|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)(B), Loss of Safety Function - Remove Residual Heat
10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
|ENS 53000||10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 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)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material|
|4402017006R00 - NRC Website|
|Person / Time|
|From:||Hamilton D B|
FirstEnergy Nuclear Operating Co
Document Control Desk, Office of Nuclear Reactor Regulation
|Download: ML17335A065 (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 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.
- 006 - 00 05000-440 YEAR 2017 Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
On October 4, 2017, at0155 hours
, while in Mode 1 and 100 percent rated thermal power, inoperability of both trains of Motor Control Center, Switchgear, and Miscellaneous Electrical Equipment Areas Heating, Ventilation, and Air Conditioning System and Battery Rooms Exhaust System (M23/24) occurred. This resulted in a loss of safety function.
On October 4, 2017 at0155 hours
, with the plant in Mode 1 and at 100 percent rated thermal power, M23/24 Train A was shutdown and declared inoperable due to a report of excessive drive belt noise and malfunctioning belts on the A supply fan [AHU]. Concurrently, Control Complex Chilled Water (CCCW) Chiller B [KM] was out of service for planned maintenance resulting in Train B of M23/24 being inoperable. This combination resulted in a loss of safety function due to the impact to Division 1,2, and 3 electrical switchgear. At0200 hours
, M23/24 was shifted from train A to train B. CCCW Chiller C was already running and had been started at2225 hours
on 10/03/17. Cooling to the affected areas through the B train of M23/24 was maintained through use of the nonsafety related CCCW Chiller C, which is able to supply either train with chilled water.
Due to the inoperability of both trains of M23/24, actions were taken in LCO 3.8.7 for Alternating Current (AC) [EA] and Direct Current (DC) [EJ] Distribution Systems, LCO 3.8.4 for DC Sources, LCO 3.8.1 for AC Sources, and the associated support systems. The High Pressure Core Spray System (HPCS) [BC] was also declared inoperable, which is a single train safety system, and therefore an additional loss of safety function.
On October 04, 2017 at0553 hours
, event notification EN# 53000 was made to the NRC Operations Center in accordance with 50.72(b)(2)(i) & 50.72(b)(3)(v)(D) for initiation of plant shutdown and loss of safety function. Train A of M23/24 was declared operable at 0620, following belt replacement, and TS 3.0.3 was exited. The plant was restored to 100 percent rated thermal power at0804 hours
. At0926 hours
, the event notification reporting requirements were updated to include 50.72(b)(3)(v)(B) and 50.72(b)(3)(v)(C), in addition to 50.72(b)(3)(v)(D).
With the B train of the M23 system out of service for maintenance, the belt malfunction on the A train supply fan resulted in a loss of safety function and entry into Technical Specification 3.0.3. It was determined that two V-belts on the M23 A supply fan malfunctioned due to inadequate tensioning. The cause was determined to be inadequate procedural guidance in that the "general tensioning" method supplied in plant maintenance procedure, V-belt and Sheave Maintenance, which requires only a visual check of belt sag, is insufficient for restoring components utilizing V- belts to a reliable operating condition.
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 void OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 006 - 00 Perry Nuclear Power Plant Unit 1 05000-440 YEAR 2017
A Probabilistic Risk Assessment (PRA) evaluation was performed. The analysis indicates that the event resulted in a very small change to overall plant risk with a change (delta) in core damage frequency (CDF) of 1.78E-09/yr, and a change (delta) in the large early release frequency (LERF) of 1.11E-09/yr. The delta CDF and delta LERF values are well below the acceptable thresholds of 1.0E-06/yr and 1.0E-07/yr, respectively, as discussed in Regulatory Guide 1.174. Therefore, the safety significance of this event is considered to be very small.
Corrective actions in response to the event include: revising the maintenance procedure to use the Force Deflection Method for tensioning of the belts; replacing the M23 A supply fan drive belts and restoring M23/24 to operable; and performing an additional check of belt tension on the same train exhaust fan along with the opposite train supply and exhaust fans. Additionally, the belts for the Auxiliary Building ventilation EVE] exhaust fans will be checked.
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.