Ever since the Molten Salt Reactor Experiment ended at Oak Ridge National Laboratory in 1972, the idea of a commercial molten salt power reactor has captivated nuclear engineers. The idea is simple: instead of generating heat by inserting radioactive fuel rods into a solid-core reactor, pulverize the uranium fuel and mix it into a fluid of molten lithium fluoride salt. The heated salt could then be used to create steam to generate electricity, in a process not unlike that used in modern combustion plants.
Molten-salt reactors (MSRs) have, from the start, posed a number of technical challenges, not the least of which was finding a material to make a reactor vessel capable of withstanding the high heat required (700ºC). This week that milestone was achieved when a new durable steel alloy, christened "Alloy 617", was found to be capable of withstanding 950ºC, passing a critical milestone in the development of safe, gigawatt-scale nuclear reactors.