Mass spectrometric determination of 232U in uranium from irradiated thoria

Basic studies on various aspects of thorium fuel cycle have been initiated with a view for full utilization of vast resources of thorium. With increased understanding of the reactor physics, it is found to be advantageous to irradiate fresh thorium bundles in power reactors in place of depleted uranium during startup of the reactor to get uniform power. Work has been initiated to study and develop methods for reprocessing of these irradiated bundles. Unlike the natural uranium spent fuel reprocessing, thorium reprocessing has many constraints. One of them is the strong gamma emission from the daughter products of 232U, which is formed along with 233U during irradiation. The presence of 232U and its daughter products will give high radiation dose to both U and Th product streams. The gamma dose of 232U daughter products during final stages of reprocessing and fuel re-fabrication has to be minimized to reduce the exposure to the working personnel. The radiation dose of the products will depend on the amount of 232U in 233U. Hence the amount of 232U present in 233U is of great importance in designing the process and equipment for final stages of reprocessing and, fuel re-fabrication so as to minimise personnel exposure