ML20028F039
| ML20028F039 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 01/19/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20028F037 | List: |
| References | |
| NUDOCS 8301280501 | |
| Download: ML20028F039 (3) | |
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,l w NUCLEAR REGULATORY COMMISSION 3
WASHINGTON, D. C. 20555
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\\; :s j SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTCR REGULATION RELATED TO AMENCMENT NO. 61 TO FACILITY OPERATING LICENSE NO. OPR-66 DUQUESNE LIGHT COMPANY OHIO EDISON COMPANY PENNSYLVANIA POWER COMPANY BEAVER VALLEY POWER STATION, UNIT NO. 1 DOCKET N0. 50-334
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Introduction In a ' letter dated December 16, 1982, Duquesne Light requested proposed' Change Request No. 75 to the Operating License of Beaver Valley Power Station, Unit No. 1.
This change proposes to reduce to 50% from 75% the.
number of incore moveable thimbles required for the system to be operable.
The licensee provided documentation in a letter dated January 4,1983 supporting increase of the moveable incore detector map measurement uncertainty as part of the change request. Review of this documentation will be undertaken in the future. The present evaluation only considers acceptability of the proposed change on an interim basis for the duration of the present operating Cycle, Cycle 3.
Evalua tion Essentially all PWR Technical Specifications contain a requirement for operability of 75% of the incore detector locations for pe iodic mapping of the core power distribution. On a number of occasions, for various reasons, 8301280501 830119 PDR ADOCK 05000334 P
. failures in operating PWRs have approached or exceeded 25%, and relaxation of the 75% requirement has been pennitted for the duration of affected reactor operating cycles.
The licensee's proposed change allows for the increas'e' in the moveable incore map measurement uncertainty above the 5% nonnal allowance by the relationship 5% + [3-T/12.5]2%, where T is the number of unfailed detectors.
This relationship increases the uncertainty allowance to 7% when half the thimbles are used. The uncertainty in the measurement of U is 4% and is AH proposed to be increased by the relationship 4% + [3-T/12.5]1%. These allowances are similar to those made for other reactors, The licensee has provided the results of recent core maps which show that there currently is approximately 32% margin in total core peaking factor and 13%marginin(H to the Technical Specification limits for steady state operating conditions. Since the unit does not 'ioad follow, and both the totalcorepeakingfactorand[lLH nonna11y tend to decrease with burnup, we conclude that these margins, along with the proposed increases in measure-ment uncertainty, are sufficient to preclude concern that required monitoring l
of the limits could fail to detect a pr0blen for the remainder of the operating cycle.
Another safety concern relating to degradation of incore mapping ability is the ability to detect anomalous conditions in the core. One of these is inadvertent loading of a fuel assembly into an improper position. Since this is a loading problem, it is not of concern for the remainder of the operating cycle. Other anomalous conditions are conceived to produce either an axial or radial effect, which would cause either a change in quadrant,.
tilt ratio or axial offset ratio. These are monitored by the excore detectors.
and would help identify problems not fully detectable with reduced incore mapping capability. Furthennore, the core exit thennocouples in the reactor provide a useful supplement to the incore detectors to detect problems.
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, i Our review of the suitability of operation of the Beaver Valley Unit I reactor for the remainder of the Cycle 3 with a reduced number of movable incore thimble locations to as few as 50% indicates that adequate margin exists at this time in Cycle 3 and sufficiently increased uncertainity allowance has been made to ensure that Technical Specification peaking factor limits will be met. In addition, there are adequate supplemental indicators of anomalous conditions to preclude an unsafe condition from escaping detection 'in the absence of full incore detector mapping cap-ability. We therefore conclude that proposed Technical Specification Change Request No. 75 is acceptable for the remainder of the Beaver Valley Operating Cycle 3.
l Environmental Consideration We have determined that the amendment coes 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 l
l involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR Sl.5(d)(4), that an environmental impact statement or negative declaration and environ-i mental impact appraisal need not be prepared in connection with the issuance of this amendment.
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 an accident previously evaluated, does not create the possibility of an accident of a type different from any evaluated previously, and does not involve a significant reduction in a margin of safety, 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 the Commission's regulations and the issuance of this amendment will l
not be inimical to the common defense and security or to the health and safety of the public.
4' Dated: January 19, 1983 Principal Contributor M. Dunenfeld G
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