No abstract

No abstract

No abstract

No abstract

The Nirex Safety Assessment Research Programme includes an investigation into the effects of cellulosic degradation products on the sorption of radioelements onto geological materials. Previous batch sorption studies have shown that the presence of high concentrations of both authentic cellulosic degradation products (produced by alkaline degradation of wood/tissue) and the well-characterised simulant, gluconate, can cause marked reductions in actinide sorption.This work has now been extended to cover a range of concentrations of both authentic cellulosic degradation products and their simulants, gluconate and iso-saccharinate. Geological samples were from the proposed Nirex underground radioactive waste disposal site at Sellafield, Cumbria. The nuclides studied were thorium and plutonium.In the presence of gluconate or iso-saccharinate, at concentrations above 10~4 M, the present work has confirmed the trends shown by earlier experiments, with a significant reduction in actinide sorption (R D values are often reduced by over an order of magnitude). However, in the presence of lower concentrations of organic materials, sorption was reduced at most by only a small margin (R n values reduced by less than a factor of two), and in some cases the results suggested a slight increase (R" values increased by up to a factor of four).