05000282/LER-2009-002
| Prairie Island Nuclear Generating Plant | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv), System Actuation |
| 2822009002R00 - NRC Website | |
safeguard replacement pump per procedure for planned maintenance of the 12 Diesel Driven Cooling Water Pump (DDCLP). Maintenance steps were completed to a point allowing restoration and post maintenance testing (PMT) of 12 DDCLP in accordance with maintenance procedures. However, required steps in the operation's procedure to align the 121 MDCLP to its normal non-safeguards alignment prior to starting post maintenance testing were not performed.
Permission to perform testing was granted and the 12 DDCLP was started per the maintenance procedure. At 1532, the 12 DDCLP was tripped by procedure from rated speed resulting in a cooling water pressure transient. The momentary drop in pressure was large enough to automatically start the 121 MDCLP while it was aligned for safeguards service. At this point operations personnel realized that the 121 MDCLP had been rendered inoperable by the PMT of the 12 DDCLP and that the required Limiting Condition for Operation (LCO) condition entry had been missed.
Testing of the 12 DDCLP was stopped by issuing a stop work order and Technical Specification (TS) LCO 3.7.8 Condition A was entered for not having an operable safeguards pump for one train of the CL system. At 1613 the CL system was restored to an operable status by restoring operability of the 121 MDCLP and TS LCO Condition A was exited. At 1936 the 121 MDCLP was shut down and returned to standby. At this point it was still aligned as the safeguards pump for train 'A'. The following day the stop work order was lifted and work was resumed to realign 121 MDCLP to normal and restore 12 DDCLP activities.
When aligned as a safeguard pump, any unplanned actuation is reportable under 10 CFR 50.73(a)(2)(iv). This event was previously reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) on March 19, 2009.
EVENT ANALYSIS AND SAFETY SIGNIFICANCE
The 12 DDCLP was being started and stopped locally for PMT prior to restoration in accordance with preventative maintenance procedures. The 12 DDCLP had been tripped during performance of an overspeed trip test when the automatic start of the 121 MDCLP occurred. It was at this point that it was discovered that the 121 MDCLP had not been restored to its normal non-safeguards lineup and that the required Limiting Condition for Operation (LCO) Condition was not entered prior to commencing PMT and return to service testing (RTST) of the 12 DDCLP.
The significance of this event arises out of the fact that when the automatic start of the 121 MDCLP occurred, PINGP was relying on it as the safeguards pump for the Unit 1 train `A' CL header because the 12 DDCLP had not yet been returned to service.
1 BUS System Identifier: BS NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSIONLICENSEE EVENT REPORT (LER)(9-2007)�
CONTINUATION SHEET
This event is considered of low safety significance because PINGP operating procedures direct entry into the appropriate LCO Condition for not having a CL pump operable for one train. Although the procedural step was missed to enter the condition and realign the 121 MDCLP away from being a safeguards pump, the expected configuration for this PMT was to not have any safeguard CL pumps operable for this train until testing could be completed and the LCO condition exited.
CAUSE
The PMT was being performed by following steps located in multiple procedures. The PM activities had been previously included as part of a single procedure, but changes to the PINGP procedure program had the procedure split into separate procedures for operations and maintenance. The apparent cause of the event is attributed to the fact that referencing and branching did not exist between the revised maintenance and operating procedures to ensure operations procedure steps were complete prior to commencing PMT.
CORRECTIVE ACTION
Proposed corrective actions include adding instructions to the maintenance procedure to ensure that it properly references the operations procedure. A review of PM's will also be completed on safety related components to ensure proper referencing and branching is utilized where a similar unplanned safety system actuation could occur. Additional planned corrective actions include adding a PM coordinator and additional staff to assist with implementation of the procedure-upgrade program, and revising the complex work procedure to contain objective criteria for determination of complex work.
PREVIOUS SIMILAR EVENTS
There have been several instances of automatic pump starts attributed to procedural inadequacies at PINGP. These include the 121 MDCLP, 121 motor driven fire pump2, and 22 component cooling3 pump. No other instances of the 121 MDCLP auto-starting while aligned as a safeguards pump could be found.
2 EIIS System Identifier: KP 3 EIIS System Identifier: CC