An efficient but little known tool for the application of the ALARA principle: ISOE (Information System on Occupational Exposure).The Information System on Occupational Exposure to ionizing radiation (ISOE) is a program launched by the Nuclear Energy Agency (NEA) in 1992. It was developed to address the needs of nuclear power plants and safety authorities as a comparison and information tool on practices in terms of optimization (ALARA principle), in NEA member countries. To date, more than 90% of the operating nuclear power plants in the world are participating in this program, which is organized in a decentralized form, with a steering group and four technical centers (Europe, Asia, north America and IAEA). The ISOE program includes an occupational exposure database and an information exchange and communication network. The databases permit the preparation of studies and comparisons of practices, either in a factual or analytical way. Thus, the ISOE program favors exchanges to the benefit of all participants and helps to bring operational radiation protection ever closer towards the "achievable" of ALARA.

Procedure for direct determination of uranium in urine by ICP-MS.Estimation of the internal exposure of personnel by radioactive substances, especially actinides, is one of the subjects of great importance in human radiological protection. Because of constant changes in industrial processes in the nuclear fuel cycle and new radiological protection regulations, means to perform routine individual monitoring and to estimate internal exposure of workers in an accident situation must be high-efficient. The method described here is the determination of uranium in urine by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry), directly after a simple 20-fold dilution of the urine samples. Optimisation of the operational parameters has led to propose an analytical procedure that allows the determination of mass concentration for each uranium isotope. Calculations of associated uncertainties and corresponding detection limits are detailed.

At the end of July 1998, three 137Cs sources (between 0.17 and 150 GBq) were found in the vicinity of the village of Matkhoji, located at 300 km to the west of Tbilissi. This site was a former Russian military base, abandoned since 1992 and used now as pasture and a playground for the children. The Georgian Environment Ministry requested assistance from IAEA which sent a mission to the site. This established that a predominantly chronic exposure of part of the population of the village has occurred. The IAEA requested technical assistance from IPSN. A mission, made up of 4 people from IPSN and a representative of the IAEA went to the site from 12 to 17 October 1998. This mission collected information on the circumstances of the exposure and selected a potentially explored cohort of 112 people, in three groups: children of more than five years and adults of less than 50 years attending the site and members of a family who had a source in their cattle shed. An analysis of hematologic parameters was performed on these people and 85 blood samples were taken for biological dosimetry. The hematologic analysis carried out on the spot did not show any particular anomaly. The biological dosimetry by scoring of unstable chromosome aberrations (dicentric, rings centric, fragments) in blood peripheral lymphocytes was performed on blood samples after air transportation to the specialised laboratory (LDBM) of the IPSN Two successive procedures were initiated. The first was a quick phase of triage not very precise but intended to check if some of these people presented obvious signs of irradiation. Only 50 cells per subject were scored. Seven days were needed to complete this phase. Dicentrics were found in three people only indicating a whole-body dose not exceeding 0.5 Gy on average. This triage was followed of a more complete but longer examination, where chromosome aberrations were scored in 250 cells. Six weeks were necessary to score 22 000 cells from the 85 people. In total, 30 dicentrics were scored among only 17 Georgian patients. The highest dose to the whole body estimated from a reference calibration curve was 0.3 Gy The majority of these dicentrics was found in the children having played on several occasions in the former military camp. Unfortunately, the information provided by the population was too fragmentary to permit an effective reconstruction of the individual doses.