ML19347C095
| ML19347C095 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 10/14/1980 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML19347C094 | List: |
| References | |
| NUDOCS 8010160574 | |
| Download: ML19347C095 (6) | |
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APPENDIX "A"
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AN EVALUATION OF Tile SEISMIC CAPACITY OF Tile
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YANKEE NUCLEAR POWER STATION F
T Yankee Atomic Electric Company Nuclear Services Division
.25 Research Drive Westborough, Massachusetts 01581 l
October 14, 1980 m
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ABSTRACT
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l Studies have been conducted to evaluate the seismic capacity of
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the major systems and structures of the Yankee Nuclear Power p
Station.
The results of those studies are used, along with industry experience and other published studies, to evaluate the l
other systems and structures at the plant.
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It is concluded that the inherent capacity of systems and i
structures, combined with the modifications being made to the
- plant, provide adequate seismic resistance to ensure that continued plant operation during the time period of the NRC Systematic Evaluation Program (SEP) seismic review presents no undue risk to the health and safety of the public.
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I Structural Evaluation of Yankes Nucletar Power Station Yankee Atomic Electric Company, in conjunction with its consultants, has been conducting seismic evaluation studies for the past two years on the Yankee Nuclear Power Station.
l The results of those studies are included as Appendix I to this report.
The inherent suismic capacity of well engineered systems and structures has been recognized by the NRC. This report and the attached Appendix expand the existing data base with specific information relating to the Yankee Nuclear Power Station.
As discussed in the Appendix, the capacity of the major plant systems and structures meets or exceeds the loading from the site specific seismic input 2
developed by Yankee, when compared against current day NRC structural f
acceptance criteria.
Even when evaluated against the conservative LLL/ TERA spectrum 3 the systems and' structures are shown to have adequate margin to failure (under the more severe seismic loading more rigorous analytical methods are employed and concepts such as dactility and plasticity would be utilized).
The studies to date have concentrated on the major systems and structures.
However, the results from these studies can be extrapolated to the remaining systems and structures when consideration of industry experience is made.
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NRC Director's Denial DDl-80, 01/10/80.
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YAEC letter to.NRC, 05/07/80.
3 NRC letter to YAEC, 08/04/80....
The piping at the Yankee Nuclear Power Station was designed, fabricated and installed in accordance with the rules of the B31.1 Power Piping Code, 1955 Edition.
Systems important to the prevention of nuclear accidents _ received non-destructive examination (NDE) similar to that currently defined in the ASME Section III Code.
Various studies have demonstrated that the B31.1 Code is
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basically identical to the current ASME Section III Code; the k
differences are in areas that generally do not govern design.
The major limitations in piping that was not explicitly designed for seismic loading is the reduced number of lateral restraints, compared to seismic piping.
Worldwide experience has shown that well designed piping systems, even those not explicitly designed for seismic loading, can tolerate seismic excitations well in excess of the Yankee id'entified site seismic level without damage.
The ductile behavior of the materials used for nuclear systems provides assurance of significant capability for deformation without rupture; thus even though system function could be affected breach of the pressure boundary would not g
occur.
Extrapolation of the results on the major structures is somewhat difficult since the auxiliary structures are of different types of constructian.
However, since the integrity of the reactor coolant pressure boundary and containment pressure boundary (vapor container) are assured for even the most severe posulated seismic event the need for the auxiliary structures is minimal.
Not discussed explicitly in this report, but presented elsewhere a
in published material, is an evaluation of the plant site with respect to the low population density in the surrounding area and
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the historic low seismic activity of the site.
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Conclusion Our studies have shown that the plant requires no' modification to accept,
- under current NRC criteria, a seismic event equal to the largest one calculated at the site in excess of 300 years of history.
Considerably greater events can be tolerated when consideration is given to the actual seismic properties of the site.
Thus, it is the conclusion of Yankee Atomic Electric Company that, when consideration is given to the-probable seismic event at the reactor site, adequate capability exists in thc critical' systems and structures to ensure that -continued plant operation during the SEP seismic study presents no undue risk to the health and safety of the public.
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APPENDIX I O
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