ML20203C419
| ML20203C419 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 12/04/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20203C167 | List: |
| References | |
| NUDOCS 9712150301 | |
| Download: ML20203C419 (4) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS. 207 AND 188 TO FACILITY OPERATING LICENSE NOS. NPF-4 AND NPF-7 VIRGINTA ELECTRIC AND POWER COMPANY OLD DOMINION ELECTRIC COOPERATIVE
@RTH ANNA POWER STATION. UNITS N0.1 AND NO. 2 DOCKET NOS. 50-338 AND 50-339
1.0 INTRODUCTION
By application dated May 14, 1997, as supplemented by letter dated October 15, 1997. Virginia Electric and Power Company (the licensee) submitted a request for changes to the North Anna Power Station. Units 1 and 2. Technical Specifications (TS).
The requested changes would revise Surveillance Requirement (SR) 4.7.1.7.2.a for the turbine overspeed protection system to reflect the Virginia Electric and Power Company's current valve testing and verification of valve movement methodology for cycling the turbine control valves through at least one complete cycle by requiring that each of the turbine control valves be cycled and the movement verified through at least one complete cycle from the running position.
The licensee also proposes i; revise TS BASES Sections 3/4.7.1.6 and 3/4.7.1.7 to clarify the testing requirements for the turbine governor control valves.
The October 15. 1997, submittal contained clarifying information only, and did not change the proposed no significant hazards consideration determination.
2.0 BACKGROUND
North Anna. Units 1 and 2. are each equipped with a Westinghouse turbine generator.
The Westinghouse turbine is a conventional 1800-rpm, tandem-com>ound unit consisting of one double-fiow, high-pressure cylinder and two dou)le-flow. low-pressure cylinders. The turbine is provided with four moisture separator reheaters located between the high-pressure and the low-pressure cylinders.
Each high-pressure steamline to the high-pressure cylinder contains a stop-trip (throttle) valve and a governor control valve. A reheat stop valve and an intercept valve are provided in the crossover piping between each moisture separator reheater and the low-pressure turbine cylinders.
9712150301 971204 PDR ADOCK 05000338 PDP
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2 The turbine generator system is equipped with overspeed protection to minimize the probability of the generation of turbine missiles to ensure conformance with General Design Criterion (GDC) 4. " Environmental and Dynamic Effects Design Bases." To demonstrate the operability of the turbine overspeed protection system. TS 4.7.1.7.2.a currently requires that the four turbine throttle valves. the four turbine governor valves, the four turbine reheat sto) valves. and the four turbine reheat intercept valves be tested by cycling eac1 of the valves through one complete cycle of full travel and verifying movement of each of the valves through one complete cycle by direct observation.
The licensee proposed revising TS 4.7.1.7.2.a because of concerns regarding
- the testing of turbine governor valves through one complete cycle of full travel. The licensee also maintains that the definition of " full travel" is not specifically provided in the TS.
The proposed changes would clarify the SR wording to reflect the Virginia Electric and Power Company's cuarent valve i
testing and verification of valve movement methodology for cycling the valves through at least one complete cycle.
The licensee stated that depending on the turbine power at the time of testing, one or more of the governor valves would be less than fully open.
Therefore, the governor valves are cycled from their running position to the full closed position and back to the running position during each turbine overspeed protection surveillance test. The licensee's submittal of October 15, 1997, stated that during plant operations with the generator connected to the grid, the four intercept valves, the four reheat stop valves, and the four throttle valves are full open, and they are not designed to function in an intermediate position. Therefore, these valves are cycled from their running position (full open) when tested pursuant to TS 4.7.-1.7.2.a.
The licensee proposed rewording SR 4.7.1.7.2.a to clarify the test performance and verification of movement requirements for the turbine overspeed protection system.
Currently, operability of the turbine overspeed protection system is demonstrated as follows:
Existing TS a,
By cycling each of the following valves through one complete cycle of full travel and verifying movement of each of the valves through one complete cycle by direct observation:
The licensee proposed that operability of the turbine overspeed protection system be-demonstrated as follows:
a.
By cycling each of the following valves through at least one com)lete cycle from the running position and verifying movement of eac1 of the valves through one complete cycle from the running position by direct observation:
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3 In addition. the licensee also proposes to. revise TS BASES Sections 3/4.7.1.6 and 3/4.7.1.7 to clarify the testir.g requirement for the turbine governor control valves by adding the following:
The turbine governor valves are required to be tested through one complete cycle from the running position.
In normal operation, one or more governor valves may be less than fully open.
Based upon the' Westinghouse Technical Manual Operating Instructions, these valves are tested from the operating position to the full closed position and back to their pretest position. The deliberate opening of the last governor valve beyond its normal operating position would likely result-in an unstable valve configuration. The purpose of the test is to verify that the governor valves will close from their normal operating position to the fully closed position.
3.0 EVALUATION Section 10.2 of the Standard Review Plan NUREG-0800, provides guidance in evaluating the inservice inspection and testing of essential valves.
The purpose of the guidance is to ensure that the turbine overspeed protection system will perform in a manner that satisfies the requirements of GDC 4 of Appendix A to 10 CFR Part 50 with regard to the protection of structures, systems, and components important to safety from the effects of turbine missiles.
The staff has reviewed the licensee's submittal as previously discussed and finds that clarifying that the valves be cycled and that movement be verified through at least one complete cycle from the running position is consistent with NUREG-0452 " Standard Technical Specifications for Westinghouse Pressurized Water Rectors." is consistent with the current North Anna Periodic Test Procecures and Westinghouse Operating Instructions. and also does not involve a reduction in the margin of safety and, therefore, is acceptable.
4.0
SUMMARY
-The staff has completed its review of the licensee's amendment request to clarify the testing and ins)ection methodology of the turbine governor valves.
the throttle valves, the releat stop valves, and the reheat intercept valves.
End concludes that the proposed changes are acceptable based on-the above evaluation.
5.0 STATE CONSULTATION
In accordance with the Commission's regulations. the Virginia State official was-notified of the proposed issuance of the amendments.
The State official had no comment.
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6.0 ENVIRONMENTAL CONSIDERATION
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These amendments change a requirement with respect to installation or use of a
. facility component located within the restricted area as defined in 10 CFR Part 20 and change a surveillance requirement. The NRC staff has determined that the amendments involve no significant increase in-the amounts, and no significant change in the types, of any effluent that may be released offsite, and that there is no significant increase in individual-or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that these amendments involve no significant hazards consideration and there has been no public comment on such finding (62 FR
- 40860). -Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51,22(c)(9).
Pursuant to 10 CFR-51.22(b) no environmental impact statement or environmentel assessment need be prepared in connection with the issuance of the amendments.
7.0 CONCLUSION
The Commission has concluded. based on the considerations discussed above.
that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner. (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the connon defense and security or to the health and safetv of the public, Principal Contributor:
Coretta Y. Saada o
Date:
December 4.1997 W
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