ML20133C079
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SAFETY EVALUATION REPORT TO SUPPORT INTERIM TECHNICAL SPECIFICATIONS FOR DIESEL GENERATORS AND GAS TURBINE GENERATORS 1.0 Introduction For low pow *er operation the applicant has proposed to use the three gas turbines as supplemental ac sources to the onsite distribution system durinc the period of time when one TDI diesel generator (Division 1) is unavailable for disassembly and inspection of diesel engine components.
The available sources during this time will be the offsite systems (115 KV and 500 KV networks), one TDI diesel generator (Division 2), and the gas turbine generators; however, for conservatism both TDI diesel generators were considered unavailable in the staff's analysis.
We have reviewed the 500 KV and 115 KV transmission lines and the gas turbine generator set connected to the offsite system and evaluated their capacity, capability, reliability and required redundancy as follows:
2.0 Offsite Power The offsite power system had previously been reviewed in the Safety Evaluation Report of the FSAR and was found to satisfy the capacity, capability, reliability and redundancy requirements and, therefore, is acceptable.
3.0 Gas Turbine Generator The gas turbines are presently being installed at Grand Gulf near the Unit 2 diesel fuel oil, storage tanks. This location will provide an advantageous electrical connection to the non-Class 1E portion of the Unit 1 plant distribution system. The three units are connected in parallel through their associated
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' circuit breakers to the non-Class 1E 4160-volt distribution system which in turn feeds the Class 1E 4160-volt buses.
In view of the physical location of the gas turbines, surrounded by large substantial structures, it is highly unlikely th'at a tornado would damage the gas turbines simultaneously with both the 115 KV and the 500 KV offsite power sources. Therefore, the gas turbine power source is expected to be available to the onsite distribution system to provide power to the safe shutdown loads for a tornado event which may damage the offsite power sources. Also, the location will prevent unavailability of the gas turbines due to flooding and normal standing water conditions.
The gas turbine generator set consists of three units. Two units have a capacity of 2000 KW each and the third unit has a capacity of 2200 KW. Our review found that, of the three units, the combination of the two smaller units, aggregate rating of 4000 KW, is sufficient to provide power to a division of safe shutdown loads, of 3200 KW, for long-term cooling.
Each gas turbine has a separate auxiliary power unit (APU) for starting. A single APU can be used to start any one of the gas turbines. The gas turbine is designed for manual dead-line starting capability:
1.e., the gas turbine is capable of starting and accelerating to rated speed and voltage by using an APU. Af ter the three units are started and up to rated speed and voltage, the first unit's circuit breaker is closed to the dead bus and the remaining units are synchronized in sequence to the first unit and thus become ready to provide power to bus.
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. To demonstrate this capacity and starting capability feilowing initial testing, the licensee will perform periodic tests as follows:
(1) at least once every 15 days, each GTG will be started, brought to rated speed and voltage, and run for at leas't 60 minutes; (2) at least once every 31 days, the GTGs will be started, synchronized and loaded to 4700 KW in less than or equal to 25 minutes and operated with a load greater than or equal to 4700 KW for at least 60 minutes. The periodic tests and the interim surveillance require-ments for the gas turbine generators in the proposed technical specification are equivalent to that for the emergency standby power supplies. We believe that these surveillance requirements are adequate for the period of time when one TOI diesel generator is being inspected.
4.0 Technical Specifications
- 1) The current surveillance requirements and LCOs for the offsite power sources, DG #12 and DG #13 remain the same.
- 11) Surveillance requirements as stated in item 3 above and LCO for the gas turbine generators will be incorporated into the interim technical specifications, iii) Additional operability requirements for DG #12, DG #13, and GTGs during tornado warning / watch conditions will also be included in th'e interim technical specifications.
Conclusion The Reactor Systems Branch in their memorandum ( April 12, 1984, Mattson to Eisenhut,
Subject:
Risk of 5% Power Operation At Grand Gulf Considering i
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Failed DeLaval Diesel Generators) had concluded that total failure of the DeLaval diesels at Grand Gulf would not significantly increase the risk of low po.er operation and is acceptably small. Nevertheless, the licensee has provided ga's turbine generators to substitute for the out of service diesel i
generator during the period of inspection. Our evaluation of the available power sources finds that the available sources (offsite, one DeLaval and gas turbine generators),in view of the minimum power needs along with the attendant surveillance requirements for these sources, represent a power system which has the capacity, capability, reliability and redundancy for this power level and that the health and safety of the public will not be
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