05000321/LER-2017-002, Regarding High Pressure Coolant Injection System Declared Inoperable Due to Degraded Inverter
| ML17097A333 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 04/07/2017 |
| From: | Wheat J Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-17-0585 LER 17-002-00 | |
| Download: ML17097A333 (6) | |
| 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)(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 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| LER closed by | |
| IR 05000321/2017002 (3 August 2017) | |
| 3212017002R00 - NRC Website | |
text
~ Southern Nuclear Justin T. Wheat Nuclear Licensing Manager April 7, 2017 40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35242 205 992 5998 tel 205 992 7601 fax jtwheat@ southernco.com Docket Nos.: 50-321 NL-17-0585 U.S. Nuclear Regulatory Commission A TIN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Unit 1 Licensee Event Report 2017-002-00 High Pressure Coolant Injection System Declared Inoperable Due to Degraded Inverter Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(v)(D), Southern Nuclear Operating Company (SNC) hereby submits the enclosed Licensee Event Report.
This letter contains no NRC commitments. If you have any questions, please contact Greg Johnson at (912) 537-5874.
Respectfully submitted, 9~~
Justin T. Wheat Regulatory Affairs Manager JTW /jcb/lac Enclosure: LER 2017-002-00
U.S. Nuclear Regulatory Commission NL-17-0585 Page 2 cc:
Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bast, Executive Vice President & Chief Nuclear Officer Mr. D. R. Vineyard, Vice President-Hatch Mr. M. D. Meier, Vice President-Regulatory Affairs Mr. R. D. Gayheart, Fleet Operations General Manager Mr. B. J. Adams, Vice President-Engineering Mr. G. L. Johnson, Regulatory Affairs Manager-Hatch RTYPE: CHA02.004 U.S. Nuclear Regulatory Commission Ms. C. Haney, Regional Administrator Mr. R. Hall, NRR Project Manager-Hatch Mr. D. H. Hardage, Senior Resident Inspector-Hatch
Edwin I. Hatch Nuclear Plant Unit 1 LER 2017-002-00 High Pressure Coolant Injection System Declared Inoperable Due to Degraded Inverter
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150*0104 EXPIRES: 10/31/2018 (CJ6.2016)
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 />.
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LICENSEE EVENT REPORT (LER)
Reported lessons teamed are incorporated into the licensing process and fed back to industry.
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Send comments regarding burden estimate to the FOIA, Privacy and Information Collections
- ~
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(See Page 2 for required number of digits/characters for each block)
Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to lnlocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory (See NUREG-1 022, A.3 for instruction and guidance for completing this form Affairs, NEOB-10202, (3150-0104), Office ol Management and Budget, Washington, DC 20503. II a means used to impose an information collection does not display a currently valid OMB control ht!Q://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1 022/r3/l number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME
~ - DOCKET NUMBER
.PAGE Edwin I. Hatch Nuclear Plant Unit 1 05000321 1 OF3
- 4. TITLE High Pressure Coolant Injection System Declared Inoperable Due to Degraded Inverter
- 5. EVENT DATE
- 6. LEA NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME POCKET NUMBER MONTH DAY YEAR NUMBER NO.
MONTH DAY YEAR FACILITY NAME pOCKET NUMBER 02 08 2017 2017
- - 002
- - 00 4
7 2017
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: Check all that apply)
D 20.22o1(b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A) 1 D 20.2201 (d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B)
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) 181 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) 00THER Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LEA ICENSEE CONTACT
~~LEPHONE NUMBER (Include Area Code)
Carl J. Collins-Licensing Supervisor 912-366-2342
- 13. COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TOEPIX FACTURER TOEPIX 8
BJ INVT 0000 y
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR 0 YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
~NO SUBMISSION DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On February 8, 2017, at 1151 EST with Unit 1 at approximately 100 percent rated thermal power, the High Pressure Coolant Injection (HPCI) suction and discharge pressure indicators were noted to be downscale during a main control room panel walk down. Upon further investigation, it was discovered that the output voltage of the DC to AC inverter was degraded. The HPCI DC to AC inverter supplies power to the HPCI flow controller and power supply. HPCI was therefore declared inoperable due to the degraded voltage condition.
The inoperable as found condition of the HPCI pressure indicators was due to degraded output voltage from the DC to AC HPCI inverter. The degraded inverter was removed and replaced and HPCI was returned to operable status. As part of an extent of condition review, the internals of the degraded inverter were inspected to determine what caused premature failure of the inverter. Based on the findings of this inspection, the preventative maintenance frequency for inverter replacement and calibration will be adjusted as necessary.
Event Description
On February 8, 2017, at 1151 EST with Unit 1 at approximately 100 percent rated thermal power, the High Pressure Coolant Injection (HPCI) suction and discharge pressure indicators were noted to be downscale during a main control room panel walk down. Upon further investigation, it was discovered that the output voltage of the DC to AC inverter (EllS Code INVT) was degraded. This inverter provides power to multiple HPCI control room indications as well as to the HPCI flow controller and power supply. HPCI was therefore declared inoperable.
Failed Components Information
Master Parts List Number: 1 E41 K603 Manufacturer: Abacus Controls Inc.
Model Number: 452-4-120M9 Type: Inverter
Event Cause Analysis
The cause of the event is due to degradation of the output voltage of the DC to AC inverter. The HPCI DC to AC inverter supplies power to the HPCI flow controller and power supply. The flow controller maintains constant flow over the pressure range of HPCI system operation and automatically starts if HPCI system initiation is required. The power supply provides DC control power to the HPCI Turbine Speed Control logic.
Without the flow controller and the power supply, the HPCI Turbine would not be able to run if called upon, causing HPCI to be declared inoperable.
Safety Assessment
This event is reportable per 10 CFR 50.73(a)(2)(v)(D) due to an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident.
The HPCI system is a single train system designed to permit the unit to be shut down while maintaining sufficient reactor pressure vessel (RPV) water inventory. The system continues to operate until the RPV is below the pressure at which either operation of the Low Pressure Coolant Injection (LPCI) mode of the Residual Heat Removal or the Core Spray (CS) system will maintain core cooling. The HPCI system consists of a steam turbine that drives a constant flow pump, system piping, valves, controls, and instrumentation. Upon receipt of an initiation signal, the HPCI turbine stop valve and turbine control valve open simultaneously. The HPCI turbine then accelerates to a specified speed to provide necessary pump flow.
Upon a "small" or "intermediate" break resulting in a loss of coolant accident (LOCA), HPCI provides sufficient inventory to prevent the core from being uncovered. It performs a dual function by providing makeup water to the reactor pressure vessel (RPV) as well as supplementing the break in depressurizing j the RPV. If HPCI is unavailable, the Automatic Depressurization System (ADS) is credited to depressurize Page 2 of 3 (06-2016)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150*0104 EXPIRES: 10/31/2018
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LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1 022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-colleclions/nuregs/staff/sr1 0221r31)
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 />.
Reported lessons learned are incorporated into the licensing process and led back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T *5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555*0001, or by e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150*0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. LEA NUMBER Edwin I. Hatch Nuclear Plant Unit 1 05000-321 YEAR I 2017 SEQUENTIAL NUMBER
- - 002 I
REV NO.
- - 00 the RPV to enable operation of the low pressure Emergency Core Cooling Systems (ECCS) (i.e., CS and LPCI). The Reactor Core Isolation Cooling (ACIC) system is also available to restore and maintain water level in the event HPCI is inoperable.
Although HPCI was declared inoperable, ADS, CS, LPCI, and RCIC were operable to provide core cooling in the event of a small or immediate break LOCA or a design basis accident (DBA) LOCA. Therefore, based on the ability of the station to mitigate the consequences of a potential loss of the HPCI system combined with a LOCA, this event is considered to have very low safety significance.
Corrective Actions
The degraded inverter was removed and replaced to return HPCI to operable status. As part of an extent of condition review, the internals of the degraded inverter were inspected to determine what caused premature failure of the inverter. Based on the findings of this inspection, the preventative maintenance frequency for inverter replacement and calibration will be adjusted as necessary.
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