Public Meeting to Discuss ASME/ANS Trial Use PRA Standards and Multi-Module Risk Standards and Multi Module Risk June 26 2014 June 26, 2014
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Public Meeting to Discuss ASME/ANS Trial Use PRA
Standards and Multi-Module RiskStandards and Multi Module Risk
June 26 2014June 26, 2014
Agendag
TIME TOPIC
8:00 am – 8:10 am Opening Remarks & Introductions
8:10 am – 8:40 am ASME/ANS presentation on trial use standards
8:40 am – 9:10 am NRC endorsement of trial use standards
9:10 am – 10:00 am Open discussion on endorsement of trial use standards
10:00 am - 10:15am Break
10:15 am – 12:00 pm NRC criteria for evaluation of multi-module risk
12:00 pm - 12:15 pm Wrap-up
12:15 pm Adjourn
2
Outline
• Purpose of meeting
• History of past PRA standard development
• Relationship of RG 1.200 to regulatory activities
• ASME/ANS Schedule of future standards
• Future standard development/endorsement• Future standard development/endorsement
• Wrap-up
4
Purpose of Meetingg
• To communicate staff’s plans for review of trial use standard and final endorsement of t d dstandards
• Solicit stakeholder input
5
History of PRA Standards and NRC Endorsement
Standard Standard Published RG 1.200 NRC Date Published
ASME RA S 2002 April 2002 DG 1122 Nov 2002
and NRC Endorsement
ASME RA-S-2002 April 2002 DG 1122 Nov 2002
ASME RA-Sa-2003 Dec 2003 RG 1.200, Rev 0 Feb 2004
ASME RA-Sb-2005 Dec 2005 DG-1161RG 1.200 Rev 1
Sep 2006Jan 2007
ASME RA-Sc-2007, Addendum C July 2007 NRC reviewed and endorsed this standard when it reviewed and endorsed ASME/ANS RA-S-2008
ANS 58.21 External Hazards for Operating Reactors 2004 DG-1138 Aug 2004
Revision 1 of this standard was reviewed and endorsed inRevision 1 – ANS 58.21 March 2007 Revision 1 of this standard was reviewed and endorsed in ASME/ANS RA-S-2008
ANS 58.22Low Power /Shutdown for Operating Reactors These standards are being issued as part of the joint ASME/ANS standard which is the standard the
NRC will review and endorse.ANS 58.23Internal Fire
ASME/ANS RA-S-2008 April 2008 DG-1200 June 2008
ASME/ANS RA-Sa-2009 Feb 2009 RG 1.200, Rev 2 March 2009
NRC does not plan to review and endorse plans to review andASME/ANS RA-Sb-2013 CY 2013NRC does not plan to review and endorse, plans to review and endorse the new edition, which addresses NRC issues
Relationship of RG 1.200 to Regulatory ActivitiesRegulatory Activities
LicensingRisk
informed licensing changes
Tech SpecRisk
informed tech spec changes
10 CFR 50.69Risk informed categorization
and special treatment
10 CFR 52Early Site Permit and
Combined Licenses for Nuclear Power Plants
Application
RG 1.174
RG 1.177
RG 1.201
RG 1.206
Application Specific
Regulatory Guide
Generic Supporting Regulatory
Regulatory Guide 1.200
7
g yGuide
PRA Standards and Industry Programs
Proposed ASME/ANS Schedule
Trial Use Publication
• Next Edition* Sept-2016ALWR J 2015
Standard Date
• ALWR Jan-2015• Level 2 PRA Nov-2014• Level 3 PRA Dec-2014
LP/SD PRA N 2014• LP/SD PRA Nov-2014• NLWR Dec-2013• SFP PRA Cancelled
*Unclear whether next edition is published for trial use or for use
8
Proposed NRC Endorsement
Trial Use Publication NRC Endorsement
• Next Edition Sept-2016
Standard Date Date
To be determined
• ALWR Jan-2015• Level 2 PRA Nov-2014• Level 3 PRA Dec 2014
Initiate review and
• Level 3 PRA Dec-2014• LP/SD PRA Nov-2014
endorsement in Revision 3 to RG 1.200
• NLWR Dec-2013 NRC does not plan to review and endorse
9
NRC Position on Trial Use StandardsStandards
• NRC supports pilots to test the standard
Performing pilots without knowledge of NRC• Performing pilots without knowledge of NRC position can result in unnecessary staff objections
• NRC expectation that licensees will take advantage of the trial use standard and staff
iti d t it f th i d iposition and not wait for the one year period prior to fuel load or 4 year update to meet the standard
10
Proposed NRC Endorsement
• NRC review for developing staff position would occur in parallel with trial use pilots– Initiation of revision to RG 1.200 would occur with
publication of standard for trial usep– Draft guide (DG) would include language that the DG
does not constitute NRC endorsement• NRC official endorsement would occur after• NRC official endorsement would occur after
ASME/ANS (ANSI) publication of standard for use• Issuance of DG during trial use period:
– Will allow staff concerns to be factored into the pilot process
– Will inform licensees of staff position prior to publication p p pof RG allowing licensees to start modifying their models as appropriate
11
Schedule for Publication of Revision 3 of RG 1 200Revision 3 of RG 1.200
2016-2017 2018-2019 20202015ASME/ANS issues
standard for
NRC issues DG, for public review and comment, NOT FOR ENDORSEMENT
NRC reviews trial use standards for preliminary view
ASME/ANS (ANSI) issues standard for use
Trial use standard revised based on lessons learned from pilots
ASME/ANS pilots trial use standard
Public
standard for trial use
Revising Staff position in RG 1.200 based on ISGs and insights from other
regulatory activities
Public review and comment
ENDORSEMENT
Public comments
Public meeting
NRC review of
Public meeting
Public review and comment
g y
NRC issuesRG 1.200, R 3 f
NRC review and disposition of
public comments
ACRS Review
Public meeting
standard for endorsement
Rev 3 for use, INCLUDES STAFF ENDORSEMENT
Final Concurrence
p
Relationship to Fuel Loading and 4 Year Updateand 4 Year Update
RG 1.200, Rev 3, NRC d t f L l 2
RG 1.200, Rev 4, NRC endorsement of updated
ASME/ANS PRA standards less than one year prior to 4
year update, need to meet
10 CFR 50.71:(h)(1) No later than the scheduled date for initial loading of fuel, each holder of a combined license under subpart C of 10 CFR part 52 shall develop a level 1 and a level 2
Fuel Loading
endorsement of Level 2 and LPSD ASME/ANS
PRA standards one year prior to fuel load, need to
meet RG 1.200 Rev 3 PRA to be updated (completed) every 4 years from date of fuel loading
RG 1.200, Rev 3p pprobabilistic risk assessment (PRA). The PRA must cover those initiating events and modes for which NRC-endorsed consensus standards on PRA exist one year prior to the scheduled date for initial loading of fuel.
RG 1.200, Rev 3, NRC endorsement of Level 2 and
LPSD ASME/ANS PRA standards less than one year prior to fuel loading need to
RG 1.200, Rev 4, NRC endorsement of updated
ASME/ANS PRA standards one year prior
(2) Each holder of a combined license shall maintain and upgrade the PRA required by paragraph (h)(1) of this section. The upgraded PRA must cover initiating events and modes of operation contained in NRC-endorsed consensus standards on PRA in effect one year prior to each required
prior to fuel loading, need to meet RG 1.200, Rev 2,
ASME/ANS RA-Sa-2009
standards one year prior to 4 year updateupgrade. The PRA must be upgraded every
four years until the permanent cessation of operations under § 52.110(a) of this chapter.
Wrap-upp p
• Maintain continual dialogue with ASME/ANS gand other stakeholders
• NRC would expect updates (at bi-annual i i )committee meetings):
– Schedule/status of pilots and issuance of standards for use
– Insights from the pilots• Staff working on communication plan to keep
stakeholders informed; e gstakeholders informed; e.g.,– Website– Public meetings– Public meetings
14
PurposePurpose
• Discuss reasons for evaluating multi-Discuss reasons for evaluating multimodule risk
• Discuss the process the staff used to• Discuss the process the staff used to develop multi-module risk criteriaDi d l ti it i f• Discuss proposed evaluation criteria for multi-module risk
06/26/2014 16
The WhyThe Why
• Understand risk insights of the multi-Understand risk insights of the multimodule designs
• For completeness making sure the staff• For completeness - making sure the staff has looked at the full pictureP id id t ll d l• Provide guidance to small, modular reactor (SMR) applicants
• To ensure there’s no undue risk to the public health and safety
06/26/2014 17
Working Group MembersWorking Group Members
• Working group members included staffWorking group members included staff from:
Office of New Reactors (NRO)– Office of New Reactors (NRO) • Division of Safety Systems and Risk Assessment
(DSRA)( )• Division of Site Safety and Environmental Analysis
(DSEA)Di i i f Ad d R d R l ki• Division of Advanced Reactors and Rulemaking (DARR)
– Office of Nuclear Reactor Regulation (NRR)– Office of Nuclear Reactor Regulation (NRR)– Office of Nuclear Regulatory Research (RES)
06/26/2014 18
Working Group ActivitiesWorking Group Activities• Two phasesp
– Phase 1: Determined high-level parameters for guidance
– Phase 2: Developed detailed guidancep g• Held 9 working group meetings (Phase 1)• Held four half-day workshops to develop
evaluation criteria for multi module risk (Phase 2)evaluation criteria for multi-module risk (Phase 2)• Broadly discussed group’s activities at:
– ASME/ANS Joint Standards Meeting (09/13 and g (02/14)
– International Topical Meeting on Probabilistic Safety Assessment and Analysis (09/13)
– Regulatory Information Conference (03/14)06/26/2014 19
A brief historyA brief history…
• Currently we only look at Level 1 andCurrently, we only look at Level 1 and Level 2 PRAs for single units for new reactorsreactors– Current PRA Standard (ASME/ANS RA-Sa-
2009) requires that multi-unit sites with2009) requires that multi unit sites with shared systems include multi-unit site initiators that may impact the model
– Also requires multi-unit sites to include multi-unit fire and flood areas, if necessary
06/26/2014 20
Multi-Module ≠ Multi-UnitMulti Module ≠ Multi Unit
Multi Module Multi UnitMulti-Module• Designed to be built and
operated as multiples
Multi-Unit• Designed and built as
semi-independent unitsp p• Closer proximity• Multiple modules
t d b i l
• Operator is only operating a single unit
• Explicit Commissionoperated by a single licensed operator
• No explicit Commission
Explicit Commission direction to not require consideration of multi-unit riskNo explicit Commission
Policy on riskrisk
• Current RES Level 3 PRA project
06/26/2014 21
Reference plantReference plant
Module Module 1 2
Module 33
06/26/2014 22
Module 1 Risk – New ReactorsModule 1 Risk New Reactors
Module Module 1 2
Module 33
06/26/2014 23
Module 2 Risk – New ReactorsModule 2 Risk New Reactors
Module Module 1 2
Module 33
06/26/2014 24
Module 3 Risk – New ReactorsModule 3 Risk New Reactors
Module Module 1 2
Module 33
06/26/2014 25
3 Levels of PRA3 Levels of PRA
Level 1 (Core Damage Frequency - CDF)
Level 2 (Large Release Frequency - LRF)L l 3 (D tLevel 3 (Dose to the public)
06/26/2014 26
New ReactorsNew Reactors
Level 1 (CDF)
Level 2 (LRF)
Level 3
06/26/2014 27
The WhyThe Why
• Understand risk insights of the multi-Understand risk insights of the multimodule designs
• For completeness making sure the• For completeness - making sure the staff has looked at the full pictureP id id t ll d l• Provide guidance to small, modular reactor (SMR) applicants
• To ensure there’s no undue risk to the public health and safety
06/26/2014 28
Multi-Module RiskMulti Module Risk
Module Module 1 2
Module 33
04/01/2014 29
Working Group Process (Phase 1)
• Started with a blank slateStarted with a blank slate• Researched history of multi-unit risk policy
and agency activitiesand agency activities• Considered ALL options, including:
– Quantitative criteria for multi-module riskQuantitative criteria for multi module risk– Qualitative criteria for multi-module risk– Using the Quantitative Health ObjectivesUsing the Quantitative Health Objectives– Frequency-consequence curves– Developing a new radiological release metricp g g
06/26/2014 30
Working Group Process (Phase 1)
• Started with a blank slateStarted with a blank slate• Researched history of multi-unit risk policy
and agency activitiesg y• Considered ALL options, including:
– Quantitative criteria for multi-module risk–Qualitative criteria for multi-module
risk– Using the Quantitative Health Objectives– Frequency-consequence curves– Developing a new radiological release metric
06/26/2014 31
Parameters for Guidance(Transition from Phase 1 to Phase(Transition from Phase 1 to Phase
2)• Guidelines for development:Guidelines for development:
– traditional risk metrics (CDF and LRF) for a single module
– and new qualitative criteria for evaluating the risk from accidents involving multiple modulesmodules
• ConsiderationsB i t t ith hi h l l C i i– Be consistent with high-level Commission objectives
• Focus on Level 1 and Level 2 PRA results (i.e.,Focus on Level 1 and Level 2 PRA results (i.e., core damage frequency and large release frequency)06/26/2014 32
Working Group Process (Phase 2)
• Brainstormed OptionsBrainstormed Options• Identified the purpose, pros, and cons of
each optionseach options– Wanted to have pieces for prevention and
mitigationmitigation• Culled the brainstorm list• Evaluated the remaining options to
develop criteria
06/26/2014 33
Example OptionExample OptionProposed Criteria Purpose Pros Cons Comments
H l i N d t d fiHelps in design-basis accident
Need to define credible; need to define risk;
More of a qualitative review;
Demonstrate that the risk of Preventio
n of multi-
(DBA) space (event classification
;credible is used for DBAs; how it is done
e review; if credible is used in
multi-module accidents is not credible
n of multi-module accidents
classification); could be qualitative i th t
how it is done is up in the air; does not
id h
DBA, it may makenot credible piece that
focuses on means of
provide much additional guidance to
make more (or less) senseprevention
gapplicants sense
06/26/2014 34
Proposed CriteriaProposed CriteriaFor small, modular integral pressurized water reactor designs, the staff reviews the results and description of the applicant’s risk assessmentreviews the results and description of the applicant s risk assessment for a single reactor module; and, if the applicant is seeking approval of an application for a plant containing multiple modules, the staff reviews the applicant’s assessment of risk from accidents that could affect multiple modules* to ensure appropriate treatment of important insightsmultiple modules* to ensure appropriate treatment of important insights related to multi-module design and operation. [*Current wording in SRP 19.0, draft Rev. 3, the text below would be an addition.]The staff will verify that the applicant has:i. Used a systematic process to identify accident sequences,
including significant human errors, that lead to multiple module core damages or large releases and described them in the application pp
ii. Selected alternative features, operational strategies, and design options to prevent these sequences from occurring and demonstrated that these accident sequences are insignificant contributors to risk These operational strategies should alsocontributors to risk. These operational strategies should also provide reasonable assurance that there is sufficient ability to mitigate multiple core damages accidents.
06/26/2014 35
Next StepsNext StepsTask TimeframePublic Meeting June 26, 2014
Issue draft for comment August 2014August 2014
Public comment period* September 2014
Issue final for comment* October 2014
*Dates subject to change.
06/26/2014 36
AcronymsAcronyms• ANS – American Nuclear Society• CDF – core damage frequency• DARR – Division of Advanced Reactor Rulemaking• DBA – design basis accident• DBA – design basis accident• DSEA – Division of Site Safety and Environmental
AnalysisDSRA Di i i f S f t S t d Ri k• DSRA – Division of Safety Systems and Risk Assessment
• LRF – large release frequency• NRO – Office of New Reactors • NRR – Office of Nuclear Reactor Regulation• PRA – probabilistic risk assessmentPRA probabilistic risk assessment• RES – Office of Nuclear Regulatory Research06/26/2014 37
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