05000254/LER-2019-001, HPCI System Inoperable Due to Blown Fuse in the Motor Speed Changer Circuit

HPCI System Inoperable Due to Blown Fuse in the Motor Speed Changer Circuit

ML19095A380
Person / Time
Site:	Quad Cities
Issue date:	04/05/2019
From:	Ohr K Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SVP-19-019 LER 2019-001-00
Download: ML19095A380 (5)

LER-2019-001, HPCI System Inoperable Due to Blown Fuse in the Motor Speed Changer Circuit

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 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)
2542019001R00 - NRC Website

text

~***** Exelon Generation SVP-19-019 April 5, 2019 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 NRG Docket No. 50-254 10 CFR 50.73

Subject:

Licensee Event Report 254/2019-001-00 "HPCI System Inoperable Due to Blown Fuse in the Motor Speed Changer Circuit" Enclosed is Licensee Event Report 254/2019-001-00 "HPCI System Inoperable Due to Blown Fuse in the Motor Speed Changer Circuit", for Quad Cities Nuclear Power Station, Unit 1.

This report is submitted in accordance with 1 O CFR 50.73(a)(2)(v)(D) for an event or condition that could have prevented fulfillment of a safety function 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 Mark Humphrey at (309) 227-2800.

R/:¥ Kenneth S. Ohr Site Vice President Quad Cities Nuclear Power Station cc:

Regional Administrator - NRG Region Ill NRG Senior Resident Inspector-Quad Cities Nuclear Power Station

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LICENSEE EVENT REPORT (LER)

Reported lessons learned are incorporated into the licensing process and led back to

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3.Page Quad Cities Nuclear Power Station Unit 1 05000254 1

OF 4

4. Title HPCI System Inoperable Due to Blown Fuse in the Motor Speed Changer Circuit

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 05000 Facility Name Docket.Number 02 05 2019 2019 - 001 00 04 05 2019 n/a 05000

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 20.2203(a)(1)

D 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)

[8] 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

D. SAFETY ANALYSIS

System Design

YEAR 2019 SEQUENTIAL NUMBER 001 REV NO.

00 According to the Quad Cities Nuclear Power Station (QCNPS) Units 1 and 2 UFSAR Section 6.3.2.3, "High Pressure Coolant Injection Subsystem," 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 adequc;1te 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 drywell 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 significance of this event is minimal. HPCI was inoperable for approximately 68.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. The Reactor Core Isolation Cooling (RCIC)[BN] system, Automatic Depressurization System (ADS), and multiple low-pressure Emergency Core Cooling Systems (ECCS) were available during this time.

Risk Insights The HPCI system is a risk significant system in the QCNPS PRA, supports High Safety Significant and Low Safety Significant Maintenance Rule Functions and is monitored under the Mitigating System Performance Index (MSPI) for reliability and availability. Unavailability of the HPCI system during this condition was addressed under the QCNPS Configuration Risk Management program per the requirements of 1 OCFR50.65 (a)(4) to assess and manage the risk increase.

This event is a Maintenance Rule Functional Failure (MRFF), and a MSPI failure, since both the manual and automatic injection functions of HPCI were lost.

E. CORRECTIVE ACTIONS

Immediate:

1.

Replaced the LSS LS, MSC Motor, and select MSC gearbox components.

2.

Failed LS and Motor were sent to Exelon PowerLabs for further failure analysis.

Follow-up:

1.

The preventive maintenance replacement frequency of the LSS LS will be reduced from 10 years to 8 years.

F.

PREVIOUS OCCURRENCES

SEQUENTIAL NUMBER 001 REV NO.

00 The station events database, LERs, and INPO Consolidated Event System (ICES) were reviewed for similar events at QCNPS. This event was attributed to intermittent LSS LS failure resulting in MSC motor and gearbox binding and a blown fuse.

Quad Cities Unit 1 LER 05000254/95-004-00, "HPCI System Declared Inoperable From Motor Speed Changer Malfunction Due to Limit Switch Failure," involved the same system components as the current event. In 1995, the LSS LS was found to have improper setting of the internal contact block, which also resulted in intermittent performance, causing MSC damage. Corrective actions addressed proper maintenance instructions for setting of the limit switches. The corrective actions from the 1995 event were not found to contribute to the current event.

Quad Cities Unit 2 Issue Report 593863, "MSC Full Reposition Greater Than 15 Seconds," also involved the same system components as the current event. In 2007, a loose screw associated with the LSS LS allowed the MSC motor to remain energized and driving into the LSS since a logic test six days earlier. Unlike the current event, it did not result in damage to the MSC motor or gear box, and HPCI remained capable of meeting its design functions.

Corrective actions addressed verifying that the MSC motor has de-energized after returning HPCI to standby. The corrective actions from the 2007 event were not found to contribute to the current event.

G. COMPONENT FAILURE DATA

Failed Equipment: Limit Switch, Series A Component Manufacturer: General Electric Component Model Number: CR9440K1 K1 Component Part Number: N/A Failed Equipment: MSC Motor, 1/10 HP, 125 VDC Component Manufacturer: General Electric Component Model Number: 5BC26AC389B Component Part Number: N/A This event has been reported to ICES. Page _4_ of _4_