In situ characterisation of liquids in decommissioning environments by LIBS

Liquid waste streams and disposal ponds are key parts of the nuclear decommissioning challenge. Consequently, characterisation of these environments is an important aspect with sampling and off-line analysis being the conventional approach. This project aims to investigate the in situ characterisation of these environments using laser induced breakdown spectroscopy (LIBS) which can provide rapid elemental analysis. We have demonstrated success in preliminary measurements on molten salts in the AFPC-pyroprocessing project by measuring from the liquid surface but there are further questions to answer regarding whether the sampling is representative of the bulk as well as by applying multivariate data analytics and machine learning to the derived spectra. We plan to explore representative sampling by comparing 'dip-stick' sampling and direct LIBS measurement on the dip-stick as well as the development of a LIBS probe to directly sample the liquid bulk. The latter would be initially developed and trialled for ambient temperature environments. Comparisons will be made with extracted samples measured off-line by ICP.
LIBS underwater or molten salt probe measurements are particularly challenging and we will build on the experience of the bespoke LIBS and Raman systems that we have built in our laboratory for robotic application on the TORONE project (www.torone-project.com). The project would make use of the NNL LIBS instrument and be based at NNL Workington in the CINDe laboratory.