05000265/LER-1917-001, Regarding High Pressure Coolant Injection Minimum Flow Valve Failed to Open
| ML17194A817 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 07/13/2017 |
| From: | Ohr K Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVP-17-052 LER 17-001-00 | |
| Download: ML17194A817 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(i) |
| 2651917001R00 - NRC Website | |
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Exelon G n rati n,,
SVP-17-052 July 13, 2017 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Quad Cities Nuclear Power Station, Unit 2 Renewed Facility Operating License No. DPR-30 NRC Docket No. 50-265 10 CFR 50.73
Subject:
Licensee Event Report 265/2017-001-00, "High Pressure Coolant Injection Minimum Flow Valve Failed to Open" Enclosed is Licensee Event Report (LER) 265/2017-001-00, "High Pressure Coolant Injection Minimum Flow Valve Failed to Open," for Quad Cities Nuclear Power Station, Unit 2.
This report is submitted in accordance with 1 O CFR 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. Wally J. Beck at (309) 227-2800.
Res:::4 Kenneth S. Ohr Site Vice President Quad Cities Nuclear Power Station cc:
Regional Administrator - NRC Region Ill NRC Senior Resident Inspector-Quad Cities Nuclear Power Station
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMS: NO. 3150-0104 EXPIRES: 10/3112018 (06-2016)
Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.
.if'<j>-t,1t.Wllli'aq'4.I" Reported lessons learned are incorporated into the licensing process and fed back to industry.
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LICENSEE EVENT REPORT (LER)
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections
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Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail
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- 3. PAGE Quad Cities Nuclear Power Station Unit 2 05000265 1 OF 4
- 4. TITLE High Pressure Coolant Injection Minimum Flow Valve Failed to Open
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED I
SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR N/A N/A FACILITY NAME DOCKET NUMBER 05 15 2017 2017 - 001
- - 00 07 14 2017 N/A N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D 20.2201(b)
D 20.2203(a)(3)(i)
D 50. 73(a)(2)(ii)(A)
D 50. 73(a)(2)(viii)(A)
D 20.2201(d)
D 20.2203(a)(3)(ii)
D 50. 73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B) 1 D
D 20.2203(a)(1) 20.2203(a)(4)
D 50. 73(a)(2)(iii)
D 50. 73(a)(2)(ix)(A)
D 20.2203(a)(2)(i)
D 50.36(c)(1 )(i)(A)
D 50. 73(a)(2)(iv)(A)
D 50. 73(a)(2)(x)
- 10. POWER LEVEL D 20.2203(a)(2)(ii)
D 50.36(c)(1 )(ii)(A)
D 50. 73(a)(2)(v)(A)
D 73.71(a)(4)
D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50. 73(a)(2)(v)(B)
D 73.71 (a)(5)
D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50. 73(a)(2)(v)(C)
D 73.77(a)(1) 100 D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
~ 50. 73(a)(2)(v)(D)
D 73.77(a)(2)(i)
D 20.2203(a)(2)(vi)
D 50.73(a)(2)(i)(B)
D 50. 73(a)(2)(vii)
D 73. 77(a)(2)(ii)
D 50.73(a)(2)(i)(C)
D OTHER Specify in Abstract below or in C.
CAUSE OF EVENT
SEQUENTIAL NUMBER 001 REV NO.
00 The cause was determined to be failure of the HPCI Pump Discharge Flow Indicating Switch, specifically intermittent failure of the high side micro switch caused by residual material from the manufacturing process.
D.
SAFETY ANALYSIS
System Design
According to the Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2 Updated Final Safety Analysis Report (UFSAR) Section 6.3.2.3, the HPCI subsystem is designed to pump water into the reactor vessel under Loss of Coolant Accident (LOCA) conditions which do not result in rapid depressurization of the pressure vessel. The loss of coolant might be due to a loss of reactor feedwater or to a small line break which does not cause immediate depressurization of the reactor vessel. The sizing of the HPCI subsystem is based upon providing adequate core cooling during the time that the pressure in the reactor vessel decreases to a value that the Core Spray [BM]
subsystem and/or the Low Pressure Coolant Injection (LPCI) [BO] subsystem become effective.
The HPCI subsystem is designed to pump 5600 gallons per minute into the reactor vessel within a reactor pressure range of about 1120 pounds per square inch gage (psig) to 150 psig. Initiation of the HPCI subsystem occurs automatically on signals indicating reactor low-low water level or high drywall pressure. HPCI injection into the reactor vessel may be accomplished manually by the operator or without operator action by the HPCI automatic initiation circuitry. HPCI can also operate in a pressure control mode of consuming steam from the reactor vessel without providing full injection into the vessel (down to and including zero injection).
Safety Impact The safety impact of this condition was minimal. Valve MO 2-2301-14 is a normally closed valve that is used to maintain minimum flow through the HPCI pump to the Suppression Pool when the injection isolation valves are shut.
The bypass valve is automatically opened on low pump flow and closed on high flow whenever the steam supply valve to the HPCI turbine is open. According to UFSAR Section 6.3.2.3.3, the HPCI minimum flow system is provided for pump protection. The minimum flow valve is automatically opened on low pump flow and closed on high flow whenever the steam supply valve to the turbine is open. Even though the minimum flow valve failed to open, the HPCI System remained capable of performing its intended design/safety function and would not have hindered the system from fulfilling any required safety function or injection over the required 1 O minute mission time.
According to UFSAR Table 6.2-7, MO 2-2301-14 is considered a primary containment isolation valve [ISV] with a normal position of closed. MO 2-2301-14 is the only primary containment isolation valve present in line 2-2340-4"-DX.
The failure of the FIS caused MO 2-2301-14 to fail in and remain in the closed position. Since the line could effectively be isolated utilizing the primary containment isolation valve, the primary containment integrity could be assured, therefore, the primary containment system remained capable of performing its intended design/safety function.
With MO 2-2301-14 failing to open, HPCI was declared inoperable and TS 3.5.1 Condition G was entered. Required Action G.2 is to restore HPCI System to OPERABLE status, with a completion time of 14 days. The FIS was replaced, post maintenance tested and the HPCI system declared operable within the 14 day completion time. There were no other issues or problems identified with valve MO 2-2301-14 after replacement of the FIS. No other repairs were required or performed.
SEQUENTIAL NUMBER 001 REV NO.
00 The engineering analysis that was performed demonstrated this event did not constitute a Safety System Functional Failure (SSFF). (Reference NEI 99-02, Revision 7, Regulatory Assessment Performance Indicator Guideline, Section 2.2, "Mitigating Systems Cornerstone, Safety System Functional Failures, Clarifying Notes, Engineering Analyses.")
As such, this event will not be reported in the NRG Performance Indicator (Pl) for SSFF since an engineering analysis was performed which determined that the system was capable of performing its safety function during this event.
Risk Insights The plant Probabilistic Risk Assessment (PRA) model gives no credit for failure of the HPCI Minimum Flow Valve failure to open and does not include it in the model; hence, the failure of the valve to open did not contribute to an increase in risk.
In conclusion, due to the fact that the HPCI system was available to perform its safety function, the overall safety significance and impact on risk of this event were minimal.
E.
CORRECTIVE ACTIONS
Immediate:
- 1.
The failed FIS was replaced with a new commercially dedicated and bench tested FIS and post maintenance tested satisfactorily.
Follow-up:
- 1.
Site Procurement will purchase the FIS from an approved Appendix B program vendor rather than purchasing a commercially dedicated part.
- 2.
The Calibration Data Sheet for the FIS will be revised to include cycling new switches ten (10) times during bench testing.
F.
PREVIOUS OCCURRENCES
The station events database, LERs, and INPO Consolidated Event System {ICES) were reviewed for similar events at QCNPS. This event was caused by an intermittent failure of the high side micro switch of the HPCI FIS which contained residual material from the manufacturing process.
No previous occurrences were identified as applicable to the circumstances of this event.
G.
COMPONENT FAILURE DATA
Failed Equipment: Flow Indicating Switch Component Manufacturer: Barton Component Model Number: 289A Component Part Number: N/A This event has been reported to ICES as Report No. 415432 Page _4_ of _4_