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Southern Nuclear agrees to load accident tolerant fuel at Vogtle Unit 2

The fuel is designed to be more tolerant of changes in the reactor core.
Southern Nuclear agrees to load accident tolerant fuel at Vogtle Unit 2
(Nuclear fuel pellets. Source: Westinghouse Electric)

Southern Nuclear has agreed to load four Lead Test Assemblies (LTAs) with “next-generation” fuel features into Unit 2 of the Alvin W. Vogtle Electric Generating Plant in Georgia.

The installation will include pellets and cladding developed within the U.S. Department of Energy’s enhanced Accident Tolerant Fuel (ATF) program, and is expected to enhance safety and offer operational savings and efficiencies.

The LTAs include one of the first planned installations of enrichments of uranium-235 of up to 6 weight percent in a domestic commercial reactor.

Southern Nuclear Executive Vice President and Chief Nuclear Officer Pete Sena said in a statement that the use of test assemblies with enrichments higher than historical limits marks a “significant advancement” in the potential commercial deployment of advanced nuclear fuel technology.

Vogtle Unit 2 uses a Westinghouse four-loop pressurized water reactor and has a nameplate capacity of 1,152 MW. It entered service in 1989 and is licensed to operate until February 2049.

In November, Framatome said it had delivered ATF technology to Exelon Generation’s Calvert Cliffs Nuclear Power Plant in Lusby, Maryland. The LFA contains 176 chromium-coated rods and chromia-enhanced pellets, and was inserted as part of the plant’s spring 2021 refueling outage.

The Energy Department (DOE) said the assembly design is intended to improve tolerance to changes in the reactor core and is expected to reduce corrosion and hydrogen production under high-temperature conditions.  

The new fuel prototype aims to deliver the first major upgrade to the industry’s fuel and cladding technologies since the 1970s.

Fuels development

Framatome, Westinghouse, and General Electric are all currently working to have their accident tolerant fuels ready for batch loading by the mid-2020s and with commercial widespread adoption by 2030.  

Under the DOE program, 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.

GE developed IronClad fuel with support from DOE’s 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 is intended to have a lower oxidation rate when exposed to high temperature steam, improving the safety margins over zirconium cladding currently in use.

The company is also testing a second fuel and cladding concept known as ARMOR. This coated zirconium cladding was developed outside of the DOE program but is now an integral part of the program.

Framatone 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.

DOE 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.

Southern Nuclear installed GE-Hitachi ATF fuel cladding technologies in 2018 at Plant Hatch Unit 1 with samples discharged and shipped to Oak Ridge National Lab for further testing in 2020. In 2019, Vogtle Unit 2 installed four Framatome-developed GAIA lead fuel assemblies containing accident-tolerant features applied to full-length fuel rods.

Vogtle Unit 2 deployment 

The Vogtle lead test assembly program will include Westinghouse’s High Energy Fuel initiative and the EnCore Fuel program with the intent of lowering the cost of electricity while increasing the fuel’s resiliency.

Through a partnership with Idaho National Laboratory and the Department of Energy, fabrication of the LTAs is scheduled to take place in 2023. The LTAs will use four enriched lead test rods of up to 6.0 weight percent uranium-235, which is one percent higher than the current licensed limit. They will also contain ADOPT uranium dioxide pellets, AXIOM fuel rod cladding and chromium-coated cladding combined with Westinghouse’s PRIME fuel assembly design.

Southern Nuclear operates six units for Alabama Power and Georgia Power at the Joseph M. Farley Nuclear Plant near Dothan, Ala.; the Edwin I. Hatch Nuclear Plant near Baxley, Ga.; and the Alvin W. Vogtle Electric Generating Plant near Waynesboro, Ga. Southern Nuclear is the licensee of two new nuclear units under construction at Plant Vogtle, which are the first new nuclear units being built in the United States in the last three decades.

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