Determination of alternative PWR containment design including more severe than design basis accident

The principal objective of this overall study is to compare alternative containment concepts for PWRs with regard to their potential for reducing public risk and with regard to their construction costs. This study is divided into two parts; the first part, which was commenced some months before TMI-2 accident, was done using the assumptions of the design basis accident; the second part deals with a more-severe-than-a-class-8 accident, such as the partial core meltdown accident similar to TMI-2 accident (This is called a Class 8 1/2 accident here, as a matter of convenience). Based on our assumptions, the results of this study indicate that reduction of health hazard due to I131 release during a Class 8 1/2 (an interrupted large LOCA) can be achieved by installation of a PAFS system and D.C. power operated hydrogen pre-ignition system for the PWR ''dry'' containment in order to avoid overpressurization due to hydrogen burning and to reduce iodine fission gas release by use of the filtered venting system. For the PWR ''ice-condenser'' containment, reduction of latent cancer effects due to I131 release during the accident can be obtained by installation of only a PAFS system without any pre-ignition system. Discussion of this study and recommendation for future researches are also presented