ML20033C430
| ML20033C430 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 11/05/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20033C427 | List: |
| References | |
| NUDOCS 8112030194 | |
| Download: ML20033C430 (3) | |
Text
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@ KfC UNITED STATES o
NUCLEAR REGULATORY COMMISSION 5
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^ WASHINGTON, D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION
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RELATED TO AMENDMENT NO. 33'TO FACILITY'0PERATING LICENSE NO. NPF-4
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'AND AMENDMENT NO. 13 TO FACILITY OPERATING LICENSE NO. NPF-7 VIRGINIA ELECTRIC AND POWER COMPANY' sv..-
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NORTH ANNA POWER STATION, UNITS NO. 1 AND NO. 2 DOCKET NOS.'50-338'AND 50-339
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Jntroduction:
To reflect the accumulated experience obtained from operating power
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plants, the NRC issued Revision I to the Standard Technical Specifications for surveillance requirements of safety-related snubbers.
Revision 1 was transmitted to licensees of operating power plants on November 20, 1981 (exc'luding those plants under the Systematic Evaluation Program (SEP)).
_The November 20, 1981 NRC document also requested that licensees submit license amendment applications -for incorporating the requirements of Revision 1 in plant-specific Technical Specifications.
This same request was extended to the SEP plants on March 23, 1981.
By letter dated July 1,1981 (Serial No. 293) and as supplemented by
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l letter dated September 10,1981 (Serial No. 520), the Virginia Electric and Power Company (the licensee) made applications to amend Operating Licenses No. NPF-4 and No. NPF-7 for the North Anna Power Station, Units No. I and No. 2 (NA-l&2) by incorporating the requirements of Revision 1 in the NA-1&2 Technical Specifications.
Discussion:
Numerous discoveries of inoperative snubbers during the period from 1973 to 1975 led to the inclusion of snubber surveillance requirements in the Technical Spi.cifications of operating nuclear power plants.
-However, deficiencies were identified in the surveillance requirements after the original requirements ha'd been in force for several years.
These deficiencies are:
1.
Mechanical snubbers were not included in the original requirements.
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2.
The rated capacity of snubbers was usei as a limit to the inservice test requirement.
3.
NRC approval was necessary for the acceptance of seal materials'.
8112030194 811105 4'
PDRADOCK05000g
l 2-4.
Inservice test requirements were not clearly defined.
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In-place inservice testing was not permi+ted.
Since mechanical snubbers were not subject to any of the original surveillance reouirements, some.. licensees thought that mechanical snubbers were preferred ~by the NRC. Many plants used mechanical snubbers as original 6quipment and others~ requested that hydraulic snubbers be replaced with mechanical snubbers in order to simplify or avoid an inservice surveillance program.
This was not the intent of NRC, where for an unsurveyed mechanical snubber, the most likely failure will be permanent lock-up, 'and this failure mode can be harmful to safety-related
, systems during plant operations.
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During the period from 1973 to 1975, when the first hydraulic snubber surveillance requirements were drafted, a limit was placed on the testing of snabbers to not more than 50,000 pounds of rated capacity.
This limit wis specified because.of the available test equipment and i
the requirement,to test certain parameters at snubber rated loads.
Since
.then,.a greater eeuipment test capacity and, understanding of test parameters has been developed.
Therefore, to maintain the 50,'000. poQod limit could cause an unnecessary compromise on plant safety.
fhe hydraulic snub 0er problem origina.ted from leaking seals. Most seal materials of the 1973 vintage could not withstand the temperature and irradiation environments.
Ethylene propylene was the first material that could offer a reasonable service life for those seals.
In order to discourage,the use of unpreven material for those seals, the words "NRC approved material" were ^ used in tne' Technical Specifications.
Staff members were asked to approve different seal materials on many occasions.
Consequently, since the basis for the approval was not y
defined, the development of better seal materials by the industry was j.
actually discouraged.
The not-well-defined. ceptanci criteria in the earlier version of the testing requirements resulted in non-uniform interpretations and implenen-tation.
Acceptance Criteria were set individually at widely different ranges.
Since the rationale of adopting a specific acceptance criterion was not clear, I&E inspectors found it' difficult to make appropriate
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corrections.
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The testibg of snubbers in the past has been usually accomplished by
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removing snubbers from installed positions, mounting the snubbers on
- a test rig, conducting the test, removing the snubbers from the test riij and meinstalling in the working position. Many snubbers were
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damaged in this process which defeated the purpose for conducting the 4
snubber tests.
Methods and equipment have not been developed.to conduct in-place tests on snebyers.
These developments can provide cost savings byl reducing the tfie required for testing and minimizing damage to snutbers.
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For-the reasons stated above it was concluded that the original snubber surveillance reouirement should be revised.
Evaluation:
Revision 1 tr> the Standard Technical Specifications for snubber sur_v.elllance rsquirements address the above.noted deficiencies 1,n.
th6'fo11owing manner:
1.
Mechanical snubbers are now included in th'e surveillance program.
2.
No arbitrary snubber. capacity is used as a limit to the inser.vice test requirements.
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3J Seal material n~o lorig'e~r re ='uires'NRC approval.
A monitoring g
. -program shall, be implemented -to assure -that snubbers are functioning.
~~within their service'l'iTe.
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4 Clearly defined inservice test requirements for snubbers shall be
. 1mplemented..
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In-place inservice te. sting shall be p,ermitted.-
Based on our review of the licensee's. application, we find the licensee's submittal to be in conformance with the snubber surveillance requirements as stated in Revision 1.
Therefore, we find the proposed changes to the NA-1&2 Technical Specifications to be acceptable.
Environmental Consideration We have determined that the amendments do not authorize a change in effluent types or total anounts nor an increase in power level and will not result in any significant environ.nental impact. Having made this determination, we have further concluded that the amendments involve an action which is insignificant from the standpoint of environnental impact and, pursuant to 10 CFR $51.5(d)(4), that an environmental impact statement or negative declaration and. environ-mental impact appraisal need not be preparel in connectian with the issuance of these amendments.
Conclusion 5~
We have concluded, L3 sed on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase Lj in the probability et consequences of accidents previously considered and do not involve a significant decrease in a safety margin, the amendments do not involve a significant hazards consideration, (2)
N there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activit'.es 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 security or to the health and safety of the public.
Date:
Noveaber 5, 1931