05000461/LER-2008-003, For Clinton Power Station Unit 1, Regarding Excessive Leakage Through Feedwater Isolation Valve 1B21F032A
| ML101470418 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 05/17/2010 |
| From: | Kearney F Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| U-603959 LER 08-003-00 | |
| Download: ML101470418 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(b)(2)(v) 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 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 |
| 4612008003R00 - NRC Website | |
text
Exelon, Nuclear Clinton Power Station 8401 Power Road Clinton, IL 61727 U-603959 SRRS 5A.108 May 17, 2010 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001
.ClintonPower Station, Unit1.-.- -.
Facility Operating License No. NPF-62 NRC Docket No. 50-461 Subject:'
Licensee Event Report 2008-003-00 Enclosed.is Licensee Event Report (LER) No. 2008-003-00: Excessive Leakage through Feedwate" Isolation Valve 1 B21 -F032A,. 'This report is being. submitted in accordance with-.
10 CFR 50.73 (a)(2)(ii), a degraded or unanalyzed condition, and 10 CFR 50.73 (b)(2)(v), a condition that could have prevented the fulfillment of a safety function.
There are no regulatory commitments contained in this letter.'
Should you have any questions concerning this report, please contact Mr. T. W. Parrent at (217) 937-3382.
Respectfully, F. A. Kearney Site Vice President Clinton Power Station RSF/blf
Enclosures:
Licensee Event Report 2008-003-00 cc:
Regional Administrator -. NRC Region III NC RSenior Resident Inspector-' Clinton Power Station' Office of Nuclear Facility Safety - IEMA Division of Nuclear Safety
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2010 (9-2007)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the digis/caracersinformation collection.
- 3. PAGE Clinton Power Station, Unit 1 05000461 1 OF 4
- 4. TITLE Excessive Leakage through Feedwater Isolation Valve 1 B21 F032A
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAA I
R FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEUENTIAL REV MONTH DAY YEAR 05000 YERINUMBER NO.
FACILITY NAME DOCKET NUMBER 01 21 2008 2008 003 -
00 05 17 2010 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
[1 20.2201(b)
E] 20.2203(a)(3)(i)
I]
50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii) 5[ 20.2201(d)
[] 20.2203(a)(3)(ii)
E 50.73(a)(2)(ii)(A)
[I 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
[I 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 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)
El 50.73(a)(2)(iv)(A)
[j 50.73(a)(2)(x)
[I 20.2203(a)(2)(iii)
[I 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4) 0 El 20.2203(a)(2)(iv)
[l 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5)
[I 20.2203(a)(2)(v)
[: 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C)
El OTHER El 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
SAFETY ANALYSIS
This event is reportable under the provisions of 10 CFR 50.73(a)(2)(ii) due to a degraded or unanalyzed condition and 10 CFR 50.73(a)(2)(v) due to a condition that could have prevented fulfillment of the safety function of the feedwater containment isolation valves to ensure offsite doses are not exceeded following a design basis loss of coolant accident (DBA LOCA).
The feedwater isolation valves and the FWLCS provide a sealing system to ensure that offsite doses are not exceeded following a DBA LOCA. The 2 gpm leakage limit in TS SR 3.6.1.3.11 has been shown by testing and analysis to bound the condition following a DBA LOCA where, for a limited time, both air and water are postulated to leak through this pathway. No release of radioactive material occurred as a result of this event.
Feedwater check valve 1 B21 -F032A must close to isolate containment from the feedwater system during emergency and post accident periods by providing a barrier necessary for the Feedwater Leakage Control System (FWLCS) to create a water-seal on the containment penetration. This check valve must also close to prevent a significant loss of reactor coolant inventory and provide immediate isolation should a break occur in the feedwater line.
This issue would not impact Core Damage Frequency or Large Early Release Frequency. The Feedwater System function of supplying the reactor vessel with water is not impacted and thus there is no impact on core damage frequency. Failure of the valve disc to properly seat will not affect the 1B21F032A function to pass flow into the reactor vessel, but impacts leak tightness of the check valve in the closing direction. However, when Feedwater shutdown occurs, hydraulic conditions are generally such that sufficient backpressure will exist to firmly seat the check valve even without the assistance of the air actuator. The air assist function has been provided to give tight shutoff even when the backpressure across the valve is very low, but low backpressure would rarely exist at the time feedwater shuts down. Radionuclide release paths through the Feedwater System lines are not regarded as credible Large Early Release Frequency (LERF) release pathways because there are multiple barriers against a large release through this pathway.
CORRECTIVE ACTIONS
The valve was repaired by cleaning and lubricating the valve's air actuator linkages. Following completion of repairs, the valve was stroked and, prior to performing post-maintenance LLRT, the valve was closed by normal means. An LLRT was completed on January 26, 2008 with satisfactory results of 0.65 gpm. During refueling outage C1 R12 (2010), the LLRT of check valve 1 B21-F032A was completed with satisfactory results of 0.28 gpm.
Preventive maintenance activities will be established to lubricate and overhaul the 1B21-F032 actuators; a six-year frequency has been recommended for lubrication of the actuators.
PREVIOUS OCCURRENCES
This is the first failure of the 1 B21 -F032A since the installation and implementation of a Feedwater Leakage Control system in 2000.
The following LERs occurred prior to the installation of a Feedwater Leakage Control system:
LER 92-003 dated March 31, 1992 - Local Leak Rate Test Failure of Feedwater Containment Isolation Valves Results in Total Leakage Rates in Excess of Technical Specification and 10CFR50 Appendix J Limits.
LER 95-002-01 dated June 6, 1995 - Local Leak Rate Test Failures of Feedwater Containment Isolation Valves Results in Total Leakage Rates Greater than Technical Specification and 10CFR50, Appendix J Limits.
LER 96-013-01 dated July 24, 1997 - Inadequate Actuator Design and Failure to Recognize Limitations of Resilient Seat Design Result in Local Leak Rate Test Failures of Feedwater Containment Isolation Valves and Total Leakage Rates Greater than Technical Specification and 10CFR50, Appendix J Limits.
COMPONENT FAILURE DATA
Feedwater valve 1B21-F032A is a 20-inch, air-assisted, non-slam tilting disc check valve, manufactured by Anchor Darling Valve Company.
The air actuator on check valve 1 B21 -F032A is a station specific design and was built in accordance with Engineering Change Notice 30103.PRINTED ON RECYCLED PAPERPRINTED ON RECYCLED PAPER