05000353/LER-2005-001

LER-2005-001, Core Alterations Performed With Source Range Monitor Alarm Horn Inoperable

Docket Number
Event date:	03-12-2005
Report date:	05-6-2005
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3532005001R00 - NRC Website

Unit Conditions Prior to the Event Unit 2 was in Operational Condition (OPCON) 5 (Refueling) at 104 degrees Fahrenheit reactor coolant temperature and zero psig reactor pressure conducting refueling operations. There were no structures, systems or components out of service that contributed to this event.

Description of the Event

On Saturday March 12, 2005, at 07:43 hours, the annunciator (El IS:ANN) horn for Unit 2 Main Control Room (MCR) was continuously sounding and could not be silenced due to an equipment failure. Fuses were removed to silence the horn. The operators entered procedure ON-122, Loss Of Main Control Room Annunciators. This equipment failure adversely affected 13 alarm panels in that the audible alarms were unavailable while the visual alarms remained functional. A dedicated individual with no concurrent duties was assigned to monitor the alarm panels and alert the duty reactor operator when any visual alarms were present.

Technical Specification (TS) 3.9.2 Refueling Operations — Instrumentation requires that at least one source range monitor (SRM) (El IS:PI) have an audible alarm in the control room. This alarm became inoperable when the alarm horn fuses were removed but the licensed operators did not immediately recognize this. At 12:11 core alterations resumed resulting in a condition prohibited by TS.

Following shift turnover the licensed operators identified the TS requirement for an SRM audible alarm and suspended core alterations. Operations shift management decided that the dedicated individual monitoring the visual alarms could be credited as performing the SRM audible alarm function and permitted core alterations to continue. Following additional review, it was determined that core alterations be suspended until the plant staff could perform further review of the SRM operability determination.

At 21:50 the alarm horn was restored to operable status; core alterations resumed at 21:58.

Concurrently the plant staff determined that SRM operability was not supported by use of the dedicated individual as the audible alarm function.

This event involved a condition prohibited by Technical Specifications. Therefore, this LER is being submitted pursuant to the requirements of 10CFR50.73(a)(2)(i)(B).

Analysis of the Event

There were no actual safety consequences associated with this event. The potential safety consequences of this event were also minimal. The affected alarms lost the audible alarm function but retained the visual alarm function and were continuously monitored by a dedicated individual. SRM count rate, period indications and rod block functions remained functional. In addition, a reactor operator was monitoring SRM count rate as each fuel assembly was inserted into the core and was directed by procedure to suspend component movement if any SRM count rate doubled between steps. Further, NUREG-1433 Rev.3 (Standard Technical Specifications General Electric Plants, BWR/4) does not require an SRM alarm function, only indication of count rate is required.

The alarm horn is classified as non-safety related equipment. However, it is required to support the operability of the SRMs. The non-safety related classification of the alarm horn contributed to the licensed operator failure to identify the impact on SRM operability.

Cause of the Event

The cause of the event was that procedural guidance was less than adequate to ensure rule- based evaluation of infrequently used refuel and outage related TS.

Corrective Action Completed The SRM audible alarm function was restored.

The procedure for loss of main control room annunciators was revised to address the TS impact of a loss of the SRM audible alarm function.

Corrective Action Planned An evaluation of Operations' procedures will be performed to identify those affected by infrequently used refuel and outage related TS. Enhancements to the affected procedures will be implemented as required to ensure rule-based evaluations of TS impacts are performed.

This action will be completed by December 1, 2005.

Previous Similar Occurrences There were two previous similar occurrences of a condition prohibited by TS during refueling operations. LER 1-03-002 was submitted for a previous event when Unit 2 core alterations were conducted with refueling enclosure secondary containment integrity inoperable. LER 2- 97-001 was submitted for a previous event when SRMs were inoperable during multiple control rod removals.

Component data:

System:� IB� (Annunciator System) Component:� ANN (Annunciator) Manufacturer:� 170E (Edwards) Model number:� 5531-P1