Applications of On-Line Continuous Solvent Extraction in Nuclear Chemistry

Sammanfattning: Methods and procedures for on-line continuous chemical separation of iodine species in reactor water and for transactinides in heavy element chemistry have been developed.

Radioiodine is one of the more important fission products in terms of nuclear reactor safety due to its high fission yield, significant radiobiological hazard and potential volatility.A method for separation (speciation) of iodine species in reactor water, based on continuous solvent extraction using mixer-settlers has been developed. Using this method the chemical behaviour of iodine (iodide, iodate, elemental iodine, organic iodides and residual iodine) in the three boiling water reactors in Forsmark, Sweden, has been investigated.

For separation of transactinides, fast on-line solvent extraction using the multistage centrifuge system SISAK has been used. Procedures have been evaluated off-line and on-line for the separation of rutherfordium (element 104), dubnium (element 105), seaborgium (element 106) and bohrium (element 107). ²²⁴Pa was used to show that the method can be used to study a-decaying nuclides with half-lives down to ~ 0.85 s. A method for decay correction for the transport through the SISAK system has been developed. The chemical separation system for rutherfordium has been greatly improved.