ML20246N135
| ML20246N135 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 08/28/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20246N132 | List: |
| References | |
| NUDOCS 8909080044 | |
| Download: ML20246N135 (3) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION o
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.....,o SAFETY EVALUATION bY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NOS.147 AND 149 TO FACILITY OPERATING LICENSE NOS. DPR-44 and DPR-56 PHILADELPHIA ELECTRIC ~ COMPANY-PUBLIC SERVICE ELECTRIC AND GAS COMPANY DELMARVA POWER AND LIGHT COMPANY ATLANTIC CITY ELECTRIC COMPANY PEACH BOTTOM ATOMIC POWER STATION. UNIT NOS. 2 AND 3 DOCKET NOS. 50-277 AND 50-278 1.0 -INTRODUCTION By letter dated December 28, 1988, the Philadelphia Electric Company requester' an amendment to facility Operating License Nos. DPR-44 and DPR-56 for Peach Bottom Atomic Power Station (PBAPS), Unit Nos. 2 and 3.
The request was to change the requirement for the Source Range Monitor (SRM) minimum count rate during refueling from 3 counts per second (cps) to a relationship which specifies the minimum required count rate as a function of the signal to noise ratio. A.similar amendment incorporating a revised minimum SRM count rate for startup activities, as set forth in a new Figure 3.3.1, was issued as amendment nos.140 and 142 to the PBAPS
-licenses on March 15, 1989.
2.0 EVALUATION The current PBAPS Technical Specifications (TSs) require the SRM to have a minimum count rate of 3 cps for refueling. Because of a long shutdown time, the licensee anticipates that Unit 3 may not be able to achieve
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this count rate for.the.. forthcoming reloading of fuel. The licensee has therefore proposed changes to the TS which would permit such refueling operations, when necessary, with a count rate less than 3 cps.
Unit 2 would also be changed so that consistent TS would be provided for both units. The revised count rate remains within the range of the SRM and no hardware changes are required to the SRM.
The proposed changes are to TS 3/4.3.B. 3/4.10.B and associated BASES.
The changes to TS 3/4.3.B modify the asterisked footnote, which was added by amendment nos. 140 and 142 for startup operations, to make it also applicable to refueling activities. The footnote is also added to TS 3/4.10 which governs core alterations. A portion of the staff's evaluation as included with amendment nos. 140 and 142 is also applicable to this amendment and is included herein for completeness.
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SRM minimum count-rates have previously been? lowered for several k
-reactors, with GE' concurrence, to.0.7 cps with a S/N ratio of'2 for F*
first cycle startup with weak neutron sources resulting from delayed-schedules. GE later evaluated this reduction for reload cores (with
' increased noise) and found that.an increased S/N-limit is required to.-
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. achieve.the same probability of detecting r2al signals. This.
L analysis was done at PECo's request (as a plant specific analysis) for Peach Bottom 2 and 3.
This analysis (for SRM downscale trip i-setpointdetermination)involvesseveralassumptionsaboutthe signal and noise characteristics and probability. requirements, and -
uses the new standard GE setpoint methodology for setpoint-uncertainties. The assumed signal characteristics are straightforward and acceptable. A primary assumption is:that;there will be only a 5 i
percent probability of incorrectly detecting neutrons when they are absent and a.95 percent probability of detecting them when present.-
This is a reasonable criterion. The NRC review of'these various assumptions and probability requirements, and of the analysis methodology concludes that an acceptable analysis has'been developed
.to provide the SRM downscale setpoint and corresponding TS limit for SRM operability.
As noted above, the primary statistical basis for the ' values on the count rate to signal-to-noise curve of Figure 3.3.1 is the same as for the minimum value of 3 cps, namely that there is a statistical neutron monitoring confidence of 95% that the indicated signal is correct. The
' licensee has found no need to modify this basis for events related to refueling activities. The staff has compared the UFSAR analyzed events for the startup activities (the control rod drop accident'and the continuous rod withdrawal) with those' analyzed for refueling activities (the control rod removal error during refueling and the fuel assembly insertion error) and concludes that the primary issue'for either startup or refueling is whether the SRMs provide an' acceptable level'of confidence of detecting neutrons when they are present. Having found the licensee's rationale to be acceptable in this regard the staff concludes that the proposed change to TS 3/4.3.B, 3/4.10.B and BASES, providing alternate limits for refueling as set forth in Figure 3.3.1, is acceptable. This approval is specific to the Peach Bottom units.
The staff notes that the licensee's analysis in its December 28, 1988 applicationdiscussesthecorrelationofthelowestallowaglecountrateon Figure 3.3.1 (0.7 cps) to e value of approximately 7 x 10~ of rated power. The licensee then relates this power level to an assurance that the assumptions used in the transient analyses are not invalidated. This is clearly applicable for the startup events analyzed in the UFSAR, however, the staff finds no similar criterion referenced in the FSAR for the refueling gents, naniely that they are assumed to be initiated at or above about 10 of rated power, and therefore this appears to be an extraneous comment for the refueling events analyzed by the application.
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This does not detract from the staff's findings as noted above since the
-principle issue is whether the relationship of Figure 3.3.1 provides the same confidence level as the former limit of 3 cps.
A change in the title of the station superintendent to " Plant Manager" on L
'TS BASES page 110 is also made to provide consistency with changes to the organization that were reviewed and approved in amendment nos 132 and 135
.on June 22, 1988. This change is straight forward and is acceptable.
3.0 ENVIRONMENTAL-CONSIDERATIONS These amendments involve a change to a requirement with respect to the installation or use cf a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements..
The staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite and that there is no significant increase in individual'or cumulative occupational radiation exposure. The Comission has previously issued a proposed finding that the amendments involve no significant hazards consideration and there has been no public comment on such finding. Accordingly, the amendments meet the eli criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9)gibility Pursuant to 10 CFR 51.22(b), no environmental impact statement nor environmental assessment need be prepared in connection with the issuance of the amendments.
4.0 CONCLUSION
The Comission made a proposed determination that the amendments involve no significant hazards consideration which was published in the Federal Register (54 FR 27232) on June 28, 1989 and consulted with the State of Pennsylvania.
No public coments were received and the State of Pennsylvania did not have any coments.
The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the ublic will not be endangered by operation in the proposed manner, and p(2) such activities will be conducted in compliance with the Comission's regulations, and the issuance of the amendments will not be inimical to the comon defense and security or to the health and safety of the public.
Principal Contributors:
R. Martin, H. Richings Dated:
August 28, 1989
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