05000254/LER-2007-002, Re Safety Function Not Met Due to Out of Tolerance Turbine First Stage Pressure Switches
| ML080230509 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 01/15/2008 |
| From: | Tulon T Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVP-08-003 LER 07-002-00 | |
| Download: ML080230509 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(vii)(A), Common Cause Inoperability 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)(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 |
| 2542007002R00 - NRC Website | |
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Exelon Generation Company, LLC www.exeloncorp.com NucleaT Quad Cities Nuclear Power Station 22710 206th Avenue North Cordova, IL 61242-9740 January 15, 2008 SVP-08-003 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Quad Cities Nuclear Power Station, Unit 1 Renewed Facility Operating License No. DPR-29 NRC Docket No. 50-254
Subject:
Licensee Event Report 254/07-002, "Safety Function Not Met Due to Out of Tolerance Turbine First Stage Pressure Switches Enclosed is Licensee Event Report (LER) 254/07-002, "Safety Function Not Met Due to Out of Tolerance Turbine First Stage Pressure Switches," for Quad Cities Nuclear Power Station, Unit 1.
This report is submitted in accordance with the requirements of the Code of Federal Regulations, Title 10, Part 50.73(a)(2)(v)(A), 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 shut down the reactor and maintain it in a safe shutdown condition, and Part 50.73(a)(2)(vii)(A), which requires the reporting of any event where a single cause or condition caused at least one independent train or channel to become inoperable in multiple systems or two independent trains or channels to become inoperable in a single system designed to shutdown the reactor and maintain it in a safe shutdown condition.
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, Tim y J. Tulon sit,/ice President Q ad Cities Nuclear Power Station cc:
Regional Administrator - NRC Region Ill NRC Senior Resident Inspector - Quad Cities Nuclear Power Station AJ~12
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 intnrmatinn nnllpc.tinn.
- 3. PAGE Quad Cities Nuclear Power Station Unit 1 05000254 1 OF 4
- 4. TITLE Safety Function Not Met Due to Out of Tolerance Turbine First Stage Pressure Switches
- 5. EVENT DATE
- 6. LER NUMBER
'7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MNH DYSEQUENTIAL IREV M
FACILITY NAME DOCKET NUMBER MNH DY YEAR YEAR NUMBER NO.
MONTH DAY YEAR N/4 N/A lFACILITY NAME DOCKET NUMBER 11 16 07 2007
- - 002 00 01 15 2008 N/A N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
El 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
U 50.73(a)(2)(vii) 1 El 20.2201(d)
El 20.2203(a)(3)(ii) r] 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
[I 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
[I 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii)
[I 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
[I 50.73(a)(2)(x)
[E 20.2203(a)(2)(iii)
El 50.36(c)(2)
- 50.73(a)(2)(v)(A)
E] 73.71(a)(4)
El 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)
El 50.73(a)(2)(v)(C)
[E OTHER El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
[E 50.73(a)(2)(v)(D)
Specify in Abstract below or in C.
CAUSE OF EVENT
A root cause investigation (ongoing) has identified that the replacement Ashcroft pressure switches were overpressurized during the commercial grade dedication testing process by Trentec because the Ashcroft switch nameplate proof pressure was in error. The switches were tested to 2400 psig, which was provided as the switch nameplate proof pressure. The Instrumentation, Systems, and Automation Society (ISA) industry standard for nameplate proof pressure is a pressure that would not damage the switch. The testing performed at 2400 psig resulted in damage to the switches and.led to a reduction in the repeatability of calibration to the required switch setpoint.
Should the-final results of the root cause investigation significantly impact the information of this LER, a Supplemental LER will be issued.
D.
SAFETY ANALYSIS
The safety significance of this event was minimal. The unit was operating atfull power at the time of the event with the switches enabled for the turbine stop valve closure scram function and enabled for the turbine control valve fast closure (trip oil pressure-low) scram function. Therefore, the turbine stop valve closure and turbine control valve fast closure signals would have properly caused a reactor scram if required. In addition, it was determined that the reset value of the switch (the point where the scram would be bypassed when the power level is being reduced) was well below the enable value due to the improved -deadband-properties. Unit 1 has no other applications in which this switch is used, and Unit 2 has no applications in which this switch is used. Consequently, plant impact of this condition with the plant operating was minimal.
E.
CORRECTIVE ACTIONS
The switches were recalibrated to within their required as-left setting tolerances on 11/16/07.
A compensatory action identified in the Operability Determination required a temporary increase in the quarterly calibration frequency-of the switches to a monthly frequency to reduce the likelihood of time related setpoint drift. The as-found values at the first recalibration of all four switches (on 12/07/07) and second recalibration (01/04/08) were satisfactory.
The switches are anticipated to be replaced like for like, or with a suitable substitute by the end of February 2008, pending the outcome of the ongoing root cause investigation.
The commercial parts dedicator (Trentec), has been contacted to ensure this issue is entered into their corrective action program.
Station Procurement is revising procurement requirements for these pressure switches to ensure testing is p1e-rf*riedt*t-h Kerquired pressures.
F.
PREVIOUS OCCURRENCES
One of two Division II switches was found to have exceeded its required tolerance during testing on 10/29/07. This is the only other event where an Ashcroft switch had exceeded the required tolerance that would have prevented fulfillment of a reactor scram safety function during power ascension between 38.5% RTP and the as-found switch setpoint.
G.
COMPONENT FAILURE DATA
The turbine first stage pressure switches are Ashcroft Model B450SXCH-400PSI. The switches are a commercial grade product supplied by Ashcroft and were dedicated for a Safety Related application by a qualified vendor (Trentec). An EPIX/NPRDS search identified no failure reports concerning this Ashcroft model switch, nor any failures of Ashcroft switches with similar model numbers.
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