RRFM 2009 Transactions - European Nuclear Society

IRIS PROGRAM: IRIS4 FIRST RESULTS
F. CHAROLLAIS, M. RIPERT, MC. ANSELMET
Commissariat à l’Énergie Atomique -Cadarache, DEN/DEC,
13108 St Paul lez Durance – Cedex – France
P. BOULCOURT, X. TIRATAY
Commissariat à l’Énergie Atomique - Saclay, DEN/DRSN,
91191 Gif sur Yvette – Cedex – France
P. LEMOINE
Commissariat à l’Énergie Atomique - Saclay -DEN/DSOE,
91191 Gif sur Yvette – Cedex – France
C. JAROUSSE
AREVA-CERCA ◊
Les Bérauds – BP1114 – 26104 Romans –– Cedex – France
ABSTRACT
In the framework of the French IRIS program of high density UMo/Al fuel
development, the latest alternative solution was focused on the development of
advanced UMo atomised particles surrounded by a tailored oxide layer. The IRIS4
irradiation, launched in October 2008 in OSIRIS, is currently testing this concept
where the oxide layer is aimed to act as a protective barrier. The potential positive
contribution of silicon effect is also studied since two kinds of matrix are tested:
pure Al and Al + 2.1wt% Si.
This paper describes the IRIS4 experiment and reminds its main objectives. First
visual examinations and plate thickness measurements at the current level of
irradiation are compared to those of previous irradiations allowing the discussion of
both effects of oxide layer and silicon addition on the irradiation behavior.
1. Introduction
Despite the intrinsically good irradiation stability of UMo alloys, the UMo dispersion fuel
development has still to challenge the poor in-pile behaviour of the (atomised) UMo
dispersed in pure Al evidenced by past in-pile experiments such IRIS2, FUTURE and
RERTR irradiations [1, 2, 3]. Extensive porosity is formed in the reaction layer, at the
fuel/matrix interface, resulting in an unacceptable pillowing and/or swelling of the fuel plate. A
large part of the instability of (atomised) UMo/Al fuel is attributed to the behaviour of the
fission gas release and the properties of the UMoAl interaction layer (IL) formed during the
irradiation.
In that context, current development of advanced UMo/Al dispersion fuel has two main
objectives:
- either decrease the IL formation kinetics,
- or/and improve the IL in-pile behaviour, i.e. to enhance its fission gas retention.
To reach these goals, the French IRIS program has already tested two kinds of improvement
on full-size plates in the OSIRIS reactor using high density UMo fuel by modifying the Al
matrix composition and/or the UMo powder characteristics [4].
◊ AREVA-CERCA, a subsidiary of AREVA NP, an AREVA and SIEMENS Company
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