Panagiotis Apostolopoulos

Contaminated Concrete Removal Using Controlled Heat-Induced Spalling

Supervisors: Dr Giacomo Torelli, Dr Maurizio Guadagnini, Dr Shan-Shan Huang, Prof. Stefano Dal Pont (Univ. Grenoble Alpes)

Nuclear power stations generate approximately 20% of the UK's electricity. However, most of the currently operating plants will reach their end of life by 2030, where they will need to be successfully decommissioned. For decommissioning to take place, the contaminated walls and floors need to be remediated by removing the contaminated concrete from the structure. This accounts for a large percentage of the total costs. The current annual decommissioning costs are approximately £3 billion, and are expected to increase as more nuclear power stations will go offline.

An opportunity to significantly reduce these costs is to develop and employ new methods for the removal of contaminated concrete, with a higher concrete removal speed. A promising technique is heat-induced spalling, which takes advantage of a phenomenon occurring when a concrete member is heated rapidly that leads to layers breaking off from its surface. The key challenge with this technique is to accurately control the depth of the spalled layers.

This work aims to address this challenge, via modelling the spalling mechanisms. Research includes the development and implementation of accurate numerical models by simultaneous coupling of thermal, hygral, and mechanical mechanisms as concrete is heated. These models are validated against experiments to improve their accuracy.

It is expected that the developed numerical models will be able to predict heat-induced spalling. This will underpin the development of a rapid and cost-effective technique to remove layers of contaminated concrete of a desired depth, thus lowering the cost of decommissioning in the nuclear industry.