Design Bases From 1957 to 2003 June 18, 2007 Chuck Casto Region II NRC

HISTORY OF DESIGN BASES Atomic Energy Act of 1954 –(1957 Thru 1962) Section 182 Technical Specifications are part of license Implemented in 10CFR50.34 & Hazards Summary Report –Safety Analysis Report

HISTORY OF DESIGN BASES (cont’d) Two approaches for Tech Specs –Vallecitos –Include entire Hazard Summary Report –Yankee Atomic – TS culled from Hazard Summary Report Section 189 – Mandatory hearing for issuance of license or license amendment

HISTORY OF DESIGN BASES (cont’d) Results were unworkable –Diminishing return – Mandatory Hearing –Need recognized for discriminating significant and insignificant changes The Vallecitos Decision (1960) –Concept of Unreviewed Safety Question (10CFR50.59) –No significant hazards consideration (10CFR50.92)

HISTORY OF DESIGN BASES (cont’d) Regulations to manage changes –10CFR50.59 –10CFR50.91 –10CFR50.92

Early History of “ Clarifies” the extent which the licensee may make changes, conduct tests & experiments not specifically provided in the license Changes: –1. Explicit license authority –2. Credible probability by possibility –3. Licensee can conduct test & experiments in HAR approved by NRC April 8, 1961 (AEC) NRC issues proposed Rule June 9, issued

Early History of Changed reference to Safety Analysis Report from HAR (HSR) Tech Specs could serve purpose with less content. The PSAR & SAR explicitly specified and Bases for TS were required Final Rule change brought in –1. Consideration of “malfunctions” –2. Inclusions of the “margin of safety” as defined in the bases for any TS 1966 August 16, 1986 Proposed Rule change December 17, 1988 Rule Revised

Public Impact of 50.59

Historical Definitions and Assumptions No undue risk to health safety No unreviewed safety questions remain Licensee’s have freedom to control the plant Drew a line across which the licensee could not step without NRC approval Permitted the license to determine if line crossed

Historical Definitions and Assumptions (cont’d) Consequences equal dose 50.2 defines design basis as..”That information which identifies the specific functions to be performed by a SSC of a facility, and the specific values or ranges of values chosen for controlling parameters as reference bounds for design.”

Historical Definitions and Assumptions (cont’d) Experiment – an operation carried out under controlled conditions in order to discover an unknown effect. Test – the procedure of submitting a statement to such conditions or operations as will lead to its proof or disproof to its acceptance or rejection.

Historical Definitions and Assumptions (cont’d) Malfunction – Failure, breakdown, or inaccurate operation. In 50.59, the term malfunction is more component or equipment oriented, e.g., single failure. Margin of safety – the difference between the acceptable limit and the design failure point.

Historical Definitions and Assumptions (cont’d) Unreviewed safety question – If the probability of occurrence or consequences of an accident or malfunction or equipment important to safety previously evaluated in the SAR may be increased; or If a possibility for an accident of malfunction of a different type than any evaluated previously in the SAR may be created; or

Historical Definitions and Assumptions (cont’d) USQ (cont’d) If the margin of safety as defined in the basis for any TS is reduced. –Seven questions were used to determine if a change was a USQ –USQ did not mean unsafe

Regulatory Significance of the FSAR Tech Specs are incorporated into the license (50.36) –Commission approval to change (50.90/91) Descriptive information –Controlled under Descriptive information not controlled under –Subject to 50.9

History of Design Basis Configuration Davis Besse incident NUMARC NUREG 1327 Assessment of DBR 1990 FSAR update Rule GL Commission Policy Statement 1992 Regulatory Review Group

History of Design Basis Configuration (cont’d) 1993/1995 National Performance Review August 1995 plant events July 1996 Commission Policy on Voluntary Industry Initiatives Risk Informed Regulation Special Treatment

Design Bases Interpretation Appendix B of NEI proves guidance for interpreting 10 CFR 50.2 design bases Commission endorsement through RG CFR 50.2 design bases includes: –Design bases functions –Design bases values

Design Bases Functions SSC functions required by, or otherwise necessary to comply with, regulations, license conditions, tech specs or orders; or SSC functions credited in licensee safety analyses to meet NRC requirements

Design Bases Values Design bases values: –Values or ranges of values of controlling parameters established as reference bounds for design to meet design bases functional requirements Established by NRC requirement Derived from or confirmed by safety analyses Chosen by licensees from an applicable code, standard, guidance document

Why are these definitions important? Common understanding of 10 CFR 50.2 “design bases” supports: –UFSAR updates –10 CFR implementation –Proper characterization of design discrepancies

Simplified Relationship

10 CFR Establishes criteria for making changes to the licensing/design bases Guideline for implementation NEI Endorsement of NEI through RG 1.187

10 CFR Objectives of guidelines: –Update existing guidance and provide guidance on new provisions –Provide guidance on when to apply processes other than 10CFR50.59 –Promote more consistent, effective implementation

10 CFR Final Rule changes: –Eliminated “zero standard” –Established “minimal” standard –Enhanced screening process –Replaced problematic “margin of safety” –Clarified role of overlapping requirements –Affirmed purpose as a “regulatory threshold” No more “unreviewed safety questions”

10 CFR Key changes in implementation: –Broad scope of “design functions” as used in “change” definition –Only adverse changes “screen in” Determination based on effects on design functions Change is not adverse if effects are within the bounds of existing safety analysis

10 CFR –Always consider adverse and screen in: Any change to barrier design basis limits Fundamental changes in how required functions are performed (e.g., manual vs. automatic action) –Other clarifications: Applicability of MR(a)(4) to installation and post- mod testing of plant changes Minimal increase in malfunction in likelihood Use of alternative methodologies

10 CFR –Control of maintenance procedures –Definition of “design functions” –Consideration of human factors –Analog-digital upgrades

UFSAR Updates 10CFR50.71e RG 1.181, Sept 1999, endorses NEI UFSAR updates must reflect: –New Commission Requirements –Effects on USFAR info of: Changes made to facility and procedures Evaluations in support of changes Requested analysis of new safety issues

UFSAR Updates

Commitment Management RIS endorses NEI 99-04, Guideline for Managing NRC Commitment changes

Licensing Basis Today!!! Hierarchical approach to licensing basis –Obligations – legally binding requirements imposed by rule, reg, order and licenses. –Mandated documents – documents for which the NRC has established required content, e.g, UFSAR, security, EP, QA plans. –Regulatory Commitments – explicit statements agreed to and submitted on the docket.

Configuration Control Insights Great job! <5% of NRC findings CC all green Big hitters: –Human Performance (~20%) –Failure to follow procedures (~20%) –Decision making (~20%) –Outside design basis (~15%) –Less than adequate procedures (~10%) –Tagging (~8%)

Design Control Insights ~13% of NRC findings related to DC –Design control (~30%) –Awareness of criteria (~22%) –Calculation error (~15%) –Configuration control (~15%) –Corrective action (~6%) –Other (Op Evals, FSAR, OE, vendor, materials) ~(12%)

Human Performance in Industry January 2005 – Present Reference NRC Human Factors Information System Human Performance Cause Codes in LER’s & Inspection Reports –“Work Practices” –Problem identification & resolution –Procedures

Human Performance in Engineering January 2005 – Present Reference NRC Human Factors Information System Human Performance Cause Codes in LER’s & Inspection Reports –Work Practices 20% Design work –Skill –Non-conservative decisions –Implementation of action less than adequate –PI&R 18% Problem Identification Problem Resolution Problem Evaluation

Human Performance in Engineering January 2005 – Present Reference NRC Human Factors Information System Human Performance Cause Codes in LER’s & Inspection Reports –Procedures 16% Design Content of procedures Maintenance/surveillance

Questions????