Investigating the ³⁶Cl memory effect in pyrolysis of solid samples from nuclear decommissioning activities

During the optimization of ³⁶Cl determination in solid wastes from nuclear decommissioning, a residual ³⁶Cl signal was observed in procedural blanks measured after processing active samples. To uncover the possible causes, we investigated the interaction of chlorine with the components of a Pyrolyser-6 Trio^TM, as well as the chemicals used during the procedure. Different treatments for identifying the source of chlorine carryover were thoroughly investigated, demonstrating that the ³⁶Cl memory effect arises from the interaction with pyrolyser components and that it occurs almost every time when the analysis procedure is performed. Therefore, results obtained using this analysis procedure need to be corrected for this memory effect by measuring procedural blank samples before and after measuring ³⁶Cl-containing samples.