Lead test assemblies of accident-tolerant fuel (ATF) installed in unit 1 of Southern Nuclear's Edwin I Hatch nuclear power plant in early 2018 have completed a 24-month fuel cycle. A sample of the lead test rods will now undergo testing.

Workers transfer lead test rods to Hatch 1's used fuel pool (Image: Southern Nuclear)

Hatch 1 was restarted on 4 March 2018 after the loading of lead test assemblies using an iron-chromium-aluminium fuel cladding material, known as IronClad, and coated zirconium fuel cladding, known as ARMOR. IronClad material is designed to provide oxidation resistance and "excellent material behaviour" over a range of conditions, with low oxidation rates of at higher temperatures further improving safety limit margins, according to supplier Global Nuclear Fuels (GNF).

Two variants of IronClad material were installed at Hatch 1: one in a fuel rod form but not containing fuel, while the other was in the form of a solid bar segment. The IronClad lead test assemblies are the first developed through the US Department of Energy's (DOE's) Enhanced Accident-tolerant Fuel programme to be installed in a commercial nuclear reactor. ARMOR coating is applied to a standard zirconium fuel rod. It provides enhanced debris protection and greater resistance to oxidation compared with standard zirconium cladding.

During a recent planned maintenance and refuelling outage, operators transferred a sample of the lead test rods from the core of Hatch 1 into the unit's used fuel pool. An initial inspection of the rods has already been completed. The rods' material and coating properties will be further evaluated at the DOE's Oak Ridge National Laboratory. The data obtained from this analysis will be used by Southern Nuclear and GNF to guide further development of ATF technologies and provide information to the US Nuclear Regulatory Commission licensing review process.

"Our initial inspections have confirmed that the fuel performed as expected and we anticipate leveraging this success and the data with our fuel vendors into the continued development of this innovative technology," said John Williams, director of fuels and analysis at Southern Nuclear. "We will continue to pursue solutions like advanced fuel that enhance the performance and reliability of our operating plants and ensure the safety and health of our customers and our employees."

Lead test assemblies using GNF's ARMOR-coated zirconium cladding and IronClad accident-tolerant fuel solutions have also been installed at Exelon's Clinton plant.

GNF is a GE-led joint venture with Hitachi and operates primarily through Global Nuclear Fuel-Americas in Wilmington, North Carolina, and Global Nuclear Fuel-Japan Co, in Kurihama, Japan.

Framatome and Westinghouse are also developing ATF concepts with the help of DOE funding. ATF development programmes are also under way in China and Russia.

Researched and written by World Nuclear News

Date: Thursday, 27 February 2020
Original article: world-nuclear-news.org/Articles/ATF-assemblies-complete-first-fuel-cycle-at-Hatch