Design and evaluation of a thorium fueled reactor with seed-blanket assembly configuration

Abstract

Recently, thorium fuel cycle is receiving increasing attention as one of possible ways to solve the problems of existing reactor design. In particular, a competitive thorium fuel cycle for pressurized water reactors of current technology, Radkowsky Thorium Reactor (RTR), was suggested by Radkowsky, et al. Main design concept of RTR is to replace the fuel assemblies of existing reactors with new thorium fueled assemblies with seed-blanket configuration. Except for the use of Seed-Blanket Units (SBUs), RTR has almost the same hardware componens with existing PWR technology. With minor modification, RTR concepts may be adopted to PWR. In this thesis, we designed a thorium fueled reactor according to the design features of RTR and carried out the assessment of its overall performance. For numerical estimation, we used the cell code system HELIOS and the 2-group diffusion nodal code system AFEN. The link of these two code systems was done for depletion calculation. To compare its performance with existing PWRs, the $ABB/CE type SYSTEM 80^{+}$ core was also modeled and calculated. From the preliminary results of performance analysis of an RTR-type thorium reactor, and comparison with the ABB/CE type reactor, we could ascertain some advantages and problems. Although some technical problems still remain, i.e., the need of extensive use of burnable absorbers and other thermo-mechanical problems, we conclude that RTR-type thorium reactor may is one of the effective ways to solve the two main problems of existing nuclear technology, i.e., possible diversion of the spent fuel for weapons and the storage and disposal of the spent fuel (discharged fuel is less in amount and poor in fissile plutonium quality). From RTR-type thorium fuel cycle, we can also achieve economical benefits because it requires much less uranium and thorium than existing PWR to produce the same amount of energy.