Vogtle-2 returns to service with Enhanced Accident Tolerant Fuel

Southern Nuclear, the plant's operator, said it had installed "the world's first complete, fuelled, full-length test assemblies, known as accident tolerant fuel, containing both pellets and claddings", which France's Framatome had delivered in January.

"This is an important milestone for Framatome and the industry," said Lionel Gaiffe, senior executive vice president of the Fuel Business Unit at Framatome. "We applaud Southern Nuclear's consistent support of EATF initiatives, and we are pleased to deploy an economical advanced fuel technology that offers operators additional response time and greater operational flexibility."

With support from the US Department of Energy's (DOE's) Accident Tolerant Fuel programme, Framatome developed the fuel assemblies with Southern Nuclear as part of Framatome's PROtect programme of research and development.

Framatome said its "advanced chromium coating added to the state-of-the-art M5 Framatome zirconium alloy cladding" improves high-temperature oxidation resistance and reduces hydrogen generation during loss of cooling. The chromium coating also "greatly reduces" creep to maintain a coolable geometry and has mechanical properties that allow for more operator response time, it added. The coating also offers increased resistance to debris fretting during normal operations, it said.

In addition to chromium coated cladding, the fuel design includes chromia-enhanced fuel pellets, which have a higher density, reduced fission gas release and improved behaviour during loss of cooling, Framatome said, adding that Reduced Pellet Clad Interaction (PCI) also better supports power manoeuvring.

John Williams, Southern Nuclear fuel and analysis director, said: "This innovative technology is expected to enhance the plant's already robust safety performance, as well as potentially lower plant operating costs. The safety and health of our customers and our employees is always our top priority, and we will continue to pursue innovations that enhance safety and offer more operational flexibility."

The installation of complete test assemblies "marks another significant advancement", Southern Nuclear said, in the potential commercial deployment of accident tolerant fuel technology, with the US company previously installing test assemblies containing fuel segments into unit 1 of the Hatch nuclear power plant as part of a refuelling outage in 2018.

Each unit at Vogtle requires new fuel every 18 months. In addition to refuelling the reactor and performing regular maintenance and testing, workers made upgrades to plant systems and components. Last refuelled in 2017, unit 2 completed a 522-day breaker-to-breaker run, remaining online for more than 17 months of continuous operation.

"The work that this team safely performed during this outage will position unit 2 for another full cycle of reliable operation," said Vogtle Site Vice President Darin Myers.

This was the 20th refuelling for unit 2 since commercial start-up in May 1989.

Framatome said the support of the DOE’s accident tolerant fuel programme had allowed the company to significantly improve on its initial target of 2022 to deploy this technology. European partners, like CEA, which initially explored and identified the suitable cladding coating process, and also EDF, Goesgen Nuclear Power Plant in Switzerland and leaders from across the nuclear sector have collaborated for several years on aspects of this fuel design, it said.

Framatome fabricated the fuel assemblies at its fuel manufacturing facility in Richland, Washington, as part of a 2017 contract with Southern Nuclear, which operates a total of six units for Alabama Power and Georgia Power.