05000374/LER-2023-003, Automatic Actuation of Reactor Protection System (RPS) During Restoration from Hydrostatic Test Conditions I
| ML23122A016 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 05/02/2023 |
| From: | Van Fleet J Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RA23-021 LER 2023-003-00 | |
| Download: ML23122A016 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| 3742023003R00 - NRC Website | |
text
Constellation~
RA23-021 May 2, 2023 U.S. Nuclear Regulatory Commission A TIN: Document Control Desk Washington, DC 20555-0001 LaSalle County Station, 2 Renewed Facility Operating License No. NPF-11 NRC Docket No. 50-374 LaSalle County Station 2601 North 21 " Road Marseilles, IL 61341 815-415-2000 Telephone 10 CFR 50.73
Subject:
Licensee Event Report 2023-003-00, Automatic Actuation of Reactor Protection System (RPS) During Restoration from Hydrostatic Test Conditions In accordance with 10 CFR 50. 73(a)(2)(iv)(A), Constellation Energy Generation, LLC (CEG) is submitting Licensee Event Report (LER) Number 2023-003-00 for LaSalle County Station, Unit 2.
There are no regulatory commitments in this letter. Should you have any questions concerning this report, please contact Mr. Dan Mearhoff, Regulatory Assurance Manager, at (815) 415-2800.
Respectfully,
~,/4;;/JJ;r John Van Fleet Jr Acting Site Vice President LaSalle County Station
Enclosure:
Licensee Event Report cc:
Regional Administrator-NRC Region Ill NRC Senior Resident Inspector - LaSalle County Station
E
Abstract
At 0910 CST on March 4, 2023, with Unit 2 in Mode 4 at O percent power, an actuation of a reactor scram on low charging water header pressure occurred during restoration from ASME Class 1 System Leakage Test conditions. All control rods were already fully inserted prior to the receipt of the scram signal.
The scram occurred due to a valid signal and all systems responded as expected. Low charging water header pressure is not required to be operable in Mode 4 but is active if not bypassed. The scram signal should have remained bypassed per station procedures.
- 2. DOCKET NUMBER
- 3. LER NUMBER SEQUENTIAL REV YEAR NUMBER NO.
374 2023 -
003 00 LaSalle County Station Unit 2 is a General Electric Boiling Water Reactor with 3546 Megawatts Thermal Rated Core Power. The affected system was the Reactor Protection System (RPS).
RPS initiates a rapid insertion of all the control rods (scram) when monitored variables exceed their pre-established limits, neutron flux instrumentation becomes inoperable, or a manual scram signal is inserted by the operator. In addition, the setpoints, power sources, and controls and instrumentation are arranged in such a manner as to preclude spurious scrams.
Condition Prior to Event
Unit(s): 2 Reactor Mode(s): 4
Description
Date: March 4, 2023 Mode(s) Name: Cold Shutdown Time: 0910 CST Power Level: 0%
Following completion of required ASME Class 1 System Leakage Testing, actions were taken to commence reactor depressurization. As governed by the testing procedure, the Control Rod Drive (CRD) Charging Water Stop Valve was closed. The Low Charging Water Header Pressure scram signal was verified to be bypassed at the start of the Hydrostatic Test. The scram signal was then restored during the transition into scram time testing. With the CRD Charging water Stop valve closed and the Low Charging Water Header Pressure scram signal not bypassed, reactor depressurization resulted in an RPS Scram on Low Charging Water Header Pressure.
At the time of the Scram, the unit was in Mode 4 with all rods inserted. The Low Charging Water Scram Signal is not required in Mode 4 for Rod Cycling and the Scram signal should have remained bypassed, in accordance with station procedures.
Reportability and Safety Analysis
The Low Charging Water Pressure Scram is only required to be enabled in Mode 2 and Mode 5 to ensure that a reactor scram is initiated before Scram capability is compromised during low reactor pressure operations. At the time of the event the reactor was in Mode 4 with all rods inserted. Therefore, there was no increased risk to the public as a result of this event.
The event is reportable under 10 CFR 50. 72(b )(3)(iv)(A) as an event or condition that results in the valid actuation of the Unit 2 RPS system. An ENS report was made to the NRC at 1642 on March 4, 2023 (EN 56389).
Safety System Functional Failure Review The system equipment responses did not result in a safety system functional failure (SSFF) as defined in accordance with NEI 99-02, "Regulatory Assessment Performance Indicator Guideline." The RPS logic safety function was satisfied by its actuation for designed inputs.
Corrective Actions
- 2. DOCKET NUMBER YEAR 374 2023 -
- 3. LER NUMBER SEQUENTIAL NUMBER 003 REV NO.
00 The personnel involved in the event were coached in accordance with Constellation processes.
Station procedures will be revised include steps to verify the Low Charging Water Header Pressure Scram is bypassed prior to closing the CRD charging water stop valve. Page _3_ of _3_