05000354/LER-2015-003
| Hope Creek Generating Station | |
| Event date: | 05-04-2015 |
|---|---|
| Report date: | 07-06-2015 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3542015003R00 - NRC Website | |
PLANT AND SYSTEM IDENTIFICATION
General Electric — Boiling Water Reactor (BWR/4)* Reactor Pressure Vessel (AC) — EllS Identifier {AC/RPV} Core Spray (BM) — EllS Identifier {BM} RHR/LPCI (BO) ---- EllS Identifier {BO} *Energy Industry Identification System (EllS) codes and component function identifier codes appear as {SS/CCC}
IDENTIFICATION OF OCCURRENCE
Event Date: May 4, 2015 Discovery Date: May 5, 2015
CONDITIONS PRIOR TO OCCURRENCE
Hope Creek was shut down for Refueling Outage H1R19 in Operational Condition (OPCON) 4 — Cold Shutdown.
DESCRIPTION OF OCCURRENCE
From May 4 through 5, 2015, Hope Creek conducted a planned Reactor Pressure Vessel {AC/RPV} pressure test following RPV reassembly during refuel outage H1R19. The RPV pressure test is considered to be an Operation With the Potential to Drain the Vessel (OPDRV) because some isolation interlocks are bypassed during the test to preclude instrument failures that could lead to over-pressurization of the RPV.
Technical Specification (TS) 3.5.2, ECCS Shutdown, requires that at least two Low Pressure Emergency Core Cooling System (ECCS) subsystems be OPERABLE in Operational Condition 4. The TS requires that with only one ECCS subsystem operable, two subsystems shall be restored to operable status within four hours, or suspend all operations with the potential to drain the reactor vessel. Contrary to this requirement, Hope Creek conducted an OPDRV activity with only one low pressure ECCS subsystem operable.
Hope Creek has a total of six low pressure ECCS subsystems that could be used to meet the requirements of TS 3.5.2. The status of each of the subsystems at the time of the event is provided in Table 1, below. Although only one Core Spray {BM} subsystem was operable at the time, there were two additional low pressure subsystems that were available with operator action in the event that ECCS injection was required. The 'C' RHR {BO} subsystem was aligned for the Low Pressure Coolant Injection (LPCI) mode of operation with the pump breaker in the Pull-To-Lock (PTL) position. When in the PTL position, breaker closure is inhibited for automatic and manual start signals.
Removing the breaker from PTL requires dispatching an operator to the breaker to reposition a single switch on the front of the breaker cubicle. The 'A' RHR subsystem was aligned for shutdown cooling, but isolated from the reactor coolant system to support the RPV pressure test. The 'A' RHR subsystem could be realigned from the control room to the LPCI mode of operation by repositioning pump suction and discharge valves.
With some Low Pressure ECCS subsystems already inoperable, 'B' and 'D' RHR Pumps were removed from service for outage-related maintenance. The collective operability status of the Low Pressure ECCS Pumps was not appropriately assessed for TS compliance. Table 1 summarizes the status of ECCS subsystems used to meet TS 3.5.2 during the period in question.
This condition existed from May 4, at 0400 until May 5 at 1042, a period of 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> and 42 minutes. TS compliance was restored on May 5 at 1042, when the condition was recognized and a second low pressure ECCS system was returned to operable.
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.
Hope Creek Generating Station 05000354 Table 1 — HCGS Low Pressure ECCS status and is an the in the Standard change There is LP ECCS subsystem Status of system Notes 'A' Core Spray subsystem Inoperable; out of service for maintenance `B' Core Spray subsystem Operable and in standby 'A' RHR / LPCI subsystem Aligned for SDC; inoperable for ECCS but available for realignment Could be realigned for LPCI from the Control Room 'B' RHR / LPCI subsystem Inoperable; out of service for maintenance 'C' RHR / LPCI subsystem Inoperable but available; pump breaker in PTL Could be restored to operable at the pump breaker 'D' RHR / LPCI subsystem Inoperable; out of service for maintenance
CAUSE
The subsystems
SAFETY
The can
LPCI
operating The by
LPCI
Technical for to There no for
OF EVENT
cause of the event was determined to be failure to properly assess the operability status of all the ECCS which could be used to meet TS 3.5.2 prior to rendering 'B' and 'D' RHR inoperable for scheduled maintenance.
CONSEQUENCES AND IMPLICATIONS
Emergency Core Cooling System (ECCS) network has built-in redundancy so that adequate inventory makeup be provided, even with other failures. In Operational Condition 4, the primary purpose of the Core Spray subsystems is to provide reactor vessel inventory makeup during postulated drain-down events. LPCI mode of the RHR system.
'A' RHR subsystem was aligned for shutdown cooling, but isolated from the reactor coolant system to support RPV pressure test. The 'A' RHR subsystem could be realigned from the control room to the LPCI mode of operation repositioning pump suction and discharge valves. In addition, the 'C' RHR subsystem was available to place mode of operation, if required, by removing the pump breaker from the pull-to-lock position. Improved Specifications (ISTS) recognized that LPCI subsystems aligned for SDC could be considered OPERABLE ECCS provided the subsystem was otherwise OPERABLE and capable of being manually realigned. This the applicability of TS 3.5.2 was endorsed by the NRC approval of TSTF-416, "LPCI Valve Alignment Verification Note Location.
were no actual consequences due to inoperability of the second required low pressure ECCS system.
safety significance associated with this event based on the other low pressure ECCS systems that were available inventory makeup.
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.
There were no safety system equipment problems associated with this event; therefore, there was no safety system functional failure as defined in NEI 99-02, Revision 7, Regulatory Assessment Performance Indicator Guideline.
PREVIOUS EVENTS
A review of HOGS LERs from the past three years did not reveal any similar previous events.
CORRECTIVE ACTIONS
The procedure used for operability assessment and equipment control will be revised to clarify the implementation requirements of TS 3.5.2.
Other corrective actions are being tracked in the licensee's Corrective Action Program.
COMMITMENTS
This LER contains no regulatory commitments.