EN ISO 15646:2016

European foreword
Foreword
1 Scope
2 Brief description of procedure
3 Incidents
4 Apparatus
5 Reagents
6 Sampling
7 Procedure
8 Evaluation
9 Precision of the procedure
10 Test report
Annex A (informative) - Relationship between pellet
        mass evolution and O/M ratio evolution
Bibliography

ISO 15646:2014 describes a procedure for measuring the densification of UO2, (U,Gd)O2, and (U,Pu)O2 pellets, achieved by heat treatment under defined conditions.The densification of fuel in power operation is an important design feature. Essentially, it is dependent on structural parameters such as pore size, spatial pore distribution, grain size, and in the case of (U,Gd)O2 and (U,Pu)O2, oxide phase structure. A thermal re-sintering test can be used to characterize the dimensional behaviour of the pellets under high temperature. The results of this test are used by the fuel designer to predict dimensional behaviour in the reactor, because thermal densification in the reactor is also dependent on these structural parameters, albeit in a differing manner in terms of quantity.