This review covers: (a) The continuous countercurrent ion exchangers which have been described in the patent and/or technical literature. (b) Some of the other moving bed processes which are similar in mechanical arrangement to a continuous countercurrent ion exchange and which might have certain features adaptable to an ion exchange unit. (c) The auxiliary mechanical devices which are or may be used in an ion exchange apparatus.

The small amount of irradiation tenting experience on the plutonium-aluminum type elements planned for the Plutonium Recycle Test Reactor (PRTR) has made such testing of great importance. The high temperature pressurized recirculating water 1706 KER facility is one possible place for conducting investigations of the irradiation behavior of this type fuel element. To obtain the maximum information from the in-reactor testing and to detect possible problems, out-of-reactor test both at room and anticipated operating temperatures must be made. Room temperature pressure drop measurements and high temperatures performance of two prototypical fuel element designs proposed for KER testing are reported in this document.