ARPA-E seeks input from a broad range of disciplines and fields, including, but not limited to, nuclear science and engineering; materials science and engineering; sensor science and technology; instrumentation and control engineering; automation science and engineering; power systems engineering; and safety by design for innovative concepts for technical innovation that will enable accelerated development and regulatory acceptance of modular nuclear energy options involving either Gen III+ or Gen IV design features.

If made technically and economically viable, modular nuclear reactor technologies can augment large-scale reactors in providing clean, safe, secure, carbon-free electricity as well as heat energy for various non-electrical applications (e.g., industrial processes, mining activities, hydrogen production, and seawater desalination).

According to ARPA-E, there are several motivations for advanced reactors in addition to the need to reduce overall capital and operational costs, while incorporating new safety features developed for Gen III+ reactors:

1. A key motivation is related to enhanced passive safety features, building on those offered by the recently-deployed Gen III+ reactors. The majority of the new advanced concepts aim to be considered truly ‘walkaway-safe’ reactors for which, in case abnormal operation necessitates shutdown of the reactor, such a shutdown could be done with no human intervention.

2. Some advanced reactor concepts feature load-following capabilities (i.e., quickly ramp up or down in power) for integration with intermittent solar and wind electricity and offer heat and electricity options to cogeneration applications, such as desalination and various process heat applications.

3. Some advanced reactors of the fast neutron spectrum type offer the ability to produce more fissile matter than they consume thus reducing the need for fresh fuel. Such reactors could also burn spent fuel and reduce overall spent fuel radioactivity, which could offer an attractive path for substantial nuclear waste reduction in addition to other advantages.

However, several technical and economic challenges stand in the way of commercialization of advanced nuclear reactors. Many of these challenges are tied to materials and systems engineering issues. Essentially all advanced reactor types operate at very high temperatures; their core components are exposed to extremely corrosive environments and are subjected to the high-energy neutrons generated during nuclear reactions.

These materials challenges create significant uncertainty in the pathways for licensing and deployment of such advanced reactors.

ARPA-E is particularly interested in innovations that enable reactor designs to be:

1. inherently safe (beyond passive safety) with multiple safety mechanisms to prevent core melting in case of a loss of coolant accident (LOCA);

2. extremely secure without exposure of radioactive nuclides in case of LOCA or an enclosure breach with a zero or near zero emergency planning zone (EPZ);

3. quickly responsive to external load variations with control mechanisms that can also add safety beyond passive cool down;

4. long-lasting with operational durations of 10 to 20 years without refueling;

5. substantially autonomous in operations with minimal operator intervention; and

6. proliferation resistant.

The purpose of the RFI is solely to solicit input for ARPA-E consideration to inform the possible formulation of future programs.