Plant Building Steel
I. PURPOSE AND SCOPE
The purpose of the BNP plant building steel verification program is to close out Licensee Event Report (LER) 1-88-35, Unresolved Item (UI) 89-18-02, and the Notice of Deviation in NRC Inspection Report (IR) 92-14. LER 1-88-35 and UI 89-18-02 identified an overstress condition in one beam in each Reactor Building. In response, in 1990, CP&L began walkdowns of miscellaneous steel in the Reactor Building outside the drywell. Walkdowns and analyses performed to date have shown that, despite occasional minor construction variances, construction of miscellaneous steel in the Reactor Building outside the drywell is generally of good quality and none of the variances adversely affect safe plant operation.
The current verification program, which has been expanded by CP&L to include drywell platform steel (because of similarities with miscellaneous steel design and construction) is being accomplished in two phases. The Phase I Program consists of engineering walkdowns of miscellaneous steel outside the drywell to categorize each steel member and connection as adequate or requiring further action; the Phase I walkdowns will be completed during the current Unit 1 and 2 outages. The Phase II Program consists of analysis of representative platform sections in the drywell and in the Reactor Building outside the drywell, and of documentation and verification (through photographs, reviews, and measurements) of miscellaneous structural steel.
When this program is completed successfully, all the structural steel affected by the program will satisfy the design requirements of the 1978 Edition of the AISC Specification for the Design, Fabrication, and Erection of Structural Steel Buildings, consistent with the Brunswick Plant Updated FSAR. Furthermore, there will be greater assurance that plant drawings accurately reflect current as-built conditions.
II. EVALUATION
Schedule Index: (-13) - No nuclear safety problems have been found to date and none are expected; the purpose of this program is to verify that building steel meets design requirements in the updated FSAR. Nevertheless, even though the likelihood that a seismically-induced failure of a structural member could damage a safety-related system is very remote, such a failure could have an impact on a safety system function of high importance (0.2 x 32). The walkdowns necessary to implement the program will greatly increase the chance that a worker could be injured due to a fall or falling objects (-0.5 x 29) and will result in significant worker dose even though steps (such as the use of photographs) have been taken to minimize the accumulated dose for the project effort (-1 x 9). The added confidence in structural steel design margins and in the currency of design drawings and calculations, and the contribution these make to the efficiency of the modification process, represent a moderate plant enhancement (0.5 x 8).
Economic Aspects: This two-phase program is required to provide the assurance that building steel meets design requirements in the updated FSAR. Once completed, this program will result in negligible continued financial costs. The updated drawings and calculations resulting from the program will make subsequent plant modifications, which relate to or interface with structural steel, easier and quicker to complete.
Related Standards: The Work Management Policies for material condition and design documentation apply to this program.
Other Considerations: Walkdowns and photographs in the drywell require a plant outage to accomplish.
III. CONCLUSION
The Phase I Program is currently in progress and is scheduled for completion during the current Unit 1 and 2 outages, as are the drywell and bounding analyses portions of the Phase II Program.
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