05000254/LER-2007-003, Regarding Safety Function Not Met Due to Control Room Emergency Ventilation System Air Filtration Unit Heater Flow Switch Failure
| ML080250056 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 01/18/2008 |
| From: | Tulon T Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVP-08-006 LER 07-003-00 | |
| Download: ML080250056 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 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)(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)(i)(B), Prohibited by Technical Specifications |
| 2542007003R00 - NRC Website | |
text
Exeln Exelon Generation Company, LLC www.exeloncorp.com NuClear Quad Cities Nuclear Power Station 22710 206th Avenue North Cordova, I L 61242-9740 January 18, 2008 SVP-08-006 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Quad Cities Nuclear Power Station, Units 1 and 2 Renewed Facility Operating License Nos. DPR-29 and 30 NRC Docket Nos. 50-254 and 50-265
Subject:
Licensee Event Report 254/07-003, "Safety Function Not Met Due to Control Room Emergency Ventilation System Air Filtration Unit Heater Flow Switch Failure" Enclosed is Licensee Event Report (LER) 254/07-003, "Safety Function Not Met Due to Control Room Emergency Ventilation System Air Filtration Unit Heater Flow Switch Failure,"
for Quad Cities Nuclear Power Station, Units 1 and 2.
This report is submitted in accordance with the requirements of the Code of Federal Regulations, Title 10, Part 50.73(a)(2)(v)(D), which requires the reporting of any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident.
There are no regulatory commitments contained in this letter.
Should you have any questions concerning this report, please contact Mr. W. J. Beck at (309) 227-2800.
Respectfully, T i thy J. Tulon S.i Vice President Quad Cities Nuclear Power Station cc:
Regional Administrator - NRC Region III NRC Senior Resident Inspector - Quad Cities Nuclear Power Station
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BYOMB: 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 inf..rm.tinn oll.tinn.
- 3. PAGE Quad Cities Nuclear Power Station Unit 1 05000254 1 OF 4
- 4. TITLE Safety Function Not Met Due to Control Room Emergency Ventilation System Air. Filtration Unit Heater Flow Switch Failure
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
[
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV I-FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR Quad Cities Unit 2 05000265.
1FACILITY NAME DOCKET NUMBER 11 20 07 2007
- - 003-00 01 18 2008 [
N/A N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REoUIREMENTS OF 10 CFR §: (Check all that apply)
[1 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii) 1 El 20.2201(d)
[E 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
[I 50.73(a)(2)(viii)(B) 0_ 20.2203(a)(2)(i) 0l 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
[I 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL
-] 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
[E 50.73(a)(2)(v)(A)
[] 73.71(a)(4) 97%
[j 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5)
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
[I 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
U 50.73(a)(2)(v)(D)
Specify in Abstract below or in charcoal adsorbers to less than 70%.
A relative humidity (RH) of less than 70% increases the efficiency of the charcoal adsorber in removing radioactive iodide from the air. Maintaining a relative humidity of less than 70%
ensures that Tech Spec 5.5.7.c (Ventilation Filter Testing Program) is met, which requires that methyl iodide penetration is less than 0.5%, when tested at 300C and 70% RH.
Flow switch FS 0-5795-350 is correctly classified and preventive maintenance tasks were being performed correctly per the maintenance template for air handling units. System monitoring and trending data for the AFU heater revealed no signs of degradation.
No operating experience information could be found on switches failing within one month of operation. The operating procedures for the CREVS AFU are sufficientand within the design basis for the components. There have been no previous issues with the quality of parts obtained for this application.
Exelon Powerlabs initial failure analysis identified an issue with the open switch contact, in that when testing it would not close when it reached its setpoint on several different occasions. This is an infant mortality issue, given the fact that this was only the second time the switch was required to operate after installation.
C.
CAUSE OF EVENT
Flow switch FS 0-5759-350 was installed as part of a preventive maintenance task on October 23, 2007. The flow switch was then successfully tested on October 24, 2007. The AFU had not been operated from October 24, 2007 until November 20, 2007,.when the AFU heater was found not operating. During troubleshooting on November 20, 2007, Instrument Maintenance (IM) removed the flow switch sensing line, and upon reinstallation the flow switch contact could be heard going closed. IM was unable to recreate the open contact condition.
Exelon Powerlabs initial failure analysis indicated a problem with the open switch contact which would not close when it reached its setpoint on several different occasions when tested. The resultant failure is attributed to infant mortality, since this switch was only installed for one month and its failure occurred during its second installed actuation.. This is the first issue the station has had with this make and model flow switch since its initial installation in 1985.
D.
SAFETY ANALYSIS
The safety significance of this event was minimal. Despite the loss of the AFU heater, the charcoal adsorber methyl iodide removal efficiency was sufficient to meet the Tech Spec requirements and there would be no impact to any control room dose calculations or assumptions.
The flow switch used to control the operation of the CREVS AFU heater is a Columbus Electric Manufacturing Model RH15-05-D1. This model switch is not used in any other application at Quad Cities Station. Consequently, impact of this condition with the plant operating was minimal.
E.
CORRECTIVE ACTIONS
FS 0-5795-350 was replaced with a new switch.
0 The Exelon Powerlabs failure analysis final report will be reviewed to identify and initiate any additional necessary corrective actions.
F..
PREVIOUS OCCURRENCES
There were no previous occurrences at Quad Cities Station that involved failure of this flow switch. This is the first issue the station has had with this make and model flow switch since its initial installation in 1985. There was a prior degraded heater event on October 12, 2005 at Quad Cities in which the AFU heater was found degraded. This event is, however, not applicable as a previous occurrence since the AFU heater was found degraded due to issues with Measurement and Test Equipment (M&TE) instruments that were being used to measure voltage and amps on the heater. When two different M&TE instruments were used, the heater was found to be operating properly.
G.
COMPONENT FAILURE DATA
The flow switch used to control the operation of the CREVS AFU heater is a Columbus Electric Manufacturing Model RH15-05-D1. This make and model switch is not used in any other application at Quad Cities Station. The Standby Gas Treatment System contains an electric heater that is started based on a flow switch. However, this flow switch is a Rosemount model flow switch.
An EPIX/NPRDS search identified Palo Verde 1 - Failure Number 811 (6/7/2005) Fuel Building AFU heaters failed to operate due to a failed flow switch. This failure is partially applicable to the Quad Cities event in that.the switch was the same make and model flow switch as used in the Quad Cities CREVS AFU heater circuit. However, the Palo Verde failure mode was thermal degradation due to age of the switch diaphragm. The Palo Verde switch had been installed for 15 years when the failure occurred. The Quad Cities flow switch had been installed for one month when the failure occurred.
NRC FORM 36~A (9-2007)
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