05000272/LER-2003-001
| Salem Generating Station Unit 1 | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2722003001R01 - NRC Website | |
, � FACILITY NAME (I) SALEM UNIT 1 DOCKET (2) NUNIBER (2) . LER NUMBER (6) 05000272 , 03 ❑ 0 1 01 � OF 4
PLANT AND SYSTEM IDENTIFICATION
Westinghouse — Pressurized Water Reactor Auxiliary Feedwater System (BA/-) * Energy Industry Identification System (EllS) codes and component function identifier codes appear as (SS/CCC)
CONDITIONS PRIOR TO OCCURRENCE
Salem Unit 1 was in Mode 1 at 100% power at the time of discovery. No additional equipment was out of service that contributed to this event.
DESCRIPTION OF OCCURRENCE
On May 23, 2003, during the performance of surveillance testing on the 13 Turbine Driven Auxiliary Feedwater (TDAFW) pump (BN-), the TDAFW pump tripped. During the start of the 13 TDAFW pump, the steam admission valve (1MS132) valve popped open. The popping open of the 1 MS132 valve caused an in-rush of steam and mechanical agitation (shaking and vibration) of the steam line.
This mechanical agitation resulted in the unlatching of the steam trip valve (1MS52) for the 13 TDAFW pump causing the pump to trip. Prior to running the TDAFW pump for testing, the trip latch for the 11V1552 trip valve is tested and re-latched. Operators involved in the latching of the 1M85,2 valve during this test state that the latch was properly
- reset.
The last time the 13 TDAFW pump was successfully run was during the last quarterly surveillance test performed on February 28, 2003. Since there is no evidence to determine the exact time that the 13 TDAFW pump was inoperable, it is being conservatively assumed that this pump has been inoperable for greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. In accordance with TS 3.7.1.2, action 'a' requires that, "with one auxiliary feedwater pump inoperable, restore the required auxiliary feedwater pumps to operable status with 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 />? This LER is being submitted pursuant to 10CFR50.73(a)(2)(i)(B) for "any operation or condition which was prohibited by the plant's Technical Specifications,' and 10CFR50.73(a)(2)(v)(B) & (ID), any event or condition that could have prevented the fulfillment of the safety structures that are needed to:
remove residual heat and mitigate the consequences of an accident? FACILITY NAME (I) .
. - � .
DOCKET (2) LER NUMBER (6) PAGE (3) SALEM UNIT 1 � �
CAUSE OF OCCURRENCE
The cause of the 13 TDAFW pump trip is attributed to the popping open of the 1MS132 steam valve due to the split block being loose, which created a mechanical agitation of the steam line that led to the unlatching of the 1MS52 trip valve. The popping of the 11V15132 valve appears to have been caused by the valve plug and cage binding during initial opening of valve. This binding only occurred when steam was applied to the valve. A steam vortex and pressure wave formed as the inrush of steam through the cage impacted the plug immediately after the pilot lifted. As a result, the valve plug and stem assembly could shift slightly to the side arid be rotated if the valve stem is not properly restrained at the split block. The split block on the 1MS132 was found to be loose and required tightening. During the investigation of this event, it was determined that the maintenance procedure for Masonelian valve actuators does not provide any guidance regarding the tightening of the split block blot(s); thus, leaving the tightening of this connection to the skill-of-the-craft. Once properly tightened, the 1MS132 valve operated smoothly and the pump was satisfactorily started.
PRIOR SIMILAR OCCURRENCES
A review of LERs for Salem and Hope Creek for the previous two years did not identify any similar occurrences of improper valve operation due to mechanical binding leading to the unavailability of safety related equipment.
SAFETY CONSEQUENCES
A review of operations logs identified several instances of removal of one of the two Motor-Driven AFW (MDAFW) pumps from service during the period between February 28 and May 23. With the 13 TDAFW pump inoperable, removing one of the MDAFW pumps from service only leaves one MDAFW pump to respond to an event. In accordance with Salem UFSAR Sections 15.2.8, "Loss of Normal Feedwater," and 15.2.9, "Loss of Offsite Power to the Station Auxiliaries," these analyses assume that the auxiliary feedwater system will deliver 700 gpm of flow to the steam generators. One MDAFW pump is only capable of delivering 440 gpm, which is insufficient auxiliary feedwater flow to meet the assumptions of the analyses. Although, only one MDAFW pump would be available at the start of the event, emergency operating procedures direct the operators to restore the TDAFW pump to service if it failed to start. Guidance to perform the restoration of the TDAFW pump is contained in plant operating procedures. Upon restoration of the TDAFW pump, more than sufficient AFW flow would be available to mitigate these events. Following the trip of the 13 AFW pump, a review of procedures and a walkdown of the 13 TDAFW pump by operators determined that the pump could have been readily restarted.
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PACE (3) LER NUMBER (6) DOCKET (2) SALEM UNIT 1 105000272 spopmeinAL, I REVISION SAFETY CONSEQUENCES (coed) During the period of February 28 to May 23, 2003, there were no actual events that required the operation of the AFW system. Salem Unit 1 continued to operate in Mode 1 during this entire period.
Therefore there were no actual safety consequences associated with this event.
A review of this event determined that this condition was a Safety System Functional Failure (SSFF) as defined in Nuclear Energy Institute (NEI) 99-02.
CORRECTIVE ACTIONS:
1. Tightened the split block for the 1MS132 steam admission valve and satisfactorily re-tested the valve.
2. Procedure SH.IC-GP.ZZ-0002(Q), "Disassembly, Inspection, Reassembly and Testing of Masoneilan Model 37/38 Air Operated Actuators", is being revised to include instructions for tightening split blocks.
3. A walkdown of other safety related valves that utilize the split block connection was performed at both Salem and Hope Creek to ensure that the split blocks on these valves were not loose. In addition, the Salem Unit 2 2MS132 valve for the 23 TDAFW pump was verified to be at the correct torque value.
The above actions are being tracked in accordance with PSEG Nuclear's corrective action program.
COMMITMENTS
The corrective actions cited in this LER are voluntary enhancements and do not constitute commitments.