05000440/LER-2017-005

LER-2017-005, Controller Malfunction results in Momentary Degradation of Secondary Containment Pressure

Perry Nuclear Power Plant
Event date:	08-14-2017
Report date:	10-04-2017
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 52903	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
4402017005R00 - NRC Website

LER 17-005-00 for Perry Nuclear Power Plant Regarding Controller Malfunction Results in Momentary Degradation of Secondary Containment Pressure

ML17278A070
Person / Time
Site:	Perry
Issue date:	10/04/2017
From:	Hamilton D B FirstEnergy Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-17-305 LER 17-005-00
Download: ML17278A070 (5)

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 Infocollects.Resource@nrc gov. and to the Desk Officer, Office of Information and Regulatory Affairs NEOB-10202, (3150-0104). Office of Management and Budget. Washington. DC 20503 If a means 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.

- 005 - 00 Perry Nuclear Power Plant Unit 1 05000-440 YEAR 2017 Energy Industry Identification System (EIIS) codes are identified in the text as [XX].

INTRODUCTION

On August 14, 2017 at 2257, with both trains of the Annulus Exhaust Gas Treatment System [VC] (AEGTS) running in parallel, Secondary Containment [NH] vacuum momentarily degraded to 0.52" water gauge differential pressure when AEGTS B was shutdown to Standby Readiness. After an approximate 15 second delay, AEGTS A responded to maintain the normal vacuum. Technical Specification (TS) Surveillance Requirement (SR) 3.6.4.1.1 requires a minimum of 0.66" water gauge differential pressure to be maintained between ambient and annulus pressure at all times. The failure to comply with SR 3.6.4.1.1 caused Secondary Containment to be inoperable resulting in Technical Specification 3.6.4.1 not being met.

EVENT DESCRIPTION

On August 14, 2017 at 2019 hours0.0234 days <br />0.561 hours <br />0.00334 weeks <br />7.682295e-4 months <br />, with the plant in mode 1 and at 100% power, AEGTS A was manually started in parallel with AEGTS B in support of flow switch calibration testing.

At 2257 hours0.0261 days <br />0.627 hours <br />0.00373 weeks <br />8.587885e-4 months <br />, AEGTS B was shutdown to standby. During the shutdown, Operations personnel received an unexpected Annulus Differential Pressure Low alarm. Secondary Containment vacuum dropped to 0.52" water gauge for approximately 15 seconds. After the approximate 15 second delay, AEGTS A responded to maintain the normal vacuum. Technical Specification (TS) 3.6.4.1 "Secondary Containment" condition A was entered. Condition A addresses secondary containment being inoperable in modes 1, 2, or 3, with operability to be restored within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. Surveillance Requirement (SR) 3.6.4.1.1 was not met which states, "Verify secondary containment vacuum is > 0.66 inch of vacuum water gauge".

On August 15, 2017 at 0458 hours0.0053 days <br />0.127 hours <br />7.572751e-4 weeks <br />1.74269e-4 months <br />, event notification EN# 52903 was made to the NRC Operations Center in accordance with 50.72(b)(3)(v)(C) & 50.72(b)(3)(v)(D) for loss of safety function.

CAUSE

A causal analysis was conducted and determined the most likely cause to be age-related degradation of the Bailey [B040] controller card [PC] transformer nylon screw, resulting in less than optimum response.

EVENT ANALYSIS

With respect to the degraded controller and the resulting sluggish response of the AEGTS A subsystem, the Loss of Coolant Accident (LOCA) analysis assumes the bypassing of the Secondary Containment for the first 40 seconds of the LOCA. Additionally, since the gap release (radiological release due to core damage) does not occur until 120 seconds, the capability of the AEGTS A subsystem has been shown to support recovery of the negative pressure in the annulus to greater than the required minimum of 0.66 inches vacuum water gauge within the required analytical assumptions. The LOCA is the only Design Basis Accident (DBA) for which secondary containment is credited and therefore, the recovery within two minutes will support the LOCA analysis. There is reasonable assurance that Secondary Containment can perform the required design and license functions. As a result, this condition was not a safety system functional failure.

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 Infocollects.Resource@nrc.gov. and to the Desk Officer, Office of Information and Regulatory Affairs 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 cOection - 005 2017 - 00 From the Probabilistic Risk Assessment perspective, AEGTS is not a core damage mitigation system and is not credited in any PRA models in mitigating large and early containment releases. Additionally, from an availability / functionality perspective, AEGTS was fully capable of performing its' function. On this basis, the inoperability of the AEGTS for the period of 15 seconds is determined to be of small risk (safety) significance.

This event is being reported in accordance with 10CFR50.73(a)(2)(v)(C) and 10CFR50.73(a)(2)(v)(D) as an event or condition that could have prevented the fulfilment of a safety function.

CORRECTIVE ACTIONS

Corrective actions in response to the event include: closure of the Prompt Operability Determination (POD) following replacement of the Bailey controller circuit card (completed), revise the Preventative Maintenance (PM) plan for 1M15R0060A/B-1 to replace the transformer nylon screw every six years versus as required, and create PM tasks for other same-type controllers to change the transformer nylon screw every six years.

PREVIOUS SIMILAR EVENTS

A review of LERs and the Corrective Action database for the past three years identified no similar events.

COMMITMENTS

There are no regulatory commitments contained in this report. Actions described in this document represent intended or planned actions, are described for the NRC's information, and are not regulatory commitments.