The operations of dismantling of nuclear installations are often difficult owing to the lack of knowledge about the position, identification and radiological characteristics of residual radioactivity.

As part of the investigation team for the ORCADE dismantling project at AREVA NC La Hague UP2-400 reprocessing plant, CANBERRA had the opportunity to use new nuclear measurement systems and modeling tools to develop a methodology to locate and characterise radioactive hold up.

The methodology uses different types of dose rate meters, gamma spectrometers and modelling tools, depending on the type of problem.

In this paper, the methodology and tools are described, followed by typical case studies, including hot cell activity evaluations and drum categorization methodologies. For each case, the detector and modelling tool choices are explained and justified.

This methodology helps to prepare and execute post-operational clean out and dismantling activities. These examples give concrete insights into their significance and the productivity gains they offer.

D&D, Gamma spectrometry, radioactivity modeling, source location, source identification, MERCURAD, PASCALYS, ISOCS, CARTOGAM