05000397/LER-2001-002

LER-2001-002,

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3972001002R00 - NRC Website

Event Description:

On May 2, 2001 with Columbia Generating Station at 88% power and coasting down for a refueling outage, a non-compliance with Technical Specification LCO 3.3.1.1 was discovered. The non- compliance was due to a condition in which less than the required number of channels per trip system were operable for the Scram Discharge Volume [JC] (SDV) Water Level - High function described in Technical Specification Table 3.3.1.1-1, Function 7.b. The division I displacer-type level switch was determined to have been inoperable for a period longer than the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Completion Time allowed in LCO 3.3.1.1 Condition A. This in turn, led to non-compliance with Required Action G.1 of LCO 3.3.1.1 to be in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The SDV level - High instrument channel was inoperable because the instrument isolation valve on the vent side of the displacer chamber was left in the closed position following a February 5, 2001 surveillance test.

Immediate Corrective Action:

Following performance of the quarterly Channel Functional Test (CFT) immediately after discovery of the inoperable SDV level instrument, the level switch was properly returned to service meeting the requirements of LCO 3.3.1.1. A review of maintenance and surveillance testing records was then conducted and a determination was made that the last time the instrument isolation valve had been manipulated was during performance of the previous quarterly Channel Functional Test on February 5, 2001. It was concluded that the instrument had been inadvertently left valved out of service and hence inoperable since that time. Addtionally, a "hands on" verification of all instrument isolation valves on both SDV's was performed to ensure the valve misconfiguration was an isolated event. As part of the causal analysis of this event, the personnel who performed the February 5, 2001 CFT were interviewed to ascertain the facts surrounding the valve misconfiguration. The expectations for, and importance of, proper manual valve manipulation and position verification were reinforced with these individuals.

968-26158 R1 (6/01) FACILITY NAME (1) PAGE (3) DOCKET (2) LER NUMBER (6) Columbia Generating Station 05-397

Cause of the Event:

The valve misconfiguration occurred due to personnel error. The following discussion addresses the aspects of this event pursuant to 10 CFR 50.73(b)(2)(ii)(J)(2) to the extent that they apply. The valve manipulation steps in the surveillance procedure as it is currently written have been performed correctly numerous times by instrument technicians. This is not considered to be a cognitive error. The likelihood of this personnel error was increased by design, environmental, and test methodology factors. The design of the SDV, especially this division I SDV, introduces difficulty in identifying and accessing the instrument isolation valves. The process medium (basically reactor coolant) contained by the SDV following a reactor scram is highly radioactive resulting in higher exposures in the vicinity of the SDV even when the SDV is in its normally drained condition. For this reason, personnel performing testing and maintenance are instructed to minimize their time in the area in order to limit radiation dosage. As an additional measure to keep radiation dose ALARA, simultaneous verification of valve manipulations is performed visually by an individual located approximately 10 feet away.

Additionally, the physical design of the SDV presents visual obstructions for the individuals when verifying valve manipulations.

Further Corrective Action:

A corrective action to be implemented in response to this event will be to form a group consisting of instrument technicians, a human performance training specialist, and radiation protection personnel.

This group will be tasked with identifying factors that present challenges to the SDV surveillance test performance. Specifically, the task group will address environmental, human factors, and test methodology aspects.

Assessment of Safety Consequences:

There were no safety consequences associated with this event because redundant instruments were capable of performing the safety function of Reactor Protection System actuation if an actual SDV high water level condition had occurred during the time the level instrument was out of service.

Previous Similar Events:

There are no previous similar events that involve the same underlying cause. This event is not considered a generic or recurring problem.

968-26158 RI (6/01)