Massachusetts-based Transatomic Power Corporation (TAP) on 8 July issued a technical white paper on the design of its 1,250MWt molten salt reactor (MSR), which it says offers multiple advantages over existing generation technologies. The paper shows how the TAP-MSR uses the properties of its liquid fuel to increase fuel utilization while decreasing the overall amount of waste produced.

The white paper was released after the US Department of Energy awarded Transatomic a $200,000 grant under its Gateway for Accelerated Innovation in Nuclear (GAIN) Nuclear Energy Voucher pilot programme. Transatomic  will now be able to undertake high-fidelity modelling of the design in partnership with Oak Ridge National Laboratory (ORNL). The MSR reactor technology was first demonstrated at ORNL in the 1960s.

Leslie Dewan, Transatomic's CEO, said the current design is the result of years of open, clearly communicated scientific progress. "Our research has demonstrated many-fold increases in fuel efficiency over existing technologies, and we're really excited about the next steps in our development process."                 

Liquid fuel has no long-range structure to be damaged, does not experience significant volumetric swelling, and avoids fission product poisoning through continuous fission product removal. This means it can potentially reach higher burn-ups. Transatomic's white paper presents qualitative studies into these properties based on software modelling studies.

The TAP-MSR design allows for more than twice the burn-up of conventional light water reactors by exploiting the properties of the liquid fuel through the continuous removal of fission products and the ability to vary the geometry of the reactor core. Using fuel enriched to 5% uranium-235, this increased efficiency leads to a waste reduction of about 53%. For uranium enrichments up to 20%, the waste reduction reaches 83%.

Dewan said the issue of nuclear waste presented two difficult tasks – reducing the rate at which waste is produced, and designing reactors capable of extracting the remaining energy in the waste to achieve a 'net-negative' waste profile, where a reactor produces less waste than it takes in. Transatomic chief technology officer, Mark Massie, said the calculations showed that its design would clear the first hurdle. "Even under the current fuel supply chain, which doesn't enrich fuel past 5% U-235, we still reduce annual waste production by over 50%," he said. The TAP MSR's architecture is based on inventions developed by Dewan and Massie at the Massachusetts Institute of Technology Department of Nuclear Science.