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Apr 19 – 22, 2022
Vienna, Austria
Europe/Vienna timezone
FR22 starts in Vienna 19 - 22 April 2022 Online Stream:

Modelling of the in-vessel source term during a hypothetical severe accident in an SFR

Apr 20, 2022, 1:40 PM
Vienna, Austria

Vienna, Austria

POSTER Track 2. Fast Reactor Safety Poster Session


PARTHKUMAR RAJENDRABHAI PATEL (Indira Gandhi Centre for Atmoc Research, India)


The in-vessel source term problem is to determine the partitioning of radionuclide (RN) in fuel, coolant and cover gas following a hypothetical severe accident. The determination of the in-vessel source term is a challenging task, as there is significant uncertainty involved in RN transport. The RN transport mostly controlled by their diffusion characteristics in the fuel, chemical interactions between RNs and coolant, their physical form (for ex., molten, solid, vapor, and aerosol) to mention a few phenomena.

The mechanistic modelling of in-vessel source term considering all phenomenon is a numerically demanding task. In the present work, a thermo-chemical equilibrium based approach is adopted to study the release behaviour of RN to the cover gas. We would consider this approach as the first step towards mechanistic model development for oxide fuelled SFRs. To study the chemical behaviour of RN, a medium-sized oxide fuelled, pool type SFR (1250 MWt) is chosen as a reference design. For the analysis, unprotected loss of flow accident (ULOFA) initiated by loss of flow to both the coolant pumps resulting in whole core melt is considered. The analysis is performed for different temperatures with two mixing assumptions, i.e., no mixture assumption and real mixture assumption. The no mixture assumption essentially means that, during the calculation of the equilibrium species, the solubility properties are not considered. This assumption provides conservative estimates. Whereas, for the real mixture assumption, the excess functions and solubility are considered. With the help of the equilibrium species, the release fractions are evaluated.

From the calculations, we observed that the amount of the oxygen available for the reaction affects the release dynamics of lanthanides and barium-strontium group (For example, Eu and Sr). Additionally, various mixture assumptions do affect the release behaviour of the RN in the coolant. For example, it is found that with no mixture assumption, the release fraction for Cs is about 0.9, when mixing assumption is considered, the release fractions are of the order of 1E-04 – 1E-05.

Speaker's email address
Speaker's title Mr
Country/Int. organization India
Affiliation/Organization Indira Gandhi Centre for Atomic Research, India

Primary authors

PARTHKUMAR RAJENDRABHAI PATEL (Indira Gandhi Centre for Atmoc Research, India) Mr John Arul A. (Indira Gandhi Centre for Atomic Research, India)

Presentation materials

Peer reviewing