Nickel-Based Alloy Being Studied for Molten Salt Reactors

Picture a grain of sand.

Now split it into 50 pieces.

That’s roughly the sample size researchers at Idaho National Laboratory (INL) are working with to help the development of molten salt reactors.

INL is studying Hastelloy-N, a nickel-based alloy with good corrosion resistance at high temperatures. It was developed by Oak Ridge National Laboratory as a container material for fluoride salts and researchers believe it appears to be a good candidate for use in future advanced reactors.

Testing the “grain” boundaries

INL researchers are looking closely at how the corrosion behavior of Hastelloy-N is affected by its microstructure.

Corrosion is a major limiting factor in the service lifetime of metals and alloys. By better understanding this behavior, they could improve the material’s long-term performance and extend the life span of reactor components.

INL is analyzing a sample they received from the Massachusetts Institute of Technology (MIT) after it was exposed to lithium fluoride/beryllium fluoride (Flibe) salt for 1,000 hours in a high-temperature test loop.

Using the lab’s transmission electron microscope, researchers are able to observe the microstructural changes indicative of material degradation. However, further research is needed to determine how these changes could affect the suitability of Hastelloy-N as a structural material for molten salt reactors.

What’s next?

INL and MIT plan to submit a proposal to continue this work at the INL Nuclear Science User Facilities (NSUF), enabling further analysis of the entire sample.

The NSUF provides external research teams cost-free access to reactor, post-irradiation examination and beam line capabilities at INL and a diverse mix of affiliated partner institutions at universities, national laboratories and industry facilities located across the country.