A Review of the Effect of Irradiation on the Corrosion of Copper-Coated Used Fuel Containers

Abstract

Radiation induced corrosion is one of the possible modes of materials degradation in the concept of long-term management of used nuclear fuel. Depending on the environmental conditions surrounding the used fuel container, a range of radiolysis products are expected to form that could impact the corrosion of the copper coating. For instance, γ-radiolysis of pure water produces molecular oxidants such as H2O2 and the radiolysis of humid air produces compounds such as NOx and HNO3. This review is confined to a discussion of the effect of γ-radiation on the corrosion of copper-coated containers. A simplified mixed-potential model is also presented to calculate the extent of copper corrosion by using the steady-state concentration of H2O2 generated during the first 300 years of emplacement, when the radiation field is significant.

Radiation‐induced corrosion model for copper‐coated used fuel containers. Part 1. Validation of the bulk radiolysis submodel

“…Assessments of the extent of RIC of UFC have tended to focus on the initial 300–500 years, the period corresponding to the highest dose rate due to the decay of fission products. [ 17,36 ] This is based, in large part, on the belief that radiation effects are insignificant below a dose rate of approximately 1 Gy/h. [ 9,10 ] Certainly, no assessment has been done of the corrosion consequences of the long‐term, low‐ and ultra‐low dose rates of long‐lived actinides.…”

“…Uncoupled models are the most common, for which it is assumed that the yield of radiolytic oxidants is independent on the rate at which they are consumed in the interfacial corrosion reaction. [ 17 ] The rationale for this assumption is that the primary radiolytic yields and the kinetics of the secondary radiolysis reactions are much faster than the rates of the interfacial electrochemical reactions. However, this assumption has not always proven to be valid, as demonstrated by Macdonald and Urquidi‐Macdonald.…”

Review of the Modelling of Corrosion Processes and Lifetime Prediction for HLW/SF Containers—Part 1: Process Models

“…Other uncoupled RIC models have been developed by Morco et al [197], Henshaw and Spahiu [208], and King and Behazin [202]. Morco et al [197] used a simplified version of the 730-reaction set for the humid air radiolysis model (HARM) [209] to arrive at a bounding estimate of the yield of HNO 3 produced by the radiolysis of humid air representative of the unsaturated repository environment during the initial saturation transient.…”

Hydrogen Absorption into Copper-Coated Titanium Measured by In Situ Neutron Reflectometry and Electrochemical Impedance Spectroscopy

“…3,8 Concerns have also been raised about the possibility of stress corrosion cracking (SCC) of the copper in the presence of HS⁻, although SCC is considered very unlikely to occur, due to the low concentrations of HS⁻ predicted to reach the surface of the UFC. 3,4,12 Lastly, although the possibility of hydrogen embrittlement, hydrogen blistering, and copper coating debonding is low due to the low solubility of hydrogen in copper, it is still necessary to study further the behaviour and impact of hydrogen in copper within DGR-relevant conditions. 3,13 A series of studies have been conducted to examine the effect of hydrogen absorption into copper.…”