05000272/LER-2015-003

LER-2015-003, Plant Shutdown Required by Technical Specifications

Salem Generating Station - Unit 1
Event date:
Report date:
2722015003R00 - NRC Website

0001, or by internet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Offce of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

PLANT AND SYSTEM IDENTIFICATION

Westinghouse - Pressurized Water Reactor {PWR/4} Containment Fan Cooler Unit {BK} Containment Fan Cooler Unit Motor {BK/MO} Energy Industry Identification System (EllS) codes and component function identifier codes appear as {SS/CCC}.

IDENTIFICATION OF OCCURRENCE

Event Date: 3/15/15 Discovery Date: 3/15/15

CONDITIONS PRIOR TO OCCURRENCE

Salem Unit 1 was in operational Mode 1, operating at approximately 100 percent power. No additional structures, systems or components were inoperable at the time of discovery that contributed to this event.

DESCRIPTION OF OCCURRENCE

On 3/8/15, at 1158, the 14 Containment Fan Cooler Unit (CFCU) {BK} was declared inoperable following entered Technical Specification (TS) 3.6.2.3, Action "a." for inoperability of one CFCU. TS 3.6.2.3, Action 'a.' states that with one of the required CFCU fans inoperable, the fan must be restored to operable status within 7 days or the plant must be placed in at least Hot Standby (Mode 3) within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Cold Shutdown (Mode 5) within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

Troubleshooting of the 14 CFCU was unable to identify and correct the cause of the low speed breaker trip within the 7 day allowed outage time period. The TS allowed outage time expired on 3/15/15 at 1158 and unit shutdown was initiated at 1227. At 1329, a four hour notification was made to the NRC pursuant to the requirements of 10 CFR 50. 72(b )(2)(i) for "The initiation of any nuclear plant shutdown required by the plant's Technical Specifications." Unit 1 entered Mode 3 at 1652 on 3/15/15 and Mode 5 at 1419 on 3/16/15.

This event is reported in accordance with 10 CFR 50.73 (a)(2)(i)(A), "The completion of any nuclear plant shutdown required by the plant's Technical Specifications ... "

CAUSE OF EVENT

The TS required shutdown of Salem Unit 1 was due to the 14 CFCU low speed breeker tripping on startup. Troubleshooting and vendor analysis determined that the cause of the 14 CFCU motor {BK/MO} failure to start and run in slow speed was due to failed motor stator support welds which allowed contact between the rotor and the stator upon low speed startup.

SAFETY CONSEQUENCES AND IMPLICATIONS

This event did not result in any offsite release of radioactivity or increase of offsite dose rates, and there were no personnel injuries or damage to any other safety-related equipment.

Salem's CFCUs are credited in conjunction with the Containment Spray (CS) system to (1) provide heat removal from containment (limit containment peak pressure and temperature), and (2) minimize doses by maintaining containment atmosphere iodine in solution. The Salem design consists of five CFCUs and two CS trains per unit. Salem's design basis requires at least three CFCUs and one CS train for post-accident mitigation. As such, the inoperability of a single CFCU does not result in a loss of safety function.

SAFETY SYSTEM FUNCTIONAL FAILURE

A review of this event determined that a Safety System Functional Failure (SSFF) as defined in Nuclear Energy Institute (NEI) 99-02, Regulatory Assessment Performance Indicator Guideline, did not occur. This event did not prevent the ability of a system to fulfill its safety function to either shutdown the reactor, remove residual heat, control the release of radioactive material, or mitigate the consequences of an accident.

PREVIOUS OCCURRENCES

A review of Salem Unit 1 and 2 Licensee Event Reports for the previous three years identified no other similar events.

CORRECTIVE ACTIONS

1. The 14 CFCU motor was replaced.

2. Rotor to stator air gap measurements were verified to be within acceptable limits on all 5 CFCUs.

3. Preventative Maintenance plans for CFCUs will be changed to include rotor to stator air gap inspections.

COMMITMENTS

This LER contains no regulatory commitments.