Progress on ruthenium release and transport under air ingress conditions

Summary A particular concern in the event of a hypothetical severe accident is the potential release of highly radiotoxic fission product (FP) isotopes of ruthenium. The highest risk for a large quantity of these isotopes to reach the containment arises from air ingress following vessel melt­through. One work package (WP) of the SARNET Source Term topic is producing and synthesizing information on ruthenium release and transport with the aim of validating or improving the corresponding modelling of the ASTEC code. The WP includes reactor­scenario studies that can be used to define conditions of new experiments. The experimental database currently being reviewed includes the following programmes: ­ AECL Experiments conducted on fission product release in air; results are relevant to CANDU loss of end­fitting accidents; ­ VERCORS te sts on F P r elease an d tr ansport c onducted b y C EA i n c ollaboration wi th IRSN a nd E DF; a dditional t ests m ay p otentially b e c onducted i n m ore o xidizing conditions in the VERDON facility; ­ RUSET tests by AEKI investigating ruthenium transport with and without other FP simulants; ­ Experiments by VTT on ruthenium transport and speciation in highly­oxidizing conditions.