Design and analysis of Molten Salt Reactor fueled by TRU from LWR

This study assesses the feasibility of designing a finite once-through Molten Salt Reactor (MSR) fed with trans-uranium isotopes (TRU) from LWR spent fuel to be critical and to have a low peak-to-average radiation damage to graphite. The study also quantifies the transmutation effectiveness of this MSR considering the following measures: fractional transmutation of all actinides, of 239Pu and of 237Np and its precursors, radio-toxicity and decay-heat. Three-dimensional design optimization with MCNP resulted in a graphite reflected critical core having a remarkably small peak-to-average graphite damage rate of 1.079. The optimal graphite-to-MS (C/MS) volume ratio is between 2 and 3. The transmutation characteristics of this reactor strongly depend on the MS feed-rate. They also depend on the C/MS ratio. There is no universally preferred neutron spectrum - to minimize radiotoxicity and decay heat, harder spectrum is preferred during the first few dozen years following discharge from the MSR as well as in the ten thousand and hundred thousand years time range. However, softer spectrum is preferred for periods in-between. Softer spectrum is also preferred for minimizing the inventory of fissile Pu and of 237Np and its precursors and for maximizing the graphite lifetime. (authors)