05000311/LER-2015-003

LER-2015-003, Both Trains of High Head Safety Injection Inoperable Due to a Relief Valve Failure

Salem Generating Station - Unit 2
Event date:	11-23-2015
Report date:	03-09-2016
Reporting criterion:	10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
Initial Reporting
ENS 51563	10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration
3112015003R02 - NRC Website

LER 15-003-00 for Salem, Unit 2, Regarding Both Trains of High Head Safety Injection Inoperable Due to a Relief Valve Failure

ML16027A132
Person / Time
Site:	Salem
Issue date:	01/22/2016
From:	Perry J F Public Service Enterprise Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LR-N16-0009 LER 15-003-00
Download: ML16027A132 (5)

PLANT AND SYSTEM IDENTIFICATION

Westinghouse - Pressurized Water Reactor {PWR/4} Emergency Core Cooling System / Relief Valve {BQ/RV} *Energy Industry Identification System (EIIS) codes and componentfunction identifier codes appear as {SS/CCC}.

IDENTIFICATION OF OCCURRENCE

Event Date: November 23, 2015 Discovery Date: November 23, 2015

CONDITIONS PRIOR TO OCCURRENCE

Salem Unit 2 was in operational Mode 3, the RCS was at normal operating temperature and pressure.

No additional structures, systems or components were inoperable at the time of the event that contributed to this event.

DESCRIPTION OF OCCURRENCE

At 2136 on November 23, 2015, the Boron Injection Tank (BIT) relief valve 2SJ10 exhibited increased seat leakage during the performance of troubleshooting to determine the cause of low BIT pressure. The increased seat leakage from 2SJ10 initiated a Reactor Coolant System (RCS) leak greater than 10 gallons per minute (gpm). Technical Specification (TS) 3.4.7.2.b action b was entered for RCS unidentified leakage greater than 1 gpm.

The BIT was isolated at 2137 and the leakage was stopped. Isolation of the BIT resulted in loss of the high head safety injection flow path for both trains of high head safety injection, requiring entry into TS 3.0.3.

On November 24, 2015 At 0252 Salem Unit 2 entered Mode 4, and at 0920 Salem Unit 2 achieved Mode 5, Cold Shutdown.

An eight-hour NRC Event Notification was required by 10 CFR 50.72(b)(3)(v)(D) for an event that could have prevented the fulfillment of a safety function of structures or systems that are needed to mitigate the consequences of an accident. EN 51563 was completed on November 23, 2015, at 0446. This LER is being made pursuant to the reporting requirements of 10 CFR 50.73(a)(2)(v)(D).

CAUSE OF EVENT

This event was caused by ineffective use of internal operating experience in the decision making process to reuse the 2CV141, which had been installed on the discharge of the 23 positive displacement charging pump, as a suitable replacement for the 2SJ10 during 2R21.

SAFETY CONSEQUENCES AND IMPLICATIONS

The Emergency Core Cooling System (ECCS) consists of several subsystems to ensure reactor coolant is delivered to the reactor vessel under accident conditions. The major equipment relied upon for the implementation of the injection phase functions are:

1. Two centrifugal charging pumps 2. Two safety injection (SI) pumps 3. Two residual heat removal (RHR) pumps 4. Four accumulators (one for each loop) 5. One boron injection tank (BIT) 6. Refueling water storage tank (RWST) The BIT only functions as part of the pressure boundary within the ECCS injection flow path. Upon receipt of a safety injection (SI) signal, flow from the centrifugal (high head) charging pumps is routed through the emergency flow path (i.e., the BIT) into the reactor coolant system (RCS).

A review of the Chapter 15 accidents revealed that high head safety injection is only relied upon for the small break LOCA (SBLOCA) and the steam generator tube rupture (SGTR). With the BIT isolated and high head injection unavailable, the operators would continue through the Emergency Operating Procedures (EOPs) to cooldown and reduce pressure to slow the loss of RCS inventory and allow intermediate head injection. It is unlikely that this would result in any core damage as operators would continue to follow the EOP strategy of cooldown and depressurization after a SBLOCA or SGTR.

There were no actual consequences due to the isolation of the BIT. Unit 2 was in MODE 3 following a refueling outage. Prior to the event, both BIT outlet isolation valves (2SJ12 and 2SJ13) were closed with a charging pump in service. BIT pressure was approximately 2400 psig when leakage through the BIT relief valve (2SJ10) increased. BIT inlet isolation valve 2SJ4 was closed in approximately 80 seconds to terminate the leak. The high head charging flow path was no longer OPERABLE and no RCS make up would be available until RCS pressure decreased below SI Pump shutoff head. The leak was well within the capacity of the operating charging pump and was rapidly terminated by operator action when lowering pressurizer level was recognized. The event did result in the entry into TS 3.0.3 due to the inoperability of the ECCS high head charging flow path.

SAFETY SYSTEM FUNCTIONAL FAILURE

A review of this event determined that a Safety System Functional Failure (SSFF) as defined in NEI 99-02, Regulatory Assessment Performance Indicator Guidelines, did not occur.

not conduct a sponsor, and a person is not required to respond to, the Information collection.

2. DOCKET 6. LER NUMBER

PREVIOUS OCCURRENCES

A review of Salem Unit 1 and 2 Licensee Event Reports for the previous three years identified a similar event requiring entry into TS 3.0.3 when both trains of intermediate head ECCS were rendered inoperable. That event was reported in LER 272/2014-005 'Technical Specification 3.0.3 Entry; Two ECCS Subsystems Inoperable," dated August 27, 2014.

CORRECTIVE ACTIONS

1) The 2SJ10 relief valve was replaced and retested with no identified leakage.

2) Revise procedure MA-AA-734-458, Pressure Relief Device Removal and Installation" to include a step that requires relief valve disassembly and inspection whenever predetermined criteria are met.

3) Other corrective actions are being tracked in the licensee's Corrective Action Program.

COMMITMENTS

There are no regulatory commitments contained in this LER