Comparative analyses of different modelling approaches to simulate radionuclide transport through the Dnieper reservoirs based on extremal flood 1999 scenario

¹ Ukrainian Hydrometeorological Institute, Nauka Av. 37, 251028 Kiev, Ukraine
² Institute of Mathematical Machines and Systems, National Academy of Ukraine, Prospect Glushkova 42, 03187 Kiev, Ukraine
³ ENEA, Italy

Abstract

The highest flood since the Chernobyl accident took place in River Pripyat in spring 1999. The most contaminated left-side flood-plain upstream the Chernobyl Nuclear Plant has been protected from flooding by a dike constructed in 1992. However right-side flood plain was inundated within a month. Near the Yanov Bay the shallow waste storage sites were inundated. The concentration of ⁹⁰Sr in the water discharged from this territory to the river has increased to 100000 Bq/m³ at the end of the flooding. The maximum concentration of ⁹⁰Sr in the river Pripyat the city of Chernobyl was 2000 Bq/m³. The propagation of the sharp pick of radionuclide concentration was monitored in Dnieper reservoir cascade for, approximately, six months. The measured data were processed by statistical methods and were used to develop a scenario for testing radionuclide migration models within the Inco-Copernicus project COMETES. The recommendations for the choice of the size of the computational compartments are suggested accounting for the characteristics of the water bodies.