Hungarian Academy of Sciences KFKI Atomic Energy Research Institute
Abstract
The RUSET experimental programme was launched in order to study Ru oxidation and
release from fuel in high temperature air. More than forty small scale tests have been
performed with mixed powder components of inactive materials and with short fuel rods.
The influence of temperature, air flow rate and the presence of other fission products on the
gaseous Ru release and the retention role of fuel pellets and cladding have been
investigated. The test series indicated that if an air ingress type severe accident occurs most
of the initial Ru mass can be released from the reactor core to the containment or
environment. Some part of the released gaseous Ru undergoes precipitation and deposits on
the cold surfaces, another part is released in gaseous form. The deposited Ru oxides can
serve as a secondary source for further gaseous Ru releas