US Accident Tolerant Fuel: Designs Overview
The mid-2020s will be a critical time for the United States fleet of reactors. Many of them have 60-year operating licenses that will expire in the 2030s. Getting these new fuels to market before then would increase the performance of these reactors and ultimately improve their chances of applying for extended operation with the National Regulatory Commission.
What is an accident tolerant fuel?
Accident tolerant fuels are new cladding and fuel pellet designs that increase the performance and severe accident response times of nuclear fuel. They take advantage of new materials that reduce hydrogen buildup, improve fission production retention, and are structurally more resistant to radiation, corrosion, and higher temperatures.
Accident tolerant fuels are expected to last longer than current fuel designs and could potentially extend the time between refueling, such as from 1.5 to 2 years for pressurized water reactors. This could reduce the amount of fuel assemblies needed to operate the reactor—leading to less waste production and a reduction in fuel costs over the life of the reactor.
Westinghouse
Westinghouse is testing uranium silicide fuel pellets for the first time in a commercial reactor. They use a mixture of uranium and silicon instead of uranium and oxygen to achieve a higher density of uranium atoms per pellet. This leads to longer operation times, increase power outputs and high burnups.
Uranium silicide fuel pellets enclosed in a chromium coated zirconium alloy cladding (Westinghouse).
General Electric
GE’s Global Nuclear Fuel developed IronClad fuel with support from Oak Ridge National Laboratory. It uses a combination of iron, chromium and aluminum for its fuel cladding to improve the fuel’s behavior under extremely high temperatures. The steel material has a much lower oxidation rate when exposed to high temperature steam—improving the safety margins over traditional zirconium cladding used today.
Test rod holders containing both ARMOR and IronClad rodlets. Idaho National Laboratory (General Electric)
The company is also testing a second fuel and cladding concept known as ARMOR.
Framatome
Framatome is testing chromium-coated cladding and chromia-doped fuel pellets. The special coating is designed to protect the fuel cladding from damage and oxidation at higher temperatures. The new fuel pellet mixture of chromium oxide and uranium oxide powders is expected to help the pellet last longer and perform better at high temperatures.
Chromium-coated cladding and chromia-doped fuel pellets (Framatom)
Department of Energy is providing irradiation and safety testing, along with advanced modeling and simulation, to help these companies qualify their fuels with the U.S. Nuclear Regulatory Commission.
According to energy.gov
