ML17339A477
| ML17339A477 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 12/31/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17339A476 | List: |
| References | |
| NUDOCS 8001240238 | |
| Download: ML17339A477 (2) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY'EVAL'UATION REPORT TURKEY POINT UNITS 3 AND 4 OVERPRESSURE MITIGATING SYSTEM TACS 6717 5 8789 DECEMBER 1979 PREPARED BY:
PLANT SYSTEMS BRANCH DIVISION OF OPERATING REACTORS
- 1. 0 INTRODUCTION By letter dated October 18, 1977 Florida Power 8 Light (FPL) submitted a plant specific analysis of the proposed Overpressure Mitigating System (OMS) for Turkey Point Units 3 and 4.
The electrical, instrumentation and control aspects of the proposed OMS have been reviewed.
A safety evaluation follows.
- 2. 0 EVALUATION II The enclosed Technical Evaluation Report was prepared for us by EGEG Idaho, Inc., as part of our Division of Operating Reactors (DOR} Technical Assistance Program.
- 3. 0 SYSTEM DESCRIPTION The proposed OMS includes sensors, actuating mechanisms,
- alarms, and valves to prevent a reactor coolant system transient from exceeding the pressure and temperature limits included in the Turkey Point Units 3 and 4 Technical Specifications (TS).
FPL adopted the "Reference Mitigating System" developed by 'l(estinghouse and the user's group.
The licensee proposed to modify the actuation circuitry of the existing air operated pressurizer relief valves to provide a low pressure setpoint during startup and shutdown conditions.
The low pressure setpoint is a constant 415 psig at temperatures below 300 degrees F,
Above 300 degrees F, the setpoint increases linearly to 2335 psig at 462 degrees F,
When the reactor vessel is at low temperatures, with the low pressure setpoint
- selected, a pressure transient is terminated below the Appendix G limit by automatic opening of these relief valves.
A manual switch is used to enable and disable the low setpoint of each relief valve.
An enabling alarm which SPOI. r40 g3S
monitors system pressure, the position of the enabling switch and the upstream isolation valve is provided.
The system low setpoint is enabled at a pressure of 390 psig during plant'ooldown and is disabled at' pressure of 400 psig during plant heatup.
We find the pressurizer relief valves with a manually enabled low pressure setpoint to be an acceptable concept for an OMS.
4.0 CONCLUSION
S The electrical, instrumentation, and control aspects of the Turkey Point Units 3 and 4 OMS design are adequate on the basis that:
(a) the proposed control ci rcui try meets IEEE Std. 279, (b) the system is redundant and meets the single failure criterion, (c) the design requires no operator action for ten minutes after the operator receives an over-pressure action alarm, (d) the system is testable on a periodic basis, and (e) the proposed changes to the Technical Specifications have subsequently been reviewed and are in agreement with the recommended changes described in Section 2.4 of the attached-consultant's report.