ML20073L042
| ML20073L042 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 05/08/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20073L040 | List: |
| References | |
| NUDOCS 9105130174 | |
| Download: ML20073L042 (3) | |
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l SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N05. 12/ AND 131 TO FACILITY OPERATING LICENSE N05. DPR-24 AND DPR-27 WISCONSIN ELECTRIC POWER COMPANY POINT BEACH NUCLEAR PLANT, UNIT N05. 1 AND 2 DOCKET N05.50-26f AND 50-301
1.0 INTRODUCTION
By letter dated October 30, 1990, Wisconsin Electric Power Company applied for an amendment which would allow startup of the Point Beach Nuclear Plant I
without neutron source assemblies in the reactor core.
Specifically, the licentee would revise Technical Specification 15.5.A.3.5, " Design Features, Reactor," to read " Neutron source assemblies may be used to provide a required minimum count rate during startup operations.
A source assembly, if used, would typically consist of four source rodlets comprised of a mixture of antimony and beryllium." The specification cutrently states that neutron source assemblies are used to provide a required m'nimum count rate during startup and that the core contains at least two such assemblies, each containing four source rodlets comprised of the mixture of actimony and beryllium.
The licensee would insert a new specification in Section 15.?.1.F, " Limiting Conditions for Operation, Reactor Coolant System, Minimum Cunditions for Criticality." The new specification would state thet "during an approach to criticality, at least one (1) count per second, attributable to neutrons, shall register on a narrow range source range nuclear instrument." The corresponding basis section would be revised to explain that the count rate on the source range instrumentation is evidence that the instrumentation is functioning.
2.0 EVALUATION l
Prior to reactor startup, the reactor operator should verify that the source L
range neutron flux monitoring instrumentation is functioning to ensure that the plant operators have the means to monitor the subtritical neutron multiplication during the reactor startup and approach to criticality. This reduces the probability of inadvertent criticality at this stage of operation.
The monitoring instrumentation verification is accomplished by observing that a count rate is indicated on the instruments.
For the instruments to l
indicate a count rate, there must be an active source of neutrons in the l_
reactor core prior to startup.
The NRC staff does not specify what this source of neutrons must be. The staff does address the objective in Regulatory Guide 1.68, " Initial Test 9L05130174 91050G PDR ADOCK 05000266 P
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,. Programs for Water-Cooled Nuclear Power Plants, Appendix A, Initial Test Program," recommending that "a neutron count rate at least 0.5 per second should register on the startup channels before the startup begins..."
At the time of initial fueling of a reactor, it is necessary to place neutron sources in the reactor core with the fuel to provide a count rate on the source range neutron monitors for the first sta tup.
After the reactor has been operated at power and then shut down, there is significant emission of neutrons from fission product decay in the irradiated fuel. Although the rate of neutron emissions from the fission products decreases with time after irradiation, the rate of emission at the end of a normal refueling outage should exceed the minimum count rate nehded for instrument verifi-cation. Separate secondary neutron sources are not normally required for i
subsequent restarts.
If the reactor were kept shutdown for a long duration, for example, an extended maintenance outage, neutron sources might again i
L be necessary to provide neutron indication on the source range monitors.
The licensee has stated that the amendment would not impact safety because the amended technical specifications would include a requirement that a count rate be indicated before startup, in-fact, this is a more effective requirement since it focuses more directly on the monitoring instrumentation.
The staff has reviewed the application and concurs that there is no reduction in safety resulting from making the use of the neutron sources optional.
The staff further finds that since the count rate of one count per second included in the proposed new specification exceeds the value of one-half count per second set forth in Fegulatory Guide 1.68, the proposed amendment provides an adequate margin of safety.
The description of the neutron sources was first placed in the technical specifications by License Amendments 120 and 123, dated May 8, 1989, for Units i and 2, respuctively, h issuing these earlier amendments, the staff found "the addition of the description of the neutron source assemblies is acceptable because it provides a necessary description of a core feature.'.'
The issuance of the. Amendment under current consideration does not represent a change in that po?ltion. The proposed revision indicating that the use of neutron sources is 'sptional, in light of the minimum count rate referred to in the technical specification, remains an adequate description of the core feature.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Wisconsin State official was notified of the propo'ed issuance of the amendment. The State " ficial s
l had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
These amendments involve a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 I
or change an inspection or surveillance requirement.
The staff has determined l
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1 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 occupa-tional radiation exposure.
The Commission has previously published [56 FR 11787, March 20,1991] a proposed finding that these amendments involve no significant hazards consideration and there has been no public comment on such finding.
Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 551.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of these amendments.
5.0 CONCLUSION
The staff has concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safet not be endangered by operation in the proposed manner, (2) y of the public will such activities i
will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the publb.
Principal Contributor:
Robert B. Samworth, DRPW Date: flay 8,1991 1
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