To further avoid these effects, different possibilities have been proposed as follows: 1.Īddition of some Si into the Al matrix, ,.
The build up of an Al rich diffusion layer (IDL) at the UMo/Al interface, ,, ,, , is considered as the reason of this enhanced swelling, which may even cause pillowing of the fuel plate.
#Umo firstclass full size
Up to now, most tests with full size fuel plates prepared with either of both fuel types showed a huge swelling behavior during in-pile irradiation to high burn-up. Two types of UMo powders have been used: “atomized powder” which consits of round UMo particles or “ground powder” which is produced by grinding of UMo ingots and consits of unshaped UMo particles. One option is based on UMo alloy powder (Uranium–Molybdenum alloy with Mo content between 7 and 10 wt%) which is dispersed inside an Aluminum matrix. There have been strong international efforts to develop new high-density UMo/Al fuels for research and test reactors. The presence of an oxide layer on the surface of the UMo particles hinders the formation of the SiRL. The SiRL forms more easily when an Al–Si alloy matrix – which is characterized by Si precipitates with a diameter ⩽1 μm – is used than when an Al–Si mixed powder matrix – which is characterized by Si particles with some μm diameter – is used. In the case with at least 2 wt%Si inside the matrix a Silicon rich layer (SiRL) forms at the interface between the UMo and the Al during the fuel plate production. Second, the addition of some Si inside the Al matrix and the presence of oxide layers in ground and atomized samples is studied.
Alloying small amounts of a third element to the UMo had no measurable effect on the stability of the γ-UMo phase. The first finding is that that during the fuel plate production the metastable γ-UMo phases partly decomposed into two different γ-UMo phases, U 2Mo and α′-U in ground powder or α″-U in atomized powder.
UMo-Al based fuel plates prepared with ground U8wt%Mo, ground U8wt%MoX (X = 1 wt%Pt, 1 wt%Ti, 1.5 wt%Nb or 3 wt%Nb) and atomized U7wt%Mo have been examined.
0 kommentar(er)
