Time-dependent specific Sr-90 and Cs-137 soil radioactivity in the area ofthe Research Centre Julich

The development of the measured specific Sr-90 and Cs-137 soil radioactivit y in the area of the Research Centre Julich since 1981 is presented. The de crease of the radioactivity in soil over time is clearly demonstrated Resid ence constants of the radioactive nuclides in the upper 10 cm soil layer ca n be calculated from the measurements. These constants are compared with th e residence constants officially recommended for radioecological calculatio ns. For Sr-90 the calculated constant is smaller and for Cs-137 the constan t is larger than the recommended parameters.