ML20083C838
| ML20083C838 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 09/20/1991 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TXX-91337, NUDOCS 9109270185 | |
| Download: ML20083C838 (2) | |
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1UELECTRIC Log # TXX-91337 File # 10010 v unem J. cahill, Jr.
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Ref. # 10CFR50, App. B St.ptember 20, 1991 U. 5. Nuclear Regulatory Commission Attn: Document Control Desk Washington,.D. C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES) Unit 2 DOCKET NO. 50-446 UNIT 2 DESIGN VERIFICATION REF:
- 1) TXX-88254 dated March 16, 19'8
- 2) NUREC-0797, Supplemer.t No. 17, November 1988, Section 5.1
- 3) TXX-89271 dated May 19, 1989
. Gentlemen:
Ouring the recently completed internal construction assessment on CPSES Unit 2, a questio.i was -raised regarding the scope of the design verification progrem.
Ia formulating the response to this question, it was determined that the curr0nt Unit 2 design verification program satisfies regulatory requh'em6nts. However, because design verification has been the subject of previcus correspondence-batween TU Electric and the NRC, this lette" is being submitted to assure a consistent understanding continues to exist tetween TU Electric and the NRC regarding CPSES Unit 2 design verification activities.
10CFt150, Appendix B, Criterion III specifies, in part, that design control measures s1all provide for verifying or checking the adequacy of design.
CPSES implements these requirements through its commitment to ANSI N45.2.11-1974. _During construction of CPSES Unit 1, those safety related documents which established design criteria, approach, and methodology were design verified.
In addition, to conservatively assure the proper review of the transfer of design information to other documents, design verification program requirements were also applied to other safety related drawings.
This
- 2. gram was described to the NRC in Reference 1 and acknowledged in Reference pro 0
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TXX-91337 Page 2 of 2 of Unit 2 commodities in the common areas prior to Unit 1 fuel load. Reference 3, d letion enhancements, based on experience gained during completion of Unit 1, maintained the TU Electric emphasis on quality while improving engineering and construction processes.
These concepts were continued in the restart of Unit 2 in June 1990.
One of these enhancements was to utilize reviews and checks in lieu of design verification for the transfer of design information from DBDs, specifications, calculations, etc., to other docume.'ts.
In developing these enhancements, it was determined that the processes wnich controlled the transfer of design information from design documents to other documents would provide assurance equivalent to that provided by design verification in that the integrity of design was maintained during transfer.
The basis for this conclusion was that the transfer would be subjected to procedurally mandated reviews and checks, and the information which would be transferred would have already been ubjected to design verification requirements. As an example, the design ver.f1 cation for a pipe support design is accomplished through the design verifict tion of a pipe support calculation.
The associated pipe support drawing is a pictorial representation of the calculation results, and the drawing does W include any design requirements not already contained in the design verified documents. The drawing is reviewed to assure that the design information from the calculation is appropriately incorporated into the drawing. The drawing, coupled with the installation and inspection requirements of the installation specification (a document subject to design verification), provides necessary engineering direction for installation of the verified design. As a result, it was decided to structura the Unit 2 design verification program around " Key Design Documents." This concept was presented to the NRC during i
'"1v 17, 1990, Public Heeting, the purpose of which was to present the plan!
ming construction of CPSES Unit 2.
Key Design Documents are those des, aents which establish design criteria, approach, methodology or otherwl
..rine the design. Key Design Documents include safety related DBDs, flow diagrams, Instrument and Control Diagrams, one-line diagrams, calculations, and specifications.
This decision was reviewed internally with respect to earlier design verification program descriptions which was docketed in References 1 and 2, and it was determined that tle Unit 2 approach was technically appropriate, compliant with regulatory requirements, and consistent with the intent of the original design verification program.
Sincerely, W
With -
f.
William J. Cahill, Jr.
By:
Mb Roger D. Walker Manager of Huclear Licensing TLH:bm c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (2) i
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