American Nuclear Society (ANS) Town and Country Hotel, San … · 2010. 10. 12. · ANS-58.22 Working Group Chair Don Wakefield reminded members that the last ballot on the LPSD Draft

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American Nuclear Society (ANS) Risk Informed Standards Committee (RISC)

Meeting Minutes June 16, 2010

Town and Country Hotel, San Diego, California Members present: Robert Budnitz (RISC Chair), Lawrence Berkeley National Lab; Patricia Schroeder (RISC Secretary), ANS; Allen Camp, Los Alamos National Lab; Paul Amico, SAIC; Robert Bari*, Brookhaven National Lab; Richard Black, US DOE; Biff Bradley*, NEI; Mary Drouin*, US NRC; David Finnicum, Westinghouse; John Gaertner, EPRI; Dennis Henneke, General Electric; Rick Hill, ERIN; Gene Hughes, ETRANCO; Greg Krueger, Exelon;; D. Bill Stillwell*, STPNOC; Donald Wakefield, ABS Consulting Alternates present: Doug Hance, EPRI Observers, liaisons, and guests present: Nathan Bixler, Sandia National Labs; Greg Hardy, Simpson, Gumpertz, and Heger; N. Prasad Kadambi (Standards Board Chair), Individual; Stuart Lewis, EPRI; Jocelyn Mitchell, US NRC; Charles Moseley (NRMCC Co-chair), Individual; Vinod Mubayi, Brookhaven National Lab; Grant Teagarden, ERIN; Keith Woodard, ABS Consulting * = participated by phone

1. Roll Call and Introductions Roll call was taken and introductions were made. A quorum was established. A moment of silence was taken in memory of past RISC member, Jon Young, who died in May. RISC Chair Robert Budnitz introduced Charles Moseley. Moseley explained that as a member of the ANS Standards Board, he was charged with heading the 2010 Standards Service Award Ad hoc Committee. Moseley reported that the ad hoc committee received excellent nominations for the award. He informed the RISC that Allen Camp was chosen as one of the recipients for his work in advancing the development of the ANS probabilistic risk assessment (PRA) standards. Budnitz noted that the award would be presented at the next ANS meeting November 2010 in Las Vegas. Camp thanked the committee for the recognition. 2. Approval of Agenda The agenda was approved as presented. 3. Meeting Key Issues and Objectives Robert Budnitz reviewed the agenda and summarized the intent of the meeting. He explained that the agenda included an update on the formation of the Joint Committee on Nuclear Risk Management (JCNRM), status reports on writing group activities, and a discussion on training. 4. RISC Chair’s Report A. Summary of June 15 Standards Board Meeting (See Attachment A) Robert Budnitz provided a report on the Standards Board (SB) meeting the previous day. As RISC Chair, he was an ex officio member to represent RISC. Budnitz stated that the SB held

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a discussion of the proposed new JCNRM (ANS-ASME Joint Committee on Nuclear Risk Management) and that two teleconferences were held prior to the meeting. Both the SB and the ANS Board of Directors approved the merger provided that the remaining open issues would be resolved. An agreement was made so that the JCNRM’s secretariat role would rotate between the American Society of Mechanical Engineers (ASME) and the ANS on a three-year basis. Balance of interest issues had been resolved. Both the ANS SB and the ASME Board of Nuclear Codes and Standards would be required to approve all projects to make sure the JCNRM scope was not expanded. Budnitz stated that the SB found acceptable the JCNRM provision for multiple representation from the same organization with the exception of two individuals reporting to the same manager. The committee recognized Mary Drouin’s opinion that organizations should be restricted to one vote, as is currently the ANS policy. Budnitz suggested that Drouin document her objection and provide it to CNRM Chair Rick Grantom and him. Budnitz explained that the merger would create a committee of about 40 members that exceeded the membership maximum in the proposed new JCNRM rules and procedures, but that membership would be reduced gradually to 35 through natural attrition. Budnitz stated that a final draft of the JCNRM procedures would be completed in the next few days. Once completed, the procedures would be distributed to RISC and the SB. The CNRM is expected to approve the JCNRM at their September 2010 meeting. B. Nuclear Risk Management Coordinating Committee (NRMCC) Activities NRMCC Co-chair Charles Moseley updated the committee on NRMCC activities. Moseley stated that since the November 2009 RISC meeting, the NRMCC had met twice. He reported that the NRMCC strategic plan has been finalized. The National Aeronautics and Space Administration had joined the committee. C. RISC Leadership Issues During Transition to Joint Committee Robert Budnitz explained that he reluctantly took over the RISC Chair position when Allen Camp retired before his term had expired. Without a replacement identified, he agreed to continue as chair until the JCNRM merger was completed. Budnitz urged members to consider serving a term as chair. He stated that once the merger was finalized, the ANS would have an opportunity to nominate a chair and vice chair as would ASME. It was anticipated that Rick Grantom would continue as chair for ASME with Pamela Nelson as his vice chair. Budnitz explained that the JCNRM Chair for ANS would also be an ex officio member of the SB and should be a member of the NRMCC. 5. Update on Joint Committee/Reorganization Robert Budnitz noted that the RISC/CNRM merger was discussed earlier under 4A. Budnitz explained that the proposed initial organizational structure of the JCNRM that has been discussed in the last few months would be a work in progress. The organizational structure would be revisited once up and running and modified if necessary. Members preferred that the ASME electronic balloting system be used for the JCNRM and be kept consistent regardless of secretariat assignment. When concern was expressed for potential delays in balloting due to the merger, Budnitz confirmed that they had left open the possibility of existing projects being balloted solely by the initiating committee ― that is by either ANS RISC or ASME CNRM, depending on the timing. 6. Findings on Seismic PRA Pilot (See Attachment B) John Gaertner provided a report on the seismic pilot conducted at the Surry Nuclear Power Plant on the seismic PRA part of the ANS-ASME Combined Standard. The pilot was conducted to review hazard methods, determine costs to meet, and capability of meeting. He

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reminded members that the pilot was initiated in fall of 2007 but slowed due to reprioritization of resources. Gaertner introduced Greg Hardy who was a principal investigator on the pilot project. Hardy outlined the key elements of the pilot. He explained that analyzing structural responses were found to be one of the most costly parts of the seismic probabilistic risk assessment (SPRA), with soil sites found to be more expensive. Several recommendations for changes had been provided to the external events working group. Hardy said that the working group felt the findings from the pilot would be an improvement and should be introduced into the next revision of the standard. It was recognized that the standard could not reference the Electric Power Research Institute (EPRI) pilot report unless it could be made publicly available without significant cost. Robert Budnitz confirmed that the working group would incorporate the findings in a way that would not require users to need a copy of the EPRI report. Hardy suggested that EPRI might be able to issue a publicly-available paper on the full report that could be referenced in the standard. Hardy stated that there were differing opinions on the commentaries provided in the standard. RISC members discussed the use of commentaries in the PRA standards. Generally, members felt that the commentaries were useful but did not agree on the placement. Some wanted the commentaries to be relocated to an appendix while others felt this would be inconvenient to users. Still others suggested that a repeated heading of “Non-Mandatory Commentary” be included prior to each commentary. Hardy reported that current results from the Surry SPRA were in draft form and not final. He explained that Dominion needed to do some additional Surry-specific work to make it into a Category II SPRA. Hardy stated that EPRI would be interested in a pilot at a rock site and had discussed this prospect with the U.S. Nuclear Regulatory Commission (NRC). He informed members that a review panel had been put together with broad expertise to prepare a findings and lessons learned report. The resulting recommendations would be documented in the EPRI report and provided to the external events writing group. Budnitz stated that the external events working group had accepted about 75% of the preliminary comments received from the pilot, which he anticipated would be incorporated into Addendum B of the ASME/ANS Combined Standard. Hardy confirmed that the pilot did not find any requirements in the standard that could not be completed but noted that a peer review had not been performed. He also stated that the NRC could have a different view. The cost to comply with the standard for a new SPRA was estimated to be between one and two millions dollars. The high range was due to a lot of variables.

7. Guidance for Possible Training Document for ANS PRA Standards Robert Budnitz informed members that the SB Chair wanted to hold a four-hour training workshop at the upcoming ANS Utility Working Conference. The conference would be held at Amelia Island, Florida, in two months. The purpose of the workshop would be to provide a regulatory perspective on PRA. Committee members were asked to support the workshop. While members thought that the concept was interesting, many expressed concern that there wasn’t sufficient time to prepare and that members might not have the appropriate skills to be an instructor.

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8. Low Power and Shutdown (LPSD) Standard (ANS-58.22), Writing Group Report

A. Status of Comment Resolution ANS-58.22 Working Group Chair Don Wakefield reminded members that the last ballot on the LPSD Draft Standard resulted in nearly 700 comments. Responses were issued last November with a request to identify potential showstoppers. An additional 95 comments had been submitted from committee members. Wakefield believed that 30 of the additional comments had already been addressed. Working group members anticipated addressing the remaining comments within the next month. Just last week, 63 more comments were received from the NRC. Wakefield stated that the comments from the NRC would add to the time frame needed for resolution. The working group was considering a face-to-face meeting in summer. B. Anticipated Schedule (See Attachment C) Don Wakefield provided a potential long term schedule for the LPSD Standard. He considered the following to be the earliest schedule for integrating the LPSD Standard into the ASME/ANS Combined Standard.

• Dec 2010 – LPSD PRA Standard published by ANS as stand-alone standard for use in pilot applications

• 2011 – Pilot application of LPSD PRA Standard at 2 sites, lessons learned • 2012 – Revision of LPSD PRA Standard based on pilot applications, integration with

PRA Standard • Dec 2012 – ASME/ANS PRA Standard revision issued, including LPSD PRA Standard • 2013(+) – Endorsement of PRA Standard Revision 2012 by NRC in RG 1.200 Rev xx

Members felt that the schedule was reasonable. Robert Budnitz stated that if the LPSD Standard was not revised by 2012, it could have to wait until 2014 to be incorporated into the Combined Standard. C. Efforts to Develop Pilots (See Attachment D) Doug Hance reviewed gap assessment goals and objectives of a pilot. The overall goal was to ensure that methods in the LPSD Standard were ready. It was recognized that boiling water reactor (BWR) and pressurized water reactor (PWR) representation was important, meaning at least two pilots. Hance reviewed options for implementation of a pilot. They assumed that a gap assessment would require changes to the LPSD Standard for consistency and clarity and that new requirements would need to be added. Hance stated that the next step would be to evaluate the schedule and timing. They would need to identify utility participants from candidates. Hance stated that most utilities were interested but very busy. Dennis Henneke stated that there were already known gaps in LPSD methods and was wondering if anyone planned to address them. Hance stated that there was not anything budgeted by EPRI for an LPSD pilot. Greg Krueger stated that the BWR and PWR owners groups would be meeting in August 2010 and would consider this issue. Hance stated that he felt the LPSD Standard should be piloted first and then balloted. Budnitz explained that the Standards Board discussed procedures for releasing a standard for trial use at their meeting yesterday. Chuck Moseley explained that the Standards Committee procedures had previously included a policy on trial use but that they no longer do. While SB members thought it sometimes made sense to issue a standard for trial use, they questioned why the policy would have been removed. Budnitz confirmed that ASME procedures included

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a policy on trial use that required the draft to be reballoted before adoption as a regular standard. Paul Amico expressed concern that utilities would want a finalized or near finalized standard for piloting. Rick Hill stated that there would have to be a commitment from a utility to pilot or there wouldn’t be a benefit to releasing for trial use. Members were in agreement that the trial use period would have to be greater than 12 months to accommodate a pilot. As members were unsure if the BWR or PWR owner groups had the funding to support an LPSD pilot, members questioned what might happen if no one was able to pilot and if the draft would be approved/issued as is. Mary Drouin stated that if NRC felt that an application should be piloted, they would consider supporting and might waive fees. Biff Bradley confirmed that the Nuclear Energy Institute (NEI) felt strongly that an application pilot was needed. Krueger asked if there was a thought to make the pilot a blind test. He would recommend that at least a part of the test would be blind. Hance explained that they had thought to have someone running the pilot that was not involved in the development of the standard. Budnitz summarized the discussions on the LPSD Standard. He stated that members were in agreement with the proposed schedule and that work should continue with the anticipation that a ballot would be issued around Labor Day. There was a broad consensus that if the ANS SB would approve issuing the LPSD standard initially for trial use, then that procedure should be followed when the LSPD ballot is issued in the autumn. Members felt that one or more pilots should be conducted before the LPSD Standard would be ready for issuance in final form. With the BWR/PWR owner group meetings in the fall, it was hoped that utilities would be identified to conduct the pilots. The next decision point would occur in the fall based on pilot options. Allen Camp recommended that RISC maintain jurisdiction on this standard at least until a decision was made on trial use, pilots, etc. 9. Level 2 PRA Standard (ANS/ASME-58.24), Writing Group Report Robert Budnitz provided an update on the Level 2 PRA Standard on behalf of ANS-58.24 Working Group Chair Mark Leonard. Budnitz noted that the Level 2 draft was issued to RISC and CNRM members for comment ― not ballot. He explained that the working group was hoping to receive comments from the NRC soon. The working group anticipated holding a multiple-day meeting at ANS headquarters about Labor Day. Budnitz reported that Leonard anticipated the draft would be ready for ballot around November provided that significant comments would not be received from the NRC. The scope of the Level 2 PRA Standard was technology specific to LWRs and was not expected to be broadened. 10. Level 3 PRA Standard (ANS/ASME-58.25), Writing Group Report (See Attachment E) ANS-58.25 Working Group Chair Keith Woodard provided an update on the Level 3 PRA Standard. He noted that the working group held a full-day meeting the previous day and was holding a full meeting today. He reported that the draft received more than 300 comments on the preliminary review. Woodard anticipated that the working group would finish comment responses during today’s meeting. He stated that Section 5 of the draft had been completed yesterday. A decision was made to move Section 9 on computer codes to an appendix without requirements. Woodard anticipated that a final draft could be ready in about a month and questioned the next step. He did not foresee any areas of conflict.

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Rick Hill expressed concern about consistency between the Level 2 and Level 3 standards and saw value at balloting both together. Woodard believed that the two standards matched up but would coordinate with Mark Leonard prior to providing the Level 3 draft for ballot. After a discussion, the decision was made to release the Level 3 draft for formal ballot (with the exception of Section 4.5 on Level 1 and 2 interface) as soon as available. Section 4.5 would be issued for separate ballot at the same time as the Level 2 ballot. Budnitz questioned Woodard on a potential pilot for the standard. Woodard wasn’t sure how a pilot on the Level 3 Standard would work. Woodard believed that a pilot for the Level 3 Standard would need a feed from the Level 2 Standard. He thought that there would be difficulty finding a plant that wanted to spend the money to pilot. Budnitz suggested that the Level 3 Working Group consider one or more ways a pilot could be performed to test the Level 3 Standard as this would determine its purpose and potential interest. Action Item 6/10-01: ANS-58.25 Working Group to consider one or more ways a pilot could be performed to test the Level 3 Standard. Budnitz recognized that the LPSD and Level 3 draft standards could be ready for ballot at the same time requiring coordination. 11. ASME Fire PRA Writing Group Report Dennis Henneke reported that the fire writing group met the previous Monday in San Diego. He explained that the fire PRA section of the Combined Standard was originally piloted at Diablo Canyon Nuclear Power Plant in early 2008. The results of the pilot were incorporated into Addenda A. Henneke stated that Addenda A was being used for peer reviews at many plants that were transitioning to NFPA 805; mostly PWRs but five BWRs were scheduled for 2010. Henneke stated that they were getting feedback but that it didn’t include specific suggestions for changes. The working group made a number of changes to plant partitioning as this section had the most complaints. Revisions would not fix all of the problems as “analysis areas” are not fully integrated into the standard. Under circuit failure analysis, Henneke stated that it was likely that a new supporting requirement (SR) on Hot Short Duration would be included in the future. A minor change was made by removing the requirement related to NUREG/CR-6850. Henneke anticipated that a ballot could be ready around July. 12. Update on New Reactor PRA Standards A. Status of ASME PRA Standard for Non-LWRs As a member of the working group, Robert Budnitz reported for Working Group Chair Karl Fleming on the status of the ASME PRA Standard for Non-LWRs. Budnitz stated that there had been a working group meeting the previous week. Although personally pessimistic himself, Budnitz reported that Fleming anticipated the next round would be done by end of summer/next fall. B. Status of ASME PRA Standard for Advanced LWRs Gene Hughes provided an update on the ASME PRA Standard for Advanced LWRs on behalf of Working Group Chair Jim Chapman. Hughes stated that there were several meetings and that they were deciding on comprehensive change (SR by SR) to the standard or simplistic changes (more general approach with footnote). Hill didn’t believe that they had decided which way to go. Dennis Henneke thought that the changes should be consistent with the

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standard for Non-LWRs by doing a SR by SR review. Mary Drouin added that from a regulatory perspective, a standard with general guidance was not helpful to the NRC. C. Modular Helium-Cooled Reactor Design-Criteria Standard ANS-53.1 Robert Budnitz updated the committee on the status of draft standard, ANS-53.1, “Nuclear Safety Criteria and Safety Design Process for Modular Helium-Cooled Reactor Plants.” He stated that ANS-53.1 provided general design requirements and used a risk informed approach. Budnitz felt that it was somewhat controversial. Mary Drouin believed that ANS-53.1 closely mimicked technology-neutral techniques. Budnitz thought that if the standard was to become a regulation, there would need to be some rethinking. Pat Schroeder confirmed that the draft had been provided to RISC for comment along with the CNRM and that both committees would be provided another opportunity to comment when issued for a second ballot. 13. Next RISC Meeting Robert Budnitz stated that the next ANS meeting would be held November 7 – 11, 2010, in Las Vegas, Nevada. A decision on holding a RISC Committee meeting in conjunction with the ANS meeting would be made in the months ahead. Much depended on the progress of the drafts. Budnitz stated that a teleconference may be sufficient. 14. Other Business NEI Letter (See Attachment F) Robert Budnitz reminded the committee of the NEI letter to ANS, ASME, and the NRC that was distributed to the RISC prior to the meeting on the industry perspective. The letter was a request from NEI to change the overall process and schedule for the PRA standards in development. Dennis Henneke didn’t feel that the Fire PRA Standard was the issue. He agreed with the NEI letter in that the working group expedited the process not thinking about it being endorsed and that NFPA 6050 would have problems. Henneke stated that the fire PRAs were conservative and needed more refinement. In hindsight, Henneke felt that we needed to consider the implications of releasing a standard and insist on piloting before endorsement by the NRC so that similar problems were not created. As chair of the Fire PRA Working Group, Henneke would be issuing a letter to the NEI. He didn’t feel that we should slow down the development of the standards now in the works but agreed that pilots should be conducted before endorsement could occur. Budnitz stated that the actions we take in the future are what were important. Mary Drouin felt that there were a lot of issues being blamed on the standard that were not related. Greg Krueger explained that additional problems with keeping track of requirements were created by the renumbering of sections from the first issuance of the Combined Standard to Addenda A. Budnitz confirmed that the committee’s consensus was to maintain the current schedule for development of the LPSD, Level 2, and Level 3 standards but work to arrange pilots for all. 15. Adjourn The meeting was adjourned at 3:04 p.m. (PACIFIC).

Risk Informed Standards Committee (RISC) Progress Report June 2010

In RISC Ballot/Vote (or resolving comments) ANS-58.22-20xx, “Low Power Shutdown PRA Methodology”

Writing group is led by Don Wakefield, underway since 1999 Reballot was issued due to substantive changes Reballot closed October 2008 with 674 committee comments and 116 public

comments Comment responses and a revised draft were issued to RISC in November

2009 Working group is resolving the remaining issues before issuing a revised

draft for another ballot Standards in Progress ANS/ASME-58.24-20xx, “Severe Accident Progression and Radiological Release (Level 2) PRA Methodology to Support Nuclear Installation Applications”

Writing group is led by Mark Leonard, underway since 2005 Draft issued to RISC & ASME CNRM for preliminary review in January 2010 Comments were provided to the working group for consideration in May 2010 Waiting for NRC comments on the preliminary review Working group meeting is tentatively scheduled for mid-summer to resolve

comments Ballot date to be determined

ANS/ASME-58.25-20xx, “Standard for Radiological Accident Offsite Consequence Analysis (Level 3 PRA) to Support Nuclear Installation Applications”

Writing group is led by Keith Woodard, underway since 2005 Draft issued to RISC & ASME CNRM for preliminary review in October 2009 Comments were provided to the working group for consideration in February

2010 Bulk of NRC comments were provided to the working group in April 2010 Working group meeting is scheduled June 15 & 16, 2010, during the ANS

Meeting Ballot date to be determined

ANS RISC Merger with ASME CNRM The RISC met on February 24, 2010, in Dallas, Texas, in a joint meeting with the ASME CNRM. The full day meeting provided both committees an opportunity to thoroughly review the draft procedures for merging the two consensus bodies into the proposed Joint Committee on Nuclear Risk Management (JCNRM). In April, a revised procedures document was circulated to the RISC and CNRM as well as to the ANS Standards Board and the ASME Board on Nuclear Codes and Standards for comment. The ASME bodies have said that they expect to vote on approval of this merger by September 2010. RISC Meeting

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Text Box

Attachment A

The RISC will meet on Wednesday, June 16, 2010, during the ANS Annual Meeting. Members of the CNRM are invited, and it may be a joint meeting if quorums from both committees are present, which is expected. Standards Inquiries and Delinquent Standards The RISC has not received any standards inquiries and does not have any delinquent standards in need of maintenance. Other Activities

1) The ASME CNRM is sponsoring the development of two additional PRA standards, one covering PRA methods for advanced non-LWR reactors, and the other covering PRA methods for advanced light-water reactors including LWRs in the design and construction stage. Members of the RISC Committee are involved as members of both ASME writing groups, and within the past year RISC has been involved in reviewing draft versions of both of these standards to assure coordination with the PRA standards that ANS-RISC oversees.

2) NRMCC -- ,The RISC Committee’s leadership remains active within the “Nuclear Risk Management Coordinating Committee,” an ad-hoc committee whose other active representatives come from ASME, DOE, NRC, and with less active participation IEEE and NASA. This committee meets 2 or 3 times annually for a day. It was founded in 2003 to help assure that coordination rather than conflict characterizes the interactions among these organizations in the area of PRA standards development and maintenance.

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ASME/ANS SPRA Standard Pilot Plant Review - Surry

Greg HardyJohn Gaertner

ANS RISC Committee

June 16, 2010

2© 2010 Electric Power Research Institute, Inc. All rights reserved.

ASME/ANS Standard on External Events PRA

• Industry concerns delayed approval of SPRA Standard

– Hazards method and criteria for update

– Costs to meet category II

– Capability to meet category II

• Standard was approved after EPRI offered to sponsor pilot plant application using SPRA Standard

• Surry selected as pilot and started in fall 2007

• Tasks shared by EPRI and Dominion

• Project slowed because resources re-prioritized at Dominion (emergent events) and EPRI (KK response)

• Pilot of SPRA Standard complete; Surry SPRA continues

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Text Box

Attachment B

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ASME/ANS Standard on External Events PRA

• Objectives

– EPRI/Dominion: To determine any changes, additions or recommendations to the ASME/ANS External Event Standard.

– Dominion: To develop a category II SPRA for Surry plant that can be used in future risk-informed decision-making.


Project Responsibilities

ANS Std. Pilot Plant Task

EPRI Task Dominion Task

Review Surry Material X Provide Material Comparison to ANS Std. CC

II X Review

Seismic Hazard X Review In-Structure Spectra X Review Seismic Fragilities Secondary Primary

Plant Logic Development X X Quantification Review X

Final Project Report X Input to Report, Review

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Key Elements of Pilot Plant Project

• Development of Pilot Plant Uniform Seismic Hazard Spectra (USHS)– Capability Category II compatible– Uses EPRI 2004 Attenuation relationships considering

Characterizations for Charleston, New Madrid, Eastern Tennessee Seismic Zone, etc.

– Uses methods /results from new plant seismic hazard studies• Plant Walkdowns• Development of Seismic Responses Associated with New USHS

– Analyzed two structures in detail – SSI models developed– Scaled current seismic responses for the remaining safety–related

structures with median responses conservatively estimated• Representative Seismic Fragilities Generated/Re-calculated• Development of Seismic Systems Model (Fault / Event Trees) –

Broader Range of SSCs; Quantification; Sensitivity Analyses


Seismic Hazard Comparison – Old to New

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Surry Uniform Hazard – Old vs New

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.1 1 10 100

Solid = Update; Dashed = Orig.

1E‐5

GMRS

1E‐4

1E‐4

1E‐5

GMRS

Frequency


Comprehensive Surry Walkdowns

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Key Challenges/Innovations of ANS Pilot Implementation

• Structural response one of the most costly parts of a SPRA– Soil response not easily scaled from seismic design analyses

• Innovation developed for Surry - Best Estimate of Structural Response– Best estimate, upper bound and lower bound analyses for two

buildings

– Calculated the effects of probabilistic response based on the IPEEE developed probabilistic response

– Developed scaling factors for remaining buildings


Key Challenges/Innovations ANS Pilot Implementation (Cont)

• Service Building SSI Analyses

– Structurally connected to the turbine building

– Embedded foundation requires use of SASSI

– Incoherence analyses require development of stable transfer functions

– Soil sites require much more effort

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• Screening of SSEL and development of fragilities from screening process

– NP 6041 SMA screening tables used during walkdown

– Anchorage and load path need assessment in parallel

– Two Issues found with development of fragility1. HCLPF 84 approach within Fragility Guide incorrect

2. Spectral acceleration screening in conformance unclear



• Special meeting to resolve fragility issues in January

– Kennedy, Campbell, Hashimoto, Merz, Tong, Hardy

– Modern UHS incorporates peak to valley variability• Double counting to include additional PTV variability

• HCLPF50 appropriate for screening level

– In-structure spectral acceleration levels associated with 6041 screening not consistently applied in past

• Note for table specifies 2g screening level; basis unknown

• Level revised to 1.8 g which correlates to 1.5 times the 1.2 g ground spectral acceleration stated for tables

• Update to EPRI fragility report published December 2009 (Product ID #1019200)

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SSEL and Fragility Analyses

• Over 600 items of SSCs are in the Surry Unit 1 SSEL.

• Most were screened out from a detailed evaluation via walkdown and/or system considerations.

• About 110 SSCs selected for detailed fragility analysis, done by EPRI and Dominion.

• About 60 calculations were done that considered various failure modes. Scaling of previous IPEEE calculations was done where possible. Fragilities for six relay models developed using test data. In some cases, calculations are preliminary / generic data used.

• About 55 SSCs were determined to have HCLPF capacity below the screening criterion of 0.7g and they were modeled in the PRA event/fault trees.


System Analysis, Quantification and Sensitivity Analyses

• Fault/event trees developed

• CAFTA code used for quantification – 8 acceleration intervals used, “UNCERT” used for uncertainty analysis

• Seismic CDF and LERF determined by convolving PGA hazard curve with fragilities– Turbine building failure major contributor, followed by loss of

offsite power and ECST

• Sensitivity analyses were done for several scenarios:– Turbine building improved capacity

– ACC diesel improvement

– MCC improvements

– Non D & M seismic hazard curves etc.

–

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Dominion Perspective

• Current results from the Surry seismic PRA are draft and not final.

• Dominion needs to do some additional Surry-specific work to make it into a Category II SPRA – Review and finalize fragility calculations for some components

– Calculate fragilities of new fuel design, newly added or replaced items since the SSEL such as relays.

– Consider impact of revised fragilities on systems model

– Resolve discrepancies in the quantification subroutine

• Report has a disclaimer to reflect above


Project Status: EPRI Report and Review

• Draft SPRA report completed February/March 2010

• Expert panel review at EPRI – April 7-8, 2010

• Finalize SPRA pilot report – June 30 based on expert panel meeting

• SPRA lessons learned report – TBD

• ASME/ANS Standard (RISC Committee) communication– Assembled comments sent (TBD)

• Potential for second SPRA pilot– NRC also considering (SOARCA)?

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SPRA Pilot Review Panel Charter

Mission

To provide technical opinions, individual comments and insights on the findings and lessons learned of the pilot of the ANS seismic standard.

Objective

Develop a set of comments and insights on – the process used in the pilot

– the technical issues,

– required interpretations employed in the development of the pilot

– comparison with the ANS Seismic PRA Standard.


Review Panel Charter

Approach• Panel receives Charter, schedule and the draft EPRI report

• Members review the report, hold teleconferences, develop comments on the use of the Standard to perform the Surry SPRA.

• It is not the panel’s responsibility to review the SPRA for technical adequacy directly but to evaluate and advise on its use of the Standard.

• After review by the individual members and distribution of the comments the panel will meet for two days to discuss, organize and summarize the comments. The resulting recommendations will be documented in the EPRI report and provided by EPRI to the ANS/ASME Standards writing committee.

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Review Panel Composition

• EPRI convened an expert review panel that included the following representation of experience related to SPRA and standards:

• Members of the SPRA pilot project team with expertise in the three basic SPRA technical areas of expertise– Seismic fragility– Seismic hazard– Plant logic modeling and risk quantification

• Members of the SPRA Standard Writing Committee

• Nuclear utility representatives

• Nuclear Regulatory Commission representatives

• Consultants with experience in internal events and fire PRA standard development


Review Panel Members

Reviewers

• Robert Budnitz – Standard writing member• Nilesh Chokshi - Standard writing member• Ravi Ravindra - Standard writing member• Martin Stutzke – NRC, PRA• Ken Kiper (FP&L), Vince Anderson (ERIN) – PRA & fire standardsEPRI

• Robert Kassawara – EPRI PM• Ken Canavan - EPRI Manager of Risk and Safety• Greg Hardy - Principal Investigator (SGH)• Dave Moore – Individual consultant, systems and quantification • Gabe Toro – Seismic hazard (Fugro)Dominion/Surry

• Divakar Bhargava, Joe Vasquez - structural mechanics• Tommy John, Sophie Gutner – systems and quantification

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Expert Panel Meeting Results

• Comments Identified for about 2/3 of the SPRA standard supporting requirements– Editorial

– Minor changes

– Significant changes/recommendations

• GAP assessment started – Areas for further research and development

– Studies and sensitivity study recommendations

• SPRA Standard writers– Responses to majority of comments provided


EPRI Pilot Study Comparison to the SPRA Standard

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Recommendations for the SPRA Standard


Methodology Improvements, Lessons Learned and Recommendations for the Standard

• Seismic Hazard• Old IPEEE vintage

hazards may not be valid• If new UHS shape, new

site response required• Some standard

requirements too specific• Soil coherency function

• Seismic Fragility• Structural response• Screening levels & methods• Scaling for soil sites• Significant effort required in

fragility calculations

•Logic Model & Quantification•Correlation treatment•Relay review methods & human factor treatment•CAFTA improvements for use in seismic quantification

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Potential Long Term Schedule for LPSD PRA Standard

This is the earliest schedule for integrating the LPSD PRA Standard in the ASME/ANS PRA Standard.

• Dec 2010 – LPSD PRA Standard published by ANS as stand-alone standard for use in pilot applications

• 2011 – Pilot application of LPSD PRA Standard at 2 sites, lessons learned

• 2012 – Revision of LPSD PRA Standard based on pilot applications, integration with PRA Standard

• Dec 2012 – ASME/ANS PRA Standard revision issued, including LPSD PRA Standard

• 2013(+) - Endorsement of PRA Standard Revision 2012 by NRC in RG 1.200 Rev xx

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Attachment C

LPSD PRA Methods Development and the Draft LPSD PRA Standard

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Attachment D


Standards Development - EPRI Perspective

• Affirmative EPRI vote requires draft Standards refined through piloting or gap assessment of methods.

• Methods to comply with the Standard must be

– Demonstrated

– Available

– Well understood (i.e., training)


Gap Assessment Goals and Objectives

• Overall Goal – Ensure LPSD methods are ready – Improve Standard through gap assessment– Identify gaps in existing LPSD PRA methods

• Supporting Objectives– Review the Standard to

• Identify unclear requirements• Identify requirements lacking methods• Identify missing requirements and errors

– Apply the Standard to a shutdown PRA model– Develop recommendations to improve the Standard

and identify gaps in methods needed to meet it


Gap Assessment – Standard Review

• Review of draft LPSD PRA Standard

– HLRs and SRs reviewed for clarity, consistency, level of detail, and completeness.

– Clear requirements may be evaluated and screened from detailed review.

– Conclusions based on review and detailed application of the Standard to identify:

• Improvements to the Standard

• Gaps in methods


Gap Assessment – Implementation Options

1. Targeted-scope assessment – quantitative requirements

– BWR and PWR represented for assessment

– Identify all plant operating states (POSs) for the outage

– Select POSs to optimize use of SRs (consider plant conditions, SR scope, and relationship to other SRs)



– Options:

• Apply Standard to existing model and assess gaps

– Requires “questioning attitude”; detailed review of the model, i.e., meeting the Standard is not assumed.

• Develop model for the selected POSs – a skeleton PRA. Participant utility can expand.



2. Pilot-type Assessment – quantitative requirements

– Identify all plant operating states (POSs) for the outage

– Develop a PRA model for a wide range of POSs to maximize use of SRs

– Requires Owner’s Group support



3. Qualitative risk assessment (QLRA) gap assessment

– Could be implemented as part of targeted-scope assessment for selected POSs

– Considered an optional task since the draft Standard contains current QLRA methods


Gap Assessment – Conclusions

• Gap Assessment Conclusions

– Recommend changes to the draft LPSD PRA Standard

• Consistency, clarity, recommend new requirements indicated by the assessment (gaps in the Standard)

– Identify development of methods required to implement the Standard (gaps in methods)

• Identify requirements for which current methods are inadequate

• Distinguish between those requiring extension or refinement of existing guidance (either at-power or shutdown) and those requiring extensive research


Next Steps

• Evaluate schedule and timing

• Identify utility participant(s) from candidates

• Determine which path a targeted-scope assessment should take based on candidate participants

– Use of existing model

– Develop model for selected POSs


Together…Shaping the Future of Electricity

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The Level 3 Committee is Working on Comments

• Received More Than 300 Comments

• Some from Foreign Reviewers

• Met 3 Days in March 2010

• 75% Complete in Addressing Comments

• Will Meet Two Days in San Diego to Complete Draft for Balloting

History of the Level 3 Standard Development

• Started in February 2004 (5 Years Ago)

• Held 9 Meetings and one Conference Call

• Effort Involved about 120 Person-Days in Meetings and Perhaps Another 60 Person-Days in Writing and Review

• Spent 3 Days in March 2010 at NRC Rockville Office Addressing Comments Received from RISC (and Others)

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Attachment E

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Organization and Key Elements• Section 1 Introduction• Section 2 Acronyms and Definitions• Section 3 Risk Assessment Application Process• Section 4 HLRs and Supporting Requirements (SRs):

--Level ½ Interface

--Protective Action Parameters & Other Site Data

--Meteorological Data

--Atmospheric Transport and Dispersion

--Dosimetry

--Health Effects

--Economic Factors

--Quantification and Reporting• Section 5 Risk Integration• Section 6 Configuration Control• Section 7 Peer Review• Section 8 References• Section 9 Computer Codes

Key Contributors to the Draft

• Overview---(Woodard, Mitchell)• Level 1/2 Interface--- (Paul, Chisholm)• Site/Plant Input Data---(Teagarden)• Meteorology---(Woodard, Mazzola)• Atmospheric Dispersion---(Woodard, Mazzola)• Dosimetry---(O’Kula, Bixler)• Health Effects---(Mubayi, Mitchell)• Economic Factors---(Mubayi, Mitchell)• Quantification and Results Reporting---(Teagarden)• Risk Integration---(Johnson)• Computer Codes, Example I/O---(Bixler, Chisholm)

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Expense Compensation Issues

• NRC has now Provided Expense Reimbursement that was Instrumental in Facilitating Recent Meetings to Address Comments.

• We are Way Under Budget at the Present Time

1776 I Street, NW l Suite 400 l Washington, DC l 20006-3708 l P: 202.739.8081 l F: 202.533.0182 l [email protected] l www.nei.org

Anthony R. Pietrangelo

SENIOR VICE PRESIDENT

AND CHIEF NUCLEAR OFFICER

June 9, 2010 Dr. N. Prassad Kadambi American Nuclear Society 15015 Notley Road Silver Spring, MD 20905

Dear Dr. Kadambi: Industry has supported efforts by standards development organizations (SDOs) to create consensus standards for probabilistic risk assessment (PRA). We have now had significant experience with the use of these standards in a regulatory context, and believe this experience merits careful consideration relative to future standards development processes and schedules. The SDOs have received considerable input from the U.S. Nuclear Regulatory Commission regarding the NRC’s expectations for standards development. This letter provides input from the user community, and is based on discussions with the Nuclear Energy Institute’s advisory structure including the Regulatory Process Working Group. This working group provides policy advice regarding the achievement of an improved regulatory environment, including consideration of risk informed processes, and the overall goal is a stable predictable safety focused regulatory approach. This group includes chief nuclear officers from several operating companies, both reactor vendor owners groups chairs, Electric Power Research Institute, and other senior industry representatives. The working group was briefed in their last meeting on the overall direction and strategy for risk informed regulation. Based on the outcome of that discussion, the attached letter and attachments were provided to NRC on May 20, 2010. The attached letter provides a detailed discussion of industry observations on PRA standards development and their efficacy in enabling improved regulation. The letter notes the need for changes to the overall process and schedule for standards development. We request your review of this letter and your attention to the user community perspectives provided therein. Considerable effort was expended to develop a proposed process and schedule that takes into account lessons learned from existing efforts to apply PRA standards in a regulatory context. To briefly summarize the attached letter, the user community’s main points are as follows:

• We are at a crucial point in PRA standards development • Industry is limited in its ability to pursue applications due to continually evolving regulatory

expectations and standards expansion

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Attachment F

June 9, 2010 Page 2

• Fire PRA has illustrated the pitfalls of premature application of PRA standards, absent full piloting and methods development

• Several years of additional methods development are now needed for fire PRA despite the existence of a final NRC approved PRA standard

• Used improperly, PRA can lead to regulatory instability and improper decision making • No further standards should be finalized or endorsed by NRC until they are fully piloted, and

underlying analysis methods are developed and accepted • There is no compelling need to rapidly develop additional PRA standards at this time,

including expanded PRA scopes or risk management standards • The primary focus should be on correcting the fire and external events portions of the

existing American Society of Mechanical Engineers/American Nuclear Society PRA standard • A realistic schedule and process for additional standards development is proposed in

Attachment 1 of the NRC letter We believe the efforts of the SDOs in this area have been well intended, but we request your careful consideration of the user community perspectives provided above and in the attached NRC letter. The user community’s needs merit particular attention if we are to achieve our mutual goal of widespread implementation of effective PRA standards. We recommend that the current activities by the ANS and ASME PRA standards committees to create additional standards and further modify existing standards be put on hold until all stakeholders conduct an assessment of lessons learned. The overall approach and schedule for standards development should be re-evaluated. We continue to support risk-informed performance based regulatory improvement, in context with regulatory predictability and stability. Industry’s support of continued PRA standards development can continue if realistic expectations and considerations of lessons learned are factored into the process. To that end we would be happy to meet with you to discuss these issues further. Please contact me if you have any questions. Sincerely, Anthony R. Pietrangelo Attachments c: Mr. Joe Colvin

Documents

American Nuclear Society (ANS) Town and Country Hotel, San … · 2010. 10. 12. · ANS-58.22 Working Group Chair Don Wakefield reminded members that the last ballot on the LPSD Draft