05000423/LER-2014-001
| Docket Number | |
| Event date: | 01-26-2014 |
|---|---|
| Report date: | 03-17-2014 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4232014001R00 - NRC Website | |
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1. EVENT DESCRIPTION
At 1350 on January 26, 2014 while operating in Mode 1 at approximately 96% power, Millstone Power Station Unit 3 (MPS3) exceeded the Limiting Condition for Operation of plant Technical Specification (TS) 3.7.1.2 "Auxiliary Feedwater System" Action C for an inoperable auxiliary feedwater pump. The turbine driven auxiliary feedwater pump (TDAFWP) [EIIS: BA-P] had been declared inoperable at 1350 on January 23, 2014.
TS 3.7.1.2 Action C requires that the pump be restored to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The TDAFWP had been declared inoperable on January 23, 2014 when the pump tripped during a test.
Subsequent repairs, maintenance, and testing were nearing completion but, would require additional time beyond the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> TS 3.7.1.2 Action C requirements. In a teleconference call on January 26, 2014, Dominion Nuclear Connecticut, Inc. (DNC) requested a notice of enforcement discretion (NOED) from the requirements of TS 3.7.1.2, Action C. The NRC exercised enforcement discretion to not enforce compliance with TS 3.7.1.2, Action C, for an additional period of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> (to expire at 0150 January 28, 2014). The TDAFWP was restored to OPERABLE status at 0505 on January 27, 2014.
This condition is being reported as any operation or condition which was prohibited by the plant's technical specifications in accordance with 10 CFR 50.73 (a)(2)(i)(B).
2. CAUSE
Repairs, maintenance, and testing were nearing completion but, would require additional time beyond the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> technical specification requirements. MPS3 exceeded the Limiting Condition for Operation of plant Technical Specification (TS) 3.7.1.2 "Auxiliary Feedwater System" Action C upon obtaining verbal approval that the NRC exercised enforcement discretion to not enforce compliance with TS 3.7.1.2, Action C, for an additional period of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> (to expire at 0150 January 28, 2014).
2. ASSESSMENT OF SAFETY CONSEQUENCES
The request for enforcement discretion was presented per NRC Inspection Manual, Chapter 0410, "Notices of Enforcement Discretion" (MC410). During the teleconference on January 26, 2014, and further elaborated in the letter submitted on January 28, 2014 (Accession Number ML1403036A095), DNC indicated that from a risk perspective, it was unnecessary to place MPS3 into a plant shutdown in that MPS3 was operating in a stable configuration with offsite power and both MPS3 emergency diesel generators available, along with the station blackout diesel generator. Quantitatively, the estimated Incremental Conditional Core Damage Probability (ICCDP) was approximately 2.97E-08, and the Incremental Conditional Large Early Release Probability (ICLERP) was approximately 1.88E-09. Additionally, the ICCDP and ICLERP values did not take into account various additional conservatisms associated with compensatory actions.
4. CORRECTIVE ACTION
The corrective actions to affect repairs and perform necessary maintenance and testing of the tripped pump were completed at 0505 on January 27, 2014. No additional corrective actions related to exceeding the TS LCO on January 27, 2014 were deemed necessary and no associated changes to technical specifications were required.
5. PREVIOUS OCCURRENCES
There have been no previous occurrences.