05000400/LER-2016-007

LER-2016-007, Containment Spray System Valve Actuation

Shearon Harris Nuclear Power Plant - Unit 1
Event date:	10-26-2016
Report date:	02-09-2017
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation
4002016007R01 - NRC Website

LER 16-007-01 for Shearon Harris Unit 1, Regarding Containment Spray System Valve Actuation

ML17040A534
Person / Time
Site:	Harris
Issue date:	02/09/2017
From:	Hamilton T M Duke Energy Progress
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
HNP-17-013 LER 16-007-01
Download: ML17040A534 (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 e-mail to Inf000llects.Resource@nrc.gov, 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.

05000- Shearon Harris Nuclear Power Plant — Unit 1 400 Note: Energy Industry Identification System (EllS) codes are identified in the text within brackets [ ].

A. Background

Event Date: October 26, 2016 Mode: 6 Reactor Power: 0 percent Event Time: 1142 EDT No systems, structures, or components were inoperable at the start of this event that contributed to the event. No change in plant mode or in reactor power occurred as a result of this event. The plant was in mode 6, refueling, with the reactor vessel head removed, reactor cavity water level greater than 23 feet, core reload complete, and the residual heat removal system in operation.

This event is reportable per 10 CFR 50.73(a)(2)(iv)(A) as "an event or condition that results in valid actuation of any of the systems listed in paragraph (a)(2)(iv)(B) of [10 CFR 50.73]..." due to actuation of a valve in the containment spray (CT) system [BE].

The purpose of the CT system is to spray borated sodium hydroxide solution into Containment [NH] to cool the atmosphere and to remove the fission products that may be released into the containment atmosphere following a loss of coolant accident (LOCA) or main steam line break (MSLB). It has two principal modes of operation: 1) the initial injection mode, during which time the system sprays borated water taken from the refueling water storage tank (RWST) [TK], and 2) the recirculation mode, which is initiated when low-low level is reached in the RWST. During recirculation mode, the pump suction is transferred from the RWST to the containment sump by opening the containment sump suction valves and closing the valves at the outlet of the RWST. This switchover is accomplished automatically.

B. Event Description

On October 26, 2016, at 1142 EDT, the Shearon Harris Nuclear Power Plant (Harris) was in a planned refueling outage.

Operations was in the process of restoring the CT system following maintenance, with the reactor cavity filled with water and the RWST level less than 23.4 percent. During the CT system restoration, Operations started the 'B' CT pump [P], which was aligned to the RWST. With RWST level less than 23.4 percent, the logic was satisfied to initiate CT switchover to the containment sump. This caused the containment sump suction valve, 1CT-102 [ISV], to open, establishing a flow-path which allowed water to be transferred from the RWST to the containment sump.

Immediate action was taken by Operations to restore the desired plant configuration. This was achieved by securing the CT pump and re-closing 1CT-102. During the event, the CT system was aligned for recirculation of 'B' CT pump discharge back to the RWST, so no water flowed through the spray header.

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 Inf000llects.Resource@nrc.gov, 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.

05000- Shearon Harris Nuclear Power Plant — Unit 1 400 C. Causal Factors The primary cause of this event was a procedural deficiency. The procedure did not establish a physical barrier to prevent the containment sump valves from opening in Modes 5, 6 and defueled.

D. Corrective Actions

Completed Actions:

Immediate corrective action to provide just-in-time training for Operations as a refresher on the operation of the spray system switchover actuation logic.

Planned Actions:

Revise the procedure to remove power to the containment sump valves to prevent them from opening in Modes 5, 6 and defueled.

E. Safety Analysis

The safety significance of this event was minimal, as the condition had no impact on decay heat removal. The event did not affect water inventory in the reactor cavity, and there was no impact on core cooling, which was being performed by the residual heat removal system [BP] at the time of the event. This event did not impact the health and safety of the public.

F. Additional Information

There have been no related events at Harris within the past three years.