05000263/LER-1917-004, Regarding High Pressure Coolant Injection Steam Stop Valve Failed to Open During Test
| ML17229B304 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 08/16/2017 |
| From: | Gardner P Northern States Power Company, Minnesota, Xcel Energy Inc |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-MT-17-061 LER 17-004-00 | |
| Download: ML17229B304 (4) | |
| 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)(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) 10 CFR 50.73(a)(2) |
| 2631917004R00 - NRC Website | |
text
2807 West County Road 75 Monticello, MN 55362 (l Xcel Energy 800.895.4999 xcelenergy.com August 16, 2017 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket No. 50-263 Renewed Facility Operating License No. DPR-22 RES P 0 N SIB L E B V NAT U R E<l>
L-MT-17-061 10 CFR 50.73 LER 2017-004-00 "High Pressure Coolant Injection Steam Stop Valve Failed to Open During Test" Enclosed is the Monticello Nuclear Generating Plant (MNGP) Licensee Event Report (LER) 2017-004-00, "High Pressure Coolant Injection Steam Stop Valve Failed to Open During Test."
This condition is reportable to the NRC in accordance with 10 CFR 50.73(a)(2)(v)(D), as an event or condition that could have prevented fulfillment of a safety function.
Summary of Commitments This letter makes no new commitments and no revisions to existing commitments.
Peter A.
d er Site Vice President, Monticello Nuclear Generating Plant Northern States Power Company - Minnesota Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, Monticello Nuclear Generating Plant, USNRC Resident Inspector, Monticello Nuclear Generating Plant, USNRC
,NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (06-2016),.........
, !he NRC may no! conduct or sponsor, and a person is no! required to respond to, !he information collection.
~-PAGE Monticello Nuclear Generating Plant 05000-263 1 OF 3 f4. TITLE High Pressure Coolant Injection Steam Stop Valve Failed to Open During Test
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV MONTH FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.
DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 06 19 2017 2017
- - 004
- - 00 08 16 2017 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)
- 10. POWER LEVEL 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)
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) 100 D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(C)
D 73.77(a)(1)
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) 0 OTHER Specify in Abslracl below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT rELEPHONE NUMER (Include Aroa Code)
Stephen Sollom, Licensing Engineer 763-295-1611
- 13. COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPIX FACTURER TOEPIX D
BJ SHV A391 y
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR 0 YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
[gj NO SUBMISSION DATE
~BSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On June 19, 2017 following a planned High Pressure Coolant Injection (HPCI) system maintenance, a HPCI start attempt was performed per the quarterly test procedure. HPCI failed to start during the test due to the steam stop valve H0-7 not opening caused by H0-7 oil relay not functioning properly.
Since the component was not the subject of the maintenance activity, the HPCI failure was reported to he NRC under Emergency Notification System, Event Number 52814.
lfhe H0-7 oil relay was repaired and the HPCI system was returned to operable status at 13:30 on June 23, 2017.
NRC FORM 366 (06-2016)
EVENT DESCRIPTION
Plant Conditions: Mode 1, 1 00% Power YEAR 2017 SEQUENTIAL NUMBER 004 REV NO.
- - 00 On June 19, 2017, following planned High Pressure Coolant Injection (HPCI) system [BJ]
maintenance, a HPCI start attempt was performed per the quarterly test procedure. HPCI failed to start during the test due to the steam stop valve [SHV] H0-7 not opening caused by the H0-7 oil relay (manufacture Schutie and Koerting (S&K) Part Number 69-XC-1 03) not functioning properly.
Since the component was not the subject of the maintenance activity, the HPCI failure was reported to the NRC under Emergency Notification System, Event Number 52814.
H0-7, when closed, blocks reactor steam from reaching the HPCI turbine and thus when H0-7 is closed, HPCI cannot run. Valve H0-7 was last validated to open properly on June 15,2017 while performing the Operations Weekly Control Room Checklist on the night shift. The H0-7 oil relay was repaired and the HPCI system returned to operable status at 13:30 on June 23, 2017.
EVENT ANALYSIS
The event was determined to be reportable in accordance with 10 CFR 50.73 (a)(2)(V)(D), "event or condition that could have prevented fulfillment of a safety function." This event is classified as a safety system functional failure.
SAFETY SIGNIFICANCE
There were minimal safety consequences associated with the condition. The condition existed for approximately 8 days (June 15-June 23), which was less than the Technical Specification limiting condition for operation of 14 days, and the Reactor Core Isolation Cooling system and Automatic Depressurization system were operable the entire period that HPCI was inoperable.
CAUSE
As found visual inspections revealed that the H0-7 oil relay housing internal bore where the piston rings ride was not smooth. The non-smooth internal bore contributed to piston ring oil leakage.
There are two piston rings and both were found to be pitted. One piston ring was pitted significantly and one piston ring was minimally pitted. The piston ring that was more pitted also had ring edge wear and was replaced. The second piston ring was determined to provide an acceptable fit and was not replaced.
Page 2 of 3 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150*0104 EXPIRES: 10/31/2018 06-2016)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. LER NUMBER YEAR Monticello Nuclear Generating Plant 05000-263 SEQUENTIAL NUMBER REV NO.
2017 004
- - 00 The oil relay piston body and housing were cleaned and a single (one of two) piston ring, spring and gasket from the relay were replaced with new parts on June 21, 2017.
The direct cause of the HPCI failed start was the steam stop valve H0-7 not opening due to H0-7 oil relay not shuttling. The oil relay did not shuttle because of leakage past a piston ring resulting in reduced relay stroking force. The piston ring pitting and non-smooth relay internal bore surfaces are due to age related wear that occurred over the life of the HPCI turbine. Thus the direct causes are due to the piston ring not uniformly sealing resulting in reduced force and the wear particles/tight clearances causing the relay valve to not shuttle.
The apparent cause of the pitted piston rings and a non-smooth bore in the H0-7 oil relay is due to the lack of sufficient detail in the preventive maintenance procedure. H0-7 oil relay maintenance was performed in 2013. It was determined that the preventative maintenance procedure performed in 2013 lacked sufficient detail to ensure that adequate preventative maintenance was performed on the oil relay.
A contributing cause was a lack of trending information on H0-7 performance. Monitoring the opening times of the H0-7 valve may have provided some insight into the performance of the H0-7 oil relay.
CORRECTIVE ACTION
The immediate corrective action was to clean the oil relay piston body and housing, and a single (one of two) piston ring, spring and gasket from the relay were replaced with new parts on June 21, 2017.
Long term corrective actions include the following:
Provide additional steps in the HPCI preventive maintenance procedure to perform more direct inspection and maintenance of the H0-7 valve and associated oil relay components.
Perform trending of H0-7 valve opening times to provide insight into the performance of the H0-7 oil relay.
PREVIOUS SIMILAR EVENTS
There were no previous similar licensee event reports in the past three years.
ADDITIONAL INFORMATION
The Institute of Electrical and Electronics Engineer codes for equipment are denoted by [XX].