Speaker
Description
Radioactive waste as spent ion exchange resins (IER), must be conditioned for storage and disposal, in order to reduce the possibility of dispersion, elution and diffusion of radioactive elements to the environment.
In this work, the immobilization of 0, 10, 20 and 30 wt% of dry cation exchange resins (CER), in linear low density polyethylene (LLDPE), high impact polystyrene (HIPS) and recycled polyethylene (RPE), was studied. Each blend specimen was studied non-irradiated and gamma irradiated with 100 kGy in 60Co facility.
The properties studied were swelling, mechanical properties (flexural tests) and leaching resistance. The materials were formulated in a discontinuous mixer. The properties of the materials were measured using thermo- molded compression test specimen. The leaching tests were carried out only for the 30 wt% CER composition, loaded with an inactive solution of Cs+, Co2+, Ni2+ and Sr2+ cations measured by Total Reflection X-ray Fluorescence (TXRF). The study was carried out following procedures and recommendations of international standards.
For CER immobilized in LLDPE, an increase in flexural modulus was observed as the percentage of CER increased as well as irradiated compared to non-irradiated samples. In the case of RPE, no differences were observed in flexural modulus, when varying the percentage of immobilized CER or for the irradiation condition. The materials formulated with HIPS showed a decrease in the flexural modulus with increasing the percentage of immobilized CER, with rupture of the test specimen. However, no difference was observed between the irradiated and non-irradiated samples.
The cumulative fraction leached values were between 0.008 and 0.006 for Cs+ and 0.004 and 0.001 for Co2+, Ni2+ and Sr2+, respectively, for blend of 30wt% CER content in LLDPE and RPE. An increase was observed in the leaching values of the non-irradiated specimens compared to the irradiated ones for LLDPE. This effect was not observed for RPE matrix. The cumulative fraction leached for HIPS was 0.015 for Cs+ and 0.002 for the other cations, being higher in the irradiated than in the non-irradiated samples.
No swelling effect was observed for any condition and studied material.
The results obtained in this study showed that RPE presents the best performance as immobilizing matrix for 30wt% CER content. Using recycled plastic in nuclear industry is an opportunity to include plastic waste as a resource in the context of a circular economy.
| Speaker's title | Mr |
|---|---|
| Affiliation | Comisión Nacional de Energía Atómica |
| Do you wish to participate as a Young Professional? | Yes |
| Do you wish to be considered for a Young Professional grant? | Yes |
