05000458/LER-2015-006, Regarding Operations Prohibited by Technical Specifications Due to Error in Initial Operability Evaluation
| ML15272A178 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 09/14/2015 |
| From: | Brumfield N Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RBG-47616 LER 15-006-00 | |
| Download: ML15272A178 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2) 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)(iv)(A), System Actuation 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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4582015006R00 - NRC Website | |
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~En tergy Entergy Operations Inc.
River Bend Station 5485 U. S. Highway 61N St. Francisville, LA 70775 Tel 225 381 4157 Fax 225 381 4139 www.entergy.com N. Todd Brumfield Director - Regulatory & Performance Improvement nbrumfi@entergy.com RBG-4761 6 September 14, 2015 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
Licensee Event Report 50-458 /.2015-006-00 River Bend Station - Unit 1 Docket No. 50-458 License No. NPF-47 RBF1I-15-0140
Dear Sir or Madam:
In accordance with 10 CFR 50.73, enclosed is the subject Licensee Event Report.
This document contains no commitments. If you have any questions, please contact Mr. Joseph Clark at 225-381-4177.
Sincerely,
!/14' NTB /dhw Enclosure cc:
U. S. Nuclear Regulatory Commission Region IV 1600 East Lamar Blvd.
Arlington, TX 76011-4511 NRC Sr. Resident Inspector P. 0. Box 1050 St. Francisville, LA 70775
Licensee Event Report 50-458 / 2015-006-00 September 14, 2015 RBG-4761 6 Page 2 of 2 INPO (via ICES reporting)
Central Records Clerk Public Utility Commission of Texas 1701 N. Congress Ave.
Austin, TX 78711-3326 Department of Environmental Quality Office of Environmental Compliance Radiological Emergency Planning and Response Section Ji Young Wiley P.O. Box 4312 Baton Rouge, LA 70821-4312
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3160-0104 EXPIRES: 01/31/2017 (02-2014)
Estimated burden per response to comply with this mandatory collection request: 80 hourn.
.:%Reported lessons learned are incorporated into the licensing process and ted back to industry.
'*Send comments regarding burden estimate to the FOtA, Privacy and infiormation Collections LICE SEE VEN REP RT (ER)
Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by LICENSEEal o nfc EVENTsore REPORTn t te ek ffceOfic (LER)mtin n
(See Page 2 for required number of Regulatory Atfairs, NEOB-10202, (3150-0104), Office of Management and B3udget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid 0MB digits/characters for each block) control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME 2
OKTNME
.PG River Bend Station - Unit 1I50 481O
- 4. TITLE Operations Prohibited by Technical Specifications Due to Error in Initial Operability Evaluation
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED M7ONT ATF YA YER SEQUENTIALuME REVo MOT A
ER FACILITY NAME 050DOCKET NUMBER Z Z ' 21 00 00FACILITYNAMEDDCCKTN NUMBER
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D] 20.2201(b)
[]
20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vUi) 1 E 20.2201(d)
LII 20.2203(a)(3)(ii)
[] 50.73(a)(2)(ii)(A)
[] 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
[] 20.2203(a)(4)
[]
50.73(a)(2)(ii)(B)
[] 50.73(a)(2)(viii)(B)
E 20.2203(a)(2)(i)
[]
50.36(c)(1)(i)(A)
[]
50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
[]
50.73(a)(2)(iv)(A)
Li 50.73(a)(2)(x)
[] 20.2203(a)(2)(iii)
[]
50.36(e)(2)
[]
50.73(a)(2)(v)(A)
[]
73.71 (a)(4) 92 ElI 20.2203(a)(2)(iv)
[] 50.46(a)(3)(ii)
[] 50.73(a)(2)(v)(B)
[~] 73.71 (a)(5)
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20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
[]
50.73(a)(2)(v)(C~)
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OTHER LI 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D) speCity in Abstract below or in NRC Form 3B6A
- 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT TLPOENME icueAe oe Joseph A. Clark, Manager - Regulatory Assurance (2)3147CAUSE SYSTEM COPNN MANU-REPORTABLE F: ACTURE TEORAL ICMOET FACTURER TO EPIX ri*
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- 14. SUPPLEMENTAL REPORT EXETD15.
EXPECTED MONTH DAY YEAR
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- 5. XPECED UBMSSIO DAE)
NODATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewnitten lines)
On July 17, 2015, with the plant operating at 92 percent power, it was determined that an operability evaluation previously performed for a safety-related instrument in the primary containment isolation circuitry was in error, which resulted in the failure to take actions required by the Technical Specifications. On July 8, 2015, a scheduled surveillance test was performed on one channel of the primary containment isolation logic. During the test, an error message was displayed on the associated trip unit. The operators and technicians researched the vendor manual, consulted the cognizant engineers, and determined that the error message was not indicative of any inability of the system to perform its design safety function. Subsequent review found that the first operability determination on the condition report was in error, and that the trip channel was not actually capable of performing as designed. The trip unit was declared inoperable, and taken out of service to be replaced. The channel was again declared operable on July 18 at 2:44 a.m. The elapsed time between the receipt of the error message on July 8 and the restoration to an operable status exceeded the allowable outage time of Technical Specifications. The cause of the error in the first operability determination was the use of an outdated vendor manual for the initial troubleshooting. This condition is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as operations prohibited by Technical Specifications. During the time that the trip unit was inoperable, redundant channels in the isolation logic remained capable of performing the safety function. This event was, thus, of minimal safety significance to the health and safety of the public.
NRC FORM 366 (02-2014)
REPORTED CONDITION On July 17, 2015, with the plant operating at 92 percent power, it was determined that an operability evaluation previously performed for a safety-related instrument in the primary containment isolation circuitry was in error, which resulted in the failure to take actions required by the Technical Specifications. That initial evaluation performed on July 8 had determined that the affected circuitry was operable, when in fact it was not actually capable of performing its design function. This condition existed for longer than the allowable outage time, and is, thus, being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as operations prohibited by Technical Specifications.
INVESTIGATION AND IMMEDIATE CORRECTIVE ACTIONS On July 8, 2015, a scheduled surveillance test was performed on one channel of the primary containment isolation logic. The channel is part of the logic that automatically isolates the reactor water cleanup (RWCU) system if the area temperature in the RWCU heat exchanger room exceeds operating limits. If this channel is found to be inoperable, the channel must be placed in the tripped condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or else the affected primary containment path must be isolated within one hour.
During the test, an error message was displayed on the associated trip unit. The operators and technicians researched the vendor manual, consulted the cognizant engineers, and determined that the error message was not indicative of any inability of the system to perform its design safety function. A condition report was written to document the situation and provide for further review. The surveillance test was deemed a success, and the trip channel was restored to an operable status.
Subsequent review found that the first operability determination on the condition report was in error, and that the trip channel was not actually capable of performing as designed. The trip unit was declared inoperable, and taken out of service to be replaced. The channel was again declared operable on July 18 at 2:44 a.m. The elapsed time between the receipt of the error message on July 8 and the restoration to an operable status exceeded the allowable outage time of Technical Specifications.
CAUSAL ANALYSIS The cause of the error in the first operability determination was the use of an outdated vendor manual for the initial troubleshooting.
The trip unit is of a slightly different design than the original, having been installed in the past as part of a system modification. The vendor manual for the old trip unit is still available in the document control system as a reference. This investigation determined that the operators' understanding of the process for retrieving controlled documents was deficient, in that they did not know the correct method of differentiating the status of an historical document versus a current controlled document. The similarity between the old and new trip unit led others involved in the initial troubleshooting to think they were using the correct manual. It was during the engineers' follow-up evaluation of the first operability determination that the error was discovered.
Contributing to this event was the inappropriately lengthy amount of time allowed the engineers for performance of their follow-up evaluation. That is, a more timely due date for that review could have resulted in the error being discovered prior to the expiration of the Technical Specification required actions. Sufficient guidance existed in the governing procedure that should have resulted in a due date commensurate with the significance of the situation.
CORRECTIVE ACTIONS to PREVENT RECURRENCE These actions were taken (or are planned) to address the direct causes of this event, and are documented in the corrective action p)rogram:
- Senior operators were briefed on the proper use of the document control operating system.
- A user's guide was developed for the document control operating system.
- Senior operators will be briefed regarding expectations for timeliness of due dates on operability evaluations.
PRIOR OCCURRENCE EVALUATION No previous similar events have been reported at River Bend Station in the last three years.
SAFETY SIGNIFICANCE
During the time that the trip unit was inoperable, redundant channels in the isolation logic remained capable of performing the safety function. This event was thus of minimal safety significance to the health and safety of the public.