05000397/LER-2016-003

LER-2016-003, Failure of Fan to Start Results in Momentary Increase in Secondary Containment Pressure

Columbia Generating Station
Event date:	11-20-2016
Report date:	01-12-2017
Reporting criterion:	10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
Initial Reporting
ENS 52382	10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material
3972016003R00 - NRC Website

LER 16-003-01 for Columbia Regarding Failure of Fan to Start Results in Momentary Increase in Secondary Containment Pressure

ML17241A220
Person / Time
Site:	Columbia
Issue date:	08/29/2017
From:	Javorik A L Energy Northwest
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GO2-17-152 LER 16-003-01
Download: ML17241A220 (4)

comments regarding burden esfimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to 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.

05000- Columbia Generating Station 397

Plant Conditions

At the time of the event, the plant was operating in Mode 1 at approximately 97% power, and ascending to 100% power.

There were no structures, systems, or components that were inoperable at the start of the event that contributed to the event.

Event Description

On November 20, 2016 at 1402 PST, the Reactor Building [NG] exhaust air fan [FAN] (REA-FN-1B) failed to start in manual during a post-maintenance task on the fan. Prior to this event, Reactor Building Heating, Ventilation and Air Conditioning [VA] (HVAC) System A was running. Per station procedures, System A was stopped and System B was to start. The fan's failure to start resulted in no Reactor Building fans running, and increased Reactor Building pressure. For a time period of less than one minute, Secondary Containment [NH] pressure was not maintained less than or equal to -0.25 inches of water gauge (inwg), resulting in Technical Specification (TS) 3.6.4.1 not being met.

This event is reportable as an event that could have prevented fulfillment of safety functions needed to control the release of radiation, and mitigate the consequences of an accident per 10 CFR 50.73(a)(2)(v)(C) and 10 CFR 50.73(a)(2)(v)(D).

This condition was reported under 10 CFR 50.72(b)(3)(v)(C) and 10 CFR 50.72(b)(3)(v)(D) via Event Notification #52382 for an event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material.

Immediate Corrective Actions

Operations personnel manually started Reactor Building HVAC System A and quickly restored Secondary Containment pressure to less than or equal to -0.25 inwg. Secondary Containment was declared operable following successful start of the System A Reactor Building exhaust air fan.

Assessment of Safety Consequences

This event resulted in an unplanned entry into TS 3.6.4.1.A, in which Secondary Containment pressure was greater than -0.25 ;nwg for approximately one minute. The peak pressure during this event was -0.12 inwg. Whsle the actual pressure was beyond the range allowed by Technical Specifications, the purpose of maintaining a slight vacuum is to assist in drawdown of secondary containment to support accident response of the safety related Standby Gas Treatment [BH] (SGT) system. Existing engineering analysis demonstrates that for this event, the drawdown credited in accident response could have been attained using either of the two available trains of the SGT system, thus there were no potential safety consequences. There was no actual safety consequence associated with this event since there was no loss of safety function and no potential for radiological release.

Cause of Event

The investigation into the apparent cause of the unexpected failure to start of the Reactor Building exhaust air fan, and resultant loss of Secondary Containment has determined that a faulty control switch [JS] for fan REA-FN-1B was the cause of the fan failing to start.

comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to (See NUREG-1022, R.3 for instruction and guidance for completing this form used to impose an information collection does not display a currently valid OMB control number, the httpSwww.nrc.govireading-rm/doc-collections/nuregs/staff/sr1022/r3/) NRC may not conduct or sponsor, and a person is not required to respond to, the Information collection.

05000- NUMBER NO.

003 00 Columbia Generating Station 397 2016 - Similar Events A loss of the ability to maintain Secondary Containment pressure greater than required by Technical Specifications has occurred at, and was reported by, Columbia Generating Station (Columbia) twice in the past two years. The first incident was the result of an incorrectly sized lug installed in the fuse block during initial construction and the second incident occurred when an exhaust air valve unexpectedly closed. Prior to this two year time period, Columbia has experienced losses of Secondary Containment due to weather-related conditions, as well as human performance errors. Columbia has implemented corrective actions for these previous events.

Further Corrective Actions Causal evaluation determined that the failure of the fan was a result of a faulty control switch; corrective actions are to replace the control switch for fan REA-FN-1B. Additionally, the control switches for the System A exhaust air fan and both Reactor Building supply air fans will be replaced as well, as they are the same make, model, and age as the control switch in fan REA-FN-1B.

Energy Industry Identification System (EIIS) Information codes from IEEE Standards 805-1984 and 803-1983 are represented in brackets as [XX] and [XXX] throughout the body of the narrative.