Benchmarking LWR codes capability to model radionuclide deposition within SFR containments: An analysis of the Na ABCOVE tests

Abstract

Postulated BDBAs in SFRs might result in contaminated-coolant discharge at high temperature into the

containment. A full scope safety analysis of this reactor type requires computation tools properly validated

in all the related fields. Radionuclide transport, particularly within the containment, is one of those

fields. This sets two major challenges: to have reliable codes available and to build up a sound data base.

Development of SFR source term codes was abandoned in the 80’s and few data are available at present.

The ABCOVE experimental programme conducted in the 80’s is still a reference in the field.

Postulated BDBAs in SFRs might result in contaminated-coolant discharge at high temperature into

the containment. A full scope safety analysis of this reactor type requires computation tools properly

validated in all the related fields. Radionuclide deposition, particularly within the containment, is one

of those fields. This sets two major challenges: to have reliable codes available and to build up a sound

data base. Development of SFR source term codes was abandoned in the 80’s and few data are available

at present. The ABCOVE experimental programme conducted in the 80’s is still a reference in the field.

The present paper is aimed at assessing the current capability of LWR codes to model aerosol deposition

within a SFR containment under BDBA conditions. Through a systematic application of the ASTEC, ECART

and MELCOR codes to relevant ABCOVE tests, insights have been gained into drawbacks and capabilities

of these computation tools. Hypotheses and approximations have been adopted so that differences in

boundary conditions between LWR and SFR containments under BDBA can be accommodated to some

extent.

Two major outcomes result from this study: a reasonable approximation to the BDBA SFR scenario can

be achieved with LWR codes if suitable hypotheses are made and development and implementation of

new models is mandatory to enhance predictability to the required level in safety analyses. Vaporization,

nucleation and oxidation of Na and turbulent agglomeration of particles are phenomena, for which

models should be developed and implemented. Additionally, the importance of a good morphological

characterization of aerosol particles has been highlighted.