A particular concern in the event of a severe accident is release of highly-radiotoxic fission-product (FP) isotopes of ruthenium (Ru). The highest risk for a large quantity of these isotopes to reach the containment arises from air ingress following vessel melt-through. One work package (WP) of the SARNET Source Term topic is producing and synthesizing information on Ru release and transport with the aim of validating or improving the corresponding modelling of the ASTEC code. The WP includes reactor-scenario studies that can be used to define conditions of new experiments.
The experimental database currently being reviewed includes the following programmes:
AECL have conducted numerous semi-analytical tests on FP release in highly-oxidizing conditions, information on some tests is in the public domain;
VERCORS tests on FP release and transport conducted by CEA in collaboration with EDF and IRSN where potential exists for tests in more oxidizing conditions in the VERDON facility;
RUSET tests by AEKI investigated Ru transport with and without other FP simulants;
experiments by VTT on Ru transport and speciation in highly-oxidizing conditions.
In addition to the above, review of information on and modelling of fuel oxidation is being pursued since this is an essential boundary condition influencing ruthenium release.
This paper summarizes the status of this work and plans for the future.
(1) : VTT
(2) : ENEA
(3) : CEA
(4) : EDF
(5) : IRSN
(6) : INR