Interrelationships and the effects of introducing separation technologies in the nuclear fuel cycle for enhanced radioactive waste management

摘要

The nuclear fuel cycle consists of multiple processes,including electricity generation, reprocessing, andgeological disposal. In addition, various separationtechnologies have been developed for volume reduction ofradioactive waste. Especially from the viewpoint ofthermal properties of vitrified waste, the separation ofheat-generating nuclides such as cesium (Cs), strontium(Sr), and minor actinides (MA) are considered to beimportant factors. Furthermore, the separation ofmolybdenum (Mo) and platinum group metals (PGM)requires consideration of the quality of the vitrified wasteand the stable operation of the glass melter. However, theeffect of introducing separation processes depends on thenuclide inventory and the amount of high-level waste aswell as the conditions of each process in the fuel cycle.Therefore, it is important to clarify the potential impact ofseparation processes under various conditions of the fuelcycle to reduce the burden on waste management. In thisstudy, we have focused on the separation of Mo, PGM, Cs,Sr, and MA, and investigated their effects on vitrificationand geological disposal for extended cooling periods ofspent nuclear fuel and increased waste-loading in vitrifiedwaste. The relation between the cooling period andseparation was studied to maximize the benefits for thenuclear fuel cycle, especially through reductions of thevolume of vitrified waste and the waste-occupied area.