scope:

ISO 15646:2014 describes a procedure for measuring thedensification of UO2, (U,Gd)O2, and (U,Pu)O2 pellets, achieved byheat treatment under defined conditions. The densification of fuelin power operation is an important design feature. Essentially, itis dependent on structural parameters such as pore size, spatialpore distribution, grain size, and in the case of (U,Gd)O2 and(U,Pu)O2, oxide phase structure. A thermal re-sintering test can beused to characterize the dimensional behaviour of the pellets underhigh temperature. The results of this test are used by the fueldesigner to predict dimensional behaviour in the reactor, becausethermal densification in the reactor is also dependent on thesestructural parameters, albeit in a differing manner in terms ofquantity.