05000266/LER-2017-001

LER-2017-001, Control Room Barrier Inadvertently Disabled

Point Beach Nuclear Plant Unit 1
Event date:	09-18-2017
Report date:	11-16-2017
Reporting criterion:	10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
2662017001R00 - NRC Website

LER 17-001-00 for Point Beach, Unit 1, Regarding Control Room Barrier Inadvertently Disabled

ML17320A010
Person / Time
Site:	Point Beach
Issue date:	11/16/2017
From:	Coffey B Point Beach
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NRC 2017-0051 LER 17-001-00
Download: ML17320A010 (4)

comments regarding burden estimate to the Information Services Branch (T-2 F43), 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.

Point Beach Nuclear Plant Unit 1 05000266 NUMBER NO.

Description of the Event:

At 1724 [CDT] on 9/18/17 Door-061, South Control Room Door was inadvertently disabled. Door-061 is a barrier that functions to maintain the control room envelope during design basis accidents, events, and conditions (Safe Shutdown / High Energy Line Break / Fire / Flood). The barrier became wedged open against its backstop during control room ventilation testing. The barrier was subsequently disengaged from the backstop allowing it to close.

The door was inspected and returned to operable status at 1750 [CDT]. While the door was stuck open, the control room was in an unanalyzed condition, a condition that could have prevented fulfillment of a safety function, and a common cause inoperability of independent trains or channels.

This event is being reported pursuant to 10 CFR 50.73(a)(2)(ii)(B), 10 CFR 50.73(a)(2)(v)(A), 10 CFR 50.73(a)(2)(v)(D), and 10 CFR 50.73(a)(2)(vii) for a degraded barrier that affected the control room envelope.

This 60 day licensee event report is being submitted in accordance with the following requirements; 10 CFR 50.73(a)(2)(ii)(B), any event or condition that results in the condition of the nuclear power plant being in an unanalyzed condition; 10 CFR 50.73(a)(2)(v)(A) and 10 CFR 50.73(a)(2)(v)(D), any event or condition that could have prevented fulfillment of a safety function of structures or systems needed to shut down the reactor and maintain it in a safe shutdown condition or mitigate the consequences of an accident; 10 CFR 50.73(a)(2)(vii), any event where a single cause or condition caused at least one independent train or channel to become inoperable in multiple systems or two independent trains or channels to become inoperable in a single system; Where, the functions supported by the disabled barrier could not be found acceptable under all design basis accidents, events or conditions.

Cause of the Event:

The cause of the inadvertent degraded barrier was a less than adequate door stop design to control the barrier during ingress/egress activities of the control room envelope with a simultaneous differential pressure transient of the control room ventilation during testing.

Analysis of the Event:

Technical Specifications permit intermittent opening of the control room envelope boundaries under administrative controls. While the barrier was disabled, the boundary was unable to be rapidly closed. An engineering evaluation of the inadvertently disabled barrier determined the functions supported by the barrier could not be found acceptable under all design basis accidents, events and conditions. The less than adequate door stop design led to inadequate administrative control of the barrier during ingress/egress activities of the control room envelop with the simultaneous differential pressure transient of the control room ventilation during testing. The disabled barrier was promptly enabled, restoring the control room envelope support function.

Corrective Actions:

The disabled barrier was promptly enabled, restoring the control room envelope support function, and the door stop was modified with a more robust design. Additionally, an extent of condition review was completed and 00 001 2017 comments regarding burden estimate to the Information Services Branch (T-2 F43), 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.

i) Point Beach Nuclear Plant Unit 1 05000266 NUMBER NO.

corrective actions initiated for other doors with susceptible conditions.

Safety Significance:

The event was determined to be of very low safety significance. The probability of an event occurring during the short time period is very low. While the condition was present, there was no loss of any safety systems, structures or components needed to shut down the reactor, maintain safe shutdown conditions, remove residual heat, control the release of radioactive material or mitigate the consequences of an accident. There was no impact on the health and safety of the public as a result of this condition.

Similar Events:

There have not been similar events of this condition in the past three years.

Component Failure Data:

None