05000260/LER-2019-003, Automatic Reactor Scram During Startup Due to Intermediate Range Monitor Noise
| ML19336B743 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/02/2019 |
| From: | Bono S Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 2019-003-00 | |
| Download: ML19336B743 (8) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| 2602019003R00 - NRC Website | |
text
nm Tennessee Valley Authority, Post Office Box 2000, Decatur, Alabama 35609-2000 December 2, 2019 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001
Subject:
Browns Ferry Nuclear Plant, Unit 2 Renewed Facility Operating License No. DPR-52 NRC Docket No. 50-260 Licensee Event Report 50-260/2019-003-00 10 CFR 50.73 10 CFR 50.4(a)
The enclosed Licensee Event Report provides details of an automatic reactor scram due to Intermediate Range Monitor noise. The Tennessee Valley Authority is submitting this report in accordance with Title 10 of the Code of Federal Regulations 50.73(a)(2)(iv)(A), as an event that resulted in an automatic actuation of the Reactor Protection System.
There are no new regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact J. L. Paul, Nuclear Site Licensing Manager, at (256) 729-2636.
Enclosure: Licensee Event Report 50-260/2019-003 Automatic Reactor Scram during Startup due to Intermediate Range Monitor Noise.
cc (w/ Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Browns Ferry Nuclear Plant NRC Project Manager - Browns Ferry Nuclear Plant
ENCLOSURE Browns Ferry Nuclear Plant Unit 2 Licensee Event Report 50-260/2019-003-00 Automatic Reactor Scram during Startup due to Intermediate Range Monitor Noise See Enclosed
NRC FORM 366 (04-2018)
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (04-2018)
LICENSEE EVENT REPORT (LER)
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. Facility Name Browns Ferry Nuclear Plant, Unit 2
- 2. Docket Number 05000260
- 3. Page 1 OF 6
- 4. Title Automatic Reactor Scram during Startup due to Intermediate Range Monitor Noise.
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved Month Day Year Year Sequential Number Rev No.
Month Day Year Facility Name N/A Docket Number N/A 10 01 2019 2019 -
003
- - 00 12 02 2019 Facility Name N/A Docket Number N/A
- 9. Operating Mode
- 11. This Report is Submitted Pursuant to the Requirements of 10 CFR §: (Check all that apply) 2 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(i) 50.36(c)(1)(i)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x)
- 10. Power Level 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 73.71(a)(4) 0 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C) 73.77(a)(1) 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(D) 73.77(a)(2)(i) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(vii) 73.77(a)(2)(ii) 50.73(a)(2)(i)(C)
OTHER Specify in Abstract below or in Page 6 of 6 B. Interim Corrective Actions
- 1. Replaced D, E, G, and H under-vessel extension cables based on CHAR testing results.
- 2. Implemented U2 IRM mean square analog module signal filter circuit change modification, to change the time constant in the IRM Mean Square Analog card [EIIS RM].
- 3. Revised procedure for Unit Startup and Power Operation to note that SRM withdrawal has resulted in IRM spiking resulting in RPS actuations, and to recommend individual withdrawal of SRMs (rather than withdrawing multiple SRMs simultaneously).
- 4. Initiated Work Orders (WOs) for CHAR testing of IRM cables at the next outages (WOs 120834816, 120834817, and 120834819).
C. Corrective Actions to Prevent Recurrence or to reduce the probability of similar events occurring in the future
- 1. Implement a process to manage the risk of identified equipment vulnerabilities.
- 2. Implement U1 and U3 IRM mean square analog module signal filter circuit change modification, to change the time constant in the IRM Mean Square Analog card.
- 3. Revise Bridging and Mitigation Strategy Development procedure to explicitly require review of OE during bridging or mitigation strategy development.
VII. Previous Similar Events at the Same Site
This event is an example of a repeat issue that was determined to have been OE preventable. A search of LERs and the BFN Corrective Action Program revealed multiple instances of reactor scram signals at BFN which were attributed to IRM noise. The most recent event, and the only one to have occurred in the past five years, was an IRM-related manual scram occurring on March 29, 2017. This event was reported as LER 260/2017-003-00. Identified events include the following:
LER 260/2017-003 Manual Reactor Scram Initiated During Startup Due to Multiple Rods Inserting LER 296/2012-004 Manual Reactor Scram During Startup Due to Multiple Control Rod Insertion LER 260/2010-003 Reactor Scram Due to Closure of the Main Steam Isolation Valves and Subsequent Invalid RPS Scram From The Intermediate Range Monitoring System LER 260/2004-002 Automatic Reactor Scram During Startup Due To Spurious Upscale Trip On The Intermediate Range Monitors
VIII. Additional Information
There is no additional information.
IX.
Commitments
There are no new commitments.