ML20202D234
| ML20202D234 | |
| Person / Time | |
|---|---|
| Issue date: | 11/25/1997 |
| From: | Collins S NRC (Affiliation Not Assigned) |
| To: | Ralph Beedle NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT & |
| References | |
| PROJECT-689 NUDOCS 9712040202 | |
| Download: ML20202D234 (4) | |
Text
Novembhr 25, 1997 Mr. Ralph E. Beedle_-
Senior Vice President ;
and Chief Nuclear Officer Nuclear Generation -
Nuclear Energy institute Suite 400 -
1776 i Street, NW Washington, DC 20006-3708
Dear Mr. Beedle:
I am respondi.ig to the letter you sent to L. Joseph Callan on October 8,1997, that forwarded a copy of the Ni. clear Energy Institute's (NEl's)" Design Bases Program Guidelines," NEl 97-04.
I agree th:t be issue of the interpretation of design bases information is an important issue. As you are aware, it is one of the issues discussed in SECY 97-205, " Integration and Evaluation of Results From Recent Lessons-Learned Reviews," currently before the Commission.
- in order for my staff to fully understand the changer i 7 7ur document, I agree that a meeting with your staff would be beneficial. A meeting with R. an this subject will be scheduled in the near future. The staff's contact for design-bases issues is Jack Roe; he can be reached at 301-415-1199.
Sincerely, Brian W. Sheron for/
Samuel J. Collins, Director Office of Nuclear Reactor Regulation Project No. 689 Project No. 689 DISTRIBUTION: \
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%,...../ November 25, 1997 Mr. Ralph E. Beedle Senior Vice President and Chief Nuclear Officer Nuclear Generation Nuclear Energy Institute Suite 400 1776 i Street, NW Washington, DC 20006-3708
Dear Mr. Beedle:
I am responding to the letter you sent to L. Joseph Callan on October 8,1997, that forwarded a copy of the Nuclear Energy Institute's (NEl's)" Design Bases Program Guidelinos," NEl 97-04.
I agree that the issue of the interpretation of design-bases information is an important issue. As you are aware, it is one of the issues discussed in SECY-97-205, " Integration and Evaluation of Results From Recent Lessons-Leamed Reviews," currently before the Commission.
In order for my staff to fully understand the changas to your document, I agree that a meeting with your staff would be beneficial. A meeting with NEl on this subject will be scheduled in the near future. The staffs contact for design-bases issues is Jack Roe; he can be reached at 301-415-1199.
Sincerely, jdd4< JfA.
Samuel J. Collins, Director Office of Nuclear Reactor Regulation Project No. 689 l
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EDO Principal Correspondence Control FROM DUE: 11/17/97 EDO CONTROL: G970770 DOC DT: 10/08/97 FINAL REPLY:
Ralph E. Beedle Nuclear Energy Institute (NEI)
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Callan, EDO FOR SIGNATURE OF : ** GRN ** CRC NO:
Callen,-EDO~ foO>mA DESC: ROUTING:
INTERPRETATION OF DESIGN BASES INFORMATION Callan Thadani Thompson Norry Blaha Burns DATE: 10/31/97 Knapp, RES ASSIGNED TO: CONTACT:
NRR Collins SPECIAL INSTRUCTIONS OR REMARKS:
TAC 'to, M99902 MRP RECEIVED: MOVEMBER 3, 1997 NPR ACTIO*I: DRDP: ROE MRR 00llTIMr: COLLINS HIRAr,LI A ZIMMERMAN
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,~C...O.~....,0N October 8,1997 Mr. L. Joseph Callan Wd Off. ECO Executive Director for Operations ef, 10 31 ffi U. S. Nuclear Regulatory Commission ,"
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Washington, DC 20555-0001
Dear Mr. Callan:
In 1990, the nuclear industry developed NUMARC 9012, Design Bases Program ,
Guidelines, to assist utilities with the organization and collation of design bases information and supporting design information. In 1992, the guidelines were acknowledged in the Commission's Policy Statement, Availability and Adequacy of Design Bases Information at Nuclear Power Plants, as providing "... the rationale for the design bases consistent with the definition of design bases contained in 10 CFR 50.2."
The interpretation of what constitutes design bases information is a key aspect of licensee activities associated with operability and reportability determinations. The NUMARC guidelines, the Commission's Policy Statement, the applicable regulations (10 CFR 50.72 and 50.73) and regulatory guidance (Generic Letter 91-18, NUREG 1022, and NUREG-1397) have provided a stable framework for these activities.
! In recent correspondence from Mr. Ashok Thadani to Niagara Mohawk Power Corporation, a broader interpretation of design bases information is stated that is ;
I not consistent with the existing framework. The September 12,1997 letter concludes that "... the design bases include any information that was used to l
! determine the acceptability of the nuclear power plant design." While this letter addressed a plant-specific reportability issue, our concern is with the implications for future operability and reportability determinations industrywide.
l The industry and NRC guidance cited above make a clear distinction between l
design values and design bases information (reference bounds for design). Failing L
to distinguish between these terms could lead to inappropriate operability i determinations causing plant shutdowns that unnecessarily challenge plant systems and personnel. Similarly, confusion of these terms would increase the reporting burden on licensees and the review burden cn NRC. Because senior shift l
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z .3 e Mr. L. Joseph C:lkn October 8,1997 Page 2 personnel must be personally involved in the reporting process, their focus would be diverted from safe operation to filing one hour reports under 10 CFR 50.72.
Equally significant is the effort that must be expended in preparing and reviewing the Licensee Event Reports.
The interpretation of design bases information in accordance with 'O CFR 50.2 is clearly a generic matter. The industry has revised NUMARC 9012 to further clarify this issue. Enclosed for your information is the new document, NEI 97-04, which provides additional examples of design bases information and directly addresses the reportability of conditions outside the design basis of the plant. We believe these revised guidelines provide a context to resolve this issue.
We would like to discuss this matter with you and your staffin the near future. We believe that timely resolution would avoid unnecessary and adverse impacts on both licensees and the NRC.
Sincerely, 6 e >
Ralph E7Beedle ARP/
Enclosure c: Mr. A. Thadani, NRC/0EDO Mr. S. Collins, NRC/NRR l
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.3 L NEI 97-04 September 1997
. ACKNOWLEDGEMENTS This document, Design Bases Program Guidelines, NEI 97-04, was developed with the assistance of the NEI Task Force on Design Bases. It is a revision to NUMARC 9012 that was originally developed by the NUMARC Design Bases Working Group in 1990. NEI wishes to acknowledge the extensive review and comment by these and other industry members who shaped the final form of this document.
NOTICE i ,
Neither the Nuclear Energy Institute, nor any ofits employees, members, l supporting organizations, contractors or consultants make any warranty, expressed
- i. or implied, or assume any legal responsibility for the accuracy or completeness of, or assume any liability for damages resulting from any u'se of, any information l
apparatus, method, or process disclosed in this report or that such not infringe
. privately owned rights.
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1 EXECUTIVE
SUMMARY
NEI S7 041 was issued to upds' NUMARC 9012 in response to increased industry i and Nuclear Regulatory Commission (NRC) attention on design bases information.
In 1996, NRC inspection activities re emphasized the importance of maintaining ,
design bcses information. !
1 An industry task force was formed to review the existing industry guidance (NUMARC 9012, Design Basis Program Guiaelines), and determine if there was a need for additional guidance. In May 1997, the task force made the following recommendation:
. NUMARC 90-12 remains an appropriate guideline for the collation and assessment of design bases information, yet would benefit from a number of minor clarifications and additional examples. -
NEI 97 04 implements the NEI task force recommendations.
NUMARC 9012 was initially issued in 1990 in response to events at several facilities, and from concerns raised in several NRC safety system functional inspections. The guideline was issued to NUMARC members as voluntary guidance for their use, as appropriate. In a letter to NUMARC dated November 9,1990, tha NRC staff stated:
" the NUMARC approach [NUMARC 0012] will provide a useful framework
, and worthwhile insights to those utilities undertaking design bses programs l of various scopes. We share your view that no single best approach exists for a design bases program..."
l In August 1992, the NRC issued a policy statemon; titled, Aveilability and Adequacy of Design Bases Information at Nuclear Power Plants. The policy statement recognized the guidance in NUMARC 9012, and stated:
" ..this information [NUMARC 90-12] provides the rationale for design bases consistent with the definition of design bases contained in 10 CFR 50.2.....
l l
3 NEl 97 04 is a revision to NUhMRC 9012, Design Basis P ogram Guidelines. NEl (Nuclear Energy Institute) was formed in 1994 by combining the Nuclear Resourcee Management Council (NUMARC), the nuclear activities of the Edison Electric Institute (EEI). the American Nuclear Energy Council (ANEC), and the US Council for Energy Awareness (USCEA).
I
I F These guidelines are offered to NEI members for their voluntary use as appropriate.
They are not intended to describe the only method ofimplementing a design bases program. Consistent application of the guidance in Section II Definitions,Section III - Design Bases Documents, and Section V - Addressing Discrepancies, is recommended to foster a common understanding of design bases efforts in the nuclear industry. The remaining sections provide useful'information and good practices that should benefit utility design bases programs. Members are encouraged to use the guidelines as a reference point from which to review their existing or planned efforts.
The basic premise of the guidelines is to organize and collate a nuclear power plant's design bases information consistent with the definition of design bases contained in 10 CFR 50.2. This information should be strictly focused ou the specific safety functions and values of controlling parameters that bound the design of structures, systems and components. The scope of the S 50.2 design bases information is a subset of the engineering design bases that provides the specific engineering bases for design. In addition, the guidelines promote the collation of supporting design information that provides the rationale for the design bases and a reference for the detailed design information. Together, the design bases information and supporting desiga information may serve as a valuable reference to support various plant activities, and may also enhance existing design control and configuration management practices.
l Section II. Definitions, is included to provide concise language on terminology l related to design bases. These definitions seek to simply convey the meaning of ,
i these terms and to effectively communicate each concept. They are consistent with l the definitions provided in NUREG 1397, Assessment of Design ControlPractices and Design Reconstitution Programs in the Nuclear Industry, that was published in 1991. A diagram on terminology relationships is included to illustrate how the concepts fit together.
l Section IV, Dcueloping Design Bases Documents, is devoted to lessons learned in i developing Design Bases Documents (DBDs). This section was developed using the l
experience of several utilities who have implemented programs along with l information collated by INPO through workshops md site assistance visits. This j section attempts to capture various utility practices that have proven effective in l
developing DBDs. Although initially developed in the 1990 time frame, the information remains germane for licensees that are still collating design bases and l
I supporting information in 1997. The section has been revised to provide greater emphasis on the importance of accessibility, usability and staff awareness of the design bases information. It may prove useful both to utilities in the process of implementing their design bases efforts, and those who may wish to fine tune their existing programs.
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6 J Those utilities with mature design bases programs recognize that the discrepancies identified by their efforts may pose a significant challenge.Section V, Addressing Discrepancies, is devoted to guidance on addressing discrepancies and provides a managed approach to this process. The concept of a presumption of operability is promoted that credits broad engineering experience and judgment in cases where incomplete documentation is available.
The guideline also references, and is consistent with, later publications associated with operability and reportability (NRC Generic Letter 91 18, Information to Licensecs Regarding NRC Inspection Man tal Sections on Resolution of Degraded and Nonconforming Conditions and on Operability, and NUREG 1022, Licensee Event Reporting System). Another key aspect of this section addresses reportabiFty determinations and how "c,utside the design basis of thn plant" may be interpreted.
The process described in this section may be adapted to existing utility processes that address nonconformances or may be used as a stand alone process.
Validation, maintenance and control of DBDs are important to providing a reliable basis for the application of DBDs. The validation elenient provides assurance that the design bases information is consistently reflected in the physical phut and those controlled documents used to support plant operations. Without maintenance and control of DBDs, the documents may quickly loss their value as a reference to support plant activities.
The events that resulted in a renewed focus on design bases information are predominantly linked to issues that surround the validation and control of design bases and the supporting information.Section VI, Design Bases Document Validation, Maintenance and Control, and Section VII, Integration of Design Bases Program with Configuration Management and Design Control, emphasizes key aspects of validation, maintenance and control of DBDs that should be coasidered in an overall program. Further, design bases efforts need to consider existing design control and configuration management practices in order to be successful.
By providing a foundation of design bases information and supporting design information, the design bases effort can supplement and support design control and configuration management, thereby enhancing plant operation. In regard to Configuration Management, the Institute of Nuclear Power Operations (INPO) has produced a number ofindustry good practice documents associated with configuration management to assist utilities in improving such activities.
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I l TABLE OF CONTENTS 1 Section Page L I NTR O D U C TI O N . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
II. D E FI NI TI O N S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,
III. D ESI G N BAS ES DO C UME NTS .... .... .. ... .. .. ... ... . ... .. . ............... ................ ..... .. . 10 .
IV. LESSONS LEARNED IN DEVELOPING D ESI G N BAS E S DO CUME NTS ............ ... ... . ... .. . ........ . . ........... ... ....... .. .. .. .. . ... . 14 ,
V. ADD RESSING DI S CRE PANCIES ................................................................ .. 23 VI. DESIGN BASES DOCUMENT VALIDATION, MAINTENANCE AND C O NTR O L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VII. INTEGRATION OF DESIGN BASES . ROGRAM WITH CONFIGURATION MANAGEMENT AND DESIGN CONTROL................. 36 APPENDIX A: EXAMPLES OF REFERENCES FOR DESIGN BASES I N FO RMATI O N .. . . . .. . . .. . . . . . .. . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . .. 3 APPENDIX B: EXAMPLES OF DESIGN BASES INFORMATION........................... 38 APPENDIX C: EXAMPLES OF SOURCES OF SUPPORTING DESIGN i
I NFO RMATI O N . . . . . ... . . . . . . . . . . .. . . .. . .. . . . . . . . . . . .. . .. . . . . .. . . ... ... . . . . . . .. . . . . . . .. ... . .. . . . . . 4 8 I APPENDIX D: EXAMPLES OF SUPPORTING DESIGN INFORMATION.............. 49 -
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APPENDIX E: POTENTIAL DBD APPLICATIONS ................................................... 51 APPENDIX F: OTHER TYPES OF INFORMATION TO CONSIDER FOR DBDs.... 53 iv
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[ LIST OF FIGURES Firure Page
- 1. DESIGN BASES. LICENSING BASES RELATIONSHIP ............................... 5
- 2. TE RMI NO LOGY RELATI ONS HI PS ................................. ............................... 9
- 3. DESIGN BASES DISCREPANCY, RESOLUTION PROCESS ...................... 25
- 4. DESIGN BASES DEFICIENCIES - NRC ONE HOUR REPORTING R E Q UI R E M E NTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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. ,' I. INTRODUCTION The intended purpose of these guidelines is to provide guidance for the development of a design bases program that collates design bases information and supporting design information, and is not intended to identify or recreate 'he licensing basis for a plant. It is recognized that some design bases information may be coincident with licensing basis information. The document represents one method for collating and assessing design bases information and the supporting information. The method is based on the work completed in 1990 b/ the NUMARC Design Bases Issues Working Group.
In 1988, NUMARC established the Design Basis Issues (DBI) Working Group to address the clear need to develop an approach built around the many utility design bases activities to address both industry and regulatory concerns in this important area. One of the specific goals of the DBI Working Group was to review industry experience regarding the development of design bases programs and to provide guidance that captures practices that have proven effective. Since 1988, extensive resources have been allocated by utilities towards the development of design bases programs In October 1996, the NRC issued a 10 CFR 50.54(f) request for information to utilities on the adequacy and availability of design bases information. As a result, NEI formed a task force on design bases to assess the state of existing industry guidance on design bases programs. In May 1997, the task force madt the following recommendation to the NEI Regulatory Process Working Group:
- NUMARC 9012 remaint an appropriate guideline for the collation and assessment of design bases information, yet would benefit from a number of minor clarifications and additional examples.
As a result NEI.97-04 was developed to provide further clarification. Figure 1 provides a graphical representation of the relationship between design bases, licensing bases and engineering design bases. Figure 2 provides n pictorial representation of the relationships of the various terms associated with design bases The primary focus of this document is to addrese the intent, content, development, and uses of design bases documents as they relate to the 10 CFR 50.2 definition.
Also, engineering design bases, and design bases supporting information are briefly discussed in the context of how they relate to the design bases described in 50.2.
Configuration management and design control are also discussed since they are logical outlets for the information collated by a design bases program. To effectively communicate the concepts and interpretations of the various elements of design bases, the NUMARC DBI Working Group adopted a list of definitions and relationships between the applicable terminology. To this list of definitions, the NEI task force added the definition for " engineering design bases *' as depicted in .
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NUREG 1397 to cssure consistency of terminology, cnd a d:nnition for " supporting
. design information". These are presented in Section II, Definitions.
Section III, Design Bases Documents, addresses the intent of DBDs, design bases information, supporting design information, and the objectives of DBDs. This section promotes the development of a program that collates a plant's design bases information consistent with the design bases definition contained in f 50.2 and that captures the rationale or the "why"information behind a plant's design bases. The objectives of DBDs are based on a summary of the primary applications of DBDs ,
that were identified through a nuclear industry survey. These applications are focused in the engineering and licensing areas.
Lessons learned in developing DBDs is provided in Section IV. This section focuses on the administrative aspects of design bases programs. Topics discussed include organization, re Durces, pilot efforts, user input /needs, format / content, source information search and retrieval, procedures / writer's guide, and scope / planning / scheduling. The content of this section was derived from input provided by INPO and from utilities.
The disposition of discrepancies identified during the implementation of design bases programs is discussed in Section V, Addressing Discrepancies. Guidance is provided regarding determinations of operability and repoltability along with criteria to address the prioritization of discrepancies including missing information.
Section VI discusses DBD validation, maintenance and control. Discussed are alternatives for validating information contained in DBDs, along with proper indexing and cross referencing of pertinent documents and the medium used to store, retrieve, and edit these docanents.
The events in 1996 that resulted in a renewed focus on design bases information are linked to issues that surround the validation and control of design bases and the i supporting information.Section VI, Design Bases Document Validation, l Maintenance and Control, and Section VII, Integration of Design Bases Program l with Configuration Management and Design Control, emphasize key aspects of l validation, maintenance and control of DBDs that should be considered in an overall program. Further, design bases efforts need to consider existing design control and configuration management practices in order to be successful. By ,
providing a foundation of design bases informstion and supporting design information, the design bases ef#crt can supplement and support design control and
, configuration management, thereby enhancing plant operation. In regard to l configuration management, the Institute of Nuclear Power Operations (INPO) has produced a number ofindustry good practice documents associated with configuration management to assist utilities in improving such activities.
The guidance contained in Section II - Definitions,Section III - Design Bases Documents, and Section V - Addressing Discreparcies, is intended as information that will facilitate a common understanding of design bases programs within the nuclear industry and with the regulator Consistent application of this guidance is 2
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recommended. The inform: tion contained in Scction IV . Lessons Le:rned in
,[ Developing DBDs,Section VI . DBD Validation Maintenance and Control, and I Section VII Integration of DB Programs with Configuration Management and i
Design Control captures and provides guidance on the " good practices" that have proven eficctive in the past at various utilities. This information can prove to be usefulin the development of an efficient, thorough program and should help to achieve program objectives.
BACKGROUND INFORMATION The design bases definition in 10 CFR 50.2 was added to the regulations in 1968 to codify statements used in earlier Atomic Energy Commission (AEC) guidance 2 on the content of a final safety analysis report (FSAR)3. This guidance emphasized that the FSAR should contain a section on the design bases plus other sections that provide a system description and a design evaluation concerning the preparation of safety analysis reports. The AEC guidance developed in the 1965/66 time frame called for "the identification of principal criteria for design and the design bases for those major systems and components significant to plant safety".
The AEC statements indicate that the design bases information should apply to maior structures, systems and components that are significant to safety. The AEC guide provided the following definition:
" Design Bases means that information which identifies the specific functions to be performed by a major component er system in terms of performance objectives together with specific values or range of values chosen as controlling parameters as reference bounds or limits for the design. Such limits may be restraints derived from generally accepted " state of the art" l practices for achieving functional goals (such as "no center melting" restriction placed on fuel design) or requirements derived from calculating j the effects of a situation representing an upper limit which a component or system could reach under credible circumstances (such as peak pressum loading of a containment)."
I l In reviewing the AEC documentation, it is clear that the term design bases is linked to major structures, systems, and components (SSCs) associated with the protection of public bealth and safety, Also, there is a clear relationship between the principal design criteria 4 and design bases. The principal design criteria are broad I
- AEC Draft Guide, " A Guide for the Organization and Content of Facility Description and Safety Analysis Reporta", September 1,1965: and the final AEC guide dated June 30,1966 8 This guideline refers to the final safety analysis report throughout this document. Some licensees t
use the terminology " updated final safety analysis report, UFSAR or USAR", instead of FSAR.
4The current NRC regulations at 10 C.F.R. 50.34 still require a preliminary safety analysis report to specify the principal design criteria (PDC) and to specify the relation of the design bases to the PDC.10 CFR 50.34(a)(3). The General Design Criteria (GDC) were promulgated in 1971 to establish the minimum requirements for the PDC. See 10 C.F.R.50.34(a)(3)(i) and 10 CFR Part 50, App. A. Introduction." The construction permits for some plants pre-date the GDCs, and as such, some plants may not comply with the GDCs, but wi'.h specific licensing commitments associated with draft AEC criteria.
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fund: mental objectives like the GDC. The design b:ses are the functional bounds 1
., or limits for the design within the framework of the principal or general design criteria.
The draft AEC guideline included a definition of performance objectives as being,
"[t] hose fonctional requirements established for systems and major components within the framework of the principal design criteria." Again, this emphasizes the intended relationship between the design criteria and design bases. Thus, broad criteria a:e used to establish functional requirements for the plant systems, together with any specific values chosen to control parameters as reference bounds or limits for the design, within the framework of the principal design criteria.
These major functional requirements and values chosen for design purposes that bound the design are then specified as design bases in the safety analysis report.
It is clear from the early AEC guidance that not all the information contained in the FSAR is design bases material. The 10 CFR 50.2 design bases information is a subset ofinformation contained in the FSAR submitted to the NRC in support of the licensing of the plant.. It is one of many items ofinformation contained in the FSAR, and is considered a subset of the licensing basis.
In 1990, NUMARC published NUMARC 9012, Design Basis Program Guidelines.
In February 1991, following an intense period of regulatory interactions on design bases information, the NRC published NUREG 1397, Assessment of Design Control Practices and Design Reconstitution Programs in the Nue: car Power industry. In this document the NRC included a term called the " engineering design bases", and provides the following definition:
"The entire set of design constraints that are implemented, including those that are (1) part of the current licensing bases and form the bases for the staffs safety judgment and (2) those that are not included in the current licensing bases but are implemented to achieve certain economics of operation, maintenance, procurement, installation, or construction."
The Commission in its 1992 Policy Statement on the Adequacy and Availability of Design Bases It'brmation stated:
"......[NUMARC 9012] outlines a framework to organize and collate nuclear
! power plant design bases information. This information provides the
! rationale for design bases that is consistent with the definition # design bases contained in 10 CFR 50.2......"
More recently the NRC provided clarification on the scope of design bases in footnote 4 ofits October 199610 CFR 50.54(f) request for additional information regarding the adequacy and availability of design bases information. The NRC l made the following statement relative to the design bases definition:
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"As described in 10 CFR 50.2, design bases is defined as " Design bases mean that information which identifies the specific functions to be performed by a 4
structure, system, or component of a facility, end the speciSc values and 1 range of values chosen for controlling parameters as reference bounds for the I l
design..." The design bases of a facility, as so defined,is a subset of the licensing bases and is contained in the FSAR. Information developed to l implement the design bases is contained in other documents, some of which are docketed, and some of which are retained by the licensee."
The 1996 NRC statements are consistent with previous NRC and industry statements on design bases ($ 50.2) scopc ofinformation. ,
NUREG 1022, Licensee Event Reporting System, emphasizes the Licensee Event Reporting, (LER) conditions for design bases matters are those that are associated with plant and system level design bases. These reporting conditions for design bases are linked to the bounding system and plant safety functions that are directly associated with the protection of public health and safety.
There is consistency between the early AEC guidelines, the industry guideline NUMARC 9012, the NUREG 1897 statements on the scope of applicability Lr Section 50.2 design bases information, and the NRC comments in its October 1996 Saction 50.54(f) request of design bases programs. The scope of the Section 30.2 design bases is a subset of the engineering design bases and the licensing bases (see figure 1), and is at the functional level for safety systems.
Design Bases-Ucensing Bases Relationship r
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This document (a revision to NUMARC 9012) edds additional examples and text to
., better assist licensees in identifying design bases information. It improves the lihk to the genesis of the design bases term in the regulations (AEC documentation) and -
further clarifies regulatory reportability requirements associated with design bases.
This guideline continues to provide industry guidance for the development of a design bases program that includes the collation, assessment, verification and control of design bases information. In addition, where necessary and appropriate, the document provides a methodology for determining when associated design information should be reconstituted. .
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II. DEFINITIONS
- 1. DESIGN BASES: Information that identifies the specific functions to be ,
performed by a structure, system, or component of a facility and the specific !
I values or ranges of values chosen for controlling parameters as reference bounds for design. These values may be (1) restraints derived from generally accepted
" state of the art" practices for achieving functional goals or (2) requirements
. derived fron1 analysis (based on calculations and/or experiments) of the effects of a postulated accident for which a structure, system, or compor.ent must meet its functional goals. (10CFR50.2)
- 2. ENGINEERING DESIGN BASES: The entire set of design constraints that are implemented, including those that are (1) part of the current l':ensing bases and form the bases for the staffs safety judgment and (2) those that are not included in the current licensing bases but are implemented to achieve certain economies of operation, mairstenance, procurement, installation, or construction.
- 3. SUPPORTING DESIGN INFORMATION: The rationale for the engineering design bases statements and the reference material for the detailed design that supports the design bases (drawings, analyses, safety evaluations, specifications, etc. )
- 4. DESIGN CONTROL: Measures established to assure that the information from design input and design process documents for structures, systems, and components is correctly translated into the final design.
- 5. CONFIGURATION MANAGEMENT: Integrated process of maintaining the physical plant and those controlled documents required to support plant operations consistent with selected design documents.5
- 6. DESIGN INPUT: Those criteria, parameters, bases, or other design requirements upon which the detailed final design is based. (ANSIN45.2.11)
- 7. DESIGN PROCESS: Documented design practices such as calculations, analyses, evaluations, technical review checklbts, or other documented engineering activities that substantiate the fine; design.
- 8. DESIGN OUTPUT: Documents such as drawings, specifications and other documents defining the technical requirements of structures, systems, and components. (ANSI N45.2.11) 9 FINAL DESIGN: Approved design output documents and approved changes thereto. (ANSI N45.2.11) 10.OPEN ITEMS: Those items that are discovered during the implementation of design bases prbgram activities that are potential discrepancies and require 5 INPO has published a report on configuration management in the nuclear utility industry that notes the major iMerfaces of an integrated configuration management process.
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- 11. VALIDATION: Process that provides reasonable assurance that design bases l I
information is consistently reflected in the physical plant and those controlled docunsents used to support plant operations. 1
- 12. DISCREPANCIES: Those open items identified by design bases program activities that are confirmed discrepant and may have potential safety ;
significance.
Figure 1 shows the relationship between engineering design bases, the 10 CFR 50.2 scope of design bases equipment, and the licensing bases of the plant. Also, '
Figure 2 illustrates the relationship between many of the terms defined in this section. The examples provided in the document " boxes" of figure 2 are typical and :
, are not intended to be all inclusive.
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III. DESIGN BASES DOCUMENTS A. INTENT OF DESIGN BASES DOCUMENTS The intent of establishing a design bases program is to organize and collate a nuclear plant's engineering design bases information along with supporting design information that provides the rationale or " whys" for the design bases together with a set of material references that idantify the detailed design that supports the engineering deali;n bases information. This guideline emphasize: the collation of the design bases information ($ 50.2 scope ofinformation) that satisfies the regulatory requirements, and the integration of the 50.2 scope with the broader scope of engineering design bases information.
Experiences have demonstrated that for a number of plants there are additional economic and operational benefits from broadening a S 50.2 scope design bases program to include the collation and assessment of engineering design bases, and its supporting information. The collation of the two sets ofinformation (S50.2 design bases and engineering design bases)into one system or topi cal document, commonly referred to as a design bases documents (DBD) can serve as a vnluable reference for the intended usersin support of selected plant activities. Additionally, by providing a standard, well defined, and controlled interpretation of a plant's design bases, DBDs can enhance existing design ec,ntrol and configuration management practices.
Without modifications and plant improvements, the only documents that would be needed to operate a nuclear power plant would be the operational and maintenance manuals and procedures together with the Technical Specificatiors and Safety Analysis Report. However, equipment degrades, plants experience transients, ni:d modifications and improvements are implemented to increase efficiencies and sustain long term operations. In large complex and interactive designs such as commercial nuclear facilities, a minor alteration could result in the degradation of system performance in the long, or short term, which may reduce the margins of safety beyond the approved envelope. Therefore, as a minimum,it is important to collate design bases (S 50.2 scope)information and supporting design information for use in selected plant activities that support the esmtinued safe operation of the facility. In such a manner a licensee is better equipped to assess when the safety analyses described in the FSAR could be impacted.
B. DESIGN BASES INFORMATION The definition in 10 CFR 50.2 was added to the regulations in 1968 to codify statements used in earlier Atomic Energy Commission (AEC) guidance concerning the preparation of safety analysis reports. The AEC developed guidance in the 1965/GG time frame concerning the identification of principal criteria for design and the design bases for those major systems and componenis significant to plant safety. The AEC statements indicate that the term " design bases" should apply to major structures, systems and components that are significant to safety, and that the design bases requirements to be addressed in the safety analysis report are i those requirements necessary to assure the protection of public health and safety. I 10 l
., In reviewing the AEC documentation there is a clear relationship between the principal design criteria and design bases. The principal design criteria are broad fundamental objectives like the GDC. The design bases are the functional bounds or limits for the design within the framework of the principal or general design criteria.
As defined by 10CFR 50.2, the " design bases" of a structure, system, or component is comprised of that information which identifies the specific functions to be performed and the specific values or ranges of values chosen for controlling parameters as reference bounds for design. The design bases (S 50.2 scope) are those criteria associated with the bounding performance requirements necessary to satisfy the safety function of the structure, system, or component under censideration They are based on the requiwments established in the safety analysia report. It is normally that information that is directly related to the safety analyses section of the FSAR.
This information should be captured such that the following requirements are met:
- A summary of the Dafety functional requirements with references p.oviued to identify the origin of the requirements.
. Where applicable, the specific values or range of values for parameters that bound the design are summarized with references provided to identify the origin of the parameters, or range of values.
NOTE: There is significant benefit in developing a comprehensive list of the references that support the plant's engineering design bases. The appendices provide examples of references for engineering design bases information that includes the $ 50.2 scope ofinformation.
An organized review of a system's functional requirements and controlling
- parameters will facilitate a complete and consistent collation of the design bases, whether or not it incorporMes the engineering design bases irformation. For the
$50.2 scope ofinformation, the design bases should be stated in concise terms strictly limited to the scope outlined in the 10 CFR 50.2 definition (i.e., focused on the specific safety functions or controlling parameters that bound the design).
Examples of design bases information are provided in Appendix B that are consistent with the j 50.2 definition. This information should be used with appropriate input from the design authority.
C. SUPDORTING DESIGNINFORMATION l In providing the reasons why particular design bases exist, the supporting design l information establishes and maintains an understanding of the design bases that l enables successful accomplishment of key program objectives. The level of detail
' provided in the supporting design information should be directly related to the intended users' needs in supporting the program objectives. As a minimum, supporting design information should provide the rationale or " whys" that support the design bases of a nuclear power plant. This information may come from a 11
'N e vcriety of sources._ Examples of sources of supporting design information are
. provided in Appendix C.
A number oflicensees have found it beneficial to collate a hst of references that link '
the design bases to the detailed design (analyses, descriptions, drawings, etc .). By having a list of references readily available that are linked to the design bases i
provides a process for increasing personnel awareness of design bases information.
Experiences have indicated that such action reduces the likelihood ofinadvertent plant operation or activities outside of the design bases envelope. The supporting design information should be distinguished from, but linked to, the design bases information. It is important and advantageous to distinguish between the different sets ofinformation, design bases (i 50.2 scope), the engineering design bases, and ,
supporting design information. Such action can avoid potential confusion regarding reportability determinations for design bases related discrepancies.Section V, Addressing Discrepancies, provides additional information on reportability determinations.
Supporting design information should expand on the design bases statements to :
assist in evaluating the impact of modifications or procedure changes on the design :
bases. Additionally, the supporting design information can be used to assure conformance with regulatory requirements while facilitating more efficient working practices. Examples of supporting design information are contained in Appendix D.
This information should be used with appropriate input from the design authority.
D. OBJECTIVES DBDs can be used to support a variety of plant activities. However, without a clear sense of the objetives that the DBDs are developed to achieve, the prograin could produce document 0 of minimal value to the intended users. Thus, it is imperative that objectives be inentified as an initial step in the program. As DBDs are developed, they should be evaluated by the degree to which they fulfill the program objectives. The following objectives are recommended for design bases programs.
These objectives represent primary applications of DBDs as identified through a nuclear industry survey conducted by NUMARC:
. Provide a documented reference for engineering personnel to use in the design process'when considering future plant modifications.
l . Serve as a basis for technical reviews, safety reviews, and 10CFR50.59 safety
, evaluations.
. Provide a documented reference to support operability evaluations and determinations for continued operation.
. Provide a documented reference for licensing personnel in support of licensing analyses and updates to safety analysis reports.
. - Provide a documented reference to support the review of Technical Specifications changes. '
The above objectives are certainly not allinclusive. They are targeted on the engineering and licensing areas as the primary beneficiaries of DBDs. There are many other plant activities that may benefit from and be an objective for a design 12
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bases program. Appendix E provides a list of potential applications for DBDs that have been identified by utilities. These applications may also serve to provide
! useful program objectives. One should be advised, however, that targeting too many applications as primary objectives can obscure the focus of the program. l There may be benefits derived in other areas not speci0 illy targeted by the Q i program. Productivity improvements have been realized by many utilities for may different applications of DBDs. The magnitude of any benefits will be contingent o t sh .
the depth of the program.
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IV. DEVELOPING DESIGN BASES DOCUMENTS 3
The management of design bases programs ( 50.2 scope and the engineering design bases) requires careful planning and effective controls to ensure that the effort is credible, timely and cost effective. There are many important administrative aspects to consider in developing DBDs that can impact the successful completion of the project. The following subsections provide information that has been gleaned from utilities that have mature programs in place. The intent is to convey the
" lessons learned" from such programs in order to facilitate other utility efforts.
A. ORGANIZATION A senior management policy should be established that identifies a utility's lead organization for the development and maintenance of the effort. The policy should define the organization and appropriate accountabilities for development and implementation of the effort. The lead organization should be given the authority to carry out all aspects of this responsibility.
A single individual (e.g., project manager) should be assigncd the responsibility to organize and manaFe the project team and for overall project management. The project manager should have the authority to interface with appropriate department heads to ensure a streamlined flow ofinformation and to effectively manage the available resources.
The project organization should consist of project team members who are assigned full time and,if necessary, are matrixed individuals. The project team members should represent the departments affected by the design bases program and the anticipated users. Ideally, the members would have both sufficient experience and authority to speak for their respective departments concerning program decisions.
The project organization and the project manager should have the full support of senior management. This will ensure a true understanding of the utility's and senior management's commitment to the project.
The project team should include a representative from the eventual owners of the document, as well as other anticipated users. Such an organization engenders ownership and assures the documents are accessible, used, and are updated.
B. RESOURCES A design bases program may require substantial resources from the utility even if a contractor is actually developing the documents. Utility support is required for various activities such as record searches, document review and comment, program
! management, question responses, and discrepancy resolution.
l l Development of a comprehensive set of DBDs may require several years to complete. This can result in significant financial commitment requiring utility management support and monitoring throughout the project. The project should bc included in the utility's long range planning to ensure a timely and credible completion of the project and subsequent maintenance of DBDs.
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., With regard to staffing the project team, the direct participation and invclvement of l utility personnel can result in significant benefits to the utility. The key goals should be to promote ownership of the products developed and to maximize the retention of knowledge gained during the project assignments. Attainment of these goals should help to ensure prop er usage and application of the DBDs developed and also increase the productivity for each application.
Proper selection of the project team is vital to the success of the project. Since the l design bases and supporting information may involve a mixture of original plant design requirements together with other requirements imposed or adopted up to the present, it is important to consider including engineers experienced in design and regulatory requirements when the plant entered commercial operation an well as engineers experienced in current design and regulatory requirements.
Consideration should also be given to including personnel familiar with the Nuclear Steam Supply System (NSSS) vendor and the original Archite :t Engineer (A/E).
A team ofindividuals, such as utility, NSSS, and A/E personnel under utility management, organized to develop and review DBDs should enhance utility knowledge of design bases requirements, and promote subsequent ownership by the utility.
C. PILOT EFFORT DBD programs should commence with a pilot phase intended to develop the basic program process, initial cost / schedule data, format / scope, a hierarchy of requirements and documentation needs, and user interfaces. This will allow for testing the adequacy of project procedures to ensure development of consistent work products and satisfaction of project goals and objectives before the start of full-scale DBD production and further expenditure of resources. The pilot phase shou!d establish the program elements, the program process, and organize resources as for the full scope effort.
Pilot efforts are beneficial in determining the appropriate controls necessary for maintenance of DBDs, managing discrepancies and methods for controlling design bases information, and determining the depth of scope for engineering design bases and supporting design information.
Prior to starting the pilot phase, a licensee should identify the overall plant design bases used in the safety analyses for the selected systems, structures, or areas. The pilot phase should provide factualinformation needed to make decisions regarding the level of effort, objectives, approach, and the types of DBDs to be developed. To sample a wide range of potential DBDs, the following areas are recommended for inclusion in the pilot effort:
a a system deoigned by the NSSS supplier; e a safety related system designed by the A/E;
- a nonsafety related system designed by the A/E; and
- a topical area, such as Seismic or Fire Protection.
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'..' Following completion of the pilot effort, utility management should assess the usefulness of the product prior to deciding the final scope, schedule, and resources needed.
D. USER INPUT /NEEDS Design bases programs should provide controlled user-friendly information to the ,
end users as defined by the utility. Any group, department, or organization !
designated to be an end user of the product should participate in the determination !
of scope, establishment of objectives, level of detail, and the review of the DBDs.
This participation is essential to developing a sense of ownership in the products developed and will also promote usage of the products.
Acquiring early input from end users is crucial for the DBD effort to fully realize the program objectives. This should include the involvement of various engineering disciplines that use design information. Their input and feedback is imperative from the start of the project. Access, usability, update and control of DBDs are essential elements and need to be addressed at an early stage of the project, especially where electronic data is being used.
E. FORMAT / CONTENT As discussed earlier, the information contained in a DBD may consist of the design bases (S 50.2 scope), the engineering design bases, and cupporting design information. The approach taken for presenting these different sets ofinformation ,
can vary depending on a myriad of factors, such as plant vintage and design, user needs, topic of the DBD, and availability ofinformation. Thus, the type of DBD developed should be tailored to meet the individual needs and constraints of the-utility. The purpose of this subsection is to p-ovide general information on the format and content of DBDs that may assist in developing an effective approach.
The subject of the DBD should not be bounded by any particular facet of a power plant's design. However, physical boundaries of a system should be delineated prior to the start of DBD development. The DBD may address structures, systems, components or topical design considerations such as seismic, environmental qualification, fire protection, high energy line break, etc. While topical information may be addressed either within system DBDs or separately, many utilities have found that separate topical DBDs reduce redundancy in that the system DBDs can reference the applicable topical document. This approach also helps to ensure consistent application of the topical information. .
- The DBD subjects should be selected based on their importance to plant safety, reliability, and availability. A prioritization scheme for DBD subjects should be developed based on the above factors. DBDs can be formatted into three basic types ofdocuments: -
- 1) Comnrehensive provides extensive text on:
e design bases (550.2 scope) 16
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,.' . j e engint: ring d: sign bases !
i.] e supporting design information :
e component information :
e calculation summaries I e related drawings and specifications !
e codes and standards by reference, date and applicability Minimal cross referencing of documents is includei ,
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- 2) Index provides minimal text with extensive references to other ;
I- documents. Referenms mayinclude: j e system descriptions l e calculations e specifications j e other documents !
i e codes and standards :
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i 3) hiixed includes descriptive text plus extensive references. For example, a mixed approach may include texts of: 1 i e design bases l e supporting design information l e component descriptions ;
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With references to:
! e calculations e specifications
- e codes and standards e other documents ,
1 Any of the formats can prove effective in presenting the information contained in DBDs.
In general, it is unnecessary to duplicate the contents of other self-contained
! documents such as:
[ . ASME Code stress reports
. Equipment Qualification data packages
- Vendor manuals e Operations and Maintenance procedures ,
. e Industry codes and standards
. - - Specifications - j i e Generic regulatory requirements The level of detail and other decisions regarding the content of the document 4 developed should clearly reflect the program objectives, While the design bases 1 information in the-DBD should be concise, the amount of supporting design '
information to include in the document is dependent on the intended applications.
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Wh::tsvar cppro:ch is selected reg rding the format end content of DBDs,it is strongly recommended that design bases information be distinguished from supporting design information. This may be accomplished by labeling the different .
sets ofinformation, highlighting or underlining the design bases information, or some other comparable technique. This will reduce the potential for confusion when discrepancies discovered during the implementation of the program are evaluated j
- for reportability, where an item may be construed as being outside the design basis of the plant. . ,
There are many types ofinformation that may be considered for inclusion in a DBD. l Examples are provided in Appendix F.
l F. SOURCE INFORMATION SEARCH AND RETRIEVAL ;
i A large factor in the design bases program of a plant is the availability of sources ;
containing design bases information and supporting design information. This !
information can be found in a variety of sources. Many of the original design and .
construction documents for a plant may be stored in warehouses) or other files with no easy means of retrieval. Since these documents may not be indexed and the !
technical contents not identified, utilities should consider indexing of collected and i assembled documents (DBD references), and should organize this information such :
that it is readily retrievable in the utility's commonly used information system for i
future review needs. This function should be addressed in appropriate project procedures and developed prior to or during the pilot phase. ,
in order to facilitate the search for information, the project team should be provided ready access to interview and interact with appropriate utility personnel to locate, gather and collect information. Ready access to reproduction and microfilm / fiche machines should also be provided, as well as controlled files, records and archives.
l The recovery of design bases information and supporting design information can be !
resource intensive. As a result, a utility may elect to focus the search and retrieval effort to address problem areas or to where an identified need exists. j l
Recognizing that some information will be proprietary, proper consideration and
, planning for handling such material should be undertaken. This may include the l review of previous contractual arrangements and/or new agreements. Information developed prior to imposition of Appendix B of 100FR50 may be used as the authoritative technical basis for design provided that such information:
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l e can be logically followed; and e is pertinent to the current plant configuration. .
No supplementary verification may be necessary if the above attributes are present.
The program administrative procedures should provide specific utility requirements ,
for usiand incorporation of this information.- The intent is to provide e reasonable
, assurance that the recovered information is credible.
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G. PROCEDURE
S / WRITER'S GUIDE Administrative procedures consistent with the established policy are needed to effectively implement a design bases program. The development of procedures establishes management control over the process to be used to develop, review, and ,
approve the documents and ensures appropriate standards are established and communicated. Development of project specific procedures to control the technical, interface and administrative work prior to the start of the collation process is essential to the successful and cost effective completion of the project. These procedures should be written to ensure a consistent approach to the development of each DBD.
Procedures should be prepared to address and control responsibilities associated with document preparation, review and approval processes, and long term handling and control of completed documents. The following are typical topics that should be addressed in procedures:
- Project interface e Discrepancy and open item management
. DBD development (Writer's Guide)
. DBD review / approval J
H. SCOPE / PLANNING / SCHEDULING A design bases program should begin with the development and approval of a
- project plan. This document should have the buy in" of allinterested and affected parties. The project plan serves as a tool to communicate the scope and purpose for the development of the design bases documents.
The project plan should typically address the following:
. Scope / Objectives e Planning / Approach e Project Organization / Interface e Schedule -
. Budget Scope / Objectives The program should be initiated by establishing the scope of the DBD project, Without a clear definition of scope, there will be a tendency for non project related :
activities / tasks to creep into the project, thereby blurring the focus of the project and causing undue budget overruns and schedule slippages.
The scopo definition should generally address the following:
goals and objectives for the effort;
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Having established a clear dermition of project scope the next step is to initiate detailed planning. One of the first steps involves an assessment of the current status of existing design documents. The status of existing documentation can be a large factor in determining the level of effort required to review, collate and develop !
DBDa. Prior to the establishment of short and long term plans, an assessment of l the plant document status should be made. This asacssment of design documents typically should involve the following: i e location of design documents (A/E, NSSS, utility, etc.)
e availability of design documents e control of design documents Significant differences between the desired and actual condition of design documentation need to be identified and considered during the planning and development stages of the effort. Decisions are required concerning the treatment i of proprietary information. For example, the need for detailed specifications or ;
actual calculations on all equipment versus calculation summaries on selected ;
i systems and components should be evaluated and negotiated with the NSSS supplier and A/E.
The utility should decide the best approach to accomplishing the objectives of the effort during the planning phase. Management controls related to DBD development, discrepancy resolution, DBD validation, user needs for the DBDs, and information management systems needed to control and process information are examples of activities that should be considered in the plannmg of the effort. The pilot phase of the project should prove to be beneficialin establishing the approach for accomplishing the overall effort. ;
In making the determination of the level of review required for the design bases effort, consideration should be given to the following:
e status of original design and construction documents e importance to plant safety and reliability e extent or . frequency of post-construction changes e effectiveness of the plant modification conttol program After the completion of the pilot phase, the " lessons learned" should be incorporated via revision to the current project plan. Decisions regarding the project budget, ,
- scope, objectives, organization, and various other activities should be revisited as l necessary to make appropriate adjustments and fine tuning. As the project progresses, readjustments should be made as necessary to address recurrent problems or adverse trends.
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. l The project plan should address the need for a strong project organization and a streamlined interface. At a minimum the project plan should address the followmg: <
l e identification of the lead organization for the effort ,
. identification of the participating organizations involved
. identification of key interfaces anti communication methods Schedule i
A two tiered scheduling approach is effective; one tier covering the overall effort, and the other tier covering specific activities. Initially a pilot phase schedule should be developed with a gross schedule for the overall project. Subsequent to the completion of the Pilot Phase the overall project schedule will need to be refined and finalized for the production of all DBDs identified. An overall project schedule of several years or more is common.
The DBD development schedule should be integrated with the master schedule for other utility activities, including planned plant modifications and outages. This may result in a schedule that would be mutually cost effective for both the DBD project and plant modification activities. Additionally, the schedule may also be coordinated with the conduct ofinternal system assessments which would minimize redundant efforts.
Budget Initially a pilot phase budget should be developed with a gross budget for the overall project. Subsequent to the completion of the pilot phase the overall pmject budget should be refined and finalized for the overall project. The budget may also consider funding for discrepancy resolution, validation of DBDs, along with maintenance and control of DBDs.
Orientation The project plan should provide for adequate orientation of the project team. The orientation plan should also include consideration for the needs of the users of design bases documents. Initial orientation also will provide senior utility managers an opportunity to emphasize the importance of the effort, why it is necessary, and the necessity for accurate results. Line management involvement in this effort will enhance the results for a better project and subsequent use of design bases documents by the end users. Typical orientation plans should include consideration of the foilowing items:
. Project plan and project procedures program overview
. Availability, access and use of utility data base systems
. Effective writing a Format cud content of design bases documents
. NSSS/AE orientation to utility procedures for contracted work 21
o Use of devclop:d DBDs i
- Requirements of proprietary and safeguards information ;
- Maintenance of the DBD during the development phase
- Requirements for handling controlled documents '
- Identification and handling of discrepancies
- Reorientation of personnel due to turnover or attrition on long term projects
- Training of operations and engineering personnel i
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V. ADDRESSING DISCREPANCIES A. INTRODUCTION This section provides a systematic, comprehensive approach to address discrepancies identified during the implementation of design bases programs. This approach includes methodology to assess the safety significence of discrepancies, evaluates significant discrepancies for both operability and reportability issues and provides prioritization criteria to assist in the final disposition of each discrepancy.
This section also clarifies reportability determinations, and offers a reasonable method to communicate significant findings to the NRC. Additionally, a final evaluation is included following the completion of a design bases program activity that reviews the discrepancies identified for any incremental or cumulative effects.
The process described in this section may be adapted to existing utility processes that address nonconformances or may be utilized as a stand alone process.
The objective of this section is to provide a managed approach to resolving discrepancies that promotes diligent, self. initiated utility efforts toward the aggressive implementation of design bases programs that ultimately enhance safe, reliable plant operation.
B. OVERVIEW The implementation of a design bases program will identify open items which may include questions, concerns, and Cases of missing information. Industry experience indicates that the majority of these open items have little or no safety significance and are routinely dispositioned in accordance with a utility's standard work practices. Those open items that are confirmed discrepant and may have potential safety significance are considered discrepancies, and their trectment in the subject of the guidance contained in this section.
A flow chart depicting a process for addressing discrepancies is provided in Figure 3. The process is generally consistent with normal utility practices for treating non. conforming conditions identified during the course ciday to-day plant activities. The process applies to individual design bases program activities (e.g.,
system DBD efforts) that have a defined scope and timetable.
Following the identification of a discrepancy, a screening element is applied to quickly determine its safety significance. If the discrepancy does not raise a safety concern based on the results of the screen,it can continue to be evaluated and dispositioned and, pending completion of the particular design bases activity, would be subject to supplemental review during the final evaluation. If the discrepancy is determined to be safety significant, it would undergo both operability and reportability evaluations. The screening element should be completed in a time frame commensurate with the apparent safety significance of the discrepancy.
The operability evaluation would determine if an operability issue is posed by the discrepancy. An underlying premise throughout this element is a presumption of 23
operability, see NUREG 1397. In cases where broad engineering experience and l
',. judgment indicate the affected system or component to be functional, but where l inadequate information is available from which to make and fully document a final !
decision, the presumption of operability would apply. The conclusive information l should be pursued expeditiously. If an operability issue is identified, the utility l would take the applicable Technical Specification action or other appropriate action deemed necessary to maintain the plant in a safe condition. If no operability issue is identified, the discrepancy can continue to be evaluated and dispositioned and, pending completion of the particular design bases activity, would be subject to supplemental review during the final evaluation.
The reportability evaluation ensures timely reporting and regulatory compliance. If !
a reportable event is identified under the existing regulatory requirements, the
- utility would report the event to the NRC. If reportability is not required, the discrepancy would be subject to supplemental review during the final evaluation.
The reportability evaluation should be completed in accordance with current regulatory requirements.
The final evaluation determines whether the discrepancies have any incremental or cumulative effects that would result in subsequent operability issues or reportable events. Additionally, the discrepancies are prioritized based on their relative safety significance, and their final dispositions are determined in light of the information collated by the particular activity. The close out element assures that the disposition of each discrepancy is satisfactorily implemented.
C. INDIVIDUAL ELEMENT DESCRIPTIONS The following discussion elaborates on the individual elements that form the discrepancy resolution process.
Discrepancy Determination j Many questions, concerns, cases of missing information and potential discrepancies l
may be raised or identified during the course of a design bases activity. Each utility l should assure that such open items are being diligently addressed through the work process at a reasonable pace, consistent with good management practice and the level ofpotential safety significance, toward ultimate determination as to whether a discrepancy truly exists. When an open item is confirmed to be discrepant and raises a potential safety concern, it should be forwarded to the discrepancy resolution process expeditiously. Those open items that are not confirmed as discrepancies or that do not have any potential safety significance should not be forwarded to the process. Applying the same level of review to each and every open item would quickly overload the process and result in ineffective use of valuable engineering resources. The remaining open items (those not confirmed discrepant or not potentially safety significant) should be resolved in a manner consistent with the utility's standtrra work practices.
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- . .c-I Figure 3 Discropancy ,
Determination Design Basis _ Discrepancy :
Resolution Process l 4
Safety N N l Concern?
)
Opembility Y
< > Reportability i Evaluation Evaluation .
Y N N Operability Reportability issue? Issue?
yY if 1r 1r
$ry ,
Complete Report Take Tech Spec DB Activity or other act, ion to NRC 3r f Final Evaluation
- Closecut
- 6
,acreen for Safety Signincance Once a discrepancy enters the process, a method is needed to quickly screen each item to determine the safety significance (existence of safety concerns) or impact to the continued safe operation of the plant. Without this determination, the process could easily become excessively burdened by giving equal priority to items oflittle or no significance. The following questions provide a suggested screening method to initially determine the safety significare of each discrepancy:
(1) Does the discrepancy appear to adversely impact a system or component explicitly listed in the Technical Specifications?
(2) Does the discrepancy appear to comptomise the capability of a system or component to perform as described in the Safety Analysis Report? '
(3) Does the discrepancy appear to adverse?y impact any applicable licensing commitments?
If the answer to any of the above questions is yes, operability and reportability evaluations should be initiated expeditiously. Consideration should be given to informally advising the NRC resident inspector or appropriate regional NRC personnelif a significant discrepancy has been identified through the screening process, and that operability and reportability evaluations will be commencing.
(This does not preclude immediate notification requirements under 10 CFR 50.72, if applicable.) Communication with NRC at this point in the process can be an effective means of establishing support for the managed approach to the process. If none of the above questions are answered yes, the discrepancy may continue to be evaluated and dispositioned and, pending completion of the design bases activity, would be subject to supplemental review during the final evaluation.
Operability Evaluation An underlying premise throughout this element is a presumption of operability, as referenced in NUREG 1397, and the original NUMARC9012 document.
Recognizing that a primary objective for initiating a design bases program is to enhance the information on which operability determinations are based, the presumption of operability is intended to apply when broad engineering experience and judgment indicate that an affected system or component is functional, but where inadequate information is available to make and fully document the final decision on a particular discrepancy. The necessary information should be obtained or developed on a priority basis and should be acted upon thereafter The presumption of operability serves to reduce potential disincentives to the aggressive performance of the program activity. This approach also satisfies the need to l operate the plant conservatively by limiting the potential for unnecessary challenges to plant safety systems and personnel.
The operability evaluation should be consistent with normal utility practices that l address non conforming conditions diccovered during the course of routine plant i
l 26 l
l
octivities as recommended in NRC Generic letter 91 18. If the evaluation
. determines that the discrepancy results in an operability issue (i.e., the impact of the discrepancy is such that actioa needs to be taken to place the plant in a safe condition), the process would proceed to take action in accordance with the technical specifications or other regulatory or procedural requirements (Take Tech. Spec. or '
other action box) If the evaluation determines that the discrepancy does not result in an operability issue, the basis for that conclusion should be documented, and the discrepancy usay continue to be evaluated and, pending completion of the design basco activity, would be subject to supplemental review during the final evaluation. j 1
I The presumption of operability is not intended as a means of deferring necessary actions to address a discrepancy. If a discrepancy clearly impacts th9 safe operation of the plant, action to place the plant in a safe condition should be taken. When an operability issue has been determined through the evaluation, actions must be taken expeditiously to maintain the plant in a safe condition. The concept of a '
presumption of operability acknowledges that in certain cases, broad engineering expc.icnce and judgment can allow the pursuit of conclusive information to make and fully document a final operability decision. This may preclude potential plant transients and shutdowns caused by actions based on inadequate information that unnecessarily challenge safety systems and plant personnel.
Take Technical Specification Action or Other Appropriate Action TWn an operability issue is identified for a discrepancy based on the preceding operability evaluation, appropriate action should be taken to place the plant in a safe condition. The action should be consistent with normal utility practice.
Reportability Evaluation 10 CFR 50.72 and 10 CFR 50.73 describe the requirements for reportability, and NUREG 1022 provides additional guidance relating Licensee Event Reports (LERs),
f 50.72 addresses immediate, one hour reports that are associated with significant safety matters that have the potential for significant and immediate impact on the protection of public health and safety. 9 60,72 also addresses four hour reports for matters that are oflower safety significance.
Appendix B provides examples of design bases information that are applicable to the NRC reporting requirements.
Section 50.?2, and Section 50.73 require specific reporting requirements when an event or condition results in the plant being outside ofits design basis, i.e., the Section 50.2 design bases are not satisfied. What constitutec a condition outside of l
the design bases has been the subject ofindustry debate. The discussion in the Background section of this document provides the genesis and the originalintent of the "Section 50.2 design bases" term. It includes ir. formation that identifies and defines the specificsafety functions and the values or parameters that bound the design of the structures, systems or components. A licensee is considered to 27
. l
. be operating cutside ofits design bases for the structures, system i. cnd components l when it makes one of the following determinations- 1 l
(1) a structure, system, or component is, unable to perform its intended j safety functione and satisfy the parameters described in the design '
bases section ofits FSAR, or (2) an evaluation indicates that a structure, system or component would be beyond the speciSc value or range of values that were chosen for controlling parameters as its reference bounds for design.
These two conditions serve to clarify what "outside the design basis" means with respect to the regulatory requirements noted above.
A balanced interpretation of the regulation requires that the reportable condition -
the ' dant being in a condition that is outside the design bases of the plant .. be examined in the con +. ext of the other enumerated conditions which must be reported under that.e sections.
/3setton 50.72(b)(1)(li) requires one hour reports for events or conditions during cperation that result in the plant bEkg in a seriously degraded, or in an unanalyzed conditiot, that signincantly compromises plant safety, or a condition not covered by a plant's operating or emergency procedures. The regulation contemplates reports on matters to which the NRC must respond quickly or which have immediate regulatory signincance that compromises the protection of public health and safety .
The events and conditions which trigger a one hour report clearly have major potential or actual safety signincance. This is illustrated in the examples cited by th NRC in NUREG 1022 concerning reportability.
A one hour NRC reportable condition ($ 50.72(b)(1)(ii)) for design bases issues relates to events or conditions that degrade the design bases of the plant to the extent that it will immediately degrade the protection of public health and safety.
In regard to system, structure, or component design bases, a one hour report should l be made only when the overall plant functional goals (plant level design bases) would not be satis 6ed. That is, if a system, structure or component is incapable of performing its intended safety function, or satisfying its design bases as described in the FSAR, such that the overall plant functional goals (plant level design bases) would not be satis 6ed, a one hour report should be made, l
In view of the severe implications of other one hour reporting events, and the i
language in i 50.72(b)(1)(ii) relating to the design bases of the plant, it is i
appropriate to link a failure to satisfy a plant level design bases event with a one hour report. This would make the one hour reporting requirements for design bases consistent with the language in the rule, and consistent with the level of severity d other one hour reporting requirements. Conursely, making one hour reports for a l failure to satisfy a component level design bases attribute that may have no, or '
minimal safaty significance,is inconsistent with the other one hour reporting requirements of $ 50.72.
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,. This narron scope for the reporting requirements is necess:ry to avoid unn:cessary )
- exercising of the emergency notification system (part of the one hour reporting requirements) with the resultant resource burden for matters that have minimal, or no safety significance. However, plant operators should be able to quickly recognize ,
when a one hour NRC report is required without being overly distracted from their prime function, the safe control and operation of the power plant. Appropriate guidance and training should be provided to operators and shift technical advisors to enable them to readily identify when a plant level design bases attribute is not, or wiU not be satisfied. Naturally, additional guidance on design bases matters (i ,
50.2 scope and engineering) would be included in the training curriculum for design, system, and licensing engineers.
i Figure 4 provides an example of a flow chart that could be the basis of such guidance. The evaluation to determine when n plant might be operating outside of its design bases is cased when a plant's (plart and system level) design bases are clearly understood and documented.
One need not automatically assume that a condition "outside the design basis" exists. When the information necessary to make a final decision is developed or obtained, the reportability decision should be made expeditiously. Industry experience has shown that information is often 'dentified during the course of a design bases program activity that contribute. to the resolution of a previously identified discrepancy. In this process, the element entitled " Complete DB Program Activity" is included so as to allow relevant information to come to the fore, and is followed by a final evaluation where a discrepancy can be reevaluated for both operability and reportability. As noted in Section III, distinguishing the design bases information from the supporting design information also serves to facilitate the reportability evaluation.
l Section 50.72(b)(2) provides adequate details and specific reporting requirements for the four. hour NRC reports. It includes any event or condition that alone would have prevented the fulfillment of the safety function of structures or systems.
NOTE: The reporting logie descri'oed only relates to Section 50.72(b) and its relationship to design bases information. There are other NRC reporting requirements associated with Section 50.72 and other regulations and plans such as, Section 50.73, Technical Specifications, etc., and a licensee must continue to meet these other regulatory requirements.
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Det,lan Basis Deficiencies NRC 1 Hour Reoortina Reauirements
- Repo table Functionsi #
under $ 50.72(b)(O NO d ' d '
systemIStructure Functional NO O utelde NO Plant Design asses YES Re portable
$ 80.72 1 HOUR t w o T r : m. n.. ...n .a , ... .
a 'a o rta b
- s.','! *.' .'s!,*. ,.L'!/ '"' " -
s'o N'y's \;Tl.~.*;i:%*N:?.* .%
fant.r .1 Report to Nuclear Regulatory Commission (NEC)
When a discrepancy is determined reportable, a NRC report is filed. Should subsequent discrepancies identified during the design bases prograrr. result in additional reportable events, written supplemer.ts to the initial LER may be filed when the discrepancies are technically similar. For example, a program activity to develop a Residual Heat Removal (RHR) System DBD identines that a functional requirement, such as closure on a containment isolation signal, was not considered in the design basis of a motor operated valve (MOV). The esse was considered reportable and an LER was filed for the containment isolation deficiency, not as a RHR system deficiency. A subsequent program activity to develop a Containment Spray System DBD identifies that closure on a containment isolation signal was not considelvd in the design basis of another MOV. In this case, a supplement to the initial LER may be filed rather than a "new" LER, in accordance with the guidance in NUREG 1022. - '
M
~_ _,
P:rti:ns cf en initial LER (e.g., long term corr:ctive action, Anal essessment of
safety signincance, root cause) may be deferred until the speci5c program activity (e.g., RHR System DBD)is completed. When portions are deferred, a clear schedule for meeting all Section 50.73 requirements should be provided to the NRC.
Following completion of the activity, the final evaluation should comprehensively review the identified discrepancies. At that point, a supplement to the LER,if necessary, should be submitted that addresses tla deferred amas of prior filings and fulfills the pertinent regulatory requirements.
The above guidance clearly reGeets the managed approach to addnesing discrepancies during the imploraentation of design bases programs. An aggressive program may identify a number ofpotential findings, and the LER process could quickly degenerate into a proliferation of submittals and revisions. For example,-it makes little sense to propose long tenn corrective action in the Srst LER when subsequent findian may impact the decision regarding the appropriate corrective action. This would detract utility resources with no safety benent.
This approach blances the need for prompt reporting to the NRC with a structured method that ef5ciently addresses discrepancies both individually and collectively.
This method offers several advantages. Discrepancies identified during an activity such 'as the development of a system design bases document may be closely plated and should be reviewed for cumulative impact on the system's functions. Any supplemental LERs should convey the results of further engineering analysis and review of the impact of the discrepancy. For this reason, certain issues or problems that are technically similar may be reported in one LER and subsequently supplemented or revised as the overallimpact is understood. Additionally, this approach provides timely reporting wher. individual discrepancy nportability determinations are made and offers a sound rationale for combining LERa when appropriate. In summary, safety bene 5ts would be attained through the comprehensive evaluation performed at the completion of the activity, while potential disincentives to the aggressive implementation of the program would be n duced.
Complete Design Bases Prgram Activity l
The main purpose of this element is to allow all relevant information pursuant to the activity to be available for use in the subsequent " Final Evaluation" element.
As noted previously, industry experience has shown that a discrepancy can often be resolved by information identified later in the related activity. Thus, it may be premature to completely disposition an item without allowing all pertinent information to come to the fore. Additionally, by performing a final evaluation when the activity is completed, the cumulative effects of the discrepancies may be addressed in a more comprehensive manner.
Final Evaluatiorta At this point, the design bases program activity has been completed and the discrepancies associated with the activity have been assessed, and those that were 31 ,
screened as safety signif2 cant have been evaluated individually for both operability
.l and reportability issues. This element allows the tie in of applicable information gathered during the activity and applies it toward the comprehensive review of the discrepancies. There are three main objectives associated with this important element. The first is to look at the discrepancies in total and determine if there are any cumulative effects that impact operability. The second is to review the discrepancies in total with respect to reportability. The third objective is to both prioritize and finalize the disposition of the discrepancies.
If a discrepancy had previously resulted in an operability issue, the actions taken l should now be reviewed in light of any additional discrepancies or new information i identified during the activity. The other important aspect of this particular evaluation is to determine if there are any cumulative effects asaociated with the disc epancies. It is possible that several discrepancies, when reviewed individually, did not result in any significant concerns or issues, but that together may impact the ability of a system or component to perform its intended functions. If an operability issue is determined as a result of this comprehensive evaluation, then Technical Specification action, if applicable, or other appropriate actions should be taken. ,
The final evaluation for reportability should assess the cumulative impact of discrepancies on reportability determinations, it should determine if any conditions result that may be reportable under existing regulations. In addition,if any reportable events were concluded from the individual evaluations, a final supplement to the initial LER may be filed that fulfills any remaining 10CFR50.73 requirements and provides updates to corrective action plans based on the new information identified.
The final task within this element is to prioritize and disposition the remaining discrepancies that have passed through the process. The prioritization is important in that it distinguishes those items requiring more immediate corrective action from
. hose that may be resolved through routine scheduling practices and from those that may not require any action.
Several utilities have developed methods to prioritize discrepancies. Some have used probabilistic risk assessments (PRAs) for this application. Others simply route the discrepancy for disposition to the appropriate engineering discipline through the routine process for addressing nonconformances, while others have employed a review committee to determine the priority of an item. All these options may be appropriate based on an individual utility's functional organization.
- Application of prioritization criteria may be deper dent on the specific nature of the discrepancy. It is important to use broad engineering experience and judgment that takes into account the circumstances surrounding a particular item. The following suggested criteria offer a methodology to prioritize discrepancies based on general ,
safety consideratiots and should be applied together with engineering experience 32
e
't . ..
. cnd judgment:- :
(1) Does the discrepancy potentially impact the operability of a system or !
component that provides or supports a safety function?
(2) Does the discrepancy question the validity or completeness of a design change undertaken on a system or component?
(3) la resolution of the discrepancy necessary to support a future design change planned for a system or component?
(4) Would resolution of the discrepancy faciliti.te operability ;'
determinations on systems or components that have proven difficult based on past operating history? ;
If the answer to questions (1) or (2) is yes, then resolution. of the discrepancy should l be pursued as a near term action item with a completbn schedule commensurate with the safety significance. If the answer to questians (3) or (4)is yes, then i resolution should be pursued as a long term action item. If none of the questions '
are answered yes, then the discrepancies are considered non priority items that should be pursued consistent with the utility's management guidance.
Industry experience has shown that a large number of discrepancies discovered during design bases program activities are related to missing information. A main premise of the prioritization criteria is to determine whether there is a substutive ;
reason or need that calls for pursuing the resolution of an item as a priority. With respect to missing information, this means that the reconstitution of design documents need not be pursued when an established need does not exist.
Additionally, reconstitution may not be necessary when other sources of data (e.g., >
test results, operating history, related industry experience) can provide reasonable assurance of continued safe operation. It is recommended, however, that a record be kept that identifies an area where there is a lack of design documentation to avoid fruitless potential searches for this information in the future.
Closeout Once the disposition of each discrepancy is complete, the closeout element should effectively track the item to its successful resolution. The accountabilities and responsibilitics of each plant / engineering organizational unit associated with the ;
implementation of the disposition should be clearly understood. The element i should ensure that the corrective actions taken adequately address the discrepancy and should preclude repetition of any condition adverse to quality. This may include training, education, and programmatic referius as applicable. The closeout of a discrepancy should be documented appropriately.
j I
i 33 n e,_,- ,,.n , q, .-w-o 1 m - --a- ,r--
r .
. VI. DESIGN BASES DOCUMENT VALIDATION. MAINTENANCE AND CONTROL Information contained in DBDs should be validated, maintained current and controlled to provide a reliable basis for the applications, in addition, the information should remain readily identifiable and easily retrievable by end users.
The validation element provides reasonable assurance that the design bases information is consistently reflected in the physical plant and those controlled documente used to support plant operation. To effectively utilize resources, the results of previous self. assessments, audits, Safety System Functional Inspections (SSFis), DBD pilot efforts, pre operational and surveillance tests, and other related plant experience should be considered to target validation areas. For example, the results of previous efforts such as EQ programs, Appendix R, and as built walkdowns can be important in deterraining the extent of the validation effort.
Several approaches to and methods of validation exist. Validation can be integrated into the DBD development process or may be performed subsequent to development of a DBD. Alternative methods of validation include sampling of data for accuracy, field confirmation of essential attributes, programmatic review (e.g., self initiated SSFI) or any other method that establishes that the information within the DBD is conshtent with the plant configuration.
For the DBDs to retain their value over the life of the plant, they should be controlled and kept up to date. The key elements that have been identified for maintaining DBDs include the following: .
(1) Documentation Control Design bases documents and changes to the documents should be uniquely identified and controlled through the utility's document control aystem. Supporting information and computer software should be similarly controlled. Provisions to indicate the status of the documents should also be addressed.
(2)lnformation Accessibilitr To be used and iseful,information contained in DBDs shoula be readily accessible by all users. Some utilities have established computer based information systems to provide access from convenient terminals while maintaining a centralized control ofinformation.
Information retrieval systems that best support use of the informttion often include the following:
e convenient locations '
i e simple identification ofinformation sources
! e quick and simple retrieval ofinformation '
e retrieval system training for potential users
- l l
l I
l M ,
l
r* s (3)Information Resoonsibility An individual or group should be as:igned responsibility for assuring that speciSc information is correct and current. The responsible group is typically design engineering acting as the designated design authority. In the case of proprietary information retained by the A/E or NSSS vendor, the utility should address the fact that the licensee is ultimately responsible for the correctness and application of the information.
(4)Information Revision Most utilities use their exi +ing design change control process to control changes to DBD insurmation. As the designated design a.:thority, the design er seering organization usually has the primary responsibil ty la ensure changes are propotly reviewed, verified, and approved. The update of a DBD should be performed at the same time as detailed design information is revised.
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4
- VII, INTEGRATION OF DESIGN BASES PROGRAM WITH CONFIGURATION MANAGEMENT AND DESIGN CONTROL T ..
Con 6guration management is the process of maintaining the physical plant and the l i I controlled documents required to support plant operations consistent with selected I
design documents. Design controlis a process that is used to assure that information from design input and design process documents for structures, systems ;
~
and components is correctly translated into the Anal desip. Con 6guration i management and desip control are long standing practices, independent of design bases documentation eNorta, that support plant operations by preventing unknown i
a or unauthorized plant con 6guration changes. Design bases programs supplement !
and support con 6guration management and design control by providing a foundation of desip bases (i 50.2 scope and engineering design bases scope) and ;
supporting design information. From this foundation, configuration management ;
and design control can ensure that design bases requirements are being met ;
through the following:
(1) Capturing the applicable design bases for which the utility is responsible in "living documents" maintained by the utility engineering organization for use in support of various plant activities.
l (2) Ensuring that detailed desip is completed such that the design bases ;
requirements (the $50.2 scope, or engineering scope) are met and the detailed design is properly documented in design process documenta (e.g., calculations, analyses) and design outpv.t documents.
(3) Ensuring that plant configuration documents are consistent with their supporting design process and design output documents and are i therefore consistent with the bases. Plant con 5guration documents
- include those controlled documedts used to support various plant activities such as operations, maintenance, testing, procurement and training.
1 A successful design bases program is thus a key step in ensuring effective design control and configuration management. The DBDs provide a standard, well.
I defined, and controlled interpretation of the design bases (i 50.2 scope, or the engineering scope) which, when fully integrated with design control and
! configuration management, will enhance tlie continued safo operation of the plant.
- l INPO has developed a number of good practice documents and guidance relating to change control and configuration management. ,
i l Changes to the design bases often affect many documents and analyses, including the DBDs.- To assist in identifying pffected documents and analyses, matrices that 4 cross reference documents can be developed. These matrices are often computer i based because of the number and complexity ofinteractions involved.
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. APPENDIX A EXAh!PLES OF REFERENCES FOR DESIGN BASES INFORh1ATION
. Industry Codes and Standards including but not limited to:
American Society of hiechanical Engineers (AShiE)
Acerican National Standards Institute (ANSI)
American Society of Civil Engineers (ASCE)
Institute of Electrical and Electronics Engineers (IEEE) American Concrete Institute (ACI)
American Institute of Steel Construction (AISC)
Hydraulics Institute 011)
Instrument Society of America OSA)
. Code of Federal Regulations 10CFR50, Reactor Licensing, including but not limited to the following appendices:
Appendix A GeneralDesign Criteria Appendix E - Emergency Planning Appendix I ALARA Guidelines Appendix J Leak Testing Appendix K ECCS Evaluation hiodel Appendix R Fire Protection
. Code of Federal Regulations 10CFR73, Physical Protection of Plants and hinterials
+ Code of Federal Regulations 10CFR100, Reactor Site Criteria
. Architect Engineer /NSSS Design Guides and Standards
. Applicable Regulatory Guides adopted as design bases
. Utility Source References of Record 37
APPENDIX B EXAMPLES OF DESIGN BASES INFORMATION NOTE: This information should be used with appropriate input from the design authority (design engineering, NSSS vendor, etc..).
Exemnles of Plant Level Desien Bases Information If a determination is made that a plant level design bases element, such as the elements described below, would not be satisfied, an immediate (one hour) report should be made to the NRC per 10 CFR 50.72(b)(1)8
. Peak clad temperature shall remain below 2200*F
. Total oxidation of the cladding shall be limited to 17'A of original cladding thickness
. Offsite dose limit shall not exceed the valuer, described in 10 CFR Part 100
. Hydrogen generation shall be limited to less than one percent of the amount that would be generated by the complete oxidation of all metalin the cladding
. Calculated changes in core geometry shall be such that the core remains amenable to cooling.
. After any successfulinitial operation of the ECCS, the calculated core temperature shall be maintained at an acceptable low value and decay hent (heat trans/cr rate) shall be removed for an extended period of time required by the long lived radioactivity remaining in the core.
. Contml room operators shall not receive a radiation dose in excess of the values prescribed in 10 CFR 50. Appendix A, Criterion 19.
. Energy deposition of the fuel shall not exceed 280 callgm.
. Containment?
. Reactor Coolant System 1 S in some i tances, i 50.72 prescribes a four hour report instead of a one hour report in cases when the plant is shut dowrw -
2 The importance of the primary barriers for ensurism the protection of public health and safety. the Reactor Coclant System and Containment, results in their inclusion in the plant level criteria to assure appropriate consideration in the one hour NRC reporting criteria. The details of these system design bases would be provided in the system design bases sections.
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- Examnles of System Level Desien Bases Information (6 50.2 Scone)
NOTE: The examples provided are illustrative and are not inclusive. They are intended to provide the reader with a better understanding of the type of information that is considered to be design bases ( 50.2 scope)information. The specific values and criteria will vary from plant to plant because of a number of factors, including, variations in NSSS design, different architect engineers, and varying plant vintage.
In speciSc cases examples of engineering design bases information have been included in an attempt to emphasize the differences between the two sets of information.
Residual Heat Removal System PWR Residual Heat Removal System Design Bases Functions The primary function of the Residual Heat Removal System (RHRS) is to remove heat from the reactor core to mitigate the effects of an accident.
Desien Bases Values for Controlline Parameters used as Reference Bounds for the Desien qf RHRS:
- 1. The RHRS shall provide a minimum of XXX gpm Dow at YYY pressure to satisfy the core cooling requirement.
- 2. The RHRS shall remove a minimum of ZZZ hn% of heat from the reactor coolant system in the event an accident.
- 3. Fuel cladding temperatures shall be maintained at or below 2200*F 10 CFR 50.46(b)(1)
- 4. Total oxidation of the cladding shall be limited to 17% of the original cladding thickness.10 CFR 50.46(b)(2)
- 5. Hydrogen generation shall be limited to 1% of the amount that would be generated by complete oxidation of all metalin the cladding.10 CFR 50.46(b)(5)
- 6. A coolable reactor geometry shall be maintained.10 CFR 50.46(b)(4)
- 7. The core temperature shall be maintained within the acceptable limits during the long term post LOCA cooling phase.10 CFR 50.46(6)(5)
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l'.. BWR Residual Heat Removal System Design Bases Functions The primary function of the Residual Heat Removal System (RHRS), in the Low Fressure Coolant Injection (LPCI) Mode, is to restore and maintain inventory in the re. actor vessel to satisfy the plant design bases for core cooling requirements.
The primary function of the RHRS, in the Suppression Pool Cooling Mode, is to ptt vide sufficient decay heat removal capability to satisfy the plant design bases for cantainment for anticipated operational cccurrences and accidents and to assure the continuity of core cooling.
Desien Bases Values for Controlline Parameters used as Reference Bounds for the Desien of RHRS:
- 1. The RHRS shall provide a minimum of XXX gpm flow at YYY pressure to satisfy the "Are and containment cooling requirement.
- 3. The RHRS shall ensure that the Suppression Pool Temperature is less that the Heat Capacity Temperature Limit of ZZZ *F.
- 3. Fuel cladding temperatures shall be maintained at or below 2200*
10 CFR 50.46(bX1)
- 4. Total oxidation of the cladding shall be limited to 17% of the original cladding thickness.10 CFR 50.46(b)(2)
- 5. Hydrogen generation shall be limited to 1% of the amount that would be generated by complete oxidation of all metalin the cladding.10 CFR 50.46(bX3)
- 6. A coolable reactor geometry shall be maintained.10 CFR 50.46(b)(4)
- 7. The core temperature shall be maintained within the acceptable limits during the long term post LOCA coolir.g phase.10 CFR 50.46(b)(5)
- 8. System design pressure (XXXpsi) and temperature (XXX*F)
- 9. The design code is ASME Section III(19XX) x
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f I _ - _ __ __ _ __ -_ _ __ _ _ _ _ _ _ _ __ __ _ ___ __ ____ ___ __ _ __ . _ _________________ ___
. Emergency DI:s:1 Gencrctor Syst:m The primary function of the Emergency Diesel Generator System (EDG)is to provide electrical AC power to shut down the reactor and maintain it in a safe shutdown condition in the event of a loss of offsite power.
Desien Bases Values for Controlline Parameters used as Reference Bounds for the Desien of the Emercency Diesel Generator EDG) System
. Each generator shall provide power to its associated AC electrical division sufficient to safely shutdown the plant and maintain it in a safe shutdown condition for loss of offsite power and for design bases events.
. Each diesel generator shall be provided with its own fuel supply system with sufficient capacity to supply the generator for 7 days at full power.
. Each diesel generator shall be capable of operating in its service environment during and after a design bases event without support from offsite power. Each generator shall be able to start and operate with no environment cooling available for the time required to bring the cooling equipment into service as it sequences on to the bus.bar.
. Each diesel generator shall be capable of supporting *he loading sequence to full load within 65 seconds following the loading sequer< given in table XX.X.
. The air start receivers shall have sufficient capacity for at least two starts without recharging.
. **The diesel generator sets and their associated systems shall be designed and installed to withstand, or are protected from natural phenomena events as described in the natural phenomena design bas 3s document, and are designed to meet their design bases function during a natural phenomena event.
. **The indication of essential diesel generator parameters are to be available in the control room
- Indicates attribute may be included in a topical of other system document Examoles of Encineerine Desien Bases Information for EDG System
. The diesel generating shall be capable of ensuring that during recovery from transients caused by step load increases or resulting from the disconnection of the largest single load, the speed of the generator set will not exceed the overspeed trip set point.
41
.,. . The diesel generator sets shall be capable of ensuring that nominal frequency is restored within 2% of nominal within 10 sees. following a trip and restart of the largest electrical load.
. The diesel generator sets shall be capable of ensuring that nominal voltage is restored within 105 of nominal within 10 secs, following a trip and restart of the largest electricalload.
. Each diesel generator shall have a continuous load rating of XX.XX MVA at 0.8 power factor, with a two hour 110% overload rating in any 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period.
Containment System -
The primary function of the Containment System is to provide an essentially leak-tight barrier against the uncontrolled release of radioactivity to the environment.
The barrier is designed to remain effective for as long as postulated accidents require.
Dnign Bases Values for Controlline Parameters used as Reference Bounds for the Desien of the Containment System
. The Containment System shall provide a barrier which,in the event of a loss of-coolant accident (LOCA), controls the release of fission products to the secondary containment and the environment to ensure that any radiological dose to the public is less than the values prescribed in 10 CFR Part 100.
. The Containment System shall be capable of maintaining its leakage rate performance for at least 30 days following the accident.
. The containment structure shall maintain its functional integrity during and following the peak transient pressures and temperatures which would occur following a design basis LOCA.
. The system shall be capable of rapidly shutting or isolating all pipes or ducts which penetrate the containment boundary to maintain the offsite dose below that set forth in 10 CFR Part 100.
. The containment structure provides means to channel the flow from postulated pipe ruptures in the drywell to the pressure suppression pool.
. The Atmospheric Control (ACS) shall establish and maintain the containment atmosphere to less than 3.5% by volume oxygen during normal operating conditions. -
. The design pressure of the containment is XX psig and -XX psig. The design temperature is XXX*F. ,
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-e **The Containment Syster, shall be designed and installed to withstand and '
remain functional during and following any natural phenomena design bases d
events as described in the natral phenomena design bases document,
. **The. containment structure shall be protected from or designed to withstand hypotbetical missiles from internal sources and uncontrolled motion of broken pipes which might endanger the integrity of the containment.
e **The status of all automatic containment valves shall be displayed in the
, control room.
- ** System controls shall be desi;;ned to operate and control the system to ensure
- .. the safety functions are fulfilled from the Control Room and the Remote Shutdown Panel.
, e ** Containment isolation valves shall be located in the system per the requirements of the Containment design criteria document, f
- Indicates attribute may be included in a topical of other system document l Exampjes of Enrineerine Desien Bases Information for the Containment System e . The containment structure and isolation system, with concurrent operation of other accident mitigation systems, shall be designed to limit fission product
, leakago, during and following a LOCA to less than or equal to L.,1.2 percent by weight of the containment air per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at P.,42 psig. This results in offsite dose less than the value set forth in 10 CFR Part 100.
e The containment structure shall be designed to withstand coincident fluid jet forces associated with the flow from the postulated rupture of any pipe within containment.
I Auxiliary Feedwater System The primary function of the Auxiliary Feedwater System (AFW)is to provide feedwater to the steam generators to assure decay heat removal following a design E bases event.
Desien Bases Values for Controlline Parameters used as Reference Bounds for the Desien of the Auxiliary Feedwater (AFW) System
(
e The system shall supply a minimum of)OOfgpm of feedwater to the steam generators within xx secs of a design bases event using onsite or offsite power .
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supplies.
. System design pressure ()OOCpsi) and temperature (XXX'F) 43
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- The design code is ASME Section HI(192)
. The system shall be capable of providing alternative long term decay heat removal (Heat Transfer Rate)via the turbine driven auxiliary feed pump with manual operation of the atmospheric dump valves.
- The Auxiliary Feedwater system (AFWS) functions to automatically initiate AFW to either steam generator, on low steam generator level (level Xm) within H secs.
- The following topical design bases elements apply to the Auciliary Feedwater System:
- The system shall be designed and installed to meet the seismic design ,
criteria speci6ed in the FSAR
- Equipment subject to a harsh environment during normal operation or during a design bases event shall be environmentally qualified to perform it safety function.
- The system shall meet the single failure criteria.
. The system shall be protected from, or be able to withstand the natural phenomena specified in the FSAR.
. The system shall be protected from, or be able to withstand the effects of internal and external missiles, pipe whip, or jet impingement.
- The system shall be capable of performing its safety function during a loss of effsite power.
- Indicates attribute may be included in a topical of other system document Low Pressure Core Sorav fLPCS) System The primary function of the LPCS is to provide emergency core cooling at low reactor vessel pressures to mitigate the effects oflarge pipe breaks.
Desien Bases Wlues of Controlline Parameters used as Reference Bounds for the LPCS e Fuel cladding temperatuns shall be maintained at or below 2200 degrees Fahrenheit (10 CFR 50.46(b)(1))
. Total oxidation of the cladding shall be limited to 17% of the original cladding thickness. (10 CFR 50.46(b)(2))
. Hydrogen generation shall be limited to 1% of thr, amount that would be generated by complete oxidation of all metalin the cladding.
~
(10 CFR 50 46(b)(3))
.- A coolable reactor core geometry shall be maintained. (10CFR 50.46(b)(4))
44
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. o The core temperature shall be maintained within cecept2ble limits during the long term post.LOCA cooling phase. (10 CFR 50.46(b)(5))
. Parameters used to bound LPCS capability to meet the above criteria:
a) Core thermal power: 105% of rated steam flow b) Vessel steam dome pressure: 1055 psia c) LPCS system at rated Dow -
d) Vessel pressure at which LPCS flow starts: 289 psia e) Assumed pipe break is a double. ended rupture of one reactor recirculation system suction pipe.
- The LPCS is classified as Seismic Class I and shall be designed to meet the structural requirements of this classiScation. (GDO 2, RG 1.29)
. The LPCS shall be designed so as to maintain the integrity of the reector vessel and primary containment during and after a design basis event.
(GDC 14,16)
. The LPCS shall be capable of performing its safety function for 4320 hours0.05 days <br />1.2 hours <br />0.00714 weeks <br />0.00164 months <br /> in a harsh environment following a design basis accident.
(GDC 4, RG 1.89, NUREG 0588)
. The LPCS shall be capable of performing its safety function for 4320 hours0.05 days <br />1.2 hours <br />0.00714 weeks <br />0.00164 months <br /> following the safe shutdown earthquake, which may or may not coincide with a design basis accident. (GDC 2. RG 1.29)
. The LPCS shall be designed, fabricated and installed to ASME Section III requirements
. The LPCS shall be protected from the effects ofinternally generated missiles.
- e 45
e Examnle of Comnonent Level Desien Bases Main Steamline Flow Restrictors The primary function of the Main Steamline Flow Restrictors is to limit the amount of reactor coolant release prior to the shutting of the main steam isolation valvss.
Desien Bases Values for Controlline Parameters used as Reference Bounds for the Desien of the Main Steamline Flow Restrictors
. The system shall be designed and installed to limit the loss of coolant from the reactor vessel following a steamline rupture outside the containment to the extent that the reactor vessel water level remains high enough to provide cooling within the time required to close the main steamline isolation valves.
. Limit the maximum pressure differences (XXXpsi) expected across the reactor internal components following complete severance of a main steamline.
. Provide trip signals to shut the MSIVs within (X.X secs).
Reactor Vessel The primary function of the reactor vessel is to provide a high integrity pressure boundary to contain the reactor coolant, the reactor core, and fission products.
Desien Bases Values for Controlline Parameters used as Reference Bounds for the Desien of the Reactor Vessel
. The reactor vessel shall provide the reactor coolant pressure boundary to contain the reactor coolant, the reactor core, and fission products.
. The reactor vessel shall provide support for the reactor internals and the core to ensure the core remains in a coolable configuration.
. The reactor vessel shall direct main coolant flow through the core in a manner that sustains coolable geometry by close interface with the reactor internals.
. The reactor vessel shall provide support and the basis for alignment for the control rod drive mechanisms, in core instrumentation assemblies, the reactor core internals, and the reactor vessel head assembly.
. The reactor vessel provides the seal between the refueling cavity and sump during refueling operations.
. The vessel shall be designed and fabricated to ASME Section III requirements, with a design pressure of 2485 psig, and a design temperature of 650*F
. The maximum limit for chemical elements in the reactor vessel beltline regian ,
are: Copper 0.03%, Phosphorus 0.01%, Vanadium 0.05%, Sulfur 0.01%,'and Nickel 0.85%
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Toolcal Desien Bases i
Topical design bases can be used to cover design bases topics that are common to numerous systems, structures , or components, such as the following areas: natural phenomena, (e.g., tornadoes, hurricanes, flood protection, tsunami and storm surge,
. seiches, and seismic), internal Gooding, and environmental qualification, etc., .
. These documents would normally be referenced in a system, structure, or component level design bases document.
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_ -~ . - . ._ _ _ _ .. _ _ _ _ _ . . _ _ _ , .
- Anoendir C Examoles of Sources of Suonortine Desirn Information
. Engineering evaluations, practices, procedures, and instructions e Computer codes used for design or design analysis e Design baseline analyses and calculations to establish effects of postulated accidents, including:
- transient analysis
>
- seismic site specific criteria
- flooding site specific criteria e Calculations or analyses that verify that the restraints imposed by the design '
bases have not been exceeded, including:
- component classi5 cation evaluations
- load sequencing and electrical supply sizing calculations a setpoint calculations and methodologies
- equipment sizing calculationr, a motor operated valve calculations, analyses, or test results that establish switch tolerances / settings
. Reports and engineering studies that verify that the restraints imposed by the design bases have not been exceeded, including:
- equipment quali5 cation
- fire protection safe shutdown capability assessment
- relay protection coordination studies
. Personnel involved or famular with the original design activities a Correspondence, meeting minutes, and other documents pertaining to the original design 4
e 48
i Annendix D
} . .-
Exaxpoles of Sunnortina Desian Information NOTE:This information s should be used with appropriate input from the design authority.
Supporting design information provides the rationale for design bases functional requirements and values or ranges of values for controlling parameters, and provides reference material for the detailed design that supports the design bases.
This information can be collated on a structure, system, or component level.
, However, it should be recognized that component level design bases are often derived from the system level design bases.
! Examples of supporting information for the engineering design bases have been
- included in an attempt to emphasize the differences between the type of
, information associated with the two design bases: engineering and i 50.2 scope of
-- design bases.
The following are examples of supporting design information:
System Level Information
- Design Bases Requirement - LPCS injection flow starts at vessel pressure of l 289 psia.
Supporting Rationale - 289 psia is the difference between the drywell atmosphere and reactor at the time of LPCS injection assuraed in the LOCA analysis. (ref. na)
- Design Bases Requirement - High pressure injection flow must reach the
- reactor vessel within 25 seconds after ESAS signal.
Supporting Rationale - 25 seconds is the desired response time to mitigate a small break LOCA. Note: The small break LOCA analyscs assumed a 35 second response time for conservatism. (ref. pq) .
e Engineering Design Bases Requirement - CSS must maintain a minimum i post. accident sump pH of 8.5.
Supporting Rationale - A pH of 8.5 is specified to assure iodine retention in solution. (ref. xy) 1
. Supporting Design Information for Engineering Design Bases: The AFW suction header is 12 inches to (nable the system to supply 1950 gpm and provide adequate NPSH with three AFW pumps running simultaneously, one in runout, and the CST is at minimum level and maximum temperature for this flow rate.
(ref. gh)- .
. Supporting Design Information for Engineering Design Bases: Motor Operated Valve XYZ should open in ten seconds at a psid and 80% of rated 49
a
- s.
- l . voltage in order to rueet the system response time requirement of high pressure
, injection within 25 seconds at design bases conditions. (ref. mn)
. Supporting Design Infor:aation for Engineering Design Bases: Relief Valve ABC pressure setting of165 psig and flow rate of I gpm to meet ASME Section III, Section 7000 code requirements. Per code, pressure setting equals piping design pressure (ref ef), Flow rate should be sufficient to prevent a pressure greater than 110% of the design pressure due to thermal expansion and leakage through the reactor vessel isolation valves. (ref. gh)
. Supporting Design Information for Engineering Design Bases: Min. flow bypass valve XYZ should open in four seconds (the desired opening time). The valve should be designed to open as fast as practical to minimize the time that the pump operates deadheaded. Valve and bypass piping are speci5ed as 4 inch to pass pump min flow requirement (ref. st). Past experience had demonstrated that vendors can supply fast opening valves with stem stroke rates of one inch per second. Hence, a four second stroke time for this four inch valve was selected. (NOTE: ref. pq indicates that up to eight seconds is allowable.)
. Supporting Design Information for Engineering Design Bases: Reset relay for Alternate Rod Insertion system set for 45 2 seconds and is established by accident analysis (minimum time of 40 secs) to ensure all rod:: are inserted prior to reset (ref. kl). A maximum of 50 seconds is suggested to ensure reset is accomplished within a reasonable time, but it has no specific engineering significance.
. Supporting Design Information for Engineering Design Bases: AFW turbine feed pump governor is set 4100 to 4200 rpm to ensure sufficient S/G feed flow. 4100 rpm is established to ensure sufficient flow with the maxunum RCS pressure, maximum flow losses for tha piping configuration, maximum recirculation Dow of 15 gpm, and minimum NFSH. The 4200 rpm is set to prevent overpressurization of the discharge piping at maximum suction pressure and minimum flow conditions. (ref. xy)
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. Annendir E Potential DBD, Anolications ENGIhTERING
= Conceptual ~ design development and alternative considerations
. Design speci5 cation for in house or contractnr designers and for inter-discipline coordination
- Calculations and analyses
. Bases for technical reviews, safety reviews, and 10CFR50.59 safety evaluations
- Independent design veri 6 cation
- Procurement specifications
- Identi5 cation ofinformation and documents affected by change
- Installation speci6 cations
- lnstallation and functional testing requirements and acceptance criteria
. Field change request evaluations
- Evaluations of operational events and non conforming conditions
. Justifications for continued operation (JCOS)
- Selection and review of equipment performance surveillance data e Bases for operations, maintenance, and surveillance procedures review
. Evaluation of material substitution, spare parts equivalency, and material upgrades OPERATIONS e Abnormal event assessments
. Reportability determinations
. Bases for unusual system alignment (e.g., for maintenance or testing) assessments
. Temporary modiEcations reviews
. Selection and review of component and system performance data e Addressing non proceduralized events
. Operator aids and trairiing material development
. Operations procedures preparation and review MAINTENANCE
- Post-maintenance test requirements and acceptance criteria e Procedure and work instruction preparation and review e Assessment of material condition requirements 51
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LICENSING
. Licensing analyses (e.g., FSAR)
. Technical specifications review and changes
. License amendments
. Reportability determinations TRAINING
. Bases for lesson plans and training materials
. Simulator 6delity OTHER
. Performing technical audits
. Determining recommendations for reducing personnel doses
. Safety System Functional Inspections
. Probabilistic Risk Assessments
. Margin Management
. Setpoint Selection
(
52
eg O A_ noendir F o,
l Q1hu Tvoes ofInformation to Consider for DBD_s This appendix is a compendium of other types ofinformation that may be collated or referenced in a DBD, The types ofinformation included in the DBD should be directly related to speciSc user needs in support of the overall program objectives.
. System Descriptions A narrative discussion of the system configuration, system boundaries (highlighted drawings such as P& IDS, etc.), functional and operational requirements for all plant modes and operating conditions.
This information is generally obtained from:
. NSSS supplier and A/E system descriptions,
- original design interface documents,
. FSAR, and
. system design speciScations, drawings and calculations.
. Regulatory requirements A listing of applicable 10CFR50 Appendix A, General Design Criteria, and other regulatory requirements, and discussions of applicable accident scenarios that require the system to operate end the operational requirements that should be met.
. Codes and Standards - Identi5 cation of the original bases, codes and standards (including year and addenda) adopted that specifically apply to the DBD an a whole.
. Functional Process Requirements A listing or narrative description of the system process requirements. This may include the following:
. system flows, pressures, and/or heat loads,
. special system design considerations such as net positive suction head requir ements,
. plant transients and accidents the system supports and how the availability of the system is ensured, e a brief description of environmentallimitations on system operation, such as normal tadiation fields and possible post accident conditions, and
. key instrumentation and control requirements to provide remote shutdown capability and enable local monitoring of process activities.
The information to support this section could be obtained from the system calculations, FSAR, system interface specifications, the plant accident analyses, or the original NSSS supplier and A/E design engineer's file. In addition, some information could be obtained from the specialized plant hazards analyses, such as the fire hazards analysis, high energy line break analysis, and the harsh environment analysis.
. System Interfaces - A listing or narrative description of other interfacing
- systems that are required for the subject system to perform its function.
l 33
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The information to support this section could be obtained from system I
calculations, mechanical and electrical drawings, and system speciScations.
Frequently, calculations such as the electricalloading calculations or the instrument air system design calculations identify the specific system interfaces for these systems.
. System Interlocks Descriptive information on interlocks with interfacing systems, the logic at the interlock, bases ofinterlock and reference to logie
, diagram.
. System Performance Requirements Description of the safety related and non safety related performance requirements and why thcy are required, for the system and the as. built system conSguration which satisSes each requirement. .
- Structural Requirements Discussion of the seguirements for seismic, wind, thermal, water and any other static and dynamic load conditions (including accidents), stress, shock and reaction forces. Equipment foundations and major components (e.g., tanks, pumps, heat exchangers, ducts, duct supports) may be discussed, e Separation / Redundancy / Diversity Requirements SpeciSc requirements which apply to the system.
. External Hazards Discussion of the applicability of certain external hazards to the system could be addressed in Topical DBDs, such as Environmental QualiScation Requirements, Seismic Requirements, Fire Protection Requirements, and Environmental Protection Requirements (e.g., Flooding Protection, Missile Protection, Tornado Protection, Pipe Whip and Jet Impact Protection) e Special Material or System Chemistry Considerations - Discussion of any special materials used in the system or components and the basis for material selection. Any materials which are prohibited from use in components / systems shall be stipulated. In addition, any special system chemistry considerations could be defined and discussed in this section.
Inservice Inspection Requirements - Discussion ofInservice Inspection (ISI) and Inservice Testing (IST) as required by Section XI of the ASME Code.
These requirements could be summarized and the procedures that implement the specific ISI and IST requirements could be listed or referenced, e
Component Engineering Design Bases Requirements - Unique component level engineering design bases requirements and assumptions such as capacity, reliability, seismic and environmental requirements, coder and standards. Discussion could include the following: -
54
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$. o description of each major component,
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- a discuss ;on of operating modes and the role of the component in the system, and
- a discussion of how the installed component con 6guration satis 5es the system design bases requirements.
The information in this section could be presented in the form of criteria statements with tables and grapha vaed to specify operating limits.
The information to support this section could be obtained from the procurement speci6 cations, the original design engineer's file, vendor manuale, startup test data, and/or system calculations.
- Postulated Failures Description of failure modes considered in the system design. It could include passive failures, such as pipe breaks, and active failures, such as failure of a valve to close or a pump to start on demand. A discussion of the impacts of a postulated support system failure, such as a valve repositioning on a loss ofinstrument air, could also be included.
Information to support the development of this section could be obtained from the SAR accident analyses, the regulatory Safety Evaluation Reports for the plant, system design drawings and component specifications, and system tetts. In addition, plant events may require special tests or analyses that can
, be used as inr ts to this section.
e Testing and Testability Requirements Those unique system testing requirements which resulted in special system design features.
The information to support the development of this section could be obtained from the original system design specifications, operating experience sith similar equipment (such as turbine trip testing capability), startup testing requirements, Technical Specifications, surveillance testing requirements, l and ISI requirements. Additionally,information could be obtained from i correspondence that denotes specific utility desires for system testing and performance monitoring capability.
i e Operational Limitations and Precautions - Description of specific operational requirements considered in the design, such as the following:
- special operational actions to be taken in the event of component I failures or unusual operating conditions (such as severe weather),
a special system interlocks requirements, and a key operational considerations for equipment and personnel protection.
l l The information to support the development of this section could be obtained from systenrand component design specifications, correspondence between the utility and the NSSS supplier or A/E, and calculations that evaluate system performance under unusual operating conditions, such as tornadoes,
$5
- or o j
5, [ droughts, er extreme haat er cold. Experienca has shown that much of the
. information for this section may need to be recreated.
l
- ' Change History Description of the design change history. The change history section is either a narrative or a listing of changes to the system since the issuance of the plant operating licene with an erplanation of the need for each change. The advantages of this infinnation are as follows:
e provides a ready source of rationale for past changes to systems, components, and structxre.
- aids the review procus to ensure design bases re auirenants are updated and design continuity is maintained, anil -1
- essists the process of root cause determination o' operational problems. l
. Margin Description of applicable margins. This section could be presented as a table that shows the allowable parameter k vels and the expected parameter leveb the system will experience durirq operation. It could be invaluable when evaluating operability concerns. In addition, this section could be a key input to the preparation of safety reviews, since this information clearly addresses the impact of changes on the margin of safety.
However, this can be a difficult section to develop in that system sensitivity '
analyses may not have been performed which would enable identifying all component margins. Identifying and documenting margins when specific design bases information is being developed or as subsequent analyses are performed could be a valuable reference.
- References - A listing of the documents containing design bases information.
These include drawings, specifications, calculations, engineering, correspondence, (vendor & regulatory) topical reports, vendor evaluations, *
. engineering evaluations, engineering safety evaluations, and other data.
l
- Tables / Figures / Appendices Tables and Sgures may be utilized to list data.
All tables and figures should be referenced to appropriate section.
4
- Miscellaneous Items The following items should be standard items considered for DBDs:
i
- DBD Cover Sheet -
- - DBD Media (Hardcopy/ Computer dises)
- List of effective pages
- Table of Contents -
- List of Tables List of Figures (including DBD boundary definition) a 0
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