05000250/LER-2020-002-01, Manual Reactor Trip in Response to High Steam Generator Level Following Inadve1ient Opening of Feedwater Heater Bypass Valve (Rev 1)
| ML21064A212 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 03/05/2021 |
| From: | Pearce M Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2021-036 LER 2020-002-01 | |
| Download: ML21064A212 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(iv)(B)(6) |
| 2502020002R01 - NRC Website | |
text
U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001 RE: Turkey Point Unit 3 Docket No. 50-250 Rep01iable Event: 2020-002-0 I Date of Event: August 17, 2020 10 CFR 50.73 L-2021-036 March 5, 2021 Title: Manual Reactor Trip in Response to High Steam Generator Level following Inadve1ient Opening of Feedwater Heater Bypass Valve (Rev I)
The attached Licensee Event Report 05000250/2020-002-0l is submitted pursuant to l O CFR 50.73 (a)(2)(iv)(A), due to actuation of the Unit 3 Reactor Protection System and Auxiliary Feedwater System. Revision l addresses additional information that became available during subsequent evaluation of the event.
If there are any questions, please call Mr. Robert Hess at 305-246-4112 or e-mail Robert.Hess@fpl.com.
Sincerely, Michael Pearce Site Vice President - Turkey Point Nuclear Plant Florida Power & Light Company Attachments: USNRC Forms 366 and 366A, current revision cc: USNRC Senior Resident Inspector, Turkey Point Plant USNRC Regional Administrator, Region II Florida Power & Light Company 9760 SW 344th St., Homestead, FL 33035
Abstract
Turkey Point Unit 3 250 3
Manual Reactor Trip in Response to High Steam Generator Level following Inadvertent Opening of Feedwater Heater Bypass Valve - Rev. 1 08 17 2020 2020 02 01 03 05 2021 1
86%
David Stoia - Licensing Engineer (305) 246-6538 B
JJ S125 Yes B
SJ PS Yes
On 8/17/2020 at 2109 hours0.0244 days <br />0.586 hours <br />0.00349 weeks <br />8.024745e-4 months <br /> with Unit 3 at 100% power, the Low Pressure Feedwater Heater Bypass Control Valve inadvertently opened, causing an automatic turbine runback. Due to a deficiency associated with the design of the turbine runback program, levels in the Steam Generators increased in response to the runback. At approximately 86% reactor power, when 3C Steam Generator level increased to 78%, the reactor was manually tripped as directed by procedure. Following the reactor trip the Auxiliary Feedwater System automatically initiated, as expected, to maintain levels in the Steam Generators while Main Feedwater remained in service. Unit 3 was maintained stable in Mode 3 following the event.
This event is reportable pursuant to 10 CFR 50.73 (a)(2)(iv)(A) for the manual reactor trip and automatic initiation of the Auxiliary Feedwater System, which is listed as a reportable safety system by 10 CFR 50.73 (a)(2)(iv)(B)(6).
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I ID Page of 05000-
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
CORRECTIVE ACTIONS
The failed pressure switch (PS-3-2011) was replaced. The TCS Medium Runback program was modified such that inadvertent opening of CV-3-2011 no longer initiates a turbine runback. Plant operating procedures were revised to direct a manual runback of turbine load if CV-2011 spuriously opens under full feedwater flow conditions. The broken wire found in the MOV-3-1432 control circuit was replaced. To prevent a similar occurrence on Unit 4, the TCS modification was completed during the Unit 4 Fall 2020 Refueling Outage, and corresponding procedure changes made. Additional actions to address contributing causes were prescribed in Root Cause Evaluation AR 2365716.
ADDITIONAL INFORMATION
EIIS Codes are shown in the format [IEEE system identifier, component function identifier, second component function identifier (if appropriate)].
SIMILAR EVENTS
A review of reactor trip events over the previous 10 years was performed to identify potentially similar events or patterns.
This period of time coincides with the installation of the TCS Medium Runback program. No events were identified that involved manual reactor trips due to elevated steam generator levels following a turbine runback.
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