The US Department of Energy (DoE) has awarded QuesTek Innovations, a computational materials design specialist, $1.1 Million in Small Business Innovation Research (SBIR) Phase II funding. The company will use the funds to design and qualify novel materials and 3D printing processes, specifically for the development of future nuclear reactors.

QuesTek hopes the Phase II project will yield a cost-effective cold spray additive manufacturing method complete with new compatible refractory alloys. These refractory alloys are to be used as surface layers on top of ASME-certified structural materials, providing nuclear reactors with improved corrosion resistance and temperature stability.

The company is also working with 3D printing materials developer Solvus Global and Professor Vilupanur Ravi from Cal Poly Pomona, in a bid to bolster the project with materials expertise.

Dr. Pin Lu, the Principal Investigator at QuesTek, explains, “Cold spray is one of the most effective and economical coating technologies to greatly extend the lifetime of next-generation nuclear reactors. We are excited for this opportunity to apply our proven computational materials design approach to design novel high performance cold sprayable refractory materials, improving the economic feasibility and performance of future clean energy.”

QuesTek has previously developed a high-temperature aluminum alloy for powder bed fusion. Photo via QuesTek.
QuesTek has previously developed a high-temperature aluminum alloy for powder bed fusion. Photo via QuesTek.

Molten salt reactors

The project is concerned with a very specific class of nuclear fission reactor called a molten salt reactor (MSR). MSRs are special in that they use molten salt mixtures as their primary fuel and/or nuclear coolant. Unlike typical light-water reactors, which operate at very high pressures, MSRs can run at atmospheric pressure. This means they are generally smaller, cheaper, and safer as there is a reduced risk of catastrophic explosion.

Another key feature of MSRs is that they do not emit radioactive fission gases, as these are naturally absorbed into the molten salt. This reportedly eliminates the risk of surrounding land contamination, which can be a major safety concern for both wildlife and humans.

Unfortunately, the ASME code-approved materials used for MSRs often lack salt corrosion resistance, limiting their potential for long-term clean energy applications. As such, there is a need for corrosion-resistant coating – a challenge QuesTek is taking on.

A molten salt reactor developed by Oak Ridge National Laboratory. Photo via Oak Ridge National Laboratory.
A molten salt reactor developed by Oak Ridge National Laboratory. Photo via Oak Ridge National Laboratory.

Refractory alloys and cold spraying

As part of Phase I of the project, QuesTek has already designed a set of molybdenum-based alloys using its Integrated Computational Materials Engineering (ICME) technology. The materials have been tested in cold spray 3D printing trials, successfully coating 316 stainless steel structures and improving their molten salt corrosion resistances. Now, the company will apply its technology to explore additional refractory alloy designs involving niobium, tungsten, tantalum and more.

Dr. Aaron Birt, co-founder and CEO of Solvus Global, adds, “Further development of functionally graded coatings applied via cold spray will augment the commercialization of critical technologies. This project team combines all the key facets needed to successfully transfer a materials solution out of the lab and into industry, from modeling to production scale up. We look forward to continued project involvement and we are ready to deliver this materials solution at scale to the nuclear industry.”

3D printing in the nuclear energy sector

With advancements in metal 3D printing and materials research, additive manufacturing is seeing increased use for nuclear applications. Earlier this year, scientists from the Korean Atomic Energy Research Institute 3D printed a large safety valve with sufficient resistance properties to enable its use within a nuclear reactor. By combining 3D printing and CNC machining, the team was able to fabricate the 30kg faucet with a set of complex internal cooling channels, qualifying it with a ‘Class 1’ level of nuclear safety.

Elsewhere, Purdue University has previously received an $800,000 grant from the DoE to accelerate the development of a 3D printed nuclear reactor core. Led by Oak Ridge National Laboratory, the project aims to build and introduce the world’s first 3D printed microreactor by 2023 using Directed Energy Deposition (DED) technology.