Los Alamos Lab to lead $9.25M project to model materials behavior in molten salt reactors

The Department of Energy (DOE) selected Los Alamos National Laboratory (LANL) to lead a $9.25-million collaborative project in nuclear energy research through the Scientific Discovery through Advanced Computing (SciDAC) program. SciDAC brings together experts in science and energy research with those in software development, applied mathematics, and computer science to take full advantage of high-performance computing resources. This project will advance modeling the behavior and properties of structure materials under molten salt conditions.

A particular challenge in designing and deploying advanced reactor systems is determining the tradeoffs between competing safety and lifetime issues. For example, a structural material with good mechanical performance when exposed to radiation may be very susceptible to corrosion or other phenomena when exposed to a particular reactor coolant.

Ultimately, the DOE is seeking a predictive tool to assist with alloy design that would account for modeling corrosion, high temperature behavior and radiation effects (and the interplay between them) at the interface of a salt coolant with structural materials under Molten Salt Reactor conditions.

The project aims to understand and anticipate the couplings between corrosion and irradiation effects at the atomistic scale in a variety of metals exposed to molten salt in a reactor. Then, researchers can connect those effects to engineering-scale material performance to inform design decisions and safety analyses.

The team comprising experts from LANL, Idaho National Laboratory, Lawrence Berkeley National Laboratory, Sandia National Laboratories, and Carnegie Mellon University will lead the five-year partnership.

Competitive peer review selected this project under the DOE Funding Opportunity Announcement DE-FOA-0002592 “Scientific Discovery through Advanced Computing (SCIDAC): Partnership in Nuclear Energy.”

Total funding is $9.25 million for up to five years, with $1.85 million in Fiscal Year 2022 dollars and outyear funding contingent on congressional appropriations.

Background. Molten Salt Reactors (MSRs) use a fluid fuel in the form of very hot fluoride or chloride salt rather than the solid fuel used in most current nuclear reactors. Since the fuel salt is liquid, it can be both the fuel (producing the heat) and the coolant (transporting the heat to the power plant).

There are many different types of MSRs, including the Molten Salt Breeder Reactor (also know commercially as the Liquid Fluoride Thorium Reactor, or LFTR), fast breeder fluoride MSRs that don’t use thorium at all, and chloride salt-based fast MSRs that are usually studied as nuclear waste burners due to their extraordinary amount of very fast neutrons.

The development of molten salt-based reactor systems dates back to the 1950s during the US Aircraft Nuclear Propulsion Program. This program, which was later abandoned, led to the Molten Salt Reactor Experiment at Oak Ridge National Laboratory (ORNL), which demonstrated the viability of energy-generating using molten salt reactor (MSR) technology. (ORNL leads the DOE’s Molten Salt Reactor Technology Development program.)

MSRs offer a number of potential benefits, especially economics, safety and sustainability. However, there are a number of issues associated with the technology, many deriving from the fact that the radioactive fission products are basically just in a big sealed containment vessel rather than being in fuel pins surrounded by cladding. Some of the fission products have chemical effects that can degrade the containment.