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2-North Anna Extent of Condition Presentation 9-7-12 Sept 10
	ML12257A200
Person / Time
Site:	North Anna
Issue date:	09/11/2012
From:	Wirtz C; Electric Power Research Institute
To:	; Office of Nuclear Reactor Regulation
	Rezai A
References
	Download: ML12257A200 (21)
	v • d • e

Extent of Condition Chuck Wirtz FirstEnergy, BWRVIP Integration Committee Chairman, NIFG Member NRC Meeting - North Anna Actions September 11, 2012

Overview

Scope

Objective

Data Gathering Method

Responses

Data Analysis

Tentative Extent of Condtion Actions

Implementation Method

Scope

The scope of the extent of condition evaluation included all the Class 1 dissimilar metal welds in the US fleet that have been examined by ASME,Section XI, Appendix VIII, Supplement 10 procedures and personnel (NIFG Action Item 5.1)

Objective

The objective is to understand the extent and types of UT examinations performed on dissimilar metal welds (DMWs), their relative risk from an NDE perspective, the overall relative safety risk with consideration of the weld joint materials, and identify the actions to be taken (NIFG Action Item 5.2)

Method

A focused survey was developed by the NIFG team

Distributed to all US fleet ISI/NDE contacts

Key items requested:

- Identification/Description of Supp 10 Welds

- Exam Method (i.e., Auto, Encoded Manual, Manual)

- Was Site-Specific Mock-up Used

- Was Team Scanning Used

- Filler and Base Materials

- Mitigation Status

- Year of Next Scheduled Exam

Response

As of September 7, 2012

- Data received from 104 of 104 plants

Data provided on more than 2,200 DM welds

- Peer checks of the data performed

On a sampling basis, compared data to existing industry DM weld survey information from BWRVIP and MRP databases

Peer checks found data was generally consistent, but there were some anomalies that will require follow-up with the plants to resolve

- Responses allowed the NIFG team to screen all the plants and understand the extent of condition and relative safety significance

Data set screening Initial screening of data identified some anomalies resulting in an preliminary Supplement 10 population of 2107 DMW welds Automated vs Manual Examinations 1000 900 800 866 PWR 700 1241 600 BWR 500 400 300 200 100 0

Manual Automated The next screening of data eliminated welds reported as being examined from the inside surface because:

all were automated

none involved the use of site-specific mockups

Data Analysis

Approach was to quantify the data using a risk matrix

Data Analysis Considerations

High Risk Contributors

Low Risk Contributors

- NDE - NDE

Site Specific mock-up

No site specific mock-up

Manual examination

Automated examination

Team scanning*

- Materials - Materials

Susceptible base material

Non-susceptible base

Susceptible filler material material

Non-mitigated welds

Non- susceptible filler material

Ultimately not used in the data analysis

Mitigated welds because the use of team scanning was not documented consistently.

Data Analysis - Initial Strategy

Risk Assessment Tool

The risk assessment strategy is being developed into a tool This will be distributed to all licenses for their use in self assessment Materials and Mitigation strategies determine relative risk category Application of NDE drives relative risk from Red to Green

Data Analysis - Final Strategy

High Level Summary (red box)

Extent of Condition (Preliminary) 866 Welds Plants PWR BWR 13 (1.5%) 6 1241 BWR PWR 40 (3.2%) 6 Fleet 53 (2.5%) 12 (11.5%)

13 40 6

6 7

Welds Plants Utilities

Tentative Extent of Condition Actions

For welds identified as high relative risk (red box welds)

- Re-examine within 3 years using the DM weld guidance and NDE improvement tools developed by the NIFG team

Tentative EOC Actions (cont.)

For welds identified as medium relative risk (orange box welds)

- Verify the materials are non-susceptible and/or mitigated

- Perform a review of the weld repair history to determine if there were any through-wall repairs or repairs to the ID surface and disposition as follows:

If repairs history indicates ID materials could have been compromised, then the weld is to be treated the same as a red box weld and red box extent of condition actions apply

If there were no repairs or the repairs were not through-wall or ID repairs, re-examine as normally scheduled using the DM weld guidance and NDE improvement tools developed by the NIFG team

Tentative EOC Actions (cont.)

For welds identified as low relative risk (yellow box welds)

- At next scheduled examination apply the DM weld guidance and NDE improvement tools developed by the NIFG team

For welds identified as having no relative risk (green box welds)

- No action is really necessary, but these welds will also benefit from application of the DM weld guidance and NDE improvement tools developed by the NIFG team upon their next examination

Implementation

Implementation will be through the NEI 03-08 Materials Initiative Program, which will include issuing the extent of condition actions and NDE improvement guidance to the plants as Mandatory, Needed or Good Practice requirements as approved by the BWRVIP and PMMP Executive Committees.

Tentative Implementation Strategy for Red and Orange Box EOC Actions

A Risk Assessment Tool will be sent to the plants requiring them to verify or re-evaluate their DMW Supplement 10 examination status, bin their own welds in the proper risk boxes, and follow the extent of condition actions outlined in the previous slides.

NEI 03-08 guidance must be documented in plants Corrective Action programs.

The plants will report the results of their self-binning to the NDE Integration Committee.

Tentative Implementation Schedule for the Red and Orange Box EOC Actions

The targeted completion date for development of the Risk Assessment Tool is October 12th.

The Tool and the associated actions will be reviewed and approved through the committees of the applicable NEI 03-08 Issue Programs (i.e., NDE, BWRVIP, and MRP). This process is expected to take at least 8 weeks.

Requirements approved by the BWRVIP and PMMP Executive Committees will be transmitted to the plants for self-binning and implementation.

Open Discussion NRC Survey Questions

The survey did not ask for differentiation of conventional vs phased array techniques. For the purpose of the extent of condition survey all qualified Supplement 10 exams were treated equally.

The survey did not specifically ask for manual vs automated for both axial and circumferential scans. Some responses did identify that both manual and automated were used; these were treated as manual only.

The NRC provided numerous detailed questions on the specifics of the site specific mockup applications. For the purposes of the extent of condition analysis, all site specific mockups were treated as equal contributors to risk.

TogetherShaping the Future of Electricity

ML12257A200

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