Analysis of G.E. Mark III containment system drywell structure

The analysis of the drywell structure in the G.E. Mark III containment system is presented and the loadings and solution techniques are discussed in this paper. The drywell structure is a reinforced concrete cylindrical shell. In the bottom region of the shell, there are many 28 inch diameter horizontal vents arranged in a regular pattern. The main function of the drywell is to channel steam released during a main steam line break through the horizontal vents for rapid condensation in the suppression pool and to reduce radiation levels in the containment to permit normal access. The drywell is designed to sustain all operating loads, thermal loads, seismic loads and accident loads. Dynamic loads are applied to the structure statically with dynamic load factors obtained from separable analysis. Seismic loads are applied as equivalent static loads obtained from seismic analysis of lumped mass model of the structure. The design requires the various combination of dead and live loads, accident pressure loads, thermal effects under operating and accident conditions, safe shutdown and operating basis earthquakes, steam relief valve blow down loads, poolswell loads, and jet force and pipe whip loads due to pipe rupture. The loading combinations are presented in a detailed tabulated form. The analysis is carried out by finite element techniques by using the NASTRAN computer program. (Auth.)