The Shelter constructed above the destroyed Unit-4 of the Chernobyl NPP
contains 20 MCi of nuclear fuel. More than 1000 m3 of
intermediate-level radioactive water is disposed in its basement. The
purpose of this work was to simulate migration of the radionuclides
90Sr and 137Cs from the Shelter into the subsurface
environment to evaluate their migration rate and migration paths. A
mathematical model accounting for the coupled transport of water and
radionuclides in variably saturated media was used. The lack of suitable
experimental and field studies excluded the possibility of complete
validating the model. Results of the simulations will be useful for future
field studies.