Studies of hydrodynamics in the airlifts used for sampling solutions

At nuclear fuels reprocessing plants, solutions containing nuclear materials are sampled by means of airlifts. Airlifts may however deliver samples which are not perfectly representative of the solution, due to the possible evaporation of water /1/. This effect strongly depends on the operating conditions existing within the airlift. Unfortunately, in most industrial airlifts these operating conditions are not measured nor - in many cases - measurable. Therefore, in order to determine whether evaporation exists and to what extent it affects the solution representativity, it is necessary to make calculations by means of theoretical models. Existing theoretical models seem however unable to provide sufficiently accurate results in determining the motion regime of the air-solution mixture within the airlift. For this reason a study has been initiated at the JRC Ispra. This paper discusses the problems related to the hydrodynamics of airlifts and the objectives of the study.