Measurement of equilibrium distribution coefficient of selected radionuclides at KANUPP-II site

Equilibrium distribution coefficient (K/sub d/) of a particular specie in soil-water environment is an important factor to evaluate its mobility in surface water/groundwater system as it provides means of quantifying geo-chemical retardation processes. In relevance to nuclear power plant/waste disposal sites, it is very important to study this effect for relatively long half-life radionuclides for their safe disposal and management. The retention of radionuclides via ion-exchange is quantitatively expressed in terms of K/sub d/ values. K/sub d/ values of /sup 137/Cs and /sup 60/Co radionuclides for 67 soil and sediment samples collected from Karachi Nuclear Power Plant-II (KANUPP-II) site and sea-bed around the proposed effluent release point were determined. The objective of this work was to establish a database of K/sub d/ values of various radionuclides for assessment of reactor site and proposed out fall channel release point in the sea. Standard batch procedure was adopted and measurements were made with a 2' x 2' NaI(Tl) scintillation detector placed in a fixed geometry. It was observed that K/sub d/ values of /sup 137/Cs and /sup 60/Co of bore hole samples from K-II site vary from 1072 to 10558 ml/g and 357 to 2350 ml/g respectively. While K/sub d/ values of /sup 137/Cs and /sup 60/Co of sea-bed sediment samples vary from 1 to 111 ml/g and 2 to 247 ml/g respectively. (orig./A.B.)