05000416/LER-2017-001

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LER-2017-001, High Pressure Core Spray (HPCS) Jockey Pump Trip
Grand Gulf Nuclear Station, Unit 1
Event date: 1-27-2017
Report date: 3-28-2017
Reporting criterion: 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
4162017001R00 - NRC Website
LER 17-001-00 for Grand Gulf, Unit 1, Regarding High Pressure Core Spray Jockey Pump Trip
ML17087A135
Person / Time
Site: Grand Gulf Entergy icon.png
Issue date: 03/28/2017
From: Nadeau J J
Entergy Operations
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
GNRO-2017/00016
Download: ML17087A135 (7)


Reported lessons learned are incorporated into the licensing process and fed back to industry.

Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), 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.

PLANT CONDITIONS PRIOR TO THE EVENT

At the time of the event, Grand Gulf Nuclear Station (GGNS) Unit 1 was in Mode 2 and raising power in the source range to return to power operations. No other safety systems were inoperable at the time of this event.

DESCRIPTION

At

1808 hours
0.0209 days
0.502 hours
0.00299 weeks
6.87944e-4 months

on 1/27/17, the Main Control Room received "HPCS PMP SUCT PRESS ABNORMAL" (1 H13-P601-16A- D4) annunciator due to a High Pressure Core Spray (HPCS) Jockey Pump trip. The Control Room dispatched an operator and electrician to HPCS jockey pump breaker 52-170105 and dispatched an operator locally to the HPCS jockey pump. The operator reported the HPCS breaker to be in the ON position with no abnormalities noted. The local operator reported the HPCS Jockey Pump not running but no other abnormalities were identified. At

1817 hours
0.021 days
0.505 hours
0.003 weeks
6.913685e-4 months

"HPCS JKY PMP DISCH PRESS LO" annunciator alarmed and "HPCS PMP SUCT PRESS ABNORMAL" annunciator cleared. HPCS pump suction pressure indicated 23.75 psig on Main Control Room Panel 1 H13-P625. Average suction pressure over the last five years is 21.3 psig.

The LCO Action Statement entered was LCO 3.5.1.B, ECCS Operating- for HPCS System inoperable.

Initial investigation of the feeder breaker (52-170105) revealed that the overloads at the breaker were tripped. The motor amperage was measured at 53 amps during a 13 second run in which the pump did not rotate. The thermals tripped again. The decision was made to disassemble the HPCS Jockey Pump and rebuild the pump using parts from the warehouse which was performed on 1/29/17. During disassembly of the pump, the following conditions were identified:

  • Bad thrust bearing
  • A groove in the bearing housing The pump was tested to demonstrate functionality of the pump on 1/29/17 and the system was returned to service.

REPORTABILITY

Event Notification No. 52516 was made to the U.S. Nuclear Regulatory Commission (NRC) Operations Center. This LER is being submitted pursuant to Title 10 Code of Federal Regulations 10 CFR 50.73(a)(2)(v)(D) for any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. Telephonic notification was made to the NRC Operations Center via the Emergency Notification System on 1/27/17, at

2305 hours
0.0267 days
0.64 hours
0.00381 weeks
8.770525e-4 months

, pursuant to 10 CFR 50.72(b)(3)(v)(D) for any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident.

CAUSE

Direct Cause: The HPCS Jockey Pump failed on 1/27/17 due to the thrust bearing being degraded causing the pump to seize.

Apparent Cause: It was identified that the HPCS Jockey Pump (Gould 3196) does not have a time-based replacement Reported lessons learned are incorporated into the licensing process and fed back to industry.

Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), 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.

Grand Gulf Nuclear Station, Unit 1 05000-416 maintenance task. GGNS implements a predictive monitoring maintenance strategy in lieu of time-based replacement preventive maintenance tasks. The failure of the thrust bearing would have shown up in the axial vibration trends of the pump. Current preventive maintenance was not sufficient to prevent failure of the jockey pump. A conservative time- based replacement PM task to replace the pump will reduce the likelihood of another failure of the pump.

Contributing Cause: The HPCS operating instructions does not contain enough guidance to maintain the HPCS System available when the jockey pump is secured. The inadequate guidance does not cause the jockey pump to fail, but increases the consequences (non-functional time) of the event. The HPCS System can be made operable by keeping the HPCS Pump discharge line full by either the HPCS Jockey Pump or by running the HPCS Pump. During this failure, the procedural guidance did not allow for the HPCS Pump to be run to keep the HPCS System operable.

EXTENT OF CONDITION

The condition may exist in the following equipment, procedures, processes, and/or organizations:

  • No procedures are affected
  • No processes are affected
  • No organizations are affected

EXTENT OF CAUSE

The cause may exist in the following equipment, procedures, processes, and/or organizations:

  • RHR Jockey Pumps A, B, and C
  • No procedures are affected
  • No processes are affected
  • No organizations are affected

CORRECTIVE ACTIONS

The HPCS Jockey Pump was rebuilt and a partial HPCS Quarterly Functional Surveillance was performed to demonstrate functionality of the pump. This partial surveillance was completed satisfactorily on 1/29/17 and the pump was returned to service.

To prevent this failure from occurring in the future, the following actions have been taken:

  • Initiated preventive maintenance task to perform thermography and oil analysis of the HPCS Jockey Pump bearings.
  • Initiated preventive maintenance tasks to perform thermography and oil analysis of all three RHR Jockey Pump bearings.
  • Initiated preventive maintenance task to perform thermography and oil analysis of the LPCS Jockey Pump bearings.

Reported lessons learned are incorporated into the licensing process and fed back to industry.

Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), 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.

  • Initiated preventive maintenance task to replace the HPCS Jockey Pump on a conservative time-based frequency.
  • Initiated preventive maintenance task to replace all three RHR Jockey Pumps on a conservative time-based frequency.
  • Initiated preventive maintenance task to replace the LPCS Jockey Pump on a conservative time-based frequency.

SAFETY SIGNIFICANCE

The event posed no threat to the health and safety of the general public or to nuclear safety as safety-systems performed as designed. No Technical Specification safety limits were violated. Industrial safety was not challenged, and there was no potential or actual radiological release during the event.

PREVIOUS SIMILAR EVENTS

There are no known previous similar events at Grand Gulf Nuclear Station.