05000461/LER-2017-008

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LER-2017-008, Division 3 Shutdown Service Water Pump Start Failure
Clinton Power Station, Unit 1
Event date: 06-15-2017
Report date: 08-11-2017
Reporting criterion: 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
Initial Reporting
ENS 52806 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
4612017008R00 - NRC Website
LER 17-008-00 for Clinton, Unit 1 re Division 3 Shutdown Service Water Pump Start Failure
ML17228A043
Person / Time
Site: Clinton Exelon icon.png
Issue date: 08/11/2017
From: Stoner T R
Exelon Generation Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
SRRS 5A.108, U-604667
Download: ML17228A043 (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.

3. LER NUMBER

2017 - 00 008

PLANT AND SYSTEM IDENTIFICATION

General Electric -- Boiling Water Reactor, 3473 Megawatts Thermal Rated Core Power Energy Industry Identification System (EMS) codes are identified in text as [XX].

EVENT IDENTIFICATION

Division 3 Shutdown Service Water Pump Start Failure

A. Plant Operating Conditions Before the Event

Unit: 1 Event Date: 6/15/17 Mode: 1 Mode Name: Power Operation

B. Description of Event

Event Time: 0958 Reactor Power: 97 percent On June 15, 2017, Clinton Power Station (CPS) attempted to perform the quarterly surveillance test of the Division 3 shutdown service water (SX) [BI] pump [P] (1SX01PC). The pump ran for approximately 30 seconds before thermal overloads tripped the pump motor [M]. A second pump run was attempted with video recording that showed the motor spinning the shaft more quickly for the first rotation, then immediately slowed down to approximately 70 RPM. The run lasted approximately 8 seconds before the pump was manually secured.

At 0958, Operators declared the Division 3 SX, Division 3 Emergency Diesel Generator (EDG) [EK], Division 3 Inverter [EF], Division 3 Direct Current Distribution [EJ], Division 3 Alternating Current Distribution [ED] systems, and the High Pressure Core Spray (HPCS) [BG] system inoperable due to the pump trip. Operators entered the Technical Specification Actions Requirements for Limiting Conditions for Operation (LCO) 3.7.2 and LCO 3.5.1, ECCS - Operating. Operators verified within one hour that the RCIC system was operable, and entered the action to restore HPCS to Operable status within 14 days.

At

2220 hours
0.0257 days
0.617 hours
0.00367 weeks
8.4471e-4 months

, Operators completed an 8-hour non-emergency notification to the NRC (Event Notification Number 52806) under 10 CFR 50.72(b)(3)(v)(D) due to the loss of a single train safety system, that is, the loss of the HPCS system function. This event is reportable under 10 CFR 50.73(a)(2)(v)(D) due to a condition that could have prevented the fulfillment of the safety function needed to mitigate the consequences of an accident.

C. Cause of the Event

A decoupled run of the motor was performed with no issue. The motor was then sent to an off-site vendor for analysis, and pump disassembly commenced. The disassembled pump was inspected with the help of the pump vendor and site SMEs. No abnormalities were noted that were deemed significant enough to cause the motor to fail to accelerate the pump.

The Root Cause Evaluation has not been completed. A supplement is to be submitted once this information is available.

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 Infccollects.Resource@nrc.goy, 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 collection.

3. LER NUMBER

2017 - 00_ 008 D. Safety Consequences The purpose for the Division 3 SX system is to provide cooling water to Division 3 cooling loads including the HPCS pump room coolers [CLR], the Division 3 EDG and the Division 3 Switchgear Heat Removal System (VX). The Division 3 SX header is normally supplied by cooling water from the non- safety related Plant Service Water System (WS) [KG]. Under design basis event conditions such as Loss of Offsite Power (LOOP) or Loss of Coolant Accidents (LOCAs), a Division 3 SX pump start signal is generated and the cross-tie valve [V] (1SX014C) from the plant service water system closes. At this point the Division 3 SX pump would be providing cooling water flow from the lake to the Division 3 SX cooling loads.

Divisions 1 and 2 safety-related equipment are fully capable of mitigating the consequences of an accident and were available during the period of this event.

The failure of the Division 3 Shutdown Service Water Pump results in loss of Division 3 Emergency Diesel Generator safety function and a loss of the High Pressure Core Spray System safety function.

The cause of the failure of the pump has not been determined. Once determined, this information will be provided.

E. Corrective Actions

In parallel with the testing described above, several component changes were made to the overall pump/motor assembly. A new motor with higher starting torque characteristics was approved and installed. The pump breaker and thermal overloads were replaced with new units. The pump shaft sleeves were replaced and the pump packing was replaced with a flexible style equivalent.

On June 23, 2017, following a successful uncoupled run of the new motor, a coupled run was performed with no abnormalities noted. All monitored points showed normal starting characteristics for the pump. The baseline and surveillance test procedures were performed without incident.

The Division 3 SX system, including the Division 3 EDG and HPCS system were declared operable at

2345 hours
0.0271 days
0.651 hours
0.00388 weeks
8.922725e-4 months

on 6/23/17.

Additional corrective actions for this event will be provided in the follow-up LER 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.

3. LER NUMBER

2017 - 00 008 F. Previous Similar Occurrences Emergency Diesel Generator and High Pressure Core Spray Safety Functions On 9/16/14 at approximately

1905 hours
0.022 days
0.529 hours
0.00315 weeks
7.248525e-4 months

, Operators were performing an operability test of the Shutdown Service Water (SX) system. The Division 3 SX pump (1SX01PC) was started to support the 2-year Comprehensive Pump Test and the motor thermal overload protection tripped off the pump after approximately 36 seconds. The cause of the event was that procedures used to develop plant modification change packages contained an inadequate process to identify the need for further reviews and the level of design detail required by those reviews. A new pump was installed and the pump was restored to operable status on 9/21/14. (ML16006A047)).

G. Component Failure Data

The Division 3 SX pump is a Sulzer model 8X14A VCM pump with a Siemens-Allis type RGV motor.

The pump is a vertical two-stage deep well pump that consists of a discharge head, six columns, and a bowl assembly to extend 30 feet below the floor elevation. The pump is driven by a 75 horsepower, 1800 RPM, 480-volt motor.