ML20044E079
| ML20044E079 | |
| Person / Time | |
|---|---|
| Issue date: | 05/05/1993 |
| From: | Markisohn N Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| PROJECT-669A NUDOCS 9305210248 | |
| Download: ML20044E079 (15) | |
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k UNITED STATES j
,j NUCLEAR REGULATORY COMMISSION
'f WASHINGTON. D.C. 205664001
\\..... p' May 5,1993 Project No. 669 l
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APPLICANT: Electric Power Research Institute (EPRI) 1 l
PROJECT:
Advanced. Light Water Keactors (ALWRs) 1
SUBJECT:
SUMMARY
OF MEETING BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION.
(NRC) STAFF MEMBERS AND REPRESENTATIVES OF EPRI (APRIL 15,1993)
On Thursday April 15,1993, staff members from the NRC, Office of _ Nuclear Reactor Regulation, met with EPRI' representatives in Rockville, Maryland. The f
purpose of the meeting was to discuss the process for the regulatory treatment of non-safety systems (RTHSS) in passive advanced light-water reactor designs.
. is a list of meeting attendees, and Enclosure 2 is a copy of the-material presented by NRC staff.. Enclosure 3 is a copy of the material provided by EPRI.
The NRC is preparing a final safety evaluation report (FSER) of EPRI's Utility Requirements Document for passive plant designs. Satisfactory. resolution of the RTNSS issue is the key to closing approximately 80 open issues.for the FSER. NRP senior managers and members of the ALWR Steering _ Committee had met on January 22, 1993, in Palo Alto, California, to discuss several different
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policy and technical issues, with the RTNSS being the primary topic of discussion. As a result of the January 22, 1993, meeting, EPRI agreed to draft a proposed process for the RTNSS. Their submittal to the NRC dated 1
February 23, 1993, outlininc the proposed process was the specific focus of l
the d;scussion on April 15,1-13.
The NRC staff reviewed the February 23, 1993, submittal prior to the meeting i
on April 15. Shortcomings that the staff found with the proposed process were discussed and are identified in Enclosure 2.
Among the areas of concern are:
- 1) complexity of the process, 2) apparent limiting of process to defense-in-i depth systems, 3) 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> design basis issue, and 4) initiating ev,ents.
Criteria and specific actions which the staff recommends for the process were thenl discussed and are also included in Enclosure 2.
EPRI representatives-l indicated that conceptually the NRC sta_ff and EPRI are close to agreement with
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regards to the RTHSS process.
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. May 5,1993 EPRI representatives and the staff agreid to meet again in Rockville in mid-Ma
~PRI agreed to submit to the NRC, at least I week prior to the May meetir revised process for RTNSS, and the NRC staff agreed to review the revision prior to the meeting.
Originals'6iiKMv7 Nancy M. Markisohn, Project Engineer Standardization Project Directorate Associate Directorate for Advanced Reactors and License Renewal Office of Nuclear Reactor Regulation Enciosures:
1.
List of Attendees 2.
Materials presented by the NRC 3.
Materials provided by EPRI cc w/ enclosures:
See next page DISTRIBUTION w/ enclosures:
Central File PDST R/F DCrutchfield PShea PDR EJordan, MNBB3701 DISTRIBUTION: w/o enclosures:
IMurley/FMiraglia,12G18 RBorchardt GGrant, ED0 AThadani, 8E2 GBagchi, 7H15 TEssig NMarkisohn JHWilson MMalloy TBr>yce JMoore, 15B18 AEBassioni, MRubin, 8E23 JLazevnick, 7E4 TPolich, 10A19 DDiec, 8E23 YHsii, 8E23 RCorreia, 10A19 RJones, 8D)
SBajwa, 12G18 ACRS (11)
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LA:PDST:ADAR PE:PDST:ADAR NAME:
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05///93 05/[93 DATE:
0FFICIAL RECORD COPY: MTGSM415.NM l
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ALWR Utility Steering Committee EPRI I
Project No. 669 l
cc:
Mr. E. E. Kintner i
l Chairman Utility Steering Committee i
L Bradley Hill Road l
Post Office Box 682 i
Norwich, Vermont 05055 l
Mr. John Trotter.
Nuclear Power Division i
Electric Power Research Institute i
Post Office Box 10412 Palo Alto, California 94303 l
1 Mr. Brian A. McIntyre, Manager Advanced Plant Safety & Licensing i
Westinghouse Electric Corporation Energy Systems Business Unit Post Office Box 355 i
Pittsburgh, Pennsylvania 15230
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i Mr. Joseph Quirk
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GE Nuclear Energy i
Mail Code 782 General Electric Company 175 Curtner Avenue San Jose, California 95125 i
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l Mr. Stan Ritterbusch Combustion Engineering 1000 Prospect Hill Road i
Post Office Box 500 Windsor, Connecticut 06095 Mr. Sterling Franks U. S. Department of Er,ergy NE-42 Washington, D.C.
20585 Mr. Steve Goldberg Budget Examiner 725 17th Street, N.W.
Room 8002-Washington, D.C.
20503 l
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NRC/EPRI MEETING TO DISCUSS RTNSS APRIL 15, 1993 NAME AFFILIATION Adel El-Bassioni NRR/DSSA/SPSB Mark Rubin NRR/DSA/SRXB Jack DeVine EPRI Ed Rumble EPRI Jean-Pierre Berger EPRI Ashok Thadani NRR/DSSA Jim Lazevnick NRR/EELB Stephen Additon TENERA/ARSAP Jack Wheeler DOE Jim Wilson NRR/PDST John Trotter EPRI Bill Borchardt NRR/PDST/ADAR Melinda Malloy NRR/PDST/ADAR Tim Polich NRR/DRIL/RPEB David T. Diec NRR/DSA Tom Essig NRR/PDST/ADAR Y Gene Hsii NRR/DSSA/SRXB Bob Youngblood BNL Rich Correia NRR/DRIL/RPEB Ron Vijok WESTINGHOUSE Andrea Sterdis WESTINGHOUSE Terry Schulz WESTINGHOUSE Doug Mcdonald GE Brian McIntyre WESTINGHOUSE Nancy Markisohn NRR/PDST/ADAR Goutam Bagchi NRR Robert Jones NRR/SRXB Sterling Franks DOE l
Tom Boyce NRR/PDST/ADAR Enclosure I l
REGULATORY TREATMENT OF NONSAFET,Y SYSTEMS 4
By Mark Rubin Reactor Systems Branch Division of Systems Safety and Analysis i
l April 15,1993
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- 4. If nonsafety systems are relied on to meet the R/A missions, then design requirements commensurate with risk significance will be imposed on those elements involved.
- 5. NRC will not include any R/A missions in Design Certification Rule. Would include deterministic. requirements on both safety and nonsafety design features in DC rule.
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SHORTCOMINGS OF EPRI'S PROCESS
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2.
EPRI claims the RTNSS issue is limited to DID systems.
Other risk-significant nonsafety SSCs are not included in the evaluation.
This may exclude careful evaluation of less stringent requirement for ALWR off-site power systems.
3.
EPRI process is not consistent with NRC/EPRI agreement to remove nonsafety SSCs from PRA modelif no credit is taken.
The Focused PRA is constructed by removing DID systems after initiating events with IE frequencies not changed. Though the l
EPRI process will define the DID availability missions important l
for preventing IEs, it may miss some event sequences, e.g., RCS j
leakage with CVCS failure.
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NRC STAFF PROPOSED PROCESS HIGH LEVEL CRITERIA TO BE COMPLIED WITH:
1.
Deterministic performance requirements, e.g.,10 CFR 50.62, GDC 19.
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Commission's Safety Goal Guidelines: CDF 1.0E-4/yr, LRF 1.0E-6/yr.
3.
Containment performance goal, including containment bypass,
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4.
No significant adverse systems interactions.
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Consideration of all modes of operations, including shutdown.
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Selection of important nonsafety systems.
Determine any combination of nonsafety SSCs necessary to meet NRC regulations, safety goals and containment performance goal objectives.
5.
Nonsafety system R/A missions.
l identify nonsafety systems functional reliability and availability performance goals. Steps 4 and 5 should be iterated to optimize nonsafety SSCs R/A missions.
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Regulatory oversight evaluation.
1 NRC staff review vendor submittals, and develop regulatory requirements for risk significant SSCs.
7.
NRCNendor interactions to determine proper level of regulatory oversight.
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i KEYISSUES i
o Timing of implementation / Licensing Review Avoiding late surprises o
Scope of RTNSS Process Post-72 hours External events (including seismic)
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Containment Performance (>24 hours) s Diverse I & C Adverse systems interaction o
Use of PRA vs. Deterministic Methods o
Initiating Events Consideration of nonsafety systems PRA methods i
o Mitigation of Initiating Event Consequences Consideration of nonsafety systems o
Operational Regulatory Oversight Measures
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Tech. Specs, 0-RAP, Administrative Controls o
Defensible Reliability Numbers for Passive System.
Components How conservative?
o Quantitative Reliability Goals Nonsafety/D-I-D systems TLS - 4/14/93
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2 NRC Response to ALWR Program Process for Resolution of the RTNSS Issue ALWR Staff Preliminary Commets (after a few days review of the document)
General Ceraments
- ALWR positions and contentions j
- Scope - role of the RTNSS process in the overall licensing process f
- Timing of NRC input ability to manage design process to desired i
outcome
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Process Comments
- Approach to comptying with high level criteria
- Consideration of nonsafety systems versus DID systems I
Questions of clarification to the i4RC staff Specific Comments on Wording Advanced LWR Program i
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EPRL'NRC l
RTNSS Issue (cont)
ALWR Positions and Contentions Nonsafety systems centribute to ofant safety and are subiect to repu!atory oversicht Major purposes for nonsa'ety systems
- Complement safety systems to meet owner / investor requirements for very high safety 1
- Provide economic benefit and improved flexibility in plant operation The ALWR Program is committed to maintaining high performance standards for both safety and nonsafety' systems with appropriate regulatory oversight
- The ALWR Reliability Assurance Program provides high confidence to owner and regulator of nonsafety system reliability.
Advanced LWR Program
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RTNSS issue ALWR Positions and Contentions (cont)
From a total safety oatsoective. the intent is to make oassive otants simoter. more accident resistant and safer j
The ALWR Program is not avoiding any safety and licensing issues concerning passive plants The ALWR Program believes in a comprehensive and integrated l
design approach as indicated by the ALWR URD j
The comment that the ALWR RTNSS process excludes severalissues that need to be factored in is caused by a difference in approach io
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defining which process is used for each aspect of the RTNSS issue s
Severalissues unique!y associated with passive designs are important but resolvable in the existing safety and fconsing framework k
Advanced LWR Program j
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EPRL'NRC i
RTNSSissue J
ALWR Positions and Contentions (cont) 7 P
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Passive Safety Systems and the Safety Goa' Guide!!ner i
ALWRs address the Commission's Safety Goat Policy Statement by confirming that a probabilis'c risk assessment (PRA) sensitivity study, assuming no cre fit for nonsafety j
defense-in-depth systems after trip signal meets this goal
(<1.0E-4 per plant-year CDF,large release <1.0E-6 per p! ant-year)
- Advanced LWR Program
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LDB Evaluation Approach Safety Margin Basis Evaluation Approach Conservative. Established Best-Estimate Design Methods (except for a Evaluations of Design Margin small number of multiple and Safety Margin Basis failure events)
Features NRC Approved Codes. Standards.
Utility Specified Margin and and Acceptance Criteria Acceptance Criteria Credit for Safety-Related Equip-Credit for Bot.h Safety-Related ment Only (except for transients and Non Safety-Related and multiple failure events)
Equipment Deterministic Ucensing Deterministic Severe Accident-Evaluations Supplemented by )
Analyses of LDB Events t
PRA (IE-5 CDF. IE-6. 25 REM Meet Code of Federal Regulations and NRC
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Meet NRC Severe Accident i
Regulatory Guidance and Safety Goal Policy Statements
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i Containment and Containment Performance Millgation Associated Systems During Severe Accident
-LOCA Design Basis
-Margin Beyond LOCA
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-PRA Based Source Term ti Term Safety Systems to meet Safety System Features for Regulatory Requirements investment Protection 1
Core Damage
-Ucensing Specified Accid-
-Realistic Accident Se-Prevention ents (Mainly Single Failures) quences (Multiple Failures)
-Prevent Exceeding Regula-
-Additional Margin to -
tory Fuel Limits Fuel Damage Greatly improved MMIS Accident Regulatory Imposed Margin increased Margin l
Resistance In-Service Inspection and Simplicity t
Testing Improved Human Factors RCS Integrity System and Component Rell-a bility LICENSING DESIGN SAFETY MARGIN BASIS (SMB)
BASIS (LDB) (Design (Provide additional margin to meet Code of Fed-and features beyond Code eral Regulations) of Federal Regulations)
Figure 5.1-4 ALWR SAFETY FOUNDATION Page 5.1-10
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RTNSS Issue (cont)
Scope i
Rote of RTNSS in the overa!i reensino orocess i
Staff view: RTNSS process should be an enveloping one including
- fluid systems (centralRTNSS issue) f
- other passive plant issues
- other issues not unique to passive designs I
ALWR Program view: RTNSS process supplements others already in
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place, its sco@ should be limited to those issues unique to passive designs and not covered by existing processes
- existing licensing design basis and safety margin basis provide i
comprehensive foundation for licensing all aspects of the passive design that are similar to evolutionary designs
- RTNSS process addresses unique aspects of passive designs not amenable to resolution by existing processes Advanced LWR Program i
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EPRLMRC RTNSS issue (cont)
Timing of NRC input RTNSS issue resolution is part of an iterative design process i
All stakeholders need timely understanding of the expected outcome and impfcations of the RTNSS process during the design process and as I
early as possible l
- Ability to modify designs and design processes to achieve safety objectives in the most appropriate manner Need NRC staff input during the process to determine the expected J
outcome of the RTNSS process l
Advanced LWR Program
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EPRLHRC RTNSS issue (cont)
Process Comments Consideration of nonsafety versus DID systems i
- DID systems include support required to fulfill DID functions l
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- Baseline PRA will expose risk significant nonsafety systems
- Existing regulations address specific nonsafety systems
- RTNSS issue addresses unique aspects of passive design i
- DID systems are removed from the focused PRA event trees because l
they are the systems that can backup the passive safety systems ALWR approach to complying with high level criteria j
- Regulatory treatment of SSCs important during normal operation to initiating event frequencies
- Initiating event frequencies same as th Baseline PRA Advanced LWR Program f
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