ML20137U427
| ML20137U427 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 11/21/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20137U404 | List: |
| References | |
| NUDOCS 8512090299 | |
| Download: ML20137U427 (3) | |
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UNITED STATES 8
NUCLEAR REGULATORY COMMISSION o
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wAsmwoToN, p. c.zossa SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS. 72 AND 58 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 Introduction i
By letter dated September 24,1985 (Serial No.85-686), Virginia Electric and Power Company (the licensee) requested an amendment to Operating License Nos.
NPF-4 and NPF-7 for North Anna Power Station Units 1 and 2.
The requested amendment consists of changes to Section 4.7.10 of the Technical Specifications (TS) for visual inspections and functional testing of snubbers.
These changes modify portions of the snubber visual inspection acceptance criteria, establish separate sampling methods for functional testing of small bore and large bore i
snubbers (snubbers greater than 50 Kips) and establish functional test methods for large bore snubbers.
2.0 Evaluation The existing TS requires that snubbers with uncovered fluid ports be declared inoperable for the purpose of establishing the next visual inspection interval.
The licensee has modified the snubber visual inspection acceptance criteria to permit functional testing of hydraulic snubbers found with uncovered fluid ports to determine snubber operability.
The snubber will be tested in the as-found i
condition in the tension mode which is conservative since fluid is required to be supplied to the valve block and cylinder to accommodate piston rod movement in the tension direction.
Based on experience with the testing of snubbers with uncovered fluid ports at other facilities, we conclude that the margin of safety is not decreased by this change.
Functional testing of hydraulic snubbers with uncovered fluid ports from the as-found condition is an acceptable method of determining snubber operability.
The licensee has also modified the snubber visual inspection acceptance criteria, to add a statement concerning snubbers found to be inoperable as a result of physical damage caused by unexpected transients, random or isolated events. This Qg change conforms with guidance provided by the NRC to recently licensed and near n
l term OL facilities.
Co The requirements for functional testing of snubbers have been clarified by nn establishing separate initial sample sizes for testing of small bore snubbers (snubbers with load capacities of 50 Kips or less) and large bore snubbers gg (snubbers with load capacities greater than 50 Kips). The sample sizes specified
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comply with the requirement ~of NRC Generic Letter 84-13,
Subject:
Technical
%@g Specification for Snubbers.
The proposed. change will not alter the current TS requirements regarding the testing of additional snubbers for small bore snub-Sn.a.
bers. However, in the event of a large bore snubber functional test failure, an t
engineering evaluation will be performed to determine if the failure is generic
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in nature. If the failure is generic in nature, an additional ten percent of the,
large bore snubbers will be functionally tested for each large bore snubber functional test failure.
Corrective action will be based on the results of the additional functional tests.. If the failure is determined by an engineering evaluation to be nongeneric in nature, the functional testing of the additional ten percent of the large bore snubbers for each failure will be postponed until the next functional test period. At that time, the additional snubbers will be tested (ten percent of all large bore snubbers for each failure) in addition to the nomal ten percent sample scheduled for testing during that functional test period.
This is acceptable since specific isolated nongeneric functional test failures do not affect the operability of the remaining large bore snubbers, and i
thus does not decrease the margin of plant safety.
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The proposed change adds snubber valve block testing as a method of functionally l
This method of testing large bore snubbers is utilized at other facilities.
The snubber valve block testing will be accom-plished in accordance with approved procedures which incorporate the snubber manufacturer's valve block testing requirements and reconnendations.
Prior to implementing large bore snubber valve block testing, the licensee will pePform an engineering evaluation and verify that the valve block testing will adequately demonstrate snubber operability. Functional testing of the large bore snuhbers as it {s presently performed requires snubber removal, and shipping to an off-site testing facility which has the proper equipment necessary to perform the tests. After completion of the testing, the large bore snubbers are returned to the site for reinsta11ation.
The removal and transportation of these large snubbers expose the snubber and snubber components to possible damage as a result i
of this handling.
In addition, it is necessary to remove various other safety-related equipment (e.g., piping, conduit, electrical cable, etc..) to facilitate the removal and the reinstallation of the snubbers.
There is the possibility that this safety-related equipment could be damaged during snubber removal and reinsta11ation. Since most of the large bore snubbers are located in high radia-1 i
tion areas, the work involved for snubber ret. oval and reinsta11ation results in workers being exposed to radiation unnecessarily.
Valve block test can be i
performed in place, or the valve block can be removed for testing. The removal of a valve block is relatively simple in comparison to the removal of the entire snubber. Thus valve block testing decreases personnel exposure to radiation and reduces the potential of the snubbers and adjacent equipment becoming damaged during snubber removal and reinsta11ation. The margin of safety is not decreased by the use of the valve block test as a method of functional testing large bore snubbers.
Environmental Consideration These amendments involve changes in the installation of facility components located within the restricted area as defined in 10 CFR Part 20. The staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents 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
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3 there has been no public connent on such fjnding. Accordingly, the amendments meet the elig(ibility criteria for categorical inclusion set forth in 10 CFR Section 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 these amendments.
Conclusion We have 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, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and securitf or to the health and safety of the public.
Principal Contributor:
J. J. Lenahan, NRC Region II Dated: November 21, 1985 6
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