ML19311C623

Slides for Public Meeting on POV Inspections

ML19311C623
Person / Time
Issue date:	11/07/2019
From:	Douglas Bollock, Kenneth Kolaczyk, Thomas Scarbrough NRC/NRR/DRO/IRIB
To:
Bollock D, 415-6609, NRR/DRO
References
Download: ML19311C623 (22)

Text

Inspection Procedure 71111.21N Attachment 2 Power-Operated Valve Inspection Public Workshop Douglas Bollock, Kenneth Kolaczyk, Thomas G. Scarbrough, Michael F. Farnan U.S. Nuclear Regulatory Commission November 14, 2019

POV Public Meeting Agenda

• Discuss why we are Inspecting POVs

• Discussion of the POV Inspection Procedure Requirements and Guidance

• Overview of EQ Inspection Lessons Learned

• Question and Answer Period 2

Why Are We Inspecting POVs?

• Relatively few efforts in current baseline inspection, on verifying implementation of verifying POVs meet their design requirements as discussed in Generic Letter 96-05

• Operating experience indicates gaps still exist regarding MOV/POV performance:

- Browns Ferry Unit 1, October 23, 2010, Stem Disc Separation

- LaSalle County Station, Unit 2, February 11, 2017, Wedge Pin and Stem Disc Separation 3

Why Are We Inspecting POVs? (continued)

• POVs are important to the proper functioning of risk significant components, and the potential for their failure could impact multiple systems.

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POV Procedure and Guidance 5

IP 71111.21N.02 Objective

• IP 71111.21.02 (July 26, 2019), Design-Basis Capability of Power-Operated Valves under 10 CFR 50.55a Requirements, specifies that the objective is to: assess the reliability, functional capability, and design basis of risk-important POVs as required by 10 CFR 50.55a and applicable 10 CFR Part 50, Appendix A and Appendix B.

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General Guidance Section 02.01 Sample Selection

• As a pre-inspection activity, inspectors will select 30 POVs:

- Multiple systems and different valve types (MOVs, AOVs, HOVs, SOVs, and Squib Valves (as applicable), sizes and manufacturers

- Risk assessment

- Historical performance

• The Inspectors will request the licensee to make available:

- Design-basis capability information including function, safety significance, sizing, margin, and setting assumptions

- See Appendix C to the POV inspection procedure 7

General Guidance Section 02.01 Sample Selection

• Based on POV design-basis capability information, the inspectors will consider the following for selection of a 10 POV sample for detailed inspection review:

- System Risk

- POVs with high incidence of corrective maintenance and/or poor performance

- POVs with low margin

- POVs with questionable assumptions (e.g., low VF, low friction values, not all uncertainties captured)

- POVs in systems with untreated water

- POVs in high energy systems

- POVs located in elevated environments (e.g., high temperature, high radiation areas) 8

Inspection Preparation Activities

• Discuss inspection with site POV engineers and obtain information (such as POV capability calculations and assumptions)

• Evaluate POV parameter assumptions for potential issues

• Determine the of POV assumptions (such as EPRI, JOG, and ComEd) and whether conditions for each source are correctly applied 9

Typical Sample Gate Valve Data Sheet

• Valve ID SI-123

• Calc Th/Tq Close - 5685 lbs

• Safety Function - Open/Close

• Calc Th/Tq Open - 8250 lbs

• Manufacturer - Westinghouse

• Least Available - 8500 lbs

• Valve Type - Flex Wedge

• Th/Tq Dyn Close - 6200 lbs

• Valve Size - 4

• Th/Tq Dyn Open - 8700 lbs

• Actuator Make - Limitorque

• Meas Close VF - 0.5

• Actuator Size - SMB-000

• Meas Open VF - 0.47

• Risk - Medium

• Meas LSB - 9.5%

• DB Pressure C/O - 105 / 105

• Margin Close - 5%

• Assumed VF C/O - 0.3 / 0.3

• Margin Open - 3.2%

• Assumed LSB - 5%

• Basis - Extrapolated test &

• Assumed SFC - .12 revised calc 10

What Should Licensees Be Concerned With?

• For All Valves

- Low margin (less than 10%)

- Assumed friction coefficient is less than bounding values (0.2 stem-to-stem nut friction for gate, globe and 0.6 bearing coefficient for bronze bearings on butterfly valve)

- As left valve settings near structural limits

- Misapplication of EPRI MOV PPM data and methodology

- Using EPRI MOV PPM test data to justify valve factor assumptions in valve capability calculations

- Using static testing as basis for monitoring valve degradation with no engineering analysis or data 11

Inspection Process Flow One month before On-site activities the inspection, the begin, valves Three months before team leader visits the analyzed and the inspection site to coordinate the program assessed.

begins, the licensee inspection and obtain Estimated direct receives a data test data for 10 inspection effort is request regarding 30 valves from the two weeks on site, valves original sample set one week office review Issues reviewed by Exit meeting held, Report issuance- regional preliminary estimated 45 days management and observations and after exit meeting nationwide finding findings presented review panel 12

EQ Inspection Lessons Learned 13

EQ Inspection Takeaways

• EQ inspection procedure could have benefited from further background guidance

• Inspectors had difficulty interpreting each nuclear power units unique EQ licensing basis

• Communication between inspectors and NRR technical program office not consistent

• The minor, more than minor screening criteria contained in current NRC guidance was not adequate to assess specific EQ related issues 14

POV Inspection Enhancements

• Identified singular technical and programmatic points-of-contact within the NRC

• Minor/more-than-minor examples developed

• Enhanced training for inspectors was developed(both technical and inspection implementation focused)

• Enhanced Interactive SharePoint Site developed.

• Tabletop dry runs performed

• Findings review panel established proactively 15

Q & A Session 16

FAQs

• Q: What has been communicated to stakeholders?

• A: ROP monthly public meetings since May 2019

- POV inspections replacing EQ inspections beginning in January 2020

- NRC incorporated lessons learned from EQ inspection implementation 17

FAQs

• Q: What is publicly available in regards to POV material?

• A: Publicly available now:

- Inspection Procedure IP71111.21N.02 (ML19067A240)

- MOV technical training (ADAMS Package: ML19235A1212020)

- EQ lessons learned (ML19183A063) 18

FAQs

• Q: What is publicly available in regards to POV material?

• A: Publicly available by December:

- POV Inspection implementation training

- Minor/More-than-minor examples specific to POVs (as an appendix to the IP) 19

FAQs

• Q: What are the NRC resources uses per POV inspection?

• A: 3 NRC inspectors, 2 weeks onsite

- 210 hrs

- No use of contract inspectors planned 20

FAQs

• Q: Will there be other public workshops?

• A: The NRC staff plans to hold at least one more public workshop on POV inspections.

- Staff is open to date and location and will consider any input received today.

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For additional information, contact Doug Bollock Douglas.Bollock@nrc.gov Ken Kolaczyk Kenneth.Kolaczyk@nrc.gov Tom Scarbrough Thomas.Scarbrough@nrc.gov Mike Farnan Michael.Farnan@nrc.gov 22