05000263/FIN-2009007-05
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Finding | |
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| Title | EDG Fuel Oil Supply System Design does not meet the single failure criteria |
| Description | The inspectors identified an unresolved item (URI) regarding the EDG fuel oil supply system. Specifically, the diesel fuel oil supply system design does not meet the single failure criteria. The diesel fuel oil supply system consisted of two pumps, the fuel oil transfer pump and the fuel oil service pump. However, only the fuel oil transfer pump was considered safety-related. Nonetheless, TS Basis, Section 3.8.1, stated that both pumps must be operable in order for both EDGs to be operable. The original Monticello Safety Evaluation Report (SER), dated March 20, 1970, stated that the EDGs were separate and independent with respect to fuel supplies. It also concluded that the onsite emergency electric power system was acceptable since no single failure should prevent power from being supplied to the engineering safety features from onsite sources. In addition, the original Safety Analysis Report stated that auxiliaries required to ensure continuous operation of the EDGs shall be supplied from the essential buses or control power transformers associated with the EDGs. However, the fuel oil service pump was powered by a non-essential motor control center that would be load shed on an essential bus transfer load shed signal. In fact, EDG 11 does not supply either pump without manual operator action. The fuel oil transfer pump was normally powered by EDG 12. In addition, the USAR, Section 10.3.1.5, stated that the safe-shutdown analysis performed to comply with 10 CFR Part 50, Appendix R, Section G, revealed three fire areas that required repair of equipment or use of alternate fuel oil pumping methods and procedures for diesel oil pumping capability to the EDG day tanks to achieve cold shutdown. Further, the TS Basis, Section 3.8.1, described the diesel fuel oil supply piping as redundant. However, the inspectors confirmed that the actual configuration was not redundant in that both pumps discharge into common piping. The inspectors also questioned if the service pump was tested to supply an adequate flow. Specifically, TS Surveillance Requirement 3.8.1.5 verified, in part, that the fuel oil transfer system operates to transfer fuel oil from the T-44 storage tank to the day tanks. The TS Basis, Section 3.8.1, stated that this surveillance provides assurance that the required fuel oil transfer pumps are operable. Operable was defined in TS 1.1, which stated, in part, when the component is capable of performing its specified safety function. The TS Basis, Section 3.8.1, also stated that the fuel oil transfer pump and the fuel oil service pump are individually capable of maintaining the level in the day tank when both EDGs are operating at full load. However, the inspectors noted that the licensee only ensured that the fuel oil service pump transferred fuel and maintained level in just one EDG day tank. This issue is unresolved pending further NRC review of the licensing basis for the diesel fuel oil transfer system and determination of NRC courses of action for resolution of the issues. (URI 05000263/2009007-05). |
| Site: | Monticello  |
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| Report | IR 05000263/2009007 Section 1R21 |
| Date counted | Dec 31, 2009 (2009Q4) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | A Dunlop A Stone C Brown H Campbell J Bozga L Jones M Munir N Feliz Adomo S Kobylarza Dunlopg Hausman I Hafeez R Daley |
| INPO aspect | |
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Finding - Monticello - IR 05000263/2009007 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Monticello) @ 2009Q4
Self-Identified List (Monticello)
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