An experimental apparatus to study the adsorption of water on proxies for spent nuclear fuel surfaces

This paper describes the design, construction and testing of an experimental apparatus capable of conducting high temperature adsorption isotherm analyses on large quantities of powder samples inside an ultra-high vacuum chamber. Data is obtained by dosing in fixed amounts of water vapor and measuring precise pressure changes using a high temperature capacitance manometer. The rig is designed to provide insight into the wetting of failed spent nuclear fuel (SNF) under conditions conventionally regarded as ‘dry’. Validation experiments are reported based on powder CeO2 (a non-radioactive surrogate for SNF) at 100 °C. It is planned that this and successor rigs can provide ever more direct experimental evidence to address a key policy–relevant problem.