05000263/LER-2016-001, Regarding High Pressure Coolant Injection System Cracked Pipe Nipple Caused Oil Leak
| ML16140A043 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 05/18/2016 |
| From: | Gardner P Xcel Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-MT-16-029 LER 16-001-00 | |
| Download: ML16140A043 (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)(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) |
| 2632016001R00 - NRC Website | |
text
(l Xcel Energy*
May 18, 2016 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket 50-263 Renewed Facility Operating License No. DPR-22 Monticello Nuclear Generating Plant 2807 W County Road 75 Monticello, MN 55362 L-MT-16-029 10 CFR 50.73 LER 2016-01-00, "High Pressure Coolant Injection System Cracked Pipe Nipple Caused Oil Leak" Enclosed, is the Monticello Nuclear Generating Plant (MNGP) Licensee Event Report (LER) 2016-01-00 regarding a High Pressure Coolant Injection System cracked pipe nipple that caused an oil leak. 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 the Fulfillment of the Safety Function of Structures or Systems that are Needed to Mitigate the consequences of an accident.
Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.
~~
Peter A. Gardner Site Vice President, Monticello Nuclear Generating Plant Northern States Power Company-Minnesota Enclosure cc:
Regional Administrator, Region Ill, USNRC Project Manager, MNGP, USNRC Resident Inspector, MNGP, USNRC Department of Commerce, State of Minnesota
NRC FORM 366 (11-2015)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
LICENSEE EVENT REPORT (LER)
(See Page 2 for required number of digits/characters for each block)
- 1. FACILITY NAME Monticello Nuclear Generating Plant
- 2. DOCKET NUMBER 05000 -263
- 3. PAGE 1 OF 3
- 4. TITLE High Pressure Coolant Injection System Cracked Pipe Nipple Caused Oil Leak
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REV NO.
MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 05000 FACILITY NAME DOCKET NUMBER 03 22 2016 2016
- - 01
- - 00 05 18 2016 05000
- 9. OPERATING MODE 1
- 10. POWER LEVEL 100%
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(i) 50.36(c)(1)(i)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x) 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C) 73.77(a)(1) 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(D) 73.77(a)(2)(i) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(vii) 73.77(a)(2)(ii) 50.73(a)(2)(i)(C)
OTHER Specify in Abstract below or in UNIT CONDITION PRIOR TO THE EVENT On March 21, 2016, Monticello Nuclear Generating Plant was at 100% power, Mode 1. High Pressure Coolant Injection (HPCI) System [EIIS: BJ] was declared inoperable for pre-planned maintenance and testing. There were no other structures, systems or components out of service that contributed to this event on March 22, 2016.
EVENT DESCRIPTION
As part of a pre-planned maintenance and testing activities the HPCI system was declared inoperable on March 21, 2016 at 0400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br />. Following maintenance the HPCI system dynamic flow test was initiated on Monday, March 21, 2016 at approximately 2348 hours0.0272 days <br />0.652 hours <br />0.00388 weeks <br />8.93414e-4 months <br />. At approximately 0047 hours5.439815e-4 days <br />0.0131 hours <br />7.771164e-5 weeks <br />1.78835e-5 months <br /> on March 22, the HPCI turbine was removed from service per procedure. The HPCI turbine was started again at approximately 0050 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> and removed from service at approximately 0056 hours6.481481e-4 days <br />0.0156 hours <br />9.259259e-5 weeks <br />2.1308e-5 months <br /> as prescribed by the testing procedure.
Shortly after the second HPCI turbine run, the operator noticed an excessive amount of oil on the front standard that was not present during the first run of HPCI turbine. However, there was no active leak at the time. A decision was made to start the HPCI Auxiliary Oil Pump (Aux Oil Pump) to help identify the leak location.
Following the start of the Aux Oil Pump at approximately 0104 hours0.0012 days <br />0.0289 hours <br />1.719577e-4 weeks <br />3.9572e-5 months <br />, a pencil-sized stream of oil could be seen leaking from the oil pipe nipple located between pilot cylinder port D and a pipe elbow. After the leak location was identified the Aux Oil Pump was secured. At the time of discovery, HPCI was still inoperable because of the pre-planned maintenance and testing activities. The size of the leak required repair prior to declaring the HPCI system operable.
The cracked pipe nipple was replaced. An extent of condition was completed for all known leaks for the HPCI oil pipe system. Results of the extent of condition review identified two other pipe nipples and two elbows with thread leakage (no crack present). The pipe nipples and elbows were replaced and HPCI was declared operable on March 24, 2016 following repairs and successful surveillance run.
EVENT ANALYSIS
This event resulted in a condition that at the time of discovery, March 22, 2016 at 0104 hours0.0012 days <br />0.0289 hours <br />1.719577e-4 weeks <br />3.9572e-5 months <br />, could have prevented the fulfillment of the HPCI system safety function. The 8-hour NRC ENS notification (#51812) required by 10 CFR 50.72 (b)(3)(v)(D) was completed on March 22, 2016 at 0538 hours0.00623 days <br />0.149 hours <br />8.895503e-4 weeks <br />2.04709e-4 months <br />. This LER is being submitted pursuant to the requirements of 10 CFR 50.73(a)(2)(v)(D). This event is classified as a safety system functional failure.
SAFETY SIGNIFICANCE
There was no actual safety consequence associated with the event since HPCI was declared inoperable for maintenance at the time of discovery and the leak was repaired prior to restoring the system to operable Page 2 of 3 (11-2015)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. LER NUMBER Monticello Nuclear Generating Plant 05000-263 YEAR SEQUENTIAL NUMBER REV NO.
2016
- - 01
- - 00 status. The potential safety consequence of this event is a loss of HPCI system injection capability during a design basis accident if the leak was of sufficient magnitude or if the pipe would have broken when the system was required to mitigate the consequences of an accident. Equipment failure causal analysis is in progress to determine the cause of the crack and the propagation mechanism. This report will be supplemented upon completion of the failure analysis. The Reactor Core Isolation Cooling (RCIC) system remained operable March 22 through March 24. The low pressure emergency core cooling systems (ECCS) remained operable during this period, with the exception of the Low Pressure Coolant Inject (LPCI) system being declared inoperable for intermittent periods to support HPCI testing during the March 22 through March 24 period.
CAUSE
The direct cause of the HPCI oil leak was a cracked pipe nipple. An equipment failure causal analysis is in progress to determine the failure mechanism of the crack. The supplement to the LER will summarize the findings of the failure analysis.
An organizational root cause evaluation was completed to address the assessment and prioritization of repair of known oil leaks on the HPCI system. The root cause determined that management and individuals were tolerant of leaks on the HPCI system. As a result, station personnel did not effectively advocate prompt repair of the HPCI oil leak.
CORRECTIVE ACTION COMPLETED The cracked pipe nipple was replaced. An extent of condition was completed for all known leaks for the HPCI oil pipe system. Results of the extent of condition review identified two other pipe nipples and two elbows with thread leakage (no crack present). The pipe nipples and elbows were replaced and HPCI was declared operable on March 24, 2016 following repairs and successful surveillance run.
CORRECTIVE ACTIONS PLANNED Complete the failure analysis for the crack HPCI oil pipe.
Develop and implement a fluid leak management procedural guidance.
PREVIOUS SIMILAR OCCURRENCES 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]
NRC FORM 366 (11-2015)