| 摘要 |
<p>A method of estimating the crystal grain size of a nuclear fuel pellet, consisting of the steps of heating a plurality of kinds of UO2 powder in dry air at a predetermined temperature increasing rate and determining a rate of weight variation occurring due to the oxidation of each powder; determining for each kind of powder a temperature at which the composition of the powder reaches from UO2+x phase to U3O7 phase, on the basis of a change in the weight variation rate; manufacturing sintered pellets from a plurality of kinds of UO2 powder the reaching temperatures of which are known; measuring the crystal grain sizes of a plurality of kinds of resultant pellets; identifying the correlation between the reaching temperatures determined to U3O7 phase and the crystal grain sizes measured of the sintered pellets; determining a temperature at which sample UO2 powder reaches U3O7 phase under the same conditions; and estimating the crystal grain size of a sintered pellet manufactured from the UO2 powder, on the basis of this phase reaching temperature and the above-mentioned correlation. The crystal grain size of a UO2 sintered pellet manufactured from UO2 powder can be estimated from the oxidation behavior of UO2 powder without manufacturing the sintered pellet actually. This enables the crystal grain size measuring cost to be reduced.</p> |
