MODEL-DIRECTED SAMPLING IN CHERNOBYL FORESTS - GENERAL METHODOLOGY AND 1994 SAMPLING PROGRAM

Radiologically-contaminated forest and natural ecosystems contribute s ignificantly to the human radiation dose in the intermediate (several years) and long (several decades) terms following the radionuclide rel ease, As a result of the Chernobyl nuclear power plant accident in 198 6, extensive forested areas in Europe were significantly contaminated with cesium, strontium, plutonium and other radionuclides, This study develops a dynamic model that describes the pathways of radionuclides which undergo complex transfer processes in forests and natural ecosys tems. This generic model, FORESTPATH, calculates time-dependent radion uclide concentrations in forest compartments based on the information available on residence half-times, Because of the high complexity, tra ditional sampling programs often provide only limited and fragmented i nformation for the ecosystem to be modeled. A model-directed sampling program was initiated which implies close feedback between ecosystem s ampling and modeling of the radionuclide pathways using the FORESTPATH model, This program is now being applied by an international team of USA, European Union (EU) and Newly Independent States (NIS) members in the Chernobyl Nuclear Power Plant (NPP) Exclusion Zone.