Using thorium in DBI reactors decreases the volume and toxicity of waste by more than 90%, making another Yucca Mountain unnecessary.

The DBI Thorium Reactor program would drastically reduce the volume and toxicity of nuclear waste by:

• Eliminating the vast amount of solid wrappings waste
• Maintaining the fuel in the core throughout the life of the reactor
• Producing far less long-lived radiotoxic actinides
• Using almost all of the fuel in a new reactor after decommissioning
• Entombing the minimal remaining waste in the decommissioned plant

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Eliminates Voluminous Wrappings Waste
DBI has developed a way to retrieve thorium mechanically then encapsulate it. This proprietary process eliminates the vast amount of solid wrappings waste created in conventional nuclear fuel cycles due to radioactivity contaminating the automated assemblies and other equipment used in the mining, conversion, enrichment, and transportation of uranium.

Never Needs Refueling
DBI’s unique and proprietary fuel encapsulation system allows the fuel to withstand much longer periods of irradiation and burn-up than conventional fuel claddings, so the fuel can remain in the core throughout the life of the reactor—30 years or more. The accumulation of fission poisons in the fuel over time will be offset by the breeding of new fissile material at a rate that will be controlled to maintain the reactivity balance. No chemical reprocessing will be necessary to achieve historically high levels of fuel burn-up.

Significantly Less Radiotoxicity
Thorium produces no plutonium and much less other transuranic isotopes, so the innovative DBI Thorium Reactor program will produce far less waste per unit of energy—with significantly smaller concentrations of long-lived radio-actinides. Since the fuel remains in the core during the life of the reactor, the vast majority of the isotopes reach their half-lives and become inert before decommissioning, making the small amount of waste only minimally radiotoxic.

Fuel Outlives the Reactor
DBI Reactors would produce no waste for the life of the reactor—30 to 40 years, or more if the physical plant lasts longer. When a DBI reactor is decommissioned at the end of its useful life, the vast majority of the fuel can be transferred directly to the next generation of DBI reactors to continue toward still higher burn-up. The proprietary DBI Thorium Reactor fuel can be reused without reprocessing because it is encapsulated in a robust high-temperature material capable of enduring decades of radiation exposure. The extremely low neutron absorption properties of this encapsulation and the unique DBI Thorium Reactor core designs guarantee a high enough ²³³U breeding ratio to offset the accumulation of neutron-absorbing fission poisons for several decades, as modeled by Monte-Carlo simulations and finite-difference forward integration of fuel nuclide evolution over time.

Waste Entombed in the Core
Nuclear waste from conventional reactors in the United States is produced at such an alarming rate that the proposed Yucca Mountain waste repository, once complete, could be filled to capacity within 15 years. The minimal fuel not recycled into the next generation DBI Thorium Reactor will be entombed in the core on-site at the decommissioned plant, and no waste will need to be transported.

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This diagram shows the expected tonnage of nuclear fuel waste from a 100-MW_th nuclear reactor program over several generations. A conventional nuclear reactor achieves a uranium oxide (UO₂) fuel burn-up between 30,000 and 50,000 megawatt-days per ton (3-5%). Because of the accumulation of fission poisons and the relatively short 3- to 5-year lifetime of fuel cladding in the conventional reactor environment, new fuel must be added and spent fuel removed at intervals of 6-24 months. The result is a steady accumulation of about 0.7 tons of partially consumed, highly radiotoxic UO₂ waste per year (red).

In contrast DBI uses a proprietary fuel encapsulation system that will allow the initial load of fuel to be used for the entire 30-40 year life of the first reactor.

The reactivity losses associated with accumulating fission poisons in the fuel will be offset by breeding ²³³U in the thorium-oxide (ThO₂) fuel, allowing the DBI reactor to continue using its initial load of UO₂ fuel to much higher burn-up levels. Monte Carlo neutron transport models in TART, and a finite-difference forward integration of fuel isotopic evolution, show that the bred ²³³U/ThO₂ fuel and partially spent UO₂ fuel from a first generation reactor can be re-shuffled after 20-30 years, placing the spent fuel near the reactor core periphery and the bred fuel near the center, to achieve critical mass in a second generation reactor and reach still higher burn-up of the original UO₂ fuel for another 10-30 years. Thus, the first generation reactor will produce no nuclear waste and the second generation reactor will finally release its highly-burned UO₂ fuel after the 30-year mark (blue). With minimal fuel shuffling, this model indicates that at most 10% (worst-case estimate) of the 32-ton ²³³U/ThO₂ load will require replacement in any 20-year period (green) to sustain the ²³³U breeding cycle. Note that the UO₂ waste includes a much higher concentration of long-lived actinides than the ThO₂ waste. After the one-time charge of UO₂ is expended to start the DBI ²³³U/ThO₂ fuel cycle, only thorium fuel waste—in greatly reduced volume—will be produced by future generations.

After the one-time charge of UO₂ is expended to start the DBI ²³³U/ThO₂ fuel cycle, no such long-lived waste will be created again.