ML15113A174
| ML15113A174 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 07/17/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML15113A173 | List: |
| References | |
| NUDOCS 8507310236 | |
| Download: ML15113A174 (3) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.141 TO FACILITY OPERATING LICENSE NO. DPR-38 AMENDMENT NO. 141 TO FACILITY OPERATING LICENSE NO. DPR-47 AMENDMENT NO.
138 TO 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 1.0 Introduction By letter dated March 19, 1985, as supplemented on May 1, 1985, Duke Power Company (the licensee) proposed changes to the Technical Specifications (TSs) of Facility Operating Licenses Nos. DPR-38, DPR-47 and DPR-55 for the Oconee Nuclear Station, Units Nos. 1, 2 and 3. These amendments would consist of changes to the Station's common TSs.
The proposed amendments would revise TS 3.7.2(e)2 to allow a one-time extension of the allowable period of.inoperability from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 10 days per battery for the installation of new Keowee batteries and battery racks.
The reason for the replacement is that the licensee has determined that there is insufficient documentation on the seismic capabilities of the existing Keowee 125 VDC batteries and racks. The licensee has estimated that this new changeout cannot be accomplished during the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> time period currently allowed by TS 3.7.2.(e).2, but has requested a maximum of 10 days for each of the two batteries.
2.0 Discussion DC System Although diesel generators are used as the most common source of onsite electric power, Oconee Nuclear Station uses the Keowee Hydro Station as the source of two independent on-site emergency power paths. The Keowee Hydro Station is part of the Auxiliary Electrical System that assures safe reactor operation and provides for continuing availability of engineered safety features systems. The subject batteries in the Keowee Hydro Station provide only control and motive power to start the Keowee Hydros. Aside from the Keowee Hydro Station batteries, each Oconee Nuclear Station Unit maintains separate and redundant 125 VDC system (Class 1E) for the vital instrumentation and control power system which is normally required for reactor operation and orderly shutdown.
8507310236 B50717 PDR ADoCK 05000269 P-Po
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-2 The Keowee Hydro Station is in the process of ordering replacement-cells for both of the Keowee 125 VDC power system batteries. Each Keowee Hydro Unit has a separate 125 VDC power system consisting of a 125 VDC battery charger, a 125 VDC battery and a metal clad distribution center. The two 125 VDC power systems, in Keowee, can be connected through an interlocked bus tie arrangement (two breakers in series) which permits one 125 VDC battery to be removed for testing/servicing while maintaining the capability to supply the required DC loads of both Keowee Units with the remaining battery.
3.0 Evaluation Our review of the Oconee Nuclear Station offsite power system shows that the following sources are available:
- 1. The 230 kV and 525 kV transmission system;
- 2. The 100 kV transmission system;
- 3. Two Keowee Hydro Units (one 13.8 kV underground path);
- 4. The two other nuclear units (onsite).
The 230 kV (normal offsite power source) and 525 kV switchyards are separated and connected.by a transformer. Each of the switching stations (buses, disconnect switches and circuit breakers) are arranged into a reliable breaker-and-a-half scheme. Also, the number of offsite power lines to onsite distribution exceeds the minimum requirement of two. Moreover, our review of the EPRI publication (EPRI NP-2301), "Loss of Offsite Power at Nuclear Power Plants:
Data and Analysis" lists only one partial loss of offsite power event for Oconee which occurred on April 19, 1973. Although the event isolated and deenergized the 230 kV switchyard for one hour, the rest of the offsite power sources listed above were available throughout the event.
In view of the reliability inherent in the Oconee offsite power system design and the low incidence of this event at Oconee, we have determined that the potential for a loss of offsite power within the time period of the 10 days requested for installation of each of the new batteries is acceptably low.
In addition, with one of the Keowee batteries out of service, the remaining battery unit can be used to start both of the Keowee Hydro electric emergency power units.
Each of the existing Keowee batteries has an in rush (one minute) rating of 1670 amp hours and 906 amp hours for one hour while the required DC load for both Hydros is 1480 amp hours (in rush) and 308 amp hours for one hour. This indicates that one battery has more than sufficient capacity to start both Hydros. Furthermore, to ensure the capability of the battery to start two Hydro units, the licensee in a letter dated May 1, 1985 stated that they will perform a compensatory test which will demonstrate the battery capability prior to installing the new battery. The second battery replacement outage will not begin until the newly installed battery is verified operable. Thus, given a very unlikely total loss of offsite power during these short outage periods power will be available to start the emergency power units.
-3 Based on the above, we find acceptable the proposed amendment, whicERfallows a one-time extension of inoperability for a period of 10 days for each battery on a staggered basis to install new Keowee seismically qualified batteries and battery racks.
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.
We have 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 Commission has previously issued 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 51.22(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 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 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: July 17, 1985 Principal Contributor: P. Kang