Diffusion of Sr, Cs, Co and I in argillaceous rock as studied by radiotracers</p> </p>

Abstract

Summary Diffusions of85Sr,137Cs,60Co and125I radionuclides have been studied in borecore samples from Boda siltstone/claystone formation (BCF) under ambient and in situ conditions. In-diffusion (85Sr,137Cs,60Co and125I) and through-diffusion measurements (125I) were performed at ambient conditions, and for iodine, in-diffusion measurements were also carried out at in situ conditions (100 bar, 50 °C). In the case of cationic species carrier-containing solutions were also applied.60Co was detected only in the first slice of borecore at each sample, while137Cs was detected also in the first-, second- and third slices according to the concentration-increase of inactive carrier. Among the investigated cations,85Sr exhibited the fastest diffusion rate with 2.7-6.0 . 10-12m2/s apparent diffusivity values. In the course of in-diffusion measurements 4.7 . 10-11 m 2 /s, during through-diffusion investigations 1.4-1.6 . 10-12m2/s and at in situ conditions 5.0-8.0 . 10-12 m2/s apparent diffusivities were obtained fo...