Effects of Bi 2 O 3 , Al 2 O 3 , PbO on silver tellurite glass for radioactive iodine immobilization
- PDF / 1,387,931 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 30 Downloads / 216 Views
Effects of Bi2O3, Al2O3, PbO on silver tellurite glass for radioactive iodine immobilization Hyun Woo Kang1 · Ki Rak Lee1 · Jung‑Hoon Choi1 · Hwan‑Seo Park1 Received: 10 July 2020 / Accepted: 22 September 2020 / Published online: 10 October 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract An iodine immobilization matrix, the AgI–Ag2O–TeO2 glass system, was developed. The effects of different additives, i.e., Bi2O3, Al2O3, and PbO, on performance were investigated. In an ambient atmosphere and at 800 °C, the melting of the glass precursor mixture was completed after 1.0 h, without significant loss of the constituent elements of the glass except for aluminum. The loading of iodine in the matrix was approximately 11–15% by weigh, excluding oxygen. The normalized releases of all the elements from the matrix were below the order of 1 0−1 g/m2, which satisfies US regulation (2 g/m2). Additionally, each additive had a different effect on the glass system, and their effects on element release from the matrix were clarified. Keywords Iodine immobilization · Radioactive iodine · Silver tellurite glass · Vitrification · Sequestration
Introduction Radioactive iodine (129I) is generated from the fission reactions of nuclear fuel. It can be released from the reprocessing or recycling of spent nuclear fuel. Due to long half-life (1.57 × 107 years) and high mobility in geological environments, safe handling of radioactive iodine is very necessary. Most 129I is captured on the surface of silver-loaded zeolite filters in off-gas treatment processes in the form of AgI given that silver ions react effectively with iodine gas to form solid AgI. The AgI is known as an iodine compound with high chemical stability. The iodine is not easily released due to its chemical resistance to aqueous media with Ksp = 8.52 × 10−17. However, the release of sliver is also regulated by the Resource Conservation and Recovery Act (40 CFR 261) so that AgI should be immobilized by a chemically stable matrix to satisfy the regulation [1–6]. To develop an immobilization matrix for AgI, silver tellurite glass [7, 8] and silver phosphate glass [9–11] have been investigated. Reportedly, the addition of B i2O3 to silver tellurite glass is effective on normalized iodine release, which satisfies US regulation (2 g/m2). In this previous study, the structural bonding of the AgI in the immobilization * Hyun Woo Kang [email protected] 1
Korea Atomic Energy Research Institute, Daedoek‑daero 989‑111, Yuseong‑gu, Daejeon 34057, Republic of Korea
matrix was investigated. However, the effects of Bi2O3 on the crystalline structure and chemical stability of the silver tellurite glass have not yet been investigated [8]. It has also been reported that the addition of Al2O3 to silver phosphate glass enhances the chemical stability [9]. The effects of the Al2O3 on the silver phosphate glass have been further investigated in order to enhance the stability [11]. Additionally, to develop an immobilization matrix for chloride waste, tellurite glass withou
