05000397/LER-2021-001, Breach of Secondary Containment

Breach of Secondary Containment

ML21266A279
Person / Time
Site:	Columbia
Issue date:	09/23/2021
From:	David Brown Energy Northwest
To:	Document Control Desk, Office of Nuclear Material Safety and Safeguards, Office of Nuclear Reactor Regulation
References
GO2-21-113 LER 2021-001-00
Download: ML21266A279 (4)

LER-2021-001, Breach of Secondary Containment

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function
3972021001R00 - NRC Website

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David P. Brown ENERGY Columbia Generating Station P.O. Box 968, MD PE23 NORTHWEST Richland, WA 99352-0968 Ph. 509-377-8385 dpbrown@energy-northwest.com

September 23, 2021 10 CFR 50.73 GO2-21-113

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001

Subject: COLUMBIA GENERATING STATION, DOCKET NO. 50-397 LICENSEE EVENT REPORT NO. 2021-001-00

Dear Sir or Madam:

Transmitted herewith is Licensee Event Report No. 2021-001-00 for Columbia Generating Station. This report is submitted pursuant to 50.73(a)(2)(v)(C) and 50.73(a)(2)(v)(D).

There are no commitments being made to the Nuclear Regulatory Commission by this letter. If you have any questions or require additional information, please contact Ms. D.M. Wolfgramm, Regulatory Affairs Manager, at (509) 377-4792.

Executed on this ______ day of ____________, 2021.

Respectfully,

David P. Brown Site Vice President

Attachment: Licensee Event Report 2021-001-00

cc: NRC Region IV Regional Admin NRC Region IV Project Manager NRC Senior Resident Inspector/988C C.D. Sonoda - BPA/1399

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   NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2023 (08-2020)

Columbia Generating Station 397 3050001 OF

4. Title Breach of Secondary Containment

5. Event Date 6. LER Number 7. Report Date 8. Other Facilities Involved

Month Day Year Number No.

05000 07 28 2021 2021 001-- 09 23 2021Facility NameDocket Number 05000

9. Operating Mode 10. Power Level Mode 1 100%I

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16. Abstract (Limit to 1560 spaces, i.e., approximately 15 single-spaced typewritten lines)

On July 28th, 2021, Columbia Generating Station was in Mode 1 at 100% reactor power when a Secondary Containment

5HDFWRU%XLOGLQJ roof hatch was opened to support maintenance activities. The breach in Secondary Containment resulted in Surveillance Requirement 3.6.4.1.2 QRWEHLQJ met. 0aintenance personnel did not notify Operations prior to opening the roof hatch and Technical Specification Action Statement 76$63.6.4.1.A was not entered as required. The breach also resulted in Secondary Containment exceeding the 7HFKQLFDO6SHFLILFDWLRQ76limit of vacuum of less than 0.25 inches of vacuum water gauge.

While T6 limits were EULHIO\\ exceeded the resulting pressure excursion was bounded by analytical results; and thus, there were no safety consequences for this condition. This event was reported under reporting criteria 10 CFR 50.72(E)( )(v)(C) and 50.72(E)( )(v)(D) as Event Notification#55385.

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Plant Conditions

At the time of the event, the plant was operating in Mode 1 at 100% power. There were no structures, systems, or components that were inoperable at the start of the event that contributed to the event. Both Standby Gas Treatment (SGT) [BH] trains were operable.

Event Description

On July 28th, 2021 at 0922 PDT, the 6HFRQGDU\\&RQWDLQPHQW>1*@hatch was opened to access the 5HDFWRU%XLOGLQJroof for maintenance activities. A second breach occurred when the maintenance personnel exited the roof. Each of the breach times were limited to 45 second intervals. Surveillance Requirement 653.6.4.1.2 is not met when any hatch in Secondary Containment is not closed and sealed and thus the Secondary Containment system became inoperable while the hatch was open. $n alarm was received in the control room indicating a Secondary Containment vacuum of less than 0.25 inches of vacuum water gaugeZKHQWKHURRIKDWFKZDVRSHQHG

This event was reported 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 in accordance with 10 CFR 50.72(b)(3)(v)(C) and 10 CFR 50.72(b)(3)(v)(D) via Event Notification 55385.

Immediate Corrective Actions

The Control Room received a Secondary Containment pressure alarm indicating a vacuum condition of less than 0.25 inches of vacuum water gauge while the roof hatch was open. Closing the hatch allowed the pressure to recover and the alarm cleared.

Assessment of Safety Consequences

The Secondary Containment low pressure alarm indicated a condition of less than 0.25 inches of vacuum water gauge.

The maximum indicated pressure was 0.19 inches of vacuum water gauge. The purpose of maintaining a slight vacuum is to restrict the release of radioactive materials from the primary containment and to ensure the fission products entrapped within the Secondary Containment will be treated by the SGT system prior to discharge to the environment. 7here were no radiological releaseV V\\VWHPDFWXDWLRQV RULVRODWLRQVDVVRFLDWHGZLWKWKLVHYHQW

Surveillance Requirement 3.6.4.1.4 verifies that the SGT System will rapidly establish and maintain a pressure in the Secondary Containment that is less than ambient pressure. 7KHGHVLJQEDVLVGUDZ GRZQIRU&ROXPELDLV PLQXWHV An analysis was conducted WRGHWHUPLQHWKHLPSDFWRIWKHEUHDFKRQWKHVSHFLILHGVDIHW\\V\\VWHPIXQFWLRQIRUSecondary Containment at the beginning of D Design Basis Accident. The results showed that SGT would meet the credited design requirement to draw down Secondary Containment to >/= 0.25 inches of vacuum water gauge in less than 20 minutes.

Secondary Containment was able to meet its required safety function to mitigate the consequence of a Design Basis Accident. 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

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Similar Events

There has been one similar event at Columbia in the last five years reported as LER 2017-005-00 where Secondary Containment was declared inoperable due to a non-permitted penetration seal breach. Energy Northwest has implemented corrective actions for this previous event.

Further Corrective Actions

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Energy Industry Identification System codes from IEEE Standards 805-1984 and 803-1983 are represented in brackets as [WW] throughout the body of the narrative.