Advanced Fuel Cycle Initiative

Systems Studies

NE studies have explored options for an integrated nuclear waste management strategy, a strategy that uses partitioning and transmutation of spent fuel to create transmutation fuels and targets to be burned in thermal and fast spectrum systems, thereby eliminating the most problematic components of nuclear waste. System architectures under consideration include the recycling of plutonium in light water reactors and the recycling of non separated transuranics in low conversion rate fast reactors or accelerator-driven systems.

These multi-tier transmutation architectures are based on the premise that a large portion of the nuclear waste stream can be transmuted in power reactors while producing energy to offset the cost of transmutation. Although routine recycle of Pu into commercial nuclear reactors was precluded in the US by an earlier presidential directive, the option of Pu consumption in commercial reactors is being reconsidered as an option for destroying excess weapons Pu. A fast-spectrum system would be required for transmutation of the heavy isotopes of Pu, minor actinides, and some fission products.
 

In total, nine different transmutation systems were evaluated - seven multi-tier reactor and fuel technologies, a single-tier fast-reactor system, and a single-tier accelerator-driven system. The performance of each approach was also compared to an established set of high-level programmatic goals for the mission, which address most, if not all, of the concerns expressed by the National Academy of Science panel review of transmutation options (1996), and are as follows:

• Improve long-term public safety by reducing the radiotoxicity of nuclear waste below that of natural U ore within a period 1,000 years as well as reducing the dose to future inhabitants by 99%.
• Provide benefits to the geological repository by reducing the mass of commercial spent fuel by 95% and heat loads in the repository by 90%.
• Reduce the Pu proliferation risk in commercial spent fuel by reducing the inventory of Pu by 99%.
• Improve prospects for nuclear power by providing a viable and economically feasible waste management option for commercial spent fuel.

Preliminary evaluations determined that each assessed approach can reduce the radiotoxicity of spent nuclear fuel to below the radiotoxicity of natural U ore within 1,000 years, assuming 0.1% separation losses. Each assessed approach can reduce maximum predicted peak dose to future inhabitants by at least 99% in comparison to current predictions as well as reduce the inventory of materials that contribute to long-term heat loads in the repository by 90% or more. Also, each assessed approach will reduce Pu inventory by greater than 99%.
 

These system studies have provided a set of preliminary conclusions. However, the robustness of performance in light of assumptions and knowledge enhancement through R&D will be verified in future dynamic analyses.