05000272/LER-2002-005
| Salem Unit 1 | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown |
| 2722002005R00 - NRC Website | |
PLANT AND SYSTEM IDENTIFICATION
Westinghouse - Pressurized Water Reactor Feedwater/Steam Generator Level Control System (JB)* * Energy Industry Identification System (EIIS) codes and component function identifier codes appear in the text as {SS/CCC}.
IDENTIFICATION OF OCCURRENCE
Event Date: October 10, 2002 Discovery Date: October 10, 2002
CONDITIONS PRIOR TO OCCURRENCE
Mode 1 — 20%
DESCRIPTION OF OCCURRENCE
On October 10, 2002 at 2016 hours0.0233 days <br />0.56 hours <br />0.00333 weeks <br />7.67088e-4 months <br />, following the scheduled manual trip of Salem Unit 1 to begin IRIS refueling outage, an unexpected auto-start of the No. 13 Turbine Driven Auxiliary Feed pump (TDAFP) occurred. The No. 11 and 12 Motor Driven Auxiliary Feedwater pumps (MDAFP) had been started manually prior to the trip, per procedure. On the reactor trip (at 20% Reactor power), the steam generator levels lowered as expected. The auto-start of the TDAFP occurred as a result of the low-low Steam Generator (SG) level setpoints {JB} being exceeded post trip on at least two of the SGs. The TDAFP started on valid steam generator low-low levels at the steam generators. The low-low level alarm setpoints had been revised upward from 9% Narrow Range (NR) to 14% NR. This had occurred earlier in the year as a result of generic ' Westinghouse industry notification. The Salem Unit 1 scheduled refueling outage had been the first planned unit trip since the SG Low-Low level setpoints had been revised.
A review of this event determined that a Safety System Functional Failure (SSFF) as defined in NEI 99-02 did not occur. No structures, systems or components were inoperable at the time of this event that contributed to this event.
CAUSE OF OCCURRENCE
The apparent cause of the unexpected auto start of the TDAFP was ineffective implementation of the Design Change Package (DCP) for the SG low-low level setpoint change in response to a Westinghouse identified industry concern. During the DCP development, it was not recognized that the normal shrink following a reactor trip from 20% reactor power could lower levels enough to result in an auto start of the AFW pump.
PRIOR SIMILAR OCCURRENCES
Prior Salem Units 1 and 2, and Hope Creek LERs, from 1999 through 2002, were reviewed. No similar occurrences have been identified.
SAFETY CONSEQUENCES AND IMPLICATIONS
There were no actual safety consequences associated with this event. The reactor had been manually tripped at 20% power. All systems operated as required. No PORVs or Safety Relief valves lifted. Post trip, main feedwater to the SGs was isolated due to the feedwater interlock, which is expected with a reactor trip. The 11 and 12 MDAFP were operable and maintaining adequate feedwater flow to SGs, and the TDAFP was shutdown by procedure.
Based on the above, this event did not affect the health and safety of the public.
CORRECTIVE ACTIONS
1. The TDAFP was stopped and the SG levels controlled with the MDAFPs.
2. A re-evaluation will be performed of procedures (Implementing, Emergency Operating and Abnormal) to determine if additional changes are required for both Salem units. [A potential procedural change may be to include the expectation for TDAFP auto-start.] 3. An evaluation of the SG Low-Low Level Setpoint calculation will be performed to determine if there are conservatisms in the current setpoint of 14% NR.
4. An evaluation of the simulator will be performed to ensure it accurately matches the plant response for SG low-low level setpoints and safety system actuations.
5. This event will be reviewed by the Engineering Human Performance Review Board to incorporate lessons learned into the design change process.
COMMITMENTS
The corrective actions cited in this LER are voluntary enhancements and do not constitute commitments.