ML20006C395
| ML20006C395 | |
| Person / Time | |
|---|---|
| Issue date: | 01/30/1990 |
| From: | Grimes B Office of Nuclear Reactor Regulation |
| To: | Rasin W NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT & |
| References | |
| NUDOCS 9002070440 | |
| Download: ML20006C395 (5) | |
Text
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January 30, 1990 Mr. William H. Rasin, Director Technical Division Nuclear Management ALo R2 sources Council 1776 Eye Street N.W Suite 000 Washington, D.C.
20006-2496
Dear Mr. Rasin:
We appreciate the opportunity to have met with representatives of your Design
' Basis Issues Working Group for the purpose of discussing the first guideline that the Working Group developed on the handling of open items resulting from design reconstitution efforts. As you know, we have conducted a series of surveys (six utilities ano one nuclear steam supply system vendor) to develop information on industry design control programs and implementation of design reconstitution efforts. Our conclusions from those surveys will be documented in a forthcoming NUREG report.
In the interim, we have assembled the enclosed outline which describes some of the information gained during the surveys with respect to design reconstitution efforts.
We trust that the enclosed information will be of some value to your working group during the development of design reconstitution guidelines.
If you have the information conveyed in the enclosure, please any comments regarding(492-0903) or Mr. Gene Imbro (492-0954).
contact either myself Sincerely, Original signed by Brian K. Grimes, Director Division of Reactor Inspection and Safeguards Office of Nuclear Reactor Regulation
Enclosure:
As Stated Distribution:
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ENCLOSURE PERSPECTIVES OH DESIGN RECONSTITUTION PROGRAMS The NRC has performed a survey program to gain an underst6nding of the design reconstitution efforts and design control programs that are ongoing in the industry.. The survey team visited six utilities and one NSSS vendor. A standardized set of survey questions was utilized to gain specific utility feedback on their practices for design and design change cuntrol, drawing control, and the availability and accuracy of design documentation. An 6ssess-ment was performed of their design document reconstitution program, if in place. The survey results are currently being compiled into a NUREG that will provide NRC recommendations and conclusions regarding design control practices and the ongoing design docunient reconstitution programs based on the survey i
observations.
Some of the survey observations are provided below.
Need to Conduct a Design Document Reconstitution Program The perceived utility need for a design document reconstitution program wes found directly proportional with the age of the plant. Utilities with recent vintage plants have a design organization that participated directly in the initial design and construction of the plant and the design documentation is extensive and retrievable, therefore because of existing corporate memory they do not feel the need to collect the system and topical design bases in a i
central set of " upper tier" documents.
The following factors were identified as important for consideration by utili-ties in evaluating their organizations to determine the need for implementing some form of design document reconstitution program:
- 1) loss of utility, A/E, and NSSS vendor engineering and design corporate memory through personnel attrition; 2) the normal evolution of the utility organization from a design to an operating orientation with the typical shif t in priorities away from expend-ing-resources to maintain and up-date design documents; 3) lack of a central-ized design engineering organization with the responsibility for design control / configuration management shifted to the operating organization;
- 4) extensive reliance upon contracted engineering services with minimal licensee capability to provide technical oversight; 5) the availability of design bases and design analysis and calculations to support the "as-configured" plant; and 6) the ability to make timely operability i
determinations.
Design Document Reconstitution Program Scope Design document reconstitution programs have varying levels of information contained within the documentation with respect to content, format, and level of detail.
It is the prerogative of each utility to develop their approach based upon their unique needs. The general intent of the reconstitution program can be to provide a central location 1or design basis information with emphasis on the design intent (the why of the design) and be a top level directory to the design documents that define the current plant configuration.
The end result will provide information that will aid with the preparation of plant modifications and safety evaluations, and to aid in the development of m
su
,[i justifications for continued operation. The end users of the documentation can be identified end the content and format structured accordingly.
Design tas',s v's. Design Document Reconstitution One aspect of the reconstitution program is the identification of the functions performeo by structures, systems, and components and the values or ranges of controlling parameters in accordance with the definition of design bases in 10 CFR 50.2.
However reestablishment of the " design bases" without reconstitu-tion of the supporting design documents, as necessary, may not provide a sufficient level of information for the basis for future modifications. The program could also integrate an effort to establish that the supporting design documentation (essential documentation) is available, accurate, and that the reconstituted design documents accurately reflect the plant configuration. The objective woulo be to establish a continuity among the various levels of design information and physical plant characteristics.
Availability of Design Documentation Some utilities began licensed operation before the advent of design document controls such as 10 CFR 50 Appendix B and relevant ANSI standards. Because of this, and other reasons, the necessary documentation to demonstrate the accept-ability of plant modifications is not available. The spectrum of design cocumentation can be reviewed to identity the set of essential documentation necessary to support Technical Specification limiting safety system setpoint, 4
Technical Specification operating limits and bases, and to demonstrate that safety systems are designed and are being operated in accordance with their design bases. Regeneration of the missing documentation may be appropriate in a time-frame based on the safety significance.
Control of incremental Changes The surveys found that minor changes involving such things as electrical loads on Class IE buses, fluid system resistance, valve weight changes, and pipe hanger relocations are not clearly documented within existing calculations when an engineering determination concludes the item is inoividually insignificant.
While it may not be necessary to revise major calculations for incremental parameter changes, based upon engineering judgement, it is appropriate to track these changes to support the conclusion that the changes in aggregate do not affect the validity of the existing calculation and the ability of a system,
. structure or component to perform its design safety / design functions.
It is apparent that some controls are needed for the logging of incremental changes such that they may be assessed in total when a subsequent modification is performed.
Operability /Reportability Determinations for Missing Documents A design document reconstitution program can result in the identification of missing design documents with varying degrees of safety significance. Some may be minor inconsistencies in documentation while others can involve the possi-bility of operating the plant outside the design bases or in an unanalyzed cordition that will necessitate immediate action.
it is incumbent on the personnel involved with a reconstitution program to assess in a timely manner the concerns that have potential operability aspects. These concerns need to be escalated for a formal operability review on a tine scale commensurate with 2
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i theie safety significance. Applicable technical specification action state.
nents are entered as appropriate when the operability determination has been made. A justification for continued operation and an action plan can then be developed as needed on a time schedule commensurate with the safety significance.
The determination of operability /reportability is a continuous process, if new information comes to light which changes the characteristics of a previously identified issue, the operability /reportability aspects need to be promptly reconsidered. The reportebility decision follows directly from the operebility determination.
If the operability determination reveals that the plant was operating in an unanalyzed condition or outside its design basis, the item would be processed in accordance with normal reportability mechanisms.
Utility /NRC dialogue during the reconstitution process is appropriate so that -
operability issues can could be discussed even if a requirement for forral notification is not evident.
I Design Document Reconstitution (DDR) Programs Self-initiated DDR programs were found to have several common weaknesses as discussed below.
1)Thedesignreconstitutionprogramsreviewedtodatehavenotidentifieoin l
advance the documents that are necessary to demonstrate that a structure, system or component will function properly. An alternative approach would be to initially develop a template identifying the set of design documents that will be known as " essential documents." This " template approach" could serve to define the set of design documents necessary to a) establish and define the functionality and operability requirements of systems, structures and compo-nents, and b) demonstrate the systems, structures and components conformance to the design bases, and c) identify the available margin. A review could be performed utilizing the " template approach" (i.e., compare the essential document list with available design documents). Missing documents would be i
identified and prioritized for reconstitution as appropriate.
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Essential documentation could be further subdivided as follows:
Category 1 - Design documentation that supports or defines technical 7
specification safety limits, limiting conditions for operation, limiting l
safety system setpoints, surveillance requirements or bases, or that I
denionstrates that systems, structures or components addressed in the l
plant's technical specifications will perform their safety function.
Category II - Design documentation that defines controlling parameters or demonstrates the functionality of safety-related SSC that are not explic-itly addressed in the technical specifications but which provide a sup-porting function to the SSC addressed in the technical specifications.
l Category III - Design documentation that defines controlling parameters or demonstrates functionelity of safety-related SSC not included in Category I or 11.
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4 Category IV - Design documentation that defines controlling parameters or demonstrates the functionality of safety-related SSC with-regard to passive considerations (i.e., seismic).
Category V - Design docunentation that demonstrates the design of non-safety SSC is such that its failure would not impair the functionality of a safety-related SSC (i.e., seismic 11/l).
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- 2) The process for the regeneration of missing design documentation was not
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always proceouralized so that it could be handled in a systematic manner.
The regeneration of the missing docucents can be based upon the safety significance of the documentation. Particular emphasis for regeneration can be placed on documents necessary to show compliance with plant technical specifications, that define technical specification bases, or those necessary to demonstrate functionality of safety systems during postulated accidents or plant transients.
~3) The valid 6 tion of the content of specific DDR output documentation such as i
system or topical summary design documents was not always thoroughly carried out. Some level of valication of the plant configuration with respect to the reconstituted design documents is appropriate. The validation needs to address functional performance and interface requirements established within the design documents. Associated plant configuration management initiatives can be integrated into the validation program as appropriate.
- 4) One important intangible benefit from a design document reconstitution program performed with strong participation of the utility's staff is the in-depth understanding that is gained of the plant design bases. Some utili-ties that have implemented DDR programs have engaged the services of contracted engineering organizations to develop the DDR sunnary design documents. The end result is that the summary design documents are turned over to utility L
personnel who have not gained a working knowledge or appreciation of the design considerations embodied in the final design since the detailed review was performed by contractors.
In this instance, the sumary design document can l
become a less than useful document due to a lack of understanding and acceptance of the document by the working level utility staff.
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