Russian studies of the safety of anion exchange in nitric acid

The Russian literature pertinent to the thermal (chemical) and radiolytic d egradation of anion-exchange resins has been reviewed, aid some of the resu lts are summarized. The review covers strongly basic resins of both the con ventional (divinylbenzene-styrene) and the more recently developed pyridini um types. Thermal and radiolytic degradation causes loss of functional soup s (primarily in the conventional resins) and induces reactions in the polym eric structure. Experimental data on gas evolution from resin-nitric acid m ixtures are presented, including results obtained from studies of radiation effects. Process incidents involving anion exchange encountered in the Soviet nuclea r processing industry are listed. The most serious of these, a column explo sion occurring at the Mayak plant in 1993, is described in considerable det ail.