Pyrolysis of undoped and multi-element doped ion exchange resins with regard to storage properties

- Four ion exchange resins were pyrolyzed up to 650 °C with varied heating ranges.
- Volume reduction was analyzed and correlated with weight loss.
- The retention of doped elements on the resins after pyrolysis was studied.

Pyrolysis can be used as pretreatment for permanent storage of radioactively contaminated ion exchange resins. Therefore, the thermal decomposition of different ion exchange resins was investigated in fixed and fluidized bed reactors. Here, the anion and cation exchange resin mixtures for pressurized water reactors, in this case Lewatit, and boiling water reactors, in this case Powdex, were pyrolyzed up to 650 °C with varied heating rates at atmospheric pressure in different test facilities. A maximum weight loss of 63 or 75 wt.% (dry) and a reduction of the volume of the bed of 40 or 20 vol.% were founded. After specifying optimized pyrolysis conditions for the treatment, the resins were doped with cesium and various other elements to imitate the spent ion exchange resin from the nuclear power plants. With regard to cost reduction for exhaust gas cleaning, the retention of the doped elements in the pyrolysis residue was examined.