06-13-2017 | On April 15, 2017 at approximately 10:56 am, with the plant at 0% power in Mode 4 (Shutdown), while performing a plant shutdown procedure the "D" outboard Main Steam Isolation Valve ( MSIV), AO-2- 86D was functionally tested. The Monticello Nuclear Generating Plant ( MNGP) Technical Specifications (TS) Surveillance Requirement (SR) 3.6.1.3.6 requires that the isolation time of each MSIV is > 3 seconds and ime was measured at approximately 40.7 seconds. The valve was declared inoperable and subsequently repaired. The failure was attributed to the air pack pilot valves.
This component failure is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by TS 3.6.1.3 " Primary Containment Isolation Valves," since AO-2-86D may have been inoperable for greater than the TS 3.6.1.3, Required Action A.1, Completion Time of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to isolate a main steam line, and the Completion Time for TS 3.6.1.3, Required Action F, to be in Mode 3 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> when the completion time of A.1 is not met. There were minimal safety consequences associated with the condition since the primary containment isolation function was maintained. |
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Category:Letter
MONTHYEARL-MT-24-038, Subsequent License Renewal Application Response to Request for Additional Information - 3rd Round RAI2024-10-15015 October 2024 Subsequent License Renewal Application Response to Request for Additional Information - 3rd Round RAI ML24277A0202024-10-0303 October 2024 Operator Licensing Examination Approval Monticello Nuclear Generating Plant, October 2024 IR 05000263/20240112024-10-0101 October 2024 Biennial Problem Identification and Resolution Inspection Report 05000263/2024011 L-MT-24-025, Application to Revise Technical Specifications to Adopt TSTF-554, Revise Reactor Coolant Leakage Requirements2024-09-26026 September 2024 Application to Revise Technical Specifications to Adopt TSTF-554, Revise Reactor Coolant Leakage Requirements L-MT-24-029, Subsequent License Renewal Application Response to Request for Additional Information and Request for Confirmation of Information-Supplement to Set 1 Part 2 and Response to 2ci Round RAI2024-09-13013 September 2024 Subsequent License Renewal Application Response to Request for Additional Information and Request for Confirmation of Information-Supplement to Set 1 Part 2 and Response to 2ci Round RAI IR 05000263/20240052024-08-30030 August 2024 Updated Inspection Plan and Follow-Up Letter for Monticello Nuclear Generating Plant, Unit 1 (Report 05000263/2024005) L-MT-24-028, Response to RCI for RR-017 ISI Impracticality2024-08-28028 August 2024 Response to RCI for RR-017 ISI Impracticality ML24222A1822024-08-27027 August 2024 – Proposed Alternative Request VR-09 to the Inservice Testing Requirements of the ASME OM Code for Main Steam Safety Relief Valves 05000263/LER-2024-002, Low Pressure Coolant Injection Inoperable Due to Motor Valve Failure2024-08-27027 August 2024 Low Pressure Coolant Injection Inoperable Due to Motor Valve Failure IR 05000263/20244202024-08-21021 August 2024 Security Baseline Inspection Report 05000263/2024420 - Cover Letter IR 05000263/20240022024-08-14014 August 2024 Integrated Inspection Report 05000263/2024002 ML24218A2282024-08-0505 August 2024 Request for Confirmation of Information for Relief Request RR-017, Inservice Inspection Impracticality During the Fifth Ten-Year Interval ML24208A1502024-07-26026 July 2024 Independent Spent Fuel Storage Installation - Submittal of Quality Assurance Topical Report (NSPM-1) ML24215A2992024-07-23023 July 2024 Minnesota State Historic Preservation Office Comments on Monticello SLR Draft EIS ML24198A2372024-07-18018 July 2024 Information Request to Support Upcoming Biennial Problem Identification and Resolution (Pi&R) Inspection at Monticello Nuclear Generating Plant L-MT-24-022, – Preparation and Scheduling of Operator Licensing Examinations2024-07-0909 July 2024 – Preparation and Scheduling of Operator Licensing Examinations ML24164A2402024-06-10010 June 2024 Minnesota State Historic Preservation Office- Comments on Draft Monticello SLR Draft EIS L-MT-24-019, Submittal of ASME Section XI, Section IWB-3720 Analytical Evaluation in Accordance with 10 CFR 50.55a(b)(2)(xliii)2024-06-10010 June 2024 Submittal of ASME Section XI, Section IWB-3720 Analytical Evaluation in Accordance with 10 CFR 50.55a(b)(2)(xliii) L-MT-24-017, Response to Request for Additional Information Regarding License Amendment Request to Revise Monticello Technical Specification Surveillance Requirement 3.8.6.6 (EPID-L-2023-LLA-01602024-06-0404 June 2024 Response to Request for Additional Information Regarding License Amendment Request to Revise Monticello Technical Specification Surveillance Requirement 3.8.6.6 (EPID-L-2023-LLA-0160 ML24137A2792024-06-0303 June 2024 Audit Summary for License Amendment Request to Revise Technical Specification 3.8.6, Battery Parameters, Surveillance Requirement 3.8.6.6 IR 05000263/20244012024-05-30030 May 2024 Public - Monticello Nuclear Generating Plant - Cyber Security Inspection Report 05000263/2024401 ML24141A1292024-05-22022 May 2024 Northern States Power Company - Use of Encryption Software for Electronic Transmission of Safeguards Information ML24141A1782024-05-20020 May 2024 Information Request to Support the NRC Annual Baseline Emergency Action Level and Emergency Plan Changes Inspection L-MT-24-015, Response to Request for Additional Information - Alternative Request VR-09 for OMN-172024-05-16016 May 2024 Response to Request for Additional Information - Alternative Request VR-09 for OMN-17 ML24135A1902024-05-14014 May 2024 Submittal of 2023 Annual Radioactive Effluent Release Report L-MT-24-013, 2023 Annual Radiological Environmental Operating Report2024-05-14014 May 2024 2023 Annual Radiological Environmental Operating Report IR 05000263/20240102024-05-13013 May 2024 Age-Related Degrading Inspection Report 05000263/2024010 ML24128A0042024-05-0909 May 2024 Letter to Minnesota State Historic Preservation Office- Section 106 Consultation Regarding the Monticello Nuclear Generating Plant Subsequent License Renewal Application ML24127A1472024-05-0909 May 2024 Letter to Mille Lacs Band- Section 106 Consultation Regarding the Monticello Nuclear Generating Plant Subsequent License Renew. Application L-MT-24-016, 2023 Annual Report of Individual Monitoring for the Monticello Nuclear Generating Plant (MNGP)2024-05-0808 May 2024 2023 Annual Report of Individual Monitoring for the Monticello Nuclear Generating Plant (MNGP) IR 05000263/20240012024-04-29029 April 2024 Plan - Integrated Inspection Report 05000263/2024001 ML24089A2382024-04-29029 April 2024 Summary of Nuclear Property Insurance ML24115A2972024-04-25025 April 2024 Sec106 Tribal, Miller, Cole-Shakopee Mdewakanton Sioux Community L-MT-24-012, Reactor Scram, Containment Isolation, and Cooldown Rate Outside of Limits Following Technician Adjustment of Wrong Component2024-04-25025 April 2024 Reactor Scram, Containment Isolation, and Cooldown Rate Outside of Limits Following Technician Adjustment of Wrong Component ML24115A2902024-04-25025 April 2024 Sec106 Tribal, Jackson-Street, Lonna-Spirit Lake Nation ML24115A3032024-04-25025 April 2024 Sec106 Tribal, Taylor, Louis-Lac Courte Oreilles Band of Lake Superior Chippewa Indians ML24115A2892024-04-25025 April 2024 Sec106 Tribal, Fowler, Thomas-St. Croix Chippewa of Wisconsin ML24115A3062024-04-25025 April 2024 Sec106 Tribal, Wassana, Reggie-Cheyenne and Arapaho Tribes ML24115A2912024-04-25025 April 2024 Sec106 Tribal, Jacskon, Sr., Faron-Leech Lake Band of Ojibwe ML24115A2882024-04-25025 April 2024 Sec106 Tribal, Fairbanks, Michael-White Earth Nation.Docx ML24115A3012024-04-25025 April 2024 Sec106 Tribal, Seki, Darrell-Red Lake Nation ML24115A2922024-04-25025 April 2024 Sec106 Tribal, Jensvold, Kevin-Upper Sioux Community ML24115A2942024-04-25025 April 2024 Sec106 Tribal, Johnson, John-Lac Du Flambeau Band of Lake Superior Chippewa Indians ML24115A2962024-04-25025 April 2024 Sec106 Tribal, Larsen, Robert-Lower Sioux Indian Community ML24115A3052024-04-25025 April 2024 Sec106 Tribal, Vanzile, Jr., Robert-Sokaogon Chippewa Community ML24115A2952024-04-25025 April 2024 Sec106 Tribal, Kakkak, Gena-Menominee Indian Tribe of Wisconsin ML24115A3022024-04-25025 April 2024 Sec106 Tribal, Stiffarm, Jeffrey-Fort Belknap Indian Community ML24115A3072024-04-25025 April 2024 Sec106 Tribal, Williams, Jr., James-Lac Vieux Desert Band of Lake Superior Chippewa Indians ML24115A3002024-04-25025 April 2024 Sec106 Tribal, Rhodd, Timothy-Iowa Tribe of Kansas and Nebraska ML24115A2872024-04-25025 April 2024 Sec106 Tribal, Dupuis, Kevin-Fond Du Lac Band of Lake Superior Chippewa 2024-09-26
[Table view] Category:Licensee Event Report (LER)
MONTHYEAR05000263/LER-2024-002, Low Pressure Coolant Injection Inoperable Due to Motor Valve Failure2024-08-27027 August 2024 Low Pressure Coolant Injection Inoperable Due to Motor Valve Failure L-MT-24-012, Reactor Scram, Containment Isolation, and Cooldown Rate Outside of Limits Following Technician Adjustment of Wrong Component2024-04-25025 April 2024 Reactor Scram, Containment Isolation, and Cooldown Rate Outside of Limits Following Technician Adjustment of Wrong Component L-MT-23-053, Condition Prohibited by Technical Specifications Due to Inoperable Main Steam Line Low Pressure Isolation Switch2023-12-0404 December 2023 Condition Prohibited by Technical Specifications Due to Inoperable Main Steam Line Low Pressure Isolation Switch 05000263/LER-2017-0062018-01-12012 January 2018 Loss of Reactor Protection System Scram Function During Main Steam Isolation Valve and Turbine Stop Valve Channel Functional Tests due to Use of a Test Fixture, LER 17-006-00 for Monticello Regarding Loss of Reactor Protection System Scram Function During Main Steam Isolation Valve and Turbine Stop Valve Channel Functional Tests Due to Use of a Test Fixture 05000263/LER-2017-0052017-09-20020 September 2017 Diesel Generator Emergency Service Water System Automatic Transfer to Alternate Shutdown Panel, LER 17-005-00 for Monticello Nuclear Generating Plant Regarding Diesel Generator Emergency Service Water System Automatic Transfer to Alternate Shutdown Panel 05000263/LER-2015-0042017-08-22022 August 2017 Past Inoperability of Turbine Stop Valve Scram Function Exceeded Technical Specification Requirements, LER 15-004-01 for Monticello Regarding Past Inoperability of Turbine Stop Valve Scram Function Exceeded Technical Specification Requirements 05000263/LER-2017-0042017-08-16016 August 2017 High Pressure Coolant Injection Steam Stop Valve Failed to Open During Test, LER 17-004-00 for Monticello Regarding High Pressure Coolant Injection Steam Stop Valve Failed to Open During Test 05000263/LER-2017-0032017-06-14014 June 2017 Main Steam Isolation Valve Leakage Exceeds Technical Specification Limits, LER 17-003-00 for Monticello Regarding Main Steam Isolation Valve Leakage Exceeds Technical Specification Limits 05000263/LER-2017-0022017-06-13013 June 2017 Main Steam Isolation Valve Closure Time Outside of Technical Specification Requirements, LER 17-002-00 for Monticello Nuclear Generating Plant Regarding Main Steam Isolation Valve Closure Time Outside of Technical Specification Requirements 05000263/LER-2017-0012017-06-13013 June 2017 Reactor Scram and Group II Isolation Due to 11 Reactor Feed Pump (RFP) Removal from Service with 12 RFP Isolated, LER 17-001-00 for Monticello Regarding Reactor Scram and Group II Isolation Due to 11 Reactor Feed Pump (RFP) Removal from Service with 12 RFP Isolated 05000263/LER-2016-0012017-05-25025 May 2017 High Pressure Coolant Injection System Cracked Pipe Nipple Caused Oil Leak, LER 16-001-02 for Monticello Regarding High Pressure Coolant Injection System Cracked Pipe Nipple Caused Oil Leak 05000263/LER-2016-0032017-05-25025 May 2017 HPCI Declared Inoperable Due to Excessive Water Level in Turbine, LER 16-003-01 for Monticello Regarding HPCI Declared Inoperable Due to Excessive Water Level in Turbine 05000263/LER-2016-0022016-09-30030 September 2016 Inadequate Appendix R Fire Barrier Impacts Safe Shutdown Capability, LER 16-002-00 for Monticello Regarding Inadequate Appendix R Fire Barrier Impacts Safe Shutdown Capability 05000263/LER-2014-0022016-07-13013 July 2016 Torus to Drywell Vacuum Breaker Did Not Indicate Closed During Testing, LER 14-002-01 for Monticello Regarding Torus to Drywell Vacuum Breaker Did Not Indicate Closed During Testing 05000263/LER-2014-0032016-07-13013 July 2016 Torus to Drywell Vacuum Breaker Dual Indication During Testing, LER 14-003-01 for Monticello Nuclear Generating Plant RE: Torus to Drywell Vacuum Breaker Dual Indication During Testing 05000263/LER-2015-0072016-01-21021 January 2016 Loss of Residual Heat Removal Capability, LER 15-007-00 for Monticello Regarding Loss of Residual Heat Removal Capability 05000263/LER-2015-0062016-01-21021 January 2016 - Reactor Scram due to Group 1 Isolation from Foreign Material in the Main Steam Flow Instrument Line, LER 15-006-00 for Monticello Regarding Reactor Scram due to Group 1 Isolation from Foreign Material in the Main Steam Flow Instrument Line ML1015505712009-09-12012 September 2009 Event Notification for Monticello on State Offsite Notification Due to Not Meeting Permit Requirements L-MT-05-035, LER 50-004-00 for Monticello Nuclear Generating Plant Regarding Voluntary LER for Control Rod Drive Insert Line Leakage2005-05-12012 May 2005 LER 50-004-00 for Monticello Nuclear Generating Plant Regarding Voluntary LER for Control Rod Drive Insert Line Leakage ML0216100952002-05-15015 May 2002 LERs 02-001-01 & 02-002-01 for Monticello Nuclear Generating Plant Re Mechanical Pressure Regulator Failure Causes Reactor Scram & Application of Instrument Deviation Acceptance Criteria Allowed As-Found Settings to Be Outside Tech Spec Val 2024-08-27
[Table view] |
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 internet e-mail to Infocollects.Resource@nrc.gov, arid to the Desk Officer, Office of Information and Regulatory Affairs, 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.
EVENT DESCRIPTION
On April 15, 2017 at approximately 10:56 AM, with the plant at 0% power in Mode 4 (Shutdown), while performing a plant shutdown procedure the "D" outboard Main Steam [SB] Isolation Valve (MSIV) [ISV] AO-2-86D was functionally tested. The Monticello Nuclear Generating Plant (MNGP) Technical Specifications (TS) Surveillance Requirement (SR) 3.6.1.3.6 requires that the isolation time of each MSIV is > 3 seconds and MSIV closing time was measured at approximately 40.7 seconds. The valve was declared inoperable and repaired during the refueling outage.
During the test AO-2-86D was given a close signal via the control room hand switch [HS]. The valve delayed to start of closing by approximately 35 seconds and then proceeded to close normally in about 5 seconds.
On site troubleshooting activities commenced and determined that the Hiller Co. air pack pilot valves (Model No. C10010A — called V1 and V3) were the cause of the closure delay. The V1 pilot valve was found to be stuck in a closed position. The air pack was sent to the vendor to perform more inspection, testing and repair. The vendor discovered scoring on the piston rod and mounting plate of the booster assembly on the V1 pilot valve. This is evidence of binding and misalignment that caused the valve to not shuttle when called upon. The V3 pilot valve was shown through data analysis to have delayed movement during the event. The air pack was repaired by the vendor replacing the solenoid cluster and the pilot valves, and the boosters were rebuilt.
The air pack was returned to MNGP, reinstalled and AO-2-86D completed satisfactory testing on 5/5/2017.
A previous similar failure occurred on November 23, 2015 when AO-2-86D closed in 130 seconds after delaying start of closure. The troubleshooting of that failure indicated the plunger sticking or binding of an in-series solenoid valve was the cause of the failure to close in the required TS limits. Upon further review, this MSIV closure time failure is now attributed to the AO-2-86D air pack pilot valves failing to function as designed.
EVENT ANALYSIS
The event was determined to be reportable in accordance with 10 CFR 50.73 (a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications." Specifically, this component failure is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (F-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 205550001, or by Internet e-mail to 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, arid a person is not required to respond to, the information collection.
05000-263 2017 prohibited by TS 3.6.1.3 "Primary Containment Isolation Valves," since AO-2-86D was inoperable for greater than the TS 3.6.1.3, Required Action A.1, Completion Time of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to isolate a main steam line, and the Completion Time for TS 3.6.1.3, Required Action F, to be in Mode 3 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> when the completion time of A.1 is not met.
This event is not classified as a safety system functional failure as the inboard valve was fully operational.
SAFETY SIGNIFICANCE
There were minimal safety consequences associated with the condition. The inboard MSIV on Main Steam line "D" (AO-2-80D) was tested for both leak rate and closing time over the past cycle and each test was completed satisfactorily. Additionally, the inboard MSIVs are a different design and do not utilize Hiller Co. air pack pilot valves. Therefore, the primary containment isolation capability of the main steam lines remained operable which ensured the required isolation safety function was maintained.
CAUSE
The air pack assembly for AO-2-86D was sent to the vendor to perform an inspection, teardown and functional testing of the air pack. In addition to minor leaking at several fittings and around the solenoid valves and manifolds, the vendor discovered scoring on the V1 piston rod and mounting plate of the booster assembly, metallic pieces in the pilot valve body and fretting on the edges of the elastomeric valve seat. Some small black particles (foreign material) were also noted in the V3 pilot valve body and the solenoid manifold ports. Both the V1 and V3 valves must function correctly for the MSIV to close within the TS required time.
The cause of the event was attributed to a failure of both of the pilot valves. As described above the V1 pilot valve was found to be stuck in a closed position and score marks were found on the stem and bottom of the valve shaft. This is evidence of binding and misalignment that caused the valve to not shuttle when called upon.
Regarding pilot valve V3, NSPM performed a more detailed review of data from the April 15, 2017 event and previous operations of AO-2-86D. The review indicated that the MSIV Air supply pressure during the "D" MSIV delayed closure event on November 23, 2015 shows a pressure dip that corresponds to a partial opening of V3 prior to full close. The April 15, 2017 event does not show the same pressure dip, indicating that the V3 valve had delayed movement (sticking) prior to opening.
002 - 00 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 Internet e-mail to used to impose an information collection does riot display a currently valid OMB control number, the NRC may riot conduct or sponsor, arid a person is not required to respond to, the information collection.
7 LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
Monticello Nuclear Generating Plant 05000-263 2017 - 00 AO-2-86D was fully functional (closure time and leak rate) from April 14, 2014 to 1R27 as demonstrated by 1R26 As-left testing, cycle 27 On-line testing and 1R27 As-found testing. During 1R27, the AO-2-86D air pack for the AO-2-86D valve actuator was replaced thus introducing the failure mechanism (delay to close) observed twice, once on November 23, 2015 (two minute closure time) and again on April 15, 2017 (forty second closure time).
CORRECTIVE ACTION
The air pack assembly for AO-2-86D was sent to the vendor for repair. The vendor replaced the solenoid cluster, the pilot valves and the boosters were rebuilt. After the air pack was returned to MNGP, the air pack was bench tested to verify proper cycling of the assembly. The air pack was returned to MNGP, reinstalled and AO-2-86D completed satisfactory testing on May 5, 2017.
To reduce the risk of future failures NSPM is planning to develop a bench testing procedure for air pack assemblies prior to their installation in an MSIV.
PREVIOUS SIMILAR EVENTS
In LER 2015-006-00, NSPM reported that a previous similar failure occurred on November 23, 2015 when AO-2-86D closed after delaying by approximately 130 seconds. The troubleshooting from that event indicated that an in-series solenoid valve plunger sticking or binding was the cause of the failure to close within the required TS limits. Upon further review, as discussed above, this MSIV closure time failure is now attributed to the AO-2-86D air pack pilot valves failing to function as designed.
ADDITIONAL INFORMATION
The Institute of Electrical and Electronics Engineer codes for equipment are denoted by [XX].
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