ML20216F125
| ML20216F125 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 04/14/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20216F123 | List: |
| References | |
| NUDOCS 9804160424 | |
| Download: ML20216F125 (5) | |
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nat:oqk UNITED STATES g
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j NUCLEAR REGULATORY COMMISSION l~
i WASHINGTON, D.C. Soest 4001
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l SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATIQN RELATED TO AMENDMENT NOS. 209 AND 190 TO FACILITY OPERATING LICENSE NOS. NPF-4 AND NPF-7 VIRGINIA ELECTRIC AND POWER COMPANY' OLD DOMINION ELECTRIC COOPERATIVE NORTH ANNA POWER STATION. UNITS NO. 1 AND NO. 2 DOCKET NOS. 50-338 AND 50-339
1.0 INTRODUCTION
By a letter dated February 3, 1998. Virginia Electric and Power Company (VEPC0), the licensee for North Anna Power Station. Units 1 and 2.
requested NRC's approval to implement amendments to its Operating Licenses NPF-4 and NPF-7, by incorporating modifications to the Technical Specifications (TS). The proposed TS modifications will modify the TS test sequence for the reactor trip bypass breakers.
2.0 BACKGROUND
Two reactor-trip (trip) breakers and two reactor-trip-bypass (bypass) breakers at North Anna Unit: 1 and 2. are arranged in a series / parallel combination such that for each trip breaker there is a bypass breaker connected in parallel to it. Normally, bypass breakers are in a racked-in position with the contacts open and are placed in the service position (i.e. racked-in and contacts closed) only during testing of the trip breakers so that power will be provided to the control rods.
Bypass and i
trip breakers are interlocked such that only one bypass breaker can be l
closed at a given time.
Current TS require a staggered Channel Functional Test for each trip and bypass breaker every 62 days. Also, Note 8 in the North Anna Unit I TS (Note 9 for Unit 2 TS) to Table 4.3-1 stipulates that testing of the local-manual-shunt-trip of each bypass breaker must be done prior to placing the bypass breaker in service. Testing of the local-manual-shunt-trip. per j
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2 current plant procedures, is conducted, first by placing the bypass breaker in its service position. and then tripping it by using the local shunt trip device. Thus, this test sequence always resulted in a duration when the breaker has been placed in the service position (i.e. racked-in and contacts closed) without prior testing for its local-manual-shunt-trip operability. This situation placed the plant in a "non-compliance" status during the trip breaker test, as far as the requirements of Note 8 (Note 9 for Unit 2) of TS Table 4.3-1 are concerned. On October 10,1996, the licensee identified this non-compliance condition in their Deviation Report
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N 96-2304, and corrected the deficiency by testing the manual shunt trip immediately after closing the normally racked-in bypass breaker. To address this issue, the licensee issued LER N1-96-009-00 dated November 6.
1996, and tne NRC issued non-cited Violation 50-338, 339/96012-02.
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To resolve the compliance issue, the licensee as an interim measure.
revised procedures to include a modified test sequence. The modified test sequence requires the bypass breaker to be racked from its normal racked-in l
position to the test position. The breaker is then closed and tripped locally with the local-manual-shunt-trip device and then returned to the racked-in position, whereby the bypass breaker is placed in service for testing and/or maintenance of the trip breaker to commence. This modified l
test sequence requires racking breakers to the test position, which increases wear and tear on the breakers. Therefore, the licensee has proposed a revision to the TS test sequence for the bypass breakers.
3.0 PROPOSED CHANGE
S AND EVALUATION l
In their submittal, the licensee stated that the proposed changes to the TS l
notations will return the test sequence to the initial testing sequence which was followed until October 10. 1996, and the proposed notations will also clarify that the bypass breaker functional test is coordinated with the trip breaker functional test to ensure that the bypass breaker is tested prior to its associated trip breaker.
3.1 Prooosed chanae: Table 4.3-1 Note 8 for Unit 1. and Table 4.3-1 Note 9 for Unit 2. revise notation to read from " Local manual shunt trip prior to placing the bypass breaker.in to service", to read " Local manual shunt trip the reactor trip bypass breaker immediately after placing the bypass breaker into service, but prior to commencing reactor trip system testing or reactor tr L treaker maintenance."
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' Evaluation: The proposed change clarifies the intent of this Note and
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resolves the "non-compliance" state as was identified on October 10.
1996. Testing without' racking the breaker to its test position eliminates unnecessary movement thus-reducing wear and tear of components and alignment problems caused over time due to several i
J rack-in and rack-out operations. The licensee stated that although the. proposed test sequence will render the bypass breakers-in a service status for a short time before its local-shunt-trip' device is
- tested the operability of the breaker 1s-established based on a-satisfactory test conducted during the previous surveillance interval.
The word "immediately" in the Note will reduce this time to a minimum as practicable to reestablish the bypass breaker's operability prior to beginning the test and/or maintenance activities on the reactor
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trip system. The proposed revision to this Note is acceptable to the staff, as it meets.the intent of th'e TS-required testing for the reactor trip and bypass breakers.
3.2 Pronosed chanae: Table 3.3-1. Functional Unit 21B. Reactor Trip Bypass Breakers, revise Minimum Channels Operable from two to one.
Evaluation: The inoperability of any bypass breaker could mean the breaker will either fail to close or fail to open.
If one out of two bypass breakers is inoperable due to its failure to close, it will prevent test and/or maintenance activities on its associated trip breaker.
If the bypass breaker is inoperable due to failure to open (welded contacts), it will provide a continuous parallel path for its associated trip breaker and thereby diminish the ability of the trip breakers to trip the reactor.
The effect of this situation on plant safety is enveloped by the failure-analysis of the associated reactor trip breaker (single failure), and in this situation, a reactor trip could'be achieved by tripping the redundant trip breaker. The bypass breakers are interlocked such that only one bypass breaker can be closed at a given time.
Also, the plant procedures preclude closing of both bypass breakers at the same time for test and/or maintenance.
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The licensee in their submittal has stated that changing the minimum
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channels operable requirement for the bypass breakers does not effect i
operation of the reactor trip system since only one bypass breaker can be placed in service for trip breaker test and maintenance at any time. Therefore, the proposed change is acceptable to the staff.
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4.0 STATE CONSULTATION
I 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.
5.0 ENVIRONMENTAL CONSIDERATION
1 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 j
has previously issued a proposed finding that these amendments involve no significant hazards consideration and there has been no public comment on such finding (63 FR 11925). Accordingly these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR I
51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendinents.
6.0 CONCLUSION
Based on the our review of the licensee's submittal, the staff finds that j
the proposed TS changes for the test sequence and the revised notation for the North Anna Units 1 and 2 reactor trip and bypass breaker testing will preclude the plant from being in non-compliance for future TS-required survellances and will provide clarification for coordinating the trip breakers and bypass breakers functional tests as originally intended in the TS. Therefore. the staff finds the proposed TS changes acceptable.
The Commission has concluded, based on the considerations discussed above.
that:
(1) there is reasonable assurance that the health and safety of the i
public will not be endangered by operation in the proposed manner. (2) such acti',1 ties will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not ce inimical to the common defense and security or to the health and safety of the public.
Principal Reviewer:
S.
V.
Athavale l
Date:
April 14, 1998 L