Progress in a two year study of a 1200 MWe commercial tandem mirror reactor (MARS - Mirror Advanced Reactor Study) has reached the point where major reactor system technologies are identified. New design features of the magnets, blankets, plug heating systems and direct converter are described. With the innovation of radial drift pumping to maintain low plug density, reactor recirculating power fraction is reduced to 20%. Dominance of radial ion and impurity losses into the halo permits gridless, circular direct converters to be dramatically reduced in size. Comparisons of MARS with the Starfire tokamak design are made.

COBRA, in general, performs a thermal-hydraulic analysis of an actual pin bundle by subdividing the bundle cross-section into coolant subchannels, pin sectors, duct wall sectors. Its calculation includes heat convected axially upward through coolant mass flow, heat flow between pin sectors and adjoining subchannels, and heat and mass flow between coolant subchannels. COBRA-3M is a version of COBRA built for LMFBR applications, that includes a sophisticated thermal model of fuel pins and duct wall. COBRA-3M that can explicitly model a wider variety of pin bundle configurations than 3M would allow and includes significant improvements to its thermal modeling. COBRA-PI is currently being used for thermal-hydraulic analysis of hypothetical LMFBR accident transients in both power and flow. Pin bundles currently being analyzed explicitly range from 7 to 37 pins of axial lengths ranging from approx. 0.3-2.0 meters.

The nuclear performance of a candidate fission-suppressed, U233-producing blanket is assessed. It is predicted to have a breeding ratio (fusile + fissile) of 1.68 and produce U233 at a rate of 8030 kg/year from 3140 MW of DT fusion and a blanket coverage of 96%. Blanket energy multiplication is estimated to vary between 1.3 and 2.0 as the U233/Th232 ratio varies between 0 and 0.5%. Heterogeneous effects in the blanket's pebble-bed configuration were found to be important and more detailed analysis is needed to more accurately predict Li6 content required and U233 fission power versus U233 content.

None