This International Standard describes a method for measuring the densification of UO2, (U,Gd)O2 and (U,Pu)O2 pellets obtained by heat treatment under defined conditions. The compression of fuel in nuclear power operations is an important design feature. It essentially depends on structural parameters such as pore size, spatial pore distribution, grain sizes and, in the case of (U,Gd)O2 and (U,Pu)O2, the oxide phase structure. The thermal post-sintering test can be used to determine the dimensional behavior of the pellets at high temperature. The results of this test are used by the fuel planner to predict the dimensional behavior in the reactor, since thermal compression in the reactor also depends on these structural parameters, although different in terms of quantity. Based on the prediction, it is necessary to correlate the results of this test using correlation rules, because the results of this test strongly depend on the post-sintering conditions (such as heat treatment temperature, treatment time, gas content and oxygen partial pressure).
EN ISO 15646:2016 Referenced Document
ISO 3369:2006 Impermeable sintered metal materials and hardmetals - Determination of density
ISO 9278:2008 Nuclear energy - Uranium dioxide pellets - Determination of density and volume fraction of open and closed porosity
EN ISO 15646:2016 history
2016EN ISO 15646:2016 Re-sintering test for UO2@ (U@Gd)O2 and (U@Pu)O2 pellets