ENS 45816
ENS Event | |
|---|---|
00:47 Apr 7, 2010 | |
| Title | Initiation of Technical Specification Required Shutdown Due to Control Room Emergency Filtration System Being Declared Inoperable |
| Event Description | At 1650 PDT Columbia Generating Station entered LCO 3.0.3 as required by LCO 3.7.3 for both divisions of Control Room Emergency Filtration (CREF) [being] inoperable. Entry into LCO 3.0.3 was required by Condition E of LCO 3.7.3, 'Two CREF subsystems inoperable in MODE 1, 2, or 3 for reasons other than Condition B' and has a Required Action to enter LCO 3.0.3 with an immediate Completion Time. Columbia commenced a plant shutdown at 1747 as required by LCO 3.0.3.
[Columbia Generating Station] entered into Condition E of LCO 3.7.3 when it was determined that Radwaste Building Outside Air Smoke Detectors WOA-SMD-1A and WOA-SMD-1B did not meet seismic qualifications. Actuation of these smoke detectors would cause Radwaste Building Mixed Air Fire Dampers WMA-FD-1 and WMA-FD-2 to close. These fire dampers shutting would cause all CREF airflow to cease, preventing the control room from achieving a positive pressure. Both divisions of CREF [being] inoperable is an unanalyzed condition requiring immediate entry into LCO 3.0.3. This event is reportable under 50.72(b)(2)(i) due to the initiation of a plant shutdown as required by Columbia's Technical Specifications. This event is also reportable under 50.72(b)(3)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. WMA-FD-1 and WMA-FD-2 have been deactivated in the open position for the smoke actuation function. [Columbia Generating Station] entered RFOLCS (Requirements for Operability of Licensee Controlled Specifications) 1.10.6 for these fire dampers [being] nonfunctional. [Columbia Generating Station] completed the required actions of LCS 1.10.6. The CREF system remains inoperable pending completion of a TMR (Temporary Modification Request). The licensee notified the NRC Resident Inspector.
Question posed by NRC at time of initial report: Have these smoke detectors been installed since startup? Response: These smoke detectors have been installed since initial plant startup. A temporary modification request was installed to de-energize the non-seismic detector logic that causes automatic fire damper actuation for the two dampers identified above. The alarm function of the smoke detectors remains active with this temporary modification. Entry into this condition was made when it was determined that the smoke detectors were not seismically qualified and there is a possible failure mode that during an earthquake the detectors would actuate the electro-thermal link and cause the associated fire damper (WOA-FD-1 or WOA-FD-2) to close, hence impacting control room emergency filtration function. With implementation of the temporary modification at 2218 PDT on 4/6/10, the CREF system is now considered to be in an 'operable but non-conforming' status. As such, LCOs 3.7.3 and 3.0.3 were exited at 2218 PDT on 4/6/10. This event was initially reported pursuant to paragraph 50.72(b)(2)(i) as an initiation of a plant shutdown required by Columbia's Technical Specifications. Reporting pursuant to paragraph 50.72(b)(2)(i) is being retracted because negative reactivity was not inserted into the reactor prior to exiting the LCOs described above. Reporting pursuant to paragraph 50.72(b)(2)(i) would not be consistent with the guidance provided in NUREG-1022 in that no negative reactivity was inserted and the condition was corrected before exceeding the required action times. The licensee notified the NRC Resident Inspector.
Subsequent to the April 7, 2010, event report (EN #45816), an Energy Northwest engineering evaluation concluded that the identified smoke detectors would not inadvertently actuate during a design basis safe shutdown earthquake (SSE). This conclusion is based on a seismic response spectrum test report for the smoke detectors. Therefore, since the safety function of the CREF system needed to mitigate the consequences of an accident would not be affected by an SSE, the event notification made pursuant to 10 CFR 50.72 (b)(3)(iv)(D) is hereby retracted. The NRC Senior Resident Inspector (Cohen) has been notified. Notified R4DO (Clark). |
| Where | |
|---|---|
Columbia Generating Station  Washington (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-0.23 h-0.00958 days <br />-0.00137 weeks <br />-3.15054e-4 months <br />) | |
| Opened: | Eric Franke 00:33 Apr 7, 2010 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Apr 29, 2010 |
| 45816 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |