EVALUATION OF HYPOTHETICAL SEVERE ACCIDENT PROGRESSION WITH ATF CLADDING IN GENERIC INTEGRAL PWR DESIGNS IN THE FRAME OF THE SASPAM-SA PROJECT
Authors/Creators
Description
Small Modular Reactors (SMRs), particularly integral Pressurized Water Reactor (iPWR) designs, are
emerging as a viable option for providing flexible, scalable and inherently safer nuclear power generation
to meet the global energy demand. To further enhance the safety margins of these systems in the event of an
accident, Advanced Technology Fuel (ATF) materials have been proposed as alternative to traditional zirconium-based fuel cladding. Specifically, FeCrAl alloys are gaining interest due to their superior hightemperature oxidation resistance and ability to reduce the hydrogen generation, as demonstrated in separate
effect experiments and in the QUENCH-19 bundle test conducted at the Karlsruhe Institute of Technology
(KIT) in 2018. In this framework, the HORIZON-EURATOM SASPAM-SA project, initiated in 2022 and coordinated by
ENEA (Italy), aims to address fundamental knowledge gaps in the modelling and understanding of severe
accident (SA) progression in generic iPWR designs. Among the tasks within the project, one focuses on
assessing the performance of integral codes to simulate postulated SA scenarios involving FeCrAl as a
cladding material. Within Work Package 2, coordinated by KIT (Germany), numerical analyses were
conducted using the ASTEC, AC2 and MELCOR codes to investigate the behaviour of two generic iPWR
designs under SA conditions, comparing the performance of FeCrAl with conventional Zircaloy.
All codes demonstrated an overall capability to simulate the reduction of H2 production in the early stage of
the SA scenarios associated to the use of FeCrAl as cladding material. The incorporation of FeCrAl also led
to delays in the onset of high-temperature transients. Although some differences were observed across the
codes based on each model implementation, and the current models available for FeCrAl present limitations
and uncertainties at advanced degradation stages, the general trends consistently highlight the potential of
FeCrAl to mitigate risk and enhance safety.