Quantitative Comparison Study on Nuclear Nonproliferation for Plutonium in ?Spent Fuel Direct Disposal and Recycle Use

It is our responsibility to consider nuclear nonproliferation in the exit strategy for nuclear energy in order not to leave such burdensome issues to future generation. Disposal of spent fuel may be inevitable regardless of once-through or multiple fuel cycle alternatives because of the cost effectiveness in the treatment of spent fuels even resulting from thorough burning nuclear materials with recycled plutonium. However, when comparing proliferation risk of spent fuels from once-through and multiple cycles, we can differentiate proliferation risk in long term from short term. Because the once-through cycle is not entirely free of proliferation concern since the once-through cycle would result in large amount of fissionable plutonium in spent fuel repositories, which present a potential proliferation risk to future generations as “plutonium mines”. As time goes along, radiation levels will reduce, making spent fuel more accessible. Proliferation risk on reprocessing is regarded relatively high as a short term view due to the presence of large amount of separated plutonium. However it can be prevented by strict implementation of institutional measures, i.e., NPT-based safeguards, whereas, it is probable that no one can guarantee nonproliferation regime for the plutonium mines over a long period of time, e.g., beyond thousands years by the existing safeguards. This problem may not be able to be solved by the future generations once our generation buries spent fuels in the repository. In this paper, the authors compare the material-oriented Proliferation Resistance for plutonium in spent fuels resulting from both cases of direct disposal and recycle use with the extended the figure-of-merit (FOM) described in term of time, where not only weponization process but also acquisition/processing process are particularly taken into account; mainly dose of actual spent fuels and their chemical/physical properties, and material quantity are considered. This case study includes low/high burn-up and once/twice recycles with MOX-LWR and Fast Reactor.