05000382/LER-2024-003, Automatic EFAS Actuation During Surveillance Test
| ML24192A173 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 07/10/2024 |
| From: | Twarog J Entergy Operations |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| W3F1-2024-0025 LER 2024-003-00 | |
| Download: ML24192A173 (1) | |
| 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 |
| 3822024003R00 - NRC Website | |
text
- ) entergy W3F1 -2024-0025 July 10, 2024 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 John Twarog Manager Regulatory Assurance 504-739-67 4 7 10 CFR 50.73
Subject:
Licensee Event Report 50-382/2024-003-00, Automatic EFAS Actuation During Surveillance Test Waterford Steam Electric Station, Unit 3 NRC Docket No. 50-382 Renewed Facility Operating License No. NPF-38 Entergy Operations, Inc. (Entergy) submits the enclosed Licensee Event Report (LER) 50-382/2024-003-00 for Waterford Steam Electric Station, Unit 3. The events reported herein are reportable in accordance with 10 CFR 50.73(a)(2)(iv)(A), Any event or condition that resulted in manual or automatic actuation of any of the systems listed in paragraph (a)(2)(iv)(B);
Reactor protection system (RPS) including: reactor scram or reactor trip and emergency feedwater system.
The LER describes the valid, automatic actuation of Emergency Feedwater Actuation Signal and a RPS reactor trip during emergency feedwater flow verification test.
This letter contains no new commitments.
Should you have any questions concerning this issue, please contact me at 504-739-6747.
Respectfully, John Twarog JRT/ahv Entergy Operations, Inc., 17265 River Road, Killona, LA 70057
W3F1 -2024-0025 Page 2 of 2 Enclosure: Licensee Event Report 50-382/2024-003-00 cc:
NRC Region IV Regional Administrator NRC Senior Resident Inspector - Waterford Steam Electric Station, Unit 3 NRC Project Manager - Waterford Steam Electric Station, Unit 3 Louisiana Department of Environmental Quality
Enclosure W3F1-2024-0025 Licensee Event Report 50-382/2024-003-00
Abstract
At 1655 on 5/11/2024, during performance of Emergency Feedwater Pump AB (EFW AB) flow verification surveillance test, Steam Generator (SG) #1 level unexpectedly dropped from approximately 30% Narrow Range (NR) to 26.83% NR after emergency feedwater flow was initiated. At 27.4% NR in SG #1, a valid Emergency Feedwater Actuation Signal (EFAS) 1 Train A and B, and Reactor Protection Signal (RPS) reactor trip signal was generated. At the time of this event, the plant was in Mode 3 with all Control Element Assemblies (CEAs) fully inserted, Reactor Trip Circuit Breakers (RTCB) closed and individual CEA disconnects open for plant startup.
The causes of the unexpected EFAS 1 and RPS reactor trip signals was procedural guidance allowed the test to start with SG level close to the actuation setpoint and the operators did not consider the magnitude of the SG level shrink when feeding the SG with colder feedwater. Corrective actions include revising the test procedure to raise the minimum level from 30% to 40% and completion of a performance analysis.
This event is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A), any event or condition that resulted in manual or automatic actuation of any of the systems listed in 10 CFR 50.73(a)(2)(iv)(B).
Event Description
At 1655 CDT on May 11, 2024, with Waterford Steam Electric Station, Unit 3 (WF3), operating in Mode 3, a valid Emergency Feedwater Actuation Signal (EFAS) [JE] 1 Trains A and B and Reactor Protection System (RPS)[JC] reactor trip signal was received. This occurred during the performance of OP-903-014, Emergency Feedwater Flow Verification. Steam Generator (SG)[SG:SB] #1 indicated level dropped below the actuation setpoint of 27.4% narrow range (NR) when feedwater flow was initiated from Emergency Feedwater Pump AB (EFW AB) [P:BA] to SG #1.
At the time of this event, all Control Element Assemblies (CEAs) were already fully inserted, Reactor Trip Circuit Breakers (RTCB) [BKR] were closed, and individual CEA disconnects were open for plant startup. Upon exceeding the RPS trip setpoint for Steam Generator Level Low, a reactor trip signal was received and all RTCBs opened as expected. Upon receipt of EFAS 1, all Emergency Feedwater (EFW) components actuated as expected. The Reactor Operators took manual control of the Emergency Feedwater System to restored SG
- 1 level. Once SG #1 level was restored above EFAS 1 reset value, Operations personnel reset the EFAS 1 actuation signal.
This event was reported on May 11, 2024, at 2249 EDT in accordance with 10 CFR 50.72(b)(3)(iv)(A) as a valid actuation of the Emergency Feedwater System (EN 57122).
Event Cause
This event was caused by two factors. The procedural guidance to ensure the Emergency Feedwater Flow Verification surveillance test would be started with enough margin between the minimum, procedurally driven level of 30% NR and the actuation setpoint for both EFAS and the RPS at 27.4% NR was insufficient. A subsequent Engineering review of SG parameters, that existed during this test, determined that an approximately 3% NR SG level drop could occur when feedwater flow is initiated and raised to the required flow range directed by the test. The procedural SG level band of 30% to 70% NR does not adequately maintain margin to the actuation setpoint of 27.4% NR.
The second cause was the operators did not anticipate the amount of SG level reduction that would occur after feedwater flow was initiated. The test procedure and the briefing database did not contain guidance related to the potential for SG levels to lower during feeding due to level shrink and/or cooldown of the SG water inventory.
During the pre-job brief, the operators focus was on ensuring Steam Generator levels were low enough to complete the flow verification prior to SG level exceeding the upper procedure limit of 70% NR. Mitigating actions were not implemented to ensure the plant did not drop below 27.4% NR where the EFAS actuation and RPS trip signal occur.Page 3 of 3(04-02-2024)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 04/30/2027
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 1.
FACILITY NAME Waterford Steam Electric Station, Unit 3 050
- 2. DOCKET NUMBER 00382
- 3. LER NUMBER YEAR 2024 SEQUENTIAL NUMBER 003 REV. NO.
00 052
Safety Assessment
There were no safety consequences because of this event. The operators performed all actions in accordance with procedures and training. All CEAs were previously, fully inserted into the core and no control rod movement occurred due to the actuation. EFAS was reset after SG #1 level was raised above the reset setpoint. The event did not affect the availability of systems needed to maintain safe shutdown conditions, control the release of radioactivity, or mitigate the consequences of an accident.
Corrective Actions
(1) Revise OP-903-014 to raise the level band to 40% to 70% NR.
(2) Perform a review of Operations evolutions and surveillance tests that could result in an automatic actuation setpoint being reached due to a change in system inventory during the evolution or test.
(3) Reviewed event with the responsible individuals.
(4) Created a standing order that requires each crew member to participate in a Post-Job Brief at the end of each shift. The standing order also requires work preparation to include an intentional review of procedural guidance to determine if inadequate margin could exist during the activity and to establish additional controls, when necessary, to ensure undesired actuation setpoints are not challenged.
(5) Perform a training needs analysis based on the results from the performance analysis.
Previous Similar Occurrences None