General Atomics (GA) is developing a small modular reactor (SMR) and has recently submitted a proposal to the DOE SMR initiative to help bring the reactor to market. The EM2 is a modified version of General Atomics’ high-temperature, helium-cooled reactor and is capable of converting used nuclear fuel into electricity and industrial process heat, without conventional reprocessing. Each module would produce about 240 MWe of power at 850 °C.
|The core of the EM2. Click to enlarge.|
The initial “starter” section of the core provides the neutrons required to convert used nuclear fuel or depleted uranium (DU) into burnable fissile fuel. First generation EM2 uranium starters (~12% U235) initiate the conversion process. The starter U235 is consumed as the used nuclear fuel/DU is converted to fissile fuel. The core life expectancy is ~30 years (using used nuclear fuel and DU) without refueling.
Substantial amounts of valuable fissile material remain in the core. This material is reused as the starter for a second generation of EM2s, without conventional reprocessing. There is no separation of individual heavy metals required and no enrichment needed. Only unusable fission products would be removed and stored. This means that all EM2 heavy metal discharges could be recycled into new EM2 reactors, effectively closing the nuclear fuel cycle and thus reducing the need for long-term repositories and minimizing proliferation risks.
The current amount of used nuclear fuel waste in storage at US nuclear plants is sufficient for 3,000 EM2 modules. The amount of available DU material in storage is sufficient for 30,000 modules. In an EM2 fuel cycle, this material can satisfy US energy demands for centuries, GA says. 400 modules could satisfy approximately 100% of the current US electricity output of nuclear reactors. Current used nuclear fuel could be removed from utility sites and be processed into EM2s.
30 years without refueling versus 18 months for current light water reactors;
Burns depleted uranium, spent fuel, plutonium and thorium;
No water for cooling, allowing much greater siting flexibility;
A design that achieves both increased efficiency and small size—the basic reactor reduces electricity costs by 40% relative to current reactors and produces 80% less waste; and
Improved safety with a gas-cooled design, utilizing GA’s innovative high-performance silicon carbide cladding that resists melting at high temperatures.
EM2 incorporates a truck-transportable high-speed gas turbine generator, an innovation that avoids the huge size and complexity of steam-generated power plants. This means lower up front capital costs for utilities, as well as lower electricity costs for consumers. EM2 will also provide three times the energy per pound of fuel compared to current technology and reduce waste by 80% utilizing just a single pass through fuel cycle, GA says.
The San Diego-based firm is working with CB&I, a global leader in energy infrastructure whose nuclear capabilities include serving as the lead construction firm for all new US reactors currently under construction. Mitsubishi Heavy Industries brings professional service to the team, with extensive experience in the nuclear industry including involvement in the construction of Japanese advanced reactors. Idaho National Laboratory offers capabilities to test the new EM2 fuel system.