05000354/LER-2015-005

LER-2015-005, Reactor Scram Due to Invalid RRCS Actuation

Hope Creek Generating Station
Event date:	09-28-2015
Report date:	01-05-2015
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation
3542015005R01 - NRC Website

LER 15-005-01 for Hope Creek, Unit 1, Regarding Reactor Scram Due to Invalid RRCS Actuation

ML16005A082
Person / Time
Site:	Hope Creek
Issue date:	01/05/2016
From:	Carr E S Public Service Enterprise Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LR-N15-0258 LER 15-005-01
Download: ML16005A082 (5)

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 Internet 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, Hope Creek Generating Station 05000- 354

3. LER NUMBER

- 005 2015 01

PLANT AND SYSTEM IDENTIFICATION

General Electric — Boiling Water Reactor (BWR/4) Reactor Protection System — EllS Identifier {JC}* Redundant Reactivity Control System - EllS Identifier {JC}* Reactor Recirculation System - EllS Identifier {AD}* *Energy Industry Identification System {EDS} codes and component function identifier codes appear as {SS/CCC}

IDENTIFICATION OF OCCURRENCE

Event Date: 09/28/15 Discovery Date: 09/28/15

CONDITIONS PRIOR TO OCCURRENCE

Hope Creek was in Operational Condition 1 at 100 percent rated thermal power (RTP). Redundant Reactivity Control System (RRCS) {JC}, Division 1, surveillance testing was in progress.

DESCRIPTION OF OCCURRRENCE

On 9/28/2015 at 20:46, a Hope Creek Instrument and Controls technician was performing a surveillance test of RRCS division 1, channel B, to simulate a high reactor pressure condition. The RRCS system is designed to detect and respond to an Anticipated Transient Without Scram (ATWS) condition. One indication of this condition is high reactor pressure, at or above 1071 psig. Under these conditions, the RRCS is designed to trip both Reactor Recirculation Pumps (RRPs) {AD} and initiate Alternate Rod Insertion (ARI). The RRPs are tripped to reduce core flow and increase the formation of core voids, thus reducing power. ARI provides an alternate path for control rod insertion by depressurizing the scram air header through valves separate from the RPS {JC} scram valves.

During the test, a keypad on the local RRCS panel is used to enter the test parameter, the test signal value and the channel being tested. The technician was expected to enter a test pressure signal of 1400 psig into the B channel of division 1. Plant data indicate the test pressure signal was also entered in channel A of division 1. With the 1400 psig test signal in both the A and B channels of logic, division 1 of the RRCS system actuated, causing RRPs to trip and ARI to begin control rod insertion by depressurizing the scram air header.

The change in reactor power caused a reactor water level transient which reached the RPS trip set-point of +12.5 inches. Although the control rods were already moving inward due to ARI actuation, the RPS functioned as designed to ensure reactor shutdown was completed via a scram signal. After the initial transient, plant operators stabilized reactor pressure and water level using turbine bypass valves and the feed water system, respectively.

CAUSE OF EVENT

The cause of this event is that the technician made an error in the performance of the surveillance test. The error was most likely caused by pressing the incorrect key on the common keyboard for the panel (placing the wrong channel in test). Based on a review of plant data (alarms and indications) and surveillance test simulation on the RRCS training simulator, it was concluded that the technician most likely recognized the unexpected conditions and attempted to correct his error. The technician did not understand that the pressure test signal had sealed in on the incorrect channel. When faced with an unexpected condition, the technician did not stop and seek supervisory guidance. .When the test signal was subsequently entered into the correct channel, the RRCS system actuation resulted.

When the cause analysis determined that the cause was associated with a human error, and also determined the most probable error sequence, technician response to further questions could not be obtained, because the technician who was involved had resigned.

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 Internet e-mall 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.

SAFETY CONSEQUENCES AND IMPLICATIONS

There were no consequences to nuclear safety as a result of this event. The RRCS and RPS system operated as designed to shut down the reactor. All necessary support systems functioned as needed to support plant stabilization and recovery post transient.

SAFETY SYSTEM FUNCTIONAL FAILURE

A review of this condition determined that a Safety System Functional Failure (SSFF) as defined in Nuclear Energy Institute (NEI) 99-02, "Regulatory Assessment Performance Indicator Guideline," did not occur.

PREVIOUS EVENTS

A review of HCGS LERs from the past three years did not reveal any similar previous events.

CORRECTIVE ACTIONS

Following the event, the technician involved in the event was disqualified from performing any surveillance testing or other plant maintenance duties.

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

COMMITMENTS

This LER contains no regulatory commitments.