Epoxy Compounds for Immobilizing Radioactive Wastes

Abstract

The radiation resistance of epoxy compounds, solidified by crystalline hardening agents -metaphenylenediamine and phthalic anhydride -is investigated. It is shown that under conditions of γ irradiation (E = 1.33 MeV) the temperature of vitrification of the compounds depends on the dose (doses up to 1500 Mrad were investigated) and temperature 20-160°C, and the radiation gas release depends on the vitrification temperature and irradiation. It is shown that epoxy-phthalic anhydride compound is best as a matrix for immobilizing solid radioactive wastes at high temperatures (80-130°C). The experiments showed that the proposed compound can be recommended for immobilizing solid radioactive wastes.A great deal of attention is now being devoted to choosing the compounds for immobilizing radioactive wastes [1][2][3]. Epoxy compounds are promising materials for handling wastes, because such compounds possess high radiation resistance due to their content of aromatic groups [1]. The possibility of fixing radionuclides in reactor graphite by an epoxy oligomer, whose density was increased by heterocyclic aldehyde of the furan series with a filler and special-purpose additive, was demonstrated first in our country. The solidifying agents used for epoxy compounds are characterized by a crystalline and liquid aggregate state and radiation resistance. Solidifying agents such as polyethylene polyamine and polyamides are used, for example, in the immobilizing agent F and the Atomik compound, whose operational properties are described in [1]. The compounds of these solidifying agents are convenient to use because they do not require additional heating. However, the relatively low vitrification temperature (~60°C) gives rise to difficulties in using such compounds for immobilizing solid wastes, whose radiation heating exceeds 60°C. If the temperature of radiation heating exceeds 80°C, it has been suggested that compounds undergoing hot solidification be used, and metaphenylenediamine (a crystalline substance with a melting temperature of 63°C) and phthalic anhydride (a crystal substance with melting temperature 130°C) be used as the solidifying agent [4]. The wastes are solidified at temperatures not less than the melting temperature of the solidifying agent. Then the compound is in a low-viscous state and when solid wastes are immobilized it penetrates into the microcavities, forming a reliable matrix.The immobilizing agents for solid wastes must meet the following basic requirements: they must have high mechanical and adhesion strength, they must remain stable in water solutions, including solutions of acids and alkali, they must be in a glassy state under operating conditions, leaching of radionuclides should not exceed 10 -4 g/(cm 2 ·day), and the gas release should be minimal (not greater than 10 -8 -10 -9 cm 3 /(g·rad)). Under operating conditions, the deviation of the first four parameters should not decrease by more than 25%.The experiments showed that solidified epoxy compounds in a glassy state have high strength under comp...

Improving the helium gas barrier properties of epoxy coatings through the incorporation of graphene nanoplatelets and the influence of preparation techniques

“…The impregnation of this waste with epoxy resin can be effective in limiting the leaching of radionuclides from the graphite structure [7,8]. However, most polymers tend to exhibit poor gas barrier properties when compared to other materials like metals [9][10][11].…”

“…Polymers are being researched as a viable option to immobilize low‐level irradiated graphite waste from gas‐cooled graphite‐moderated nuclear reactors after being dismantled due to their versatile properties when compared to more traditional methods like Portland cements . The impregnation of this waste with epoxy resin can be effective in limiting the leaching of radionuclides from the graphite structure . However, most polymers tend to exhibit poor gas barrier properties when compared to other materials like metals .…”

Preparation and evaluation of mixed gamma sealed source for calibration purpose

“…Since epoxy compounds fulfill the requirement for radiation stability as they have excellent mechanical and sticking strength, durability in alkaline and acidic solutions, and negligible leach and gas emission even with using high activity, they are promising materials for the immobilization of radioactive waste as opposed to organic ion-exchange resins [30,31].…”

Preparation and Quality Control on 113Sn, 125Sb and 60Co Adsorbed on ZrSiW: Volume and Planar Reference Source for -Detector Calibration

“…The space above the packed ZrSiW matrix was filled with thermal silicon to the top of the capsule to fix the core material. Then, the capsule lid was compacted into the capsule base (Platonov et al, 2002;Shtrombakh et al, 2005). After 24h, the sealed sources were subjected to the quality control tests.…”