Characterization of HTR Fuel Element Samples by Activation Testing

Performance of HTR fuel particles is examined by irradiation experiments in Material Test Reactors. An important goal is the determination of particle failure fraction during irradiation. To do this a nondestructive method was developed to ensure zero failure at the begin of the irradiation test. The fueled samples are activated for half an hour in an electrically heated furnace in reactor Melusine. The resulting fission gases are trapped and quantitatively evaluated. From the resulting R/B-values the number of failed particles can be deduced. In two test series with a total number of 24 fuel compacts no defective particle could be found. Detection limit R/B Kr 85 m was 10−8.