GE Hitachi Nuclear Energy has proposed to the U.K. government to build an advanced nuclear reactor that would consume the country’s stockpile of radioactive plutonium. The technology called PRISM, or Power Reactor Innovative Small Module, would use the plutonium to generate low-carbon electricity.
The U.K. has the world’s largest civilian stockpile of plutonium. The size of the stockpile is 87 tons and growing.
Nuclear reactors unlock energy by splitting atoms of the material stored in fuel rods. This process is called fission. For fission to be effective, neutrons – the nuclear particles that do the splitting and keep the reaction going – must maintain the right speed. Conventional reactors use water to cool and slow down neutrons, keeping fission effective. But water-cooled reactors leave some 95 percent of the fuel’s potential energy untapped.
PRISM is a so-called “fast reactor.” It uses liquid sodium, rather than water, to cool the reactor. The sodium allows the neutrons to maintain higher energies and to cause fission in elements such as plutonium more efficiently than water-cooled reactors.
PRISM incorporates “passive safety” features and can shut down automatically, in the unlikely event that it should be needed. PRISM does not need any automatic systems, valves or operators, to remove reactor heat after a shutdown with a complete loss electrical power.
Another benefit is PRISM’s relatively small size and simplified design. The reactor can be built in modules and transported to the power plant site, lowering the costs and adding another level of component control.
The plutonium is stockpiled in the coastal town of Sellafield in northern England. The Guardian newspaper reported that storing this plutonium costs the British government a significant amount of money per year to maintain. “Some in government want the plutonium to be classed as an asset, rather than a liability,” the newspaper wrote. GEH said that the PRISM reactor would use practically all the stored plutonium at Sellafield to create low-carbon electricity, turning it into an asset.
The PRISM reactor is very different from other proposals to process plutonium, including turning the spent fuel into mixed oxide (MOX). The PRISM reactor actually disposes of a great majority of the plutonium as opposed to simply reusing it over again without ever actually ridding the planet of the substance.