The two main drivers of materials development in the nuclear fuel domain are safety and fuel cycle cost, says Alain Frichet, vice president of Fuel Products and Technologies at Framatome. Frichet, who joined Framatome in 1995, is leading the company’s research and development of all pressurised water reactor (PWR) and boiling water reactor (BWR) fuel technologies. This includes projects at Framatome’s sites in France, Germany and the USA, as well as worldwide technical partnerships.

In the aftermath of the 2011 accident at Fukushima Daiichi, the nuclear industry undertook a global effort to further increase fuel margins in the case of a severe accident. It led to programmes to develop enhanced accident tolerant fuel (EATF).

Framatome, as part of its PROTect programme, is developing and testing two EATF concepts: a near-term solution that involves chromia-enhanced fuel pellets and fuel rods with a chromium coating; and a longer-term solution with a silicon carbide-based cladding.

Frichet says adding a chromium coating to Framatome’s existing M5® zirconium alloy cladding, which has been demonstrated at burnup of 75MWd/kgU, improves resistance to oxidation at high temperatures and reduces hydrogen generation during a loss of cooling. The chromium coating also reduces creep and improves resistance to debris fretting during normal operations. Chromia-doped pellets can be used with UO2 and MOX (PuO2/UO2), and they reduce fission gas release, improve behaviour during loss of cooling and minimise pellet clad interaction (PCI).

“We introduced EATF in commercial reactors as early as 2015, at the Goesgen nuclear power plant in Switzerland,” says Frichet. Test rods with advanced cladding materials have now been in the reactor for two cycles, and are confirming the positive results from out-of-pile tests. “For coatings, the main challenge is ensuring the quality of the product, so that at the end of life the coating remains on the cladding and retains its functions,” he says.

View the full story at Nuclear Engineering International.