Prospects for Using Weakly Dissociated Ion Exchange Resins in Special Water Treatment Systems at VVER-Based Nuclear Power Plants for Reducing the Volume of Radioactive Waste Generated

摘要

Minimizing the amount of liquid radioactive waste generated during operation of nuclear power plants is among the important problems that have to be solved to enhance the nuclear power industry safety and economic indicators. For this purpose, it is proposed that the ion-exchange materials applied in the active water treatment systems of new power units equipped with VVER-type reactors be used only once (without regenerating them). In so doing, measures should be taken to dramatically reduce the consumption of ion-exchange resins by using materials having a higher ion-exchange capacity than the currently used universal ion-exchange resins. In addition, it is necessary to improve the ion-exchange treatment technology to achieve a higher extent of filling sorbents with the target components, primarily, with radionuclides to be buried. In this context, the properties of weakly dissociated ion-exchange resins made on the basis of acrylic acid and divinylbenzene copolymers are considered. The selected line of research is theoretically substantiated, and the results from laboratory investigations on treating model flows are presented, including those for elaborating the regeneration modes of weakly dissociated ion-exchange resins, the use of which makes it possible to fix biologically dangerous components in mineral-like structures with the minimal amount of compounds to be buried. It is shown that sequential subjecting of alkali flows contaminated with radionuclides to ionexchange treatment in the carbonaceous resin–sulfonic cation resin system results in that the solution becomes dealkalized under the effect of carbonaceous resin, after which cesium radionuclides are removed by means of sulfonic cation resin. Such redistribution of functions helps to decrease the concentration of alkali-metal and ammonium ions that compete with_(134, 137)Cs radionuclides for sorption vacations, due to which the sorbent to be buried is filled with radioactive substances to the maximal extent, thus resulting in a smaller amount of generated radioactive waste.