Aerosol measurements and nuclear accidents: a reconsideration, report of the round table discussion

Radioactivity Environmental Monitoring (REM) is commonly divided into routine and emergency monitoring. Routine REM must demonstrate the adequacy of controls on releases as well as the compliance with radiological standards. It should also be able to give an early warning in case of abnormal concentrations, so that emergency REM may be initiated promptly. It should be clear, however, that stack monitoring and other in-plant measurements are the primary information sources for abnormal conditions. Emergency REM should rapidly assess the extent of an accident and provide the information needed for taking countermeasures. The collection of in-depth information on environmental processes for model validation is usually considered as an additional benefit of both routine and emergency REM. In discussing techniques for measuring radioactive aerosols, in particular the need for new and more sophisticated techniques, one must consider the objectives of REM, define how much weight should be given to each of them, and investigate whether new techniques might help in meeting the objectives. The opinions of the experts are organized into three chapters: the first compiles experiences and opinions about radioactive aerosol monitoring and defines the experimental needs for such monitoring with respect to early warning and early assessment in case of nuclear accidents; the second chapter discusses radioactive aerosol monitoring from the point of view of the scientist who wants to increase or validate his knowledge about the behaviour of radionuclides in the atmosphere; the third chapter reviews recent developments in field of aerosol and nuclear metrology and their interest for nuclear safety. Each chapter ends with a number of conclusions and recommendations