Permeability and diffusion of tritium in bentonite

Abstract 3 H has been prepared by dilution of the National Institute of Standards and Technology (NIST) 3 H standard (4926e 49 700 ± 180  TU. One part of the device was filled with 3 H-free water and the other with 3 H-spiked water (0.6 L volume for each part). In total, five devices with bentonite and five devices with a sand–bentonite mixture were prepared this way. The devices were thoroughly sealed to avoid loss of sample and isotopic exchange with the atmosphere and put horizontally in holders. The water for 3 H activity measurements was sampled monthly or bimonthly. A total of 8 mL of the sample was taken by syringe and transferred to a measurement vial. Each vial was additionally filled with 12 mL of a scintillator (Ultima Gold LLT, PerkinElmer) and thoroughly mixed. 3 H activity was determined by a liquid scintillation counter (LSC; Quantulus 1220) at the Laboratory for Low-level Radioactivities, Ruđer Bošković Institute, Zagreb. Due to the penetration of bentonite from the barrier into the water samples, tritium-free water has relatively high activity after 2 months of the experiment (average value was 5560 ± 240  TU). In the final sampling, after a 2-month time span, the activity reached 9670 ± 2490  TU. Later, sampling and measurement were not possible due to the high bentonite amount within the samples. Tritium-free samples from the sand–bentonite mixture device were stable, and the first analyses (1 month after the experiment setup) showed an average activity of 533 ± 31  TU, while the final (5-month time span from the first sampling) average activity was 12 800 ± 3430  TU. The increase in the concentration from the beginning to the end of the experiment was almost exponential. Spiked samples from the bentonite device had an average activity of 36 950 ± 2550  TU at the first sampling and 17 580 ± 13 320  TU after a 1-month time leg. Later, sampling was not possible. Spiked samples from sand–bentonite mixture showed a decrease in tritium activity from the first sampling (43 390 ± 1310  TU) to 27 210 ± 285  TU (5 months after the first sampling). Considering the penetration of bentonite material into the water samples, only the sand–bentonite mixture can be considered for further analyses through the calculation of the diffusion.

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch

References and Relationships

• Bibliographic citation: Permeability and diffusion of tritium in bentonite ; volume:2 ; year:2023 ; pages:165-166 ; extent:2 ; Safety of nuclear waste disposal ; 2 (2023), 165-166 (gesamt 2)

Contributors, Places and Time

• Creator: Uroić, Galla ; Veinović, Želimir ; Barešić, Jadranka ; Herceg, Vjekoslav

Further information

• DOI: 10.5194/sand-2-165-2023
• URN: urn:nbn:de:101:1-2023090704315918018274
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 14.08.2025, 10:47 AM CEST