05000265/LER-2020-002, Electromatic Relief Valve 3D Did Not Actuate Due to Out of Specification Plunger
| ML20149K600 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 05/28/2020 |
| From: | Ohr K Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVP-20-037 LER 2020-002-00 | |
| Download: ML20149K600 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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)(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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| 2652020002R00 - NRC Website | |
text
Exelon Generation,%
SVP-20-037 May 28, 2020 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Quad Cities Nuclear Power Station, Unit 2 Renewed Facility Operating License No. DPR-30 NRC Docket No. 50-265 10 CFR 50.73
Subject:
Licensee Event Report 265/2020-002-00 "Electromatic Relief Valve 3D Did Not Actuate Due to Out of Specification Plunger
Enclosed is Licensee Event Report 265/2020-002-00 "Electromatic Relief Valve 3D Did Not Actuate Due to Out of Spec:ification Plunger/' for Quad Cities Nuclear Power Station, Unit 2.
This report is submitted in accordance with 10 CFR 50.73(a)(2)(i)(B) for any operation or condition which was prohibited by the plant's Technical Specifications.
There are no regulatory commitments contained in this letter.
Should you have any questions concerning this report, please contact Sherrie Grant at (309) 227-4833.
Respectfully,
~,Qo~
Kenneth S. Ohr Site Vice President Quad Cities Nuclear Power Station cc:
Regional Administrator-NRC Region Ill NRC Senior Resident Inspector - Quad Cities Nuclear Power Station
NRC FORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 04/30/2020 (04*2020) 3.Page Quad Cities Nuclear Power Station, Unit 2 05000265 1
OF 4
- 4. Title Electromatic Relief Valve 30 Did Not Actuate Due to Out of Specification Plunger
- 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 05000 Facility Name Docket Number 03 30 2020 2020 -
002 00 05 28 2020 n/a 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) 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)
D 50.36(c)(1)(i)(A)
D 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x) 1 O. 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) 0 D 20.2203(a)(2)(v)
D 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)
IZl 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)
D Other (Specify in Abstract below or in
- 3. LER NUMBER SEQUENTIAL NUMBER 002 REV NO.
00 This is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B), any operation or condition which was prohibited by the plant's Technical Specification. TS 3.5.1 Condition Hallows one ADS valve to be inoperable for a period of 14 days. The 2-0203-3D ERV was found to be inoperable for the entire cycle.
C. CAUSE OF EVENT
The cause of the failure was an out of specification plunger received from the vendor. The bent upper guide bracket was able to perform acceptably while installed during previous operating cycles but would only begin binding when initiated by the plunger.
D. SAFETY ANALYSIS
System Design
The 2-0203-3D ERV is part of the ADS. The ADS consist of five valves [4 relief valves (ERVs) and one safety/relief valve (Target Rock valve)].
Per the Updated Final Safety Analysis Report (UFSAR) 6.3.3.1.4, "The ADS is designed to depressurize the reactor to permit either the Low Pressure Coolant Injection (LPCI) or Core Spray subsystem to cool the reactor core during a small breaker Loss of Coolant Accident (LOCA)." Pressure relief of the reactor vessel may be accomplished manually by the operator or without operator action by the automatic depressurization circuitry.
Safety Impact Per TS Bases 3.5.1 Condition H.1, with one ADS valve out service, the overall reliability of the ADS is reduced, because a single failure in the OPERABLE ADS valves could result in a reduction in depressurization capability.
In addition, TS Bases for SR 3.5.10 states the actuator of each of the ADS Electromatic valves (ERVs) and the dual function safety/relief valves (S/RVs) is stroked to verify that the pilot valve strokes when manually actuated.
This SR, together with the valve testing performed as required by American Society of Mechanical Engineers (ASME) code for pressure relieving devices, verify the capability of each relief valve to perform its function.
Per UFSAR 6.3.3.1.4, Automatic Depressurization Subsystem, "All five available ADS valve were assumed operable in the LOCA analysis. One ADS valve from the five valves modeled in the LOCA analyses was assumed to fail for the single failure evaluation resulting in the operation of four valves being credited." Based on the ADS system design and accident/transient analysis, four of five ADS valves are needed to perform the required safety function.
An engineering evaluation concluded that the plant design/licensing bases were met for the past cycle (Q2C25) with the one failed ERV. Because of the number of successful stroke tests performed on the other ERVs, the out of specification plunger was determined not to be an issue with other ERVs. The target rock valve design is significantly different from the ERVs and therefore, this issue does not apply to the Target Rock valve.
This event is a Maintenance Rule Functional Failure (MRFF).
NRC FORM 366 (04-2020)
E. CORRECTIVE ACTIONS
Immediate:
- 1.
The 30 ERV and actuator were replaced and successfully tested.
Follow Up:
- 1.
Determine and implement appropriate purchase requirements to ensure new plungers meet the vendor specifications.
- 2.
In conjunction with the vendor, review plunger out of specification width for Part 21 implications.
- 3.
Enhance Maintenance ERV actuator rebuild procedure to include the following:
a.
Improved upper guide bracket inspection criteria b.
New alignment criteria c.
Additional PMT strokes d.
New plunger to switch plate check e.
Ensure plunger width is within manufacturing specification or replace plunger
F. PREVIOUS OCCURRENCES
A review of previous QCNPS events reveals a similar event in 2010 in which the valve main disc would not open during its inspection. Similar to this event, the 2010 event resulted in the loss of one ERV for the entire cycle.
- 1.
LER (254/2010-001-00) Electromatic Relief Valve Main Disc Failure - The cause of this ERV failure was determined to be improper torqueing during manufacturing valve assembly. This allowed a gap between the disc retainer and the main disc guide. This failure was in the body of the valve, where our current failure is contained in the valve actuator assembly.
G. COMPONENT FAILURE DATA
Failed Equipment: Relief Valve Actuator Component Manufacturer: General Electric Component Model Number: 362B2632G001 Component Part Number: N/A This event will be reported to IRIS.
NRC FORM 366 (04-2020)
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