ML20059L963
| ML20059L963 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 11/10/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20059L954 | List: |
| References | |
| NUDOCS 9311180034 | |
| Download: ML20059L963 (3) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION c
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WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 26TO FACILITY OPERATING LICENSE NO. NPF-86 NORTH ATLANTIC ENERGY SERVICE CORPORATION SEABROOK STATION. UNIT NO. 1 DOCKET NO. 50-443
1.0 INTRODUCTION
By "05000443/LER-1993-009, :on 930520,manual Reactor Trip from 100% Power Initiated When MSIV Closed During Quarterly Testing, Resulting in Feedwater & Two Emergency [[system" contains a listed "[" character as part of the property label and has therefore been classified as invalid. Isolations. Caused by Debris in Valves.Valves Replaced|letter dated June 18, 1993]], the North Atlantic Energy Service Corporation (North Atlantic) proposed changes to the Seabrook Station, Unit 1 Technical Specifications (TSs) to reduce the frequency of surveillance required to verify the integrity of the condensate storage tank (CST) enclosure. The present Surveillance Requirement 4.7.1.3 requires that.the integrity of the CST enclosure be verified at least every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, the same frequency that is required for verifying the CST level.
The proposed amendment would reduce the frequency of surveillance of the CST enclo;ure to at least once every 18 months.
This is the same surveillance frequency required by TS 4.6.5.1 for verifying the integrity of the containment enclosure.
2.0 EVALUATION The CST at Seabrook is the safety-related (and only) source of water for the emergency feedwater (EFW) system, therefore, it is required to remain i
functional under all conditions, including tornadoes.
Except for the tank roof, the CST is protected from tornado-generated missiles by a reinforced concrete enclosure that completely encircles the tank. This concrete enclosure is designed to contain the CST contents thereby assuring an adequate source of water for the EFW system in the unlikely event that a tornado-generated missile were to penetrate the top of the CST and cause a tank i
rupture.
In accordance with TS 4.7.1.3, the CST is verified OPERABLE at least every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> by verifying that the tank contains the minimum required volume and by verifying the integrity of the CST enclosure. The integrity verification is performed each shift by an auxiliary operator (AO). The A0 verifies the integrity of the CST enclosure by observing the immediate concrete enclosure around the tank and observing that the seals associated with the enclosure penetrations do not have work ongoing that may cause degradation.
North Atlantic asserts that the maximum 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> frequency for performing the i
integrity check is burdensome to the operating crew in that it diverts an A0 for a short time each shift to perform an activity that does not provide any substantial information related to the integrity of the enclosure. North 9311180034 931110 PDR ADOCK 05000443 P
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Atlantic considers that the activity most likely to affect the integrity of the enclosure is maintenance related to the penetration seals. Maintenance activities on the CST enclosure penetration seals would be performed in accordance with the Static,n work control program and would necessitate entry a
into the Action Statement for the enclosure being inoperable if the work occurred during MODES 1, 2 or 3.
In all cases the work control program would require the verification of the enclosure integrity at the completion of the t
maintenance.
The proposed revision to TS 4.7.1.3 would change the frequency of the enclosure integrity verification to at least 18 months. The 18-month frequency was selected based on the frequency of the containment drawdown test which is also performed every 18 months.
The containment drawdown test i
verifies the leak-tightness (integrity)- of the concrete containment and concrete containment enclosure. The concrete containment enclosure performs a function similar to the CST concrete enclosure, and, therefore, the frequency of testing should be similar.
i Under the proposed change, the 18-month CST enclosure and seals inspection will be similar to inspections performed on the containment prior to Type A testing as required by 10 CFR 50 Appendix J, Section V.A.
The procedure will.
i involve a general inspection of the accessible surfaces to uncover any t
evidence of structural or seal degradation which may affect either the structural integrity or leak-tightness. The inspections will be performed by the Station Technical Support orginization, the organization that performs similar inspections of the contair. ment and containment enclosure.
Because these personnel have the requisite expertise and knowledge to detect potential 1
degradation, the inspections will be more in-depth and superior to that which is now performed by the A0.
The staff does not know of any technical basis for inspecting the concrete enclosure every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> as required by the existing Technical Specifications.
It is a passive structure that is only relied upon following a tornado missile that has penetrated the top of the CST and somehow resulted in a tank rupture.
The staff agrees with North Atlantic that the condition of the enclosure is not expected to change from day-to-day and that an inspection frequency similar to other concrete structures performing similar functions is more appropriate. This type of inspection would be more thorough and more likely to determine if the enclosure was capable of performing its safety function.
Based on its review, as described above, the staff concludes that the existing Technical Specification for the concrete CST enclosure inspection frequency is-unnecessarily restrictive and does not provide much in the way of safety. The brief inspection that is performed every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> is not likely to find any failures other than obvious gross failures that would probably be noticed by plant personnel anyway. Therefore, the staff concludes that the proposed changes to TS 4.7.1.3 are acceptable.
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3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the New Hampshire and Massachusetts State officials were notified of the proposed issuance of the amendment. The State officials had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a surveillance requirement.
The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released i
offsite, and that there is no significant increase in individual or cumulative l
occ;gational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (58 FR 43928). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR i
51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
5.0 CONCLUSION
The Commission has 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, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
William T. LeFave Date:
November 10, 1993
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