ML20052F758
| ML20052F758 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, 05000000 |
| Issue date: | 04/28/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20052F752 | List: |
| References | |
| NUDOCS 8205130581 | |
| Download: ML20052F758 (4) | |
Text
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gaarco q'o, UNITED STATES NUCLEAR REGULATORY COMMISSION o
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WASHINGTON, D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 70 TO PROVISIONAL OPERATING LICENSE NO. DPR-19 AMENDMENT NO. 62 TO FACILITY OPERATING LICENSE N0. DPR-25, AMENDMENT NO. 76 TO FACILITY OPERATING LICENSE NO. DPR-29, AND AMENDMENT N0.70 TO FACILITY OPERATING LICENSE N0. DPR-30 COMMONWEALTH EDISON COMPANY AND IOWA-ILLIN0IS GAS AND ELECTRIC COMPANY DRESDEN STATIOM UNIT NOS. 2 AND 3 QUAD CITIES STATION UNIT NOS. 1 AND 2 Df M T NOS. 50-237, 50-249, 50-254, 50-265 MULTI-PLANT ITEMS B-17 AND B-22 INSERVICE SURVEILLANCE OF SAFETY-RELATED SNUBBERS I.
INTRODUCTION Author :
H. Shaw To reflect accumulated experience obtained from operating plants in the past several years, NRC issued Revision 1 of the Standard Technical Specifications on the surveillance requirements for safety-related snubbers. On November 20, 1980, this document was transmitted to operating plants excluding those under SEP along with a request for submittal of appropriate license amendments to incorporate the requirements of this revision within 120 days. The same request was extended to SEP plants on March 23, 1981.
II.
DESCRIPTION AND DISCUSSION Numerous discoveries of inoperative snubbers in the period of 1973 to 1975 resulted in their surveillance requirements in the Technical Specifications for operating reactor plants.
However, several deficiencies were identified af ter the original requirements were in force for several years.
These deficiencies are:
1.
Mechanical snubbers were not included in these requirements.
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. 2.
The rated capacity of snubbers was used as a limit to the inservice test requirement.
3.
NRC approval was necessary for the acceptance of seal materials.
4.
Inservice test requirements were not clearly defined.
5.
In-place inservice testing was not permitted.
Since mechanical snubbers were not subject to any surveillance require-ments, some licensees and permit holders believed that mechanical _ snubbers were preferred by NRC. Many plants used mechanical snubbers as original equipment and many others requested to replace their hydraulic snubbers with mechanical ones to simplify or avoid an inservice surveillance f
program. This is directly contradictory to NRC's intention, where for an unsurveyed mechanical snubber, the most likely failure is permanent lock-up. This failure mode can be harmful to the system during normal plant operations.
During the period of 1973-1975, when the first hydraulic snubber surveillance requirements in the Technical Specifications were drafted, a compromise was made to limit the testing of snubbers to those with rated capacity of not more than 50,000 lbs. This is because of the available capacity of the test equipment and the requirement to test-some parameters at the snubber rated load.
Since then, greater equip-ment capacity and better understanding of parametric correlation both l
developed. To maintain this arbitrary 50,000 lb. limit could mean an un w:essary compromise in plant safety.
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The original hydraulic snubber problem started from leaking seals.
i 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 l
those seals, the words "NRC approved material" were used in the Technical Specifications. Staff members were asked to approve different seal materials on many occasions. Consequently, since the basis for the approval was not defined, the development of better se31 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 specific acceptance j.
I
i 1 criteria was not clear, I&E inspectors found it impossible.to make any necessary correcti)ns.
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 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 i
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 of the Technical Specifications should be revised.
The revised surveillance requirements correct these deficiencies in the following m n 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 shall be implemented to assure that snubbers are functioning within their service life.
4.
Clearly defined inservice test requirements for snubbers shall be implemented.
5.
In-place inservice testing shall be permitted.
lj.
III.
EVALUATION l
The current Revision 3 (and the preceeding Revision 2) of the Standard Technical Specifications contain no substantive changes to the applicable sections of STS Revision 1 previously provided i
to licensees as guidance.
The proposed license amendments submitted by Commonwealth Edison Company by letter dated April 16,1981, as supplemented by letters dated September 29 and October 21, 1981, for Dresden Units 2 and 3'and Quad Cities Units 1 and 2,,have i
incorporated the nccessary requirements in Revision 3 of the Standard Technical Specifications for the surveillance of safety-related snubbers and are therefore, acceptable.
IV.
ENVIRONMENTAL CONSIDERATION We have determined that these amendments do 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 these amendments involve an
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action which is insignificant from the standpoint of environmental impact, 1
j and pursuant to 10 CFR Section Sl.5(d)(4) that an environmental impact statement, or negative declaration and environmental impact appraisal i
need not be prepared in connection with the issuance of these amendments.
V.
CONCLUSION i
We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or 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) there is reasonable assurance that the health and safety of the public will not he endangered by operation in the proposed manner, and (3) 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 security or to the health and safety of the public.
Dated: April 28,1982 l
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