05000237/LER-2013-005, Regarding Primary Containment Inboard and Outboard Feed Water Isolation Valves Exceed Leakage Limits

Regarding Primary Containment Inboard and Outboard Feed Water Isolation Valves Exceed Leakage Limits

ML14037A208
Person / Time
Site:	Dresden
Issue date:	01/13/2014
From:	Marik S Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SVPLTR# 14-0001 LER 13-005-00
Download: ML14037A208 (5)

LER-2013-005, Regarding Primary Containment Inboard and Outboard Feed Water Isolation Valves Exceed Leakage Limits

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 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)(i)(B), Prohibited by Technical Specifications
2372013005R00 - NRC Website

text

nDresden Nuclear Power Station 6500 North Dresden Road AE Exelon Generation, Morris, IL 60450 815-942-2920 Telephone www.exeloncorp.com 10 CFR 50.73 SVPLTR # 14-0001 January 13, 2014 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station Unit 2 Renewed Facility Operating License Nos. DPR-19 NRC Docket Nos. 50-237

Subject:

Licensee Event Report 237/2013-005-00, Primary Containment Inboard and Outboard Feed Water Isolation Valves Exceed Leakage Limits Enclosed is Licensee Event Report 237/2013-005-00, "Primary Containment Inboard and Outboard Feed Water Isolation Valves Exceed Leakage Limits." This event is being reported in accordance with 10 CFR 50.73(a)(2)(ii)(A), "any event or condition that resulted in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded" and 10 CFR 50.73 (a)(2)(v)(C) "any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material."

There are no regulatory commitments contained in this submittal.

Should you have any questions concerning this letter, please contact Mr. Glen Morrow at (815) 416-2800.

Respectfully, Shane M. Marik Site Vice President Dresden Nuclear Power Station Enclosure cc:

Regional Administrator - NRC Region III NRC Senior Resident Inspector - Dresden Nuclear Power Station

, z

4RC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013

10-2010)

, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information collection.

3. PAGE Dresden Nuclear Power Station, Unit 2 05000237 1 OF

4. TITLE Primary Containment Inboard and Outboard Feed Water Isolation Valves Exceed Leakage Limits

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED I

FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.

MONTH DAY YEAR N/A 05000 FACILITY NAME DOCKET NUMBER 11 14 2013 2013 - 005 -

00 01 13 2014 N/A 05000 D. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) o] 20.2201(b)

[I 20.2203(a)(3)(i)

[3 50.73(a)(2)(i)(C)

[I 50.73(a)(2)(vii) 5l 20.2201(d)

[I 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(A)

[I 50.73(a)(2)(viii)(A)

El 20.2203(a)(1)

[I 20.2203(a)(4)

El 50.73(a)(2)(ii)(B)

[I 50.73(a)(2)(viii)(B)

__ 20.2203(a)(2)(i)

El 50.36(c)(1)(i)(A)

[E 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)

[I 50.73(a)(2)(iv)(A)

El 50.73(a)(2)(x)

[] 20.2203(a)(2)(iii)

El 50.36(c)(2)

[] 50.73(a)(2)(v)(A)

El 73.71 (a)(4) 000 20.2203(a)(2)(iv)

El 50.46(a)(3)(ii)

El 50.73(a)(2)(v)(B)

El 73.71 (a)(5) 00 20.2203(a)(2)(v)

El 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C)

El OTHER 0l 20.2203(a)(2)(vi)

El 50.73(a)(2)(i)(B)

El 50.73(a)(2)(v)(D)

Specify in Abstract below or in D.

Safety Analysis

The Feed Water Primary Containment Isolation Valves (PCIV) provide containment isolation in the event of fission product release and reactor coolant pressure boundary isolation in the event of a feed water line break. The "B" Feed Water loop contains additional Safety-Related isolation valves upstream of the PCIVs to prevent High Pressure Coolant Injection (HPCI) backflow into the Feed Water system. These isolation valves were leak tested during the outage, and were determined to have been fully seated in the closed position and provided the ability to isolate containment.

It was conservatively determined that the unit was susceptible to a Feed Water line breech outside of containment with the Feed Water PCIVs failed. The Dresden FSAR describes any feedwater breech in the X-area (reactor building) as being bounded by the effects of a main steam line breech. The low probability of pipe rupture and location of the potential Feed Water line breech inside the X-area minimize the risk significance of the two primary containment isolation valve failures. The impact to the Core Damage Frequency and Large Early Release Frequency has been determined to be non risk significant.

E.

Corrective Actions

As a result of the root cause Dresden developed and implemented valve maintenance and testing best practices. Additionally, the station is evaluating long term actions to enhance the design of the Feed Water check valves and evaluating installing larger diameter test taps to provide a greater ability to test the valves at simulated accident conditions.

F.

Previous Occurrences

A search was performed to show previous occurrences for this event, with the following results:

Date

Description

Dresden Unit 3 - D3R1 6 LLRT failures of two feedwater LER 00-004-01 9/18/2000 check valves in series, resulting in Technical Specification violation.

Dresden Unit 3 - D3R21 LLRT failures of two feedwater IR 1135779 11/04/2010 check valves. Equipment Apparent Cause Analysis (EACE) performed.

Dresden Unit 2-D2R22 LLRT failures of all feedwater IR 1288720 11/10/2011 check valves; Root Cause Analysis (RCA) of the failures was requested. I R 1336479 initiated and documents the S__

performance of the RCA.

The search revealed that there was one prior incident of feedwater check valve LLRT failures since the implementation of Option B of 10CFR 50 Appendix J, that specifically resulted in Appendix J requirements not being met. Additionally, there were two similar recent events where multiple feedwater check valves failed but did not result in not meeting Appendix J criteria; an EACE and a subsequent RCA were performed to determine the failure mechanism, cause, and perform corrective actions to improve reliability.