ML17056A698
| ML17056A698 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 03/20/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17056A697 | List: |
| References | |
| NUDOCS 9003260419 | |
| Download: ML17056A698 (4) | |
Text
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+**y4 UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON,D. C. 20555 e
Enclosure 1
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PLANT SYSTEMS BRANCH CONTAINMENT SPRAY MATER SEAL PROCEDURE NINE MILE POINT, UNIT 1 DOCKET NO. 50-220
1.0 INTRODUCTION
By letter dated November 30, 1989. the Niagara Mohawk Power Corporation, the licensee for Nine Mile Point, Unit I, provided its procedure for establishing a water seal for the containment spray system discharge line isolation valves.
The staff requested the above procedures in a safety evaluation report dated May 6, 1988 which related to an exemption request for Type C air leak testing of these isolation valves.
These procedures are intended to satisfy the requirements of Appendix J Section III.C.3(b) for establishing a water seal.
- 2. 0 EVALUATION The licensee indicated that a water seal for the containment spray system discharge line isolation valves is provided from a cross-over tie between the
- containment spray primary and secondary loops utilizing two valves which will be open during normal operation.
This would maintain a water seal on all discharge isolation valves in the worst case design basis accident involving a LOCA concurrent with a single active failure when the two primary or secondary loop pumps will be operating.
The proposed sealing will satisfy Appendix 8 design criteria of the sealant pressure at 1.10 times the calculated containment peak pressure (Pa) and will be capable of being maintained for a minimum of 30 days.
One of the pumps may be shutdown after the containment pressure decreases substantially (3 psig).
The shutdown pump will be available for restart if required.
The staff has reviewed the containment spray water seal procedures and considers that the water seal can be maintained per Appendix J at a pressure of 1.10 Pa for a minimum of 30 days as enough water is available from the torus for the spray pumps.
The licensee stated that it will revise the FSAR and technical specification bases that two containment spray pumps are required because of open inter-tie valves.
The licensee also indicated that cross-tie valves may be closed under administrative controls for the purpose of systems surveillance testing or torus water cooling or level control.
These functions will be restricted by the present limiting condition for operation (LCO) which allows one pump inoperable for 15 days or one system or two pumps inoperable for up to 7 days.
The staff considers this acceptable as during the outage of one
- pump, the other three full capacity pumps will be available for containment spray, and an LCO for one system or two pump inoperable is consistent with other emergency core cooling systems.
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3.0 CONCLUSION
Based on the above, the staff concludes that the proposed procedures for establishing a water seal for the containment spray system discharge line isolation valves satisfy the acceptance criterion of Appendix J Section III.C.3(b), and therefore, are acceptable.
[Nine Mile Point TAC 74857]
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