|Perry Nuclear Power Plant|
|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
|ENS 52903||10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident|
|4402017005R00 - NRC Website|
|Person / Time|
|From:||Hamilton D B|
FirstEnergy Nuclear Operating Co
Document Control Desk, Office of Nuclear Reactor Regulation
|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].
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) 126.96.36.199.1 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 188.8.131.52.1 caused Secondary Containment to be inoperable resulting in Technical Specification 184.108.40.206 not being met.
On August 14, 2017 at2019 hours
, 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) 220.127.116.11 "Secondary Containment" condition A was entered. Condition A addresses secondary containment being inoperable in modes 1, 2, or 3, with operability to be restored within4 hours
, 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.
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.
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.
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.
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.