RRFM 2009 Transactions - European Nuclear Society

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EVITA: a semi-open loop in BR2 for RJH fuel qualification.
E. KOONEN, PH. GOUAT, PH. BENOIT, V. KUZMINOV
SCK–CEN, Boeretang 200, B –2400 Mol - Belgique
P. LEMOINE (1) , M-C. ANSELMET (2) ,
(1) CEA– Saclay, 91191 Gif sur Yvette – Cedex – France
(2) CEA– Cadarache, 13108 St Paul lez Durance – Cedex – France
S. BRISSON, S. GUILLOT
AREVA–TA, 1100, av JR Guilibert de la Lauzière, 13593 Aix-en-Provence– France
ABSTRACT
The qualification of the RJH fuel requires the demonstration of the satisfactory operation of an
actual full-size fuel element in representative conditions. Because the flux characteristics of BR2
are closest to the future characteristics of RJH and because the fuels are of comparable design,
test irradiations have already been made, including a mixed BR2-RJH fuel element,
manufactured at BR2 standard dimensions.
However, for a full-size irradiation, there are considerable differences between the BR2 and the
RJH regarding the full element diameter, the fuel cooling conditions and the pressure drop over
the core. Fortunately, there are some channels in BR2, one of which is in the centre of the
reactor, allowing the reach of the RJH required conditions with a limited equipping addition.
Furthermore, the reactor is rated at 120 MW but operates around 60 MW, so there is ample
cooling capacity.
So, EVITA is a semi-open loop, "grafted" on BR2 vessel, in which water is taken in the upper
plenum and taken to a "booster" pump, installed in BR2 pool. The pump raises the available
ΔP and re-injects the water in the central channel of BR2. The central channel is modified to
accommodate the dimensions of the full-size RJH fuel element. The water re-mixes with BR2
primary circulation in the lower plenum of the reactor. This concept takes advantage of all safety
systems of BR2 and does require minimal additional safety systems.
Given that there is no burnable poison in RJH fuel and that there is no way to move to a
"warmer" or "colder" position to compensate for the fuel burnup, the biggest challenge with this
irradiation will be to provide adequate - for RJH - irradiation conditions without penalising too
much the other users and the productions of BR2.
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