Heures thésards

Animé par Johannès Jahan

jeudi 9 juillet 2020 à 14:00

En visio

Boron and iodine behaviour during nuclear glass vapor hydration

Haohan Zhang

Subatech (équipe Radiochimie)

In France the nuclear waste glass, designed to confine high level radioactive materials, is proposed to be disposed in the disposal facilities constructed underground and with engineered barriers to prevent the release of radioactive materials.

During the long-term disposal of the nuclear glass, underground water will penetrate the engineered barriers and make the disposal cell re-saturated. It may lead to radioactive elements release upon glass dissolution. Before re-saturation, the unsaturated state may be kept for thousands of years due to the presence of hydrogen gas generated via the corrosion of glass canister. Thus, it is probable that nuclear glass will contact water vapor prior to aqueous solution. Recent studies suggested that glass vapor hydration process cannot be simulated as the glass aqueous corrosion and that the constituents of the hydrated layer were instantly released in aqueous solution [1]. As a result, understanding the durability of nuclear glass in vapor phase is indispensable for evaluating the long-term safety of nuclear glass.

The current PhD thesis focuses on studying the hydration of nuclear glass in vapor phase. The mechanism of glass vapor hydration is discussed by investigating the release of boron and iodine during the hydration process. The results indicate the possible transformation of tetrahedral 4B to trigonal 3B on the hydrated glass surface, which may result in the volatilization of boron in the form of boric acid.

 

[1] J. Neeway, et al., J. Non-Cryst. Solids 358, 21 (2012).

à venir

Yifeng CHEN

Subatech (équipe Théorie)