ML20049J106
| ML20049J106 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 03/03/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20049J105 | List: |
| References | |
| NUDOCS 8203120075 | |
| Download: ML20049J106 (4) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 63 TO FACILITY OPERATING LICENSE NO. DPR-23 CAROLINA POWER AND LIGH1 COMPANY H. B. ROBINSON STEAM ELZCTRIC PLANT, UNIT N0. 2 DOCKET NO. 50-261 Introduction By letter dated March 27, 1981, Carolina Power and Light Company (the licensee) requested amendment to Facility Operating License No. DPR-23 for the H. B.
Robinson Plant, Unit No. 2.
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 subnittal 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.
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 reactors 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.
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.
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Inservice test requirements were not clearly defined.
5.
In-place inservice testing was not permitted.
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Since mechanical snubbers were not subject to any surveillance requirements, some licensees and permit holJars believed that mechanical sn ?bbers were preferred by NRC. Many plants used mechanical snubbers as orist.al equipment and many others requested to replace their hydraulic snubbers with mechanical ones to simplify or aviod a inservice surveillance programs. 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 nonnal plant operations.
During the period of 1973-1975, when the first hydraulic snubber surveillance requirements in tne 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 requirements to test some parameters at the snubber rated load. Since then, greater equipment capacity and better understanding of parametric correlation both developed.
To maintain this arbitrary 50,000 lbs.
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 c:ivironments.
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 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 acceptance criteria in the earlier version of the testing s equirements were not-well-defined and resulted in non-uniform interpretations and imple-mentation. Acceptance criteria were set individually at widely different ranges.
Since the rationale of adopting a specific acceptance criteria was not clear, I&E 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 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 a,nd 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.
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_ From these short-comings it was concluded that the snubber surveillance requirements for the Technical Specifications should be revised.
The revised surveillance requirements correct the perceived deficiencies in the following manner:
1.
A surveillance program must cover mechnical snubbers.
H. B. Robinson Unit 2, however, does not use mechanical snubbers.
2.
No arbitrary snubber capacity is used as a limit to the inservice test requirements.
Capabilities now exist for performing functionality hydraulic tests of control valve block connectors without disassembling large sncobers.
The licensee has committed to test the functionality of the control valve block connectors for large snubbers such as those attached to steam generators.
3.
Seal material no longer requires NRC approval. The licensee has committed to a surveillance program that assures that snubbers are functioning within their service life. A visual inspection will be made every 31 days.
4.
Clearly defined inservice test requirements for snubbers shall be imple-mented.
The revisions that the licensee proposes for Section 4.13 of the Technical Specifications set forth the frequency and scope of visual inspections and functional testing.
5 In-place inservice testing shall be permitted.
The licensee plans to test, in-place, all snubbers that cannot be easily removed.
The croposed license amendment subnitted by Carolina Power and Light Company for Operating License No. DPR-23 for H. B. Robin 1on Unit 2 has incorporated the necessary requirements in Revision 1 of the Standard Technical Specifications for the surveillance of safety-related snubbers ano is therefore, acceptable.
We have made certain changes in the revised Technical Specifications submitted by the licensee.
The changes have been discussed with and accepted by the licensee.
Environmental Consideration We have determined that the amendment does not authorize a change in effluent types or total amounts not 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 151.5(d)(4),
that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
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. 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 activities will be conducted in compliance with tne Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Date:
March 3,1982 9
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