ML15112B085
| ML15112B085 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 11/22/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML15112B084 | List: |
| References | |
| NUDOCS 8212010421 | |
| Download: ML15112B085 (4) | |
Text
$10t REG,SAE o0 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 117 TO FACILITY OPERATING LICENSE NO.
DPR-38 AMENDNENT NO. 117TO FACILITY OPERATING LICENSE NO.
DPR-47 AMENDMENT NO. 114TO FACILITY OPERATING LICENSE NO.
DPR-55 DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNITS NOS.
1, 2 AND 3 DOCKETS NOS. 50-269, 50-270 AND 50-287 Introduction By letter dated April 30, 1982, Duke Power-Company (Duke or the Licensee) submitted an application to amend-the Oconee Nuclear Station (0NS) common Technical Specifications (TSs) by adding provisions for the digital logic channels in Specification 3.5 and the Emergency Power Switching Logic (EPSL) in Specification 3.7.
The lack of operating requirements for these two systems was considered, by Duke, to be a shortcoming of the current TSs.
An additional application was submitted by letter dated September 27, 1982, to revise the bases of Specification 3.3 to clarify redundant component operability testing and delete the TS requirement in Specification 6.4.2 concerning quarterly site emergency drills.
Evaluation A. Digital Logic Channels The current TSs contain operability requirements for various instrumentation systems. Specification 3.5.1, "Operational Safety Instrumentations," delineates the conditions of instru mentation and safety circuits necessary to assure reactor safety in Table 3.5.1-1, but does not address the digital logic channels.
Duke considers (and we agree) the lack of operating requirements on the digital logic channels to be a shortcoming of the TSs.
Therefore, Duke proposed, by letter dated April 30, 1982, that the digital logic channels be included in the TSs.
We have reviewed the addition of the digital logic channels and find that the proposed requirements are consistent with the current TSs for similar systems and are also consistent with current staff positions. A number of editorial corrections were made, with the concurrence of Duke, to clarify the requirements.
Since these changes are additions to incorporate acceptable new requirements, we find them acceptable.
8212010421 821122 PDR ADOCK 05000269 P
-2 B. Emergency Power Switching Logic (EPSL)
In addition to the digital logic channels discussed in A. above, Duke's April 30, 1982 application requested changes to Specification 3.7, "Auxiliary Electrical Systems." The proposal contains three major changes: 1) the addition of explicit operating requirements for the EPSL, 2) the addition of a requirement related to an extended outage of the Keowee transformer, and 3) the clarification of current requirements for the operation of the 125VDC Instrumentationand Control Systems.
The EPSL circuitry is designed to insure that a reliable source of power is available to the 4160V Main Feeder Buses (MFB) under all modes of operation. These circuits are designed to further insure that during or after any postulated accident, a continuous supply of power is available to bring the reactor to a safe shutdown condition. The EPSL provides power to the MFB by monitoring all available sources of power and closing or tripping the appropriate 4160V circuit breakers.
Available sources of power to a unit's MFB are the unit's Auxiliary Transformer (1T, 2T, 3T); the unit's Startup Transformer (CT-1, CT-2, CT-3); or the two Standby Buses (Standby Bus 1, Standby Bus 2).
The Standby Buses can, in turn, be supplied from either transformer CT4 which is powered from the Keowee hydro units or CT5 powered from the Lee Station gas turbine generator. If emergency power is required at Oconee, the EPSL is designed to automatically select an emergency source from either the Startup Transformer or the Standby Bus. The Keowee Emergency Start logic is designed to automatically start both Keowee units to supply emergency power if this source is required.
The EPSL contains undervoltage circuits that monitor each phase of the 4160V outputs of the Normal and Startup Transformers, and each phase of the two Standby Buses. A loadshed circuit is provided which is designed to automatically shed (trip) non-essential loads before a transfer to a Standby Buses occurs. A transfer to Standby and retransfer to Startup circuit is designed to, in a power-seeking configuration, automatically select the most readily available source to supply the unit's MFB.
The Keowee Emergency Start circuits monitor several plant conditions to determine the need for a Keowee hydro unit to supply electrical power to Oconee. The circuits are designed to start both Keowee units with no operator action necessary and thus insure that the EPSL circuitry can perform its intended functions.
-3 The proposed TSs on the EPSL circuitry require the operability of all EPSL circuitry for heatup above 200aF and for startup of the reactor. Operation of the unit with certain circuits or channelis of the EPSL inoperable for test or maintenance is permitted for periods of up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, provided that the inoperable circuits/
channels are in only one portion, or functional unit of the EPSL and provided that a sufficient number of circuits/channels in the affected functional unit remain operable such that the functional unit does not lose its ability to perform its designed safety function. These provisions are designed to ensure that only one portion of the EPSL is degraded at a time for test or maintenance and that the affected portion remains operable although degraded.
If the circuits or channels of more than one functional unit become inoperable, continued operation would be permitted, provided that the inoperability results from a loss of power to some of the functional units due to the inoperability of a 125VDC instrumentation and control (I&C) panelboard.
Even with the loss of a 125VDC I&C panelboard, the affected functional units are required to remain capable of performing their designed safety functions.
The inoperability of one 125VDC I&C panelboard will not cause the loss of an EPSL functional unit, but will degrade them due to the loss of power to some of the circuits/channels. Operation with an inoperable panel board would be allowed for a maximum of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> if the EPSL was not in a degraded mode prior to the panelboard inoperability.
The other changes to Specification 3.7 provide clarification of the actions to be taken in the event a Keowee transformer is inoperable and provide explicit operating requirements for the 125VDC I&C systems.
The proposed TSs meet the criteria delineated in 10 CFR 50 Appendix A, Criteria 17 and 18 as well as IEEE Standards 308, 1978 and 338, 1977.
Having reviewed the licensee's April 30, 1982 submittal consisting of the proposed TS changes and the associated discussions for their change, we have determined that safe operation can be accomplished and conclude that the proposed changes to the TSs are acceptable.
C. Redundant Component Testing By letter dated September 27, 1982, Duke applied for a revision to the Bases of Specification 3.3 related to redundant component testing.
The current Bases state that redundant component testing-:
will be performed "immediately prior to removal" of the component from service. Since the term "immediate" is subject to judgmental interpretation, Duke requested a more.definitive description and proposed "within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to removal." We agree that the term immediate is subjective and further agree that 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is a reasonable interpretation considering the time required to perform these tests. Therefore, we consider this change administrative in nature and find it acceptable.
-4 D. Emergency Drills The current Specification 6.4.2 requires selected site emergency procedure drills to be conducted quarterly. Subsequent to the incorporation of this requirement into the TSs, 10 CFR Part 50, Section 54(s) and Appendix E were revised to specify the frequency and content of site emergency drills. In accordance with these requirements, Duke revised (revision 82-5) the ONS Emergency Plan to be consistent with applicable NRC staff positions. Since these revisions raise a possible conflict between the Emergency Plan and the TSs, Duke, by letter dated September 27, 1982, requested that Specification 6.4.2 be deleted. Since the revised Emergency Plan requires an acceptable schedule for site drills and is consistent with the Emergency Plan at the McGuire Station, and since the Regulations now specify the schedule and content of site emergency drills, we find the proposed change to be an acceptable way to remove unnecessary duplication of requirements.
Therefore, Specification 6.4.2 has been removed and Specification 6.4.3 has been renumbered 6.4.2.
Environmental Consideration We have determined that the amendments do 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 amendments involve an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR §51.5(d)(4), that an environmental impact statement, or negative declaration and environ mental impact appraisal need not be prepared in connection with the issuance of these amendments.
Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or consequences of an accident previously evaluated, do not create the possibility of an accident of a type different from any evaluated previously, and do not involve a.significant reduction in a margin of safety, the amendments do 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 these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated:
November 22, 1982 The following NRC personnel have contributed to this Safety Evaluation:
Philip Wagner, William Orders.