zed and would compete with the radionuclides for the exchange sites. In the event where the waste can meet these specifications, two principal techniques are used: batch operation and column operation.The batch operation consists of placing a given quantity of waste solution and a predetermined amount of exchanger in a vessel, mixing them well and permitting them to stay in contact until equilibrium is reached. The solution is then filtered. The extent of the exchange is limited by the selectivity of the resin. Therefore, unless the selectivity for the radioactive ion is very favourable, the efficiency of removal will be low. Column application is essentially a large number of batch operations in series. Column operations become more practical. In many waste solutions, the radioactive ions are cations and a single column or series of columns of cation exchanger will provide decontamination. High capacity organic resins are often used because of their good flow rate and rapid rate of exchange.Monobed or mixed bed columns contain cation and anion exchangers in the same vessel. Synthetic organic resins, of the strong acid and strong base type are usually used. During operation of mixed bed columns, cation and anion exchangers are mixed to ensure that the acis formed after contact with the H-form cation resins immediately neutralized by the OH-form anion resin. The monobed or mixed bed systems are normally more economical to process waste solutions. Against background of growing concern over the exposure of the population or any portion of it to any level of radiation, however small, the methods which have been successfully used in the past to dispose of radioactive wastes must be reexamined. There are two commonly used methods, the storage of highly active liquid wastes and the disposal of low activity liquid wastes to a natural environment: sea, river or ground. In the case of the storage of highly active wastes, no absolute guarantee can...
