05000410/LER-2020-002-01, Failure to Meet Technical Specification MSIV Stroke Times
| ML20255A078 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 08/31/2020 |
| From: | Tierney T Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NMP2L2741 LER 2020-002-01 | |
| Download: ML20255A078 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 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), Loss of Safety Function 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) |
| 4102020002R01 - NRC Website | |
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,J Exelon Generation NMP2L2741 August31,2020 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Nine Mile Point Nuclear Station, Unit 2 Renewed Facility Operating License No. NPF-69 Docket No. 50-41 O 10 CFR 50.73
Subject:
NMP2 Licensee Event Report 2020-002, Revision 1, Failure to Meet Technical Specification MSIV Stroke Times The original NMP2 LER 2020-002 was submitted on May 5, 2020. Enclosed is NMP2 License Event Report (LER) 2020-002, Revision 1, Failure to Meet Technical Specification MSIV Stroke Times. This revision is to provide additional details on the cause of the event and the corrective actions following completion of the apparent cause analysis.
There are no regulatory commitments contained in this letter.
Should you have any questions regarding the information in this submittal, please contact Brandon Shultz, Site Regulatory Assurance Manager, at (315) 349-7012.
Respectfully, J-1.d_,a.~
Todd A. Tierney Plant Manager, Nine Mile Point Nuclear Station Exelon Generation Company, LLC
- TAT/DJW
Enclosure:
NMP2 Licensee Event Report 2020-002, Revision 1, Failure to Meet Technical Specification MSIV Stroke Times cc:
NRC Regional Administrator, Region I NRC Resident Inspector NRC Project Manager
Enclosure NMP2 Licensee Event Report 2020-002, Revision 1 Failure to Meet Technical Specification MSIV Stroke Times Nine Mile Point Nuclear Station, Unit 2 Renewed Facility Operating License No. NPF-69
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2017)
, the htti;1://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Nine Mile Point Unit.2 05000410 1 OF 5
- 4. TITLE Failure to Meet Technical Specification MSIV Stroke Times
- 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 N/A FACILITY NAME DOCKET ~UMBER 03 06 2020 2020 - 002 01 08 31 2020 N/A N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 0 20.2201 (b)
D 20.2203(a)(3)(i) 0 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A) 0 20.2201 (d)
D 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B) 4 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) 0 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) 0 50.36(c)(1 )(ii)(A)
D 50.73(a)(2)(v)(A)
D 73.71 (a)(4)
- - 20.22ci3(a)(2)(iii) -
- D 50.36(c)(2) * *
... - so.73(aj(2j(v)fs)
- - 73.7f(a.)(5)
D '20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
[gj 50.73(a)(2)(v)(C)
D 73.77(a)(1) 000 D 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(D)
D 73.77(a)(2)(i)
D 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
[gj 50.73(a)(2)(vii)
D 73.77(a)(2)(ii) 0 50.73(a)(2)(i)(C)
[gj OTHER I
Specify in Abstract below or in D. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES AND OPERATOR ACTIONS:
The dates, times, and major occurrences and operator actions for this event are as follows.
March 4, 2020 at 12:05 - Unit 2 Operators insert a manual reactor scram. Subsequently the decision is made to enter the scheduled refueling out;age.
March 5, 2020 at 08:40 - Unit 2 enters Mode 4.
March 6, 2020 at 18:00 - MSIV Technical Specification Surveillance 3.6.1.3.7 and 5.5.6 are completed concluding that MS IVs 2MSS* AOV6A, 2MSS* AOV6D and 2MSS* AOV7 A are slow and do not meet the
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maximum required Tech Spec stroke times. The three MSIVs are declared inoperable.
Refueling Outage - The air packs replaced for MS IVs {2MSS* AOV6A, 2MSS* AOV6D and 2MSS*AOV7A).
March 24, 2020 at 00:05 - MSIVs test satisfactory in accordance with N2-OSP-MSS-CS001
E. METHOD OF DISCOVERY
This event was discovered by Operations during the performance of Tech Spec required surveillance testing.
F. SAFETY SYSTEM RESPONSES:
This LER concerns a failed Tech Spec surveillance test. No system responses were necessary.
II. CAUSE OF EVENT
The cause of the MSIV failures has been determined to be delayed air pack response. The delay was caused by a buildup of corrosion product and a waxy foreign material, believed to be dried pipe thread sealant or O-ring assembly lube that accumulated on the internal surfaces of the air pack. The waxy foreign material was most likely introduced during the rebuild process conducted by the manufacturer, Trillium (previously Hiller).
III. ANALYSIS OF THE EVENT
The inoperable MS IVs are reportable under 1 O CFR 50.73{a)(2)(v)(C) and 1 O CFR 50.73(a)(2)(vii) for the failure of two MSIVs in a common line not meeting Technical REV NO.
01 Specification MSIV stroke times for structures or systems that are needed to: (C) Control the release of radioactive material. Two of the three valves were in a common Main Steam Line.
Due to the vendor deficiency, this condition is also deemed reportable under 1 O CFR Part 21.
I All design basis accident, transient criteria and regulatory limits remain satisfied with no overall impact to dose and EQ/HELB requirements. This conclusion is based on the following analyses.
- 1. Design Basis Secondary Containment HELB Outside Containment Peak Sub Compartment Pressure and Temperature. The slow closure increases the steam tunnel wall differential pressure due to the extended blowdown. The maximum differential pressure remains within the steam tunnel design margins. Steam tunnel temperature reaches the maximum prior to assumed closure of the MSIVs; therefore, the delay in
_____ the closure does not result in ct changB in_peakJ~mp_er?!_l!_re.
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- 2. Design Basis Secondary Containment HELB Piping Outside Containment-Dose rates are substantially below current USAR because the increased mass release attributable to the delayed MSIV closure is substantially offset by the actual iodine concentration.
- 3. Equipment Qualification - The peak pressure envelope is extended from the assumed 9 seconds to 11 seconds. The additional 2 second duration does not result in a significant change in the peak pressure since the rate of pressure increase is mitigated by the large primary relief path through the steam tunnel blowout panels. The peak
- temperature remains the same with the duration of the peak temperature extended from 5.5 seconds to 11 seconds. The temperature envelope duration was drawn to start to decrease at 9 seconds, the 2 second shift in the peak duration does not represent a significant change that impacts equipment qualification.
- 4. Primary containment Peak Pressure and Temperature: The impact on peak containment pressure is defined by the fast closure specification. The slow closure has no impact on the containment peak pressure and temperature since the slow closure results in less total mass energy inside containment.
Based on the above discussion, it is concluded that the safety significance of this event is low, and the event did not pose a threat to the health and safety of the public or plant personnel.
This event does affect the NRC Regulatory Oversight Process Indicator for safety system failures.
IV. CORRECTIVE ACTIONS
A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS:
The MSIV air packs were replaced and tested satisfactory in accordance with Tech Spec surveillance requirements sections 3.6.1.3.7 and 5.5.6.
B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:
YEAR 2020 SEQUENTIAL NUMBER 002 A note will be added to the procurement requirement evaluation form and purchase order for MSIV air pack refurbishments to minimize use of 0-ring lubricant and thread sealant to limit likelihood of capturing foreign material on air pack valve internals.
V. ADDITIONAL INFORMATION
A. FAILED COMPONENTS:
MS IVs 2MSS* AOV6A, 2MSS* AOV6D and 2MSS* AOV7 A, Air Packs B. PREVIOUS LERs ON SIMILAR EVENTS:
None C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) COMPONENT FUNCTION IDENTIFIER AND SYSTEM NAME OF EACH COMPONENT OR SYSTEM REFERRED TO IN THIS LER:
COMPONENT Main Steam Isolation Valves, Air Pack IEEE 803 FUNCTION IDENTIFIER VOP IEEE 805 SYSTEM IDENTIFICATION SB REV NO.
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