Patent Number: 040452891
Section: summary

BACKGROUND OF THE INVENTION This invention relates to a nuclear reactor containment structure. In more detail, the invention relates to a reactor containment building having excellent resistance to wind and seismic forces. In still more detail, the invention relates to a reactor containment building for a Safety Research Experiment Facility which is designed to be used to investigate the performance and safety characteristics of fuels and fuel assemblies for large fast breeder reactors. Many nuclear reactors are enclosed within containment structures which conventionally are free standing steel or reinforced-concrete steel-plate-lined cylindrical shells with a top dome. The entire structure generally rests on a thick reinforced-concrete base slab. This structure is the final barrier preventing release of radioactive material to the atmosphere as a result of accidental occurrences within the containment. It is a passive element of the safety system -- a static fission product barrier which must perform its safety function under all postulated operating and accident conditions. The depth of embedment of a nuclear reactor containment structure -- i.e., the depth below grade of the main foundation slab -- can range from very shallow embedment to virtually full embedment. The degree of embedment can have a profound effect on the forces for which the structure must resist, and can affect overall cost. For example, conventional containment structures which are primarily above grade must resist very high shear forces and overturning moments due to wind and seismic loads. While a structure can be designed and constructed to serve the intended purpose, the cost is probably greater than for a structure with a greater degree of embedment. Likewise, a containment structure which is fully embedded having its top at or slightly below grade would probably be substantially more expensive than a partially embedded structure due to increased excavation costs. A partially embedded reactor containment building accordingly has potential cost advantages over either shallow embedment or full embedment. Generally, such advantages depend upon the nature of the soil environment, and can be realized only if significant reductions in the shear forces and overturning moments from lateral loads can be accomplished. SUMMARY OF THE INVENTION The reactor containment building of a safety research experiment facility is constructed of reinforced concrete partially embedded in competent rock with the concrete poured in contact with the competent rock and includes a continuous, hollow, circular, reinforced-concrete ring tunnel surrounding the shell of the reactor containment building with its top at grade and having one wall integral with the containment building shell and at least its base poured in contact with the competent rock.