05000387/LER-2021-005, Automatic Reactor Scram Due to Turbine Control Valve Fast Closure

Automatic Reactor Scram Due to Turbine Control Valve Fast Closure

ML22026A512
Person / Time
Site:	Susquehanna
Issue date:	01/26/2022
From:	Cimorelli K Talen Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
PLA-7980 LER 2021-005-00
Download: ML22026A512 (3)

LER-2021-005, Automatic Reactor Scram Due to Turbine Control Valve Fast Closure

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(iv)(B), System Actuation
3872021005R00 - NRC Website

text

Kevin Cimorelli Susquehanna Nuclear, LLC Site Vice President 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3795 Fax 570.542.1504 Kevin.Cimorelli@TalenEnergy.com TALEN ENERGY

January 26, 2022

Attn: Document Control Desk 10 CPR 50.73 U. S. Nuclear Regulatory Commission Washington, DC 20555-0001

SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-387 /2021-005-00 UNIT 1 LICENSE NO. NPF-14 PLA-7980 Docket No. 50-387

Attached is Licensee Event Report (LER) 50-387/2021-005-00. The LER reports an event involving an automatic scram due to a Reactor Protection System actuation as a result of Turbine Valve fast closure. The condition is being reported in accordance with 10 CPR 50.73(a)(2)(iv)(A) as an event that resulted in automatic actuation of a system listed in 10 CPR 50.73(a)(2)(iv)(B).

There were no actual consequences to the health and safety of the public as a result of this event.

This letter contains no new or revised regulatory commitments.

Attachment: LER 50-387/2021-005-00

Copy: NRC Region I Mr. C. Highley, NRC Senior Resident Inspector Ms. A. Klett, NRC Project Manager Mr. M. Shields, PA DEP/BRP

Abstract

At approximately 12:54 on November 30, 2021, Susquehanna Steam Electric Station, Unit 1, experienced an automatic reactor scram during Turbine Valve Cycling surveillance testing. During surveillance testing of Main Stop Valve 4 (MSV-4), a simultaneous closure of Turbine Control Valve 4 (TCV-4) occurred, resulting in a Division II Reactor Protection System (RPS) actuation. While the half scram signal was actuated, a Division I RPS actuation occurred, resulting in a full reactor scram. All control rods inserted, and operators placed mode switch to shut down.

This event was reported by Event Notification 55616 in accordance with 10 CFR 50. 72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A). This event is also reportable in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in automatic actuation of a system listed in 10 CFR 50.73(a)(2)(iv)(B).

The cause of the event is under investigation and will be provided in a supplement to this report with associated corrective actions.

There were no actual consequences to the health and safety of the public as a result of this event.

U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 08/31/2023 Susquehanna Steam Electric Station, 05000-387 Unit 1 2021 - 005 - 00

NARRATIVE

CONDITIONS PRIOR TO EVENT

Unit 1 - Mode 1, approximately 80 percent Rated Thermal Power (RTP)

Unit 2 - Mode 1, approximately 100 percent RTP

Unit 1 Turbine Valve Cycling surveillance testing was in progress at the time of the event.

EVENT DESCRIPTION

At approximately 12:54 on November 30, 2021, the Susquehanna Steam Electric Station, Unit 1, experienced an automatic scram due to a Reactor Protection System (RPS) [EIIS System Code: JC] actuation during Turbine Valve Cycling surveillance testing. During the fast closure portion of the surveillance test on Main Stop Valve 4 (MSV-4) [EIIS System/Component Codes: TA/SHV], Control Valve 4 (CV-4) [TA/FCV]

unexpectedly fast closed, thereby generating a Turbine Control Valve (TCV) fast closure on Division II RPS.

While the half scram signal was in on Division II RPS, a Division I RPS trip signal was generated which caused a full reactor scram. All control rods inserted and operators placed the mode switch to shutdown.

This event was reported by Event Notification 55616 in accordance with 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A). This event is also reportable in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an event that resulted in automatic actuation of a system listed in 10 CFR 50.73(a)(2)(iv)(B).

CAUSE OF EVENT

The cause of the event is under investigation and will be provided in a supplement to this Licensee Event Report (LER).

ANALYSIS/SAFETY SIGNIFICANCE

Safety significance will be provided in a supplement to this LER.

CORRECTIVE ACTIONS

Corrective actions will be provided in a supplement to this LER.

COMPONENT FAILURE INFORMATION

Component failure information will be provided in a supplement to this LER.

PREVIOUS OCCURRENCES

Previous similar occurrences, if any, will be provided in a supplement to this LER.