Modelling of Innovative SANEX Process Maloperations

The innovative (i-) SANEX process for the separation of minor actinides from PUREX highly active raffinate is expected to employ a solvent phase comprising 0.2M TODGA with 5 v/v% 1-octanol in an inert diluent. An initial extract / scrub section would be used to extract trivalent actinides and lanthanides from the feed whilst leaving other fission products in the aqueous phase, before the loaded solvent is contacted with a low acidity aqueous phase containing a sulphonated bis-triazinyl pyridine ligand (BTP) to effect a selective strip of the actinides, so yielding separate actinide (An) and lanthanide (Ln) product streams. This process has been demonstrated in lab scale trials at Jülich (FZJ).The SACSESS (Safety of ACtinide SEparation proceSSes) project is focused on the evaluation and improvement of the safety of such future systems. A key element of this is the development of an understanding of the response of a process to maloperations. It is only practical to study a small subset of possible maloperations experimentally and consideration of the majority of maloperations entails the use of a validated dynamic model of the process.Distribution algorithms for HNO3, Am, Cm and the lanthanides have been developed and incorporated into a dynamic flowsheet model that has, so far, been configured to correspond to the extract-scrub section of the i-SANEX flowsheet trial undertaken at FZJ in 20131. Comparison is made between the steady state model results and experimental results. Results from modelling of low acidity and high temperature maloperations are presented.