves. The design features, in conjunction with the periodic leakage rate testing of boundary valves assure integrity of the high pressure boundary. No procedural changes or plant modifications are needed.

Very truly yours, C c- L< >- >

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