Computer-aided analysis and optimisation of the MARS© safe nuclear reactor

The paper presents the findings of a computational analysis and sensitivity study of the power generation section of the MARS(R) (Multipurpose Advanced inherently Safe Reactor). The MARS (Multipurpose Advanced Inherently Sale Reactor) Project is a new approach to the design and implementation of an innovative technology for an inherently safe nuclear BWR-reactor, based on a radically revised concept of core cooling which ensures passive safety under all operating conditions and all emergency situations. The concept has been originally developed starting 1983 by a research group at the Department of Nuclear Energy of the University of Roma ?, and since then it has been brought up to preliminary design stage. The analysis has been performed using as a constraint the known behaviour of the MARS nuclear reactor: more precisely, it has been assumed that the inlet and outlet conditions of both water and steam into and from the nuclear section are specified and must be maintained at their design value. Under this constraint, a sensitivity analysis of the operation of the plant has been performed to investigate the effects on the plant output and performance of different design- and siting choices. The independent parameters in the sensitivity study were: 1. the mass flow rate of the high-pressure steam used to superheat the low-pressure steam at the high-pressure turbine outlet; 2. the condenser cooling water temperature (site-dependent); 3. the high- and low-pressure turbine efficiencies. The results of the analysis are critically reviewed to assess their consequences.