ML20115B427
| ML20115B427 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 04/04/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20115B425 | List: |
| References | |
| NUDOCS 8504170665 | |
| Download: ML20115B427 (3) | |
Text
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orog 7g UNITED STATES
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WASHINGTON, D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0.90 TO FACILITY OPERATING LICENSE NO. DPR-24 WISCONSIN ELECTRIC POWER COMPANY POINT BEACH NUCLEAR PLANT, UNIT NO. 1 DOCKET NO. 50-266 Introduction On November 9,1984 Wisconsin Electric Power Company (licensee) requested Technical Specification changes for the Point Beach Nuclear Plant Units 1 and 2.
These changes would incorporate additions to Specifications 15.2.3.1.B(4),
i "Overtemperature T", and 15.2.3.1.B(5), " Overpower T", to revise certain time constants which are part of the sensing circuitry. As a result of the staff's review, the licensee provided supplemental information in letters dated November 14, and 15, 1984 and December 13, 1984.
This Safety Evaluation addresses only Point Beach Unit No. 1.
Amendment No. 91 concerning this application was issued for Point Beach Unit No. 2 on November 16, 1984.
l Discussion and Evaluation On October 5,1984 the NRC issued to Wisconsin Electric Power Company License l
Amendments 86 and 90 to Facility Operating Licenses DPR-24 and DPR-27, respec-tively. These license amendments include Technical Specification revisions to allow the use of Westinghouse optimized fuel assemblies (0FAs) at Point Beach Nuclear Plant, Units 1 and 2.. The safety evaluation provided with these amend-ments also approved several changes to the analysis and operating procedures for the reactors, including use of the Westinghouse improved thermal design procedures for the OFA fuel.
In preparation for use of 0FA fuel and the improved thermal design procedures, the'11censee observed that the primary system resistance temperature detectors (RTDs) are required to satisfy an enhanced calibration accuracy. The licensee determined that electrical noise associated with switching between a calibration 1
standard RTD and the Sostman RTDs installed at Point Beach interfered with the calibration procedure. The licensee detemined that replacing the Sostman RTDs with Rosemont RTDs would satisfy the calibration requirements. The licensee therefore, expedited procurement of Rosemont RTDs and informed Westinghouse of this action.
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Westinghouse H vised the licensee that.the more accurate Rosemont RTDs are also. fast-response RTDs and likely to produce extraneous noise spikes during plant operation. The originally installed reactor protection system instru-
. mentation channels included lag circuits for the AT and T measurements, 4
which had been set for zero intentional delay (lag) for 'uN'with the slower responding Sostman RTDs. To avoid spurious plant trips, Westinghouse recom-mended that the lag circuits be adjusted to provide a lag with a two second time constant when the Rosemont RTDs are being used.
The licensee and Westinghouse have stated that the response time of the original Sostman RTDs is believed to be 2 - 2.5 seconds, based upon results of testing performed by the manufacturer some years ago. -The response time of.the original RTD plus the associated intentional lag (for the AT and Tave measurements) was therefore 2 - 2.5 seconds.
The licensee and Westinghouse have stated that the response time of the new RTDs is believed to be 0.5 seconds, based upon results of testing performed by the manufacturer. The response time of the new RTD plus the proposed.
intentional lag is therefore 2.5 seconds.
The licensee and Westinghouse have stated that the uncertainty value used by
- Westinghouse in the overpower-delta T trip and the overtemperature-delta T trip analyses is greater than the possible 0.5 second difference between the worst case Sostman RTD value (2 seconds) and the new Rosemont RTD value (2.5 i
seconds).- In fact, the uncertainty value would also encompass any possible
- future degradation in the response time of the RTD from 0.5 second to 1.0 seconds. Therefore, this shifting of time allocations amongst various terms in the overpower-delta T and overtemperature-delta T equations is acceptable.
To assure that the response time of the new fast-response RTD stays within limits, the licensee has agreed to monitor indirectly the response time of these RTDs on a periodic basis over the rest of the plant 1ife. The method to be used is to establish the signature of.the noise response of the RTD
.and periodically compare the noise signature to the base case.
If the response
. time of the RTD degrades, the noise being generated should also change. This method is to be developed and proven during this plant operating cycle and l
then used routinely on a refueling outage basis' thereafter. We believe that this method is an adequate and acceptable method for monitoring response time t
L performance for this application for this particular nuclear plant.
l
.The proposed. Technical specifications have been modified to reflect the
. mathematical equivalent of the entire circuit.
Indeed. the change to the-overtemperature delta T and overpower delta T equations requested in this application does no more than add a mathematical term (1/1 + ts) which was always implicit in the equations in the existing' Technical Specifications, but was never explicitly stated because, with the Sostman RTDs,, was equal to 0 and 1/1 + 0 was equal to 1.
Thus, the tem previously had no mathematical l
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. significance. As stated above, the system response with the new lag filter setting and new RTD compared to the old RTD is acceptable.
Based on the information provided by the licensee and the commitments given, the staff finds the licensee's proposed Technical Specification acceptable for Point Beach Unit 1.
Point Beach Unit 2 Technical Specifications were issued on November 16, 1984 due to emergency circumstances specific to the unit.
ENVIRONMENTAL CONSIDERATION This amendment involves a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
The 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 o'ffsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Comission has previously published a proposed finding that the amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 951.22(c)(9).
Pursuant to 10 CFR 951.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
CONCLUSION We have 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, and (2) such activities will be conducted in compliance with the Comission's regulations, and the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Date: April 4, 1985 Principal Contributor:
l J. T. Beard T. Colburn I
l