Muon Tomography for Monitoring Civil Nuclear Assets

Muons are fundamental charged particles, produced in the atmosphere by cosmic rays. Every second, hundreds of high velocity muons shower each square meter of earth, providing a highly penetrating, naturally abundant, and safe particle source that can be used for passive imaging. One such imaging technique is Muon Scattering Tomography (MST), which uses sandwiches of detectors to measure statistical changes in the scattering angles of muons as they pass through an object. This provides a 3D map of the object’s density.

Passive MST has already been used to image the internal structure of ancient pyramids, voids in active volcanoes, encapsulated nuclear waste, and fissile materials concealed in shipping containers [1,2]. As muons arrive at earth from all angles, near-horizontal imaging is also possible [3]. Passive MST has an imaging rate and resolution that is defined by the background muon flux (~10^2 Hz/m^2) and the strength of the interaction between the muons and the imaged object. As such, MST works well when there are large contrasts in the atomic numbers of the particles that comprise the object: for example, a 5 cm^3 block of uranium can be discriminated from surrounding tungsten with over 80% confidence after one hour, and with over 95% confidence after four hours [1].

While MST systems for monitoring civil infrastructure have been proposed [4], this area is in its infancy. Field work to date has focussed on the geological structures surrounding tunnels [5,6], while proof-of-concept MST systems for concrete slab thickness have been limited to lab demonstrations [7]. Real applications of MST for reinforced concrete and steel structural health monitoring remain highly promising, but undeveloped.

The aim of this project is to develop an MST system for passively monitoring the structural health of reinforced and steel concrete assets.

Academic Lead: Marcus Perry
Location: University of Strathclyde