Adsorption on various leach container materials of plutonium and curium leached from nuclear waste glasses

The adsorption tendency of leached-out ²³⁸Pu and ²⁴⁴ Cm on the wall of leach containers, during the leaching of waste glasses, was studied. The test pieces of quartz glass, PFA Teflon, gold and stainless steel, which are candidates for a leach container, were immersed in deionized water with the waste glass containing ²³⁸Pu or ²⁴⁴ Cm in a Pyrex glass container at 100°C, and then they were decontaminated with dilute nitric acid. The quartz glass was found to have the smallest contamination of ²³⁸Pu and ²⁴⁴CM. The adsorption amounts of ²⁴⁴Cm on the PFA Teflon and quartz glass were approximately the same, and for ²³⁸Pu the Teflon showed about twice the amount of adsorption as that measured on the quartz glass. The gold and stainless steel showed 30–40 times the adsorption amount of ²³⁸Pu as that on the quartz glass. Adsorption and desorption of curium and plutonium were discussed in relation with difference of materials, time dependence and acidity of leachate. Curium, which has been previously leached out from waste glasses, showed a relatively simple adsorption and desorption behavior. In the case of plutonium, the colloidal species would take a large part in the adsorption and desorption processes. The relationship between the ratio of the colloidal to the ionic species of plutonium and the adsorption-desorption behavior was discussed. The observation of alpha autoradiographs elucidated that the ionic adsorption was desorbed more easily than the colloidal one.