IDEAS/IAEA Intercomparison Exercise on Internal Dose Assessment

There were several intercomparison exercises organized already at national and international levels for the assessment of occupational exposure due to intakes of radionuclides. These intercomparison exercises revealed significant differences in the approaches, methods and assumptions, and consequently in the results. In the frame of the IDEAS project “General Guidelines for the Evaluation of Incorporation Monitoring Data”, launched in the 5th EU Framework Programme, a new intercomparison exercise was performed. Originally it was planned to organise this intercomparison exercise on a European scale. Because of the relevance of the issue for the whole community of internal dosimetrists, however, it was decided to organise the exercise on a broader scale together with the IAEA. This new intercomparison exercise especially focuses on the effect of the guidelines for harmonisation of internal dosimetry. In addition it also consider the following aspects: • to provide possibilities for the participating laboratories to check the quality of their internal dose assessment methods in applying the recent ICRP recommendations (new respiratory tract model etc.), • to compare different approaches in interpretation of internal contamination monitoring data, • to quantify the differences in internal dose assessment based on the new guidelines or on other procedures, respectively, • to provide some figures of the influence of the input parameters on the monitoring results and • to provide a broad forum for information exchange. Several cases have been selected for the exercise with the aim to cover a wide range of practices in the nuclear fuel cycle and medical applications. The case were: 1. Acute intake of HTO 2. Acute inhalation of fission products 137Cs and 90Sr 3. Intake of 60Co 4. Repeated intakes of 131I 5. Intake of enriched uranium 6. Single intake of Pu radionuclides and 241Am A web-based approach was being used for the presentation of the cases, collection of responses and potential discussion of the results. Solutions to these cases were reported by 80 participants worldwide. This report presents and discuses the main findings and recommendation for future actions.