ML20040G441
| ML20040G441 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 02/03/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20040G437 | List: |
| References | |
| NUDOCS 8202160033 | |
| Download: ML20040G441 (3) | |
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4 UNITED STATES 8
3.
NUCLEAR REGULATORY COMMISSION g
~.p WASHINGTON, D. C. 20555 if* *Ci'4l SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATIONS e
SUPPORTING AMENDMENT NO. 71 TO FACILITY OPERATING LICENSE NO. DPR-3 YANKEE NUCLEAR POWER STATION (YANKEE-ROWE)
YANKEE ATOMIC ELECTRIC COMPANY DOCKET NO. 50-29
1.0 INTRODUCTION
By letter dated September 1,1981, Yankee Atomic Electric Company (the licensee) requested a change to the Technical Specifications appended to Facility Operating License No. DTR-3 for the Yankee Nuclear Power Station. This change would clarify and improve the surveillance require-ments for snubbers in response to a request from the staff which was issued to licensees involved with the Systematic Evaluation Program on March 23, 1981.
2.0 BACKGROUND
AND DISCUSSION Numerous discoveries of inoperative snubbers between 1973 and 1975 resulted in the inclusion of surveillance requirements for snubbers in the Technical Specifications for operating reactor plants. However, several deficiencies were identified after the original requirements had been in force for several years.
These deficiencies included the fact that:
1 Mechanical snubbers were not included in these requirements.
2.
The rated capacity of snubbers was used as a limit to the inservice test requirement.
, 3.
NRC staff aproval was necessary for the acceptance of seal materials.
4.
Inservice test requirements were not clearly defined.
5.
In-place inservice testing was not pemitted.
Since mechanical " snubbers were not subject.to any surveJllance requirements, some licensees and permit holders believed that mechanical snubbers were preferred by the NRC. Many plants used mechanical snubbers as original equipment and many others requested pemission to replace their hydraulic snubbers 'with mechanical ones to simplify or avoid an inservice surveillance program.
This is directly contradictory to NRC's intention, because for an unsurveyed mechanical snubber, the most likely failure is permanent lock-up.
This failure mode can be harmful to the system during nomal plant operations.
0202160033 820203 PDR ADOCK 05000029 P
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i During the period of 1973-1975, when the first hydraulic snubber surveillance requirements in the Technical Specifications were drafted.
. i a compromise was made to limit the testing of snubbers to those with rated capacity of not more than 50,000 lbs. This was because the available capacity of the test equipment was limited and because of some requirements to test some parameters at the snubber rated load.
Since then, greater equipment capacity and a-better understanding of parametric correlations have been developed. To maintain this arbitrary 50,000 lb. limit could mean an unnecessary compromise on plant safety.
The original hydraulic snubber problem started 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 unproven material for those seals, the words."NRC approved material" were used in the Technical Specifications. Staff members were asked to approve 6
different seal materials on many occasions.
Consequently, since the basis for the approval was not defined, the development of better seal materials by the. industry was actually discouraged.
The not-well-defined acceptance criteria in the earlier version of the testing requirements resulted in non-uniform interpretations 'and implementation. Acceptance criteria were set individually at widely different ranges. Since the rationale of adopting a specific acceptance criteria was not' clear, inspectors found it impossible to make any necessary corrections.
In some cases, snubbers were tested without reference to acceptance criteria.
Testing of snubbers was usually accomplished by removing snubbers from their installed positions, mounting them on a testing rig, conducting.
4 i
the test, removing them from rig, and reinstalling them to the working position. Many snubbers were damaged in the removing and reinstallation process. This defeated the purpose for conducting tests.
Since methods and equipment have been developed to conduct in-place tests on snubbers, taking advantage of these developments could result in minimizing the damage to snubbers caused by removal and reinstallation plus time and cost savings to the plants.
From these short-comings it was concluded that the snubber surveillance requirements for _the Technical Specifications should be revised.
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a 3-3.0 EVALUATION The proposed Technical Specifications submitted by the licensee are essentially identical to the model Technical Specifications and they correct the deficiencies listed above in the following manner:
1.
Mechanical snubbers are now included in the surveillance program.
2.
No arbitrary snubber capacity is used as a limit to the inservice test requirements.
3.
Seal material no longer requires NRC approval. A monitoring
' program will be implemented to assure that snubbers are functioning within their service life.
4.
Clearly defined inservice test requirements for snubbers are implemented.
5.
In-place inservice testing is permitted.
For these reasons we conclude that the proposed surveillance requirements for snubbers are acceptable.
4.0 ENVIRONMENTAL CONSIDERATION
We have determined that the. amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 851.5(d)(4), that an environmental impact state-ment or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
5.0 CONCLUSION
We have concluded, based on the considerations discussed.above, that:{(1) because.the amendment does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, the amendment does not involve a significant hazards consideration, (2) 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 actiwities will be conducted in compliance with the Commission's regulations and the~
issuance of this amendment will not be inimical to the common defense and secur,ity or to the health and safety of the public.
Date:
February 3,1982 5
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