A quantitative assessment of Imaging High-Z and Medium-Z materials using Muon Scattering Tomography

Abstract

A: Muon Scattering Tomography (MST) has been shown to be a powerful technique for the non-invasive imaging of high-shielded objects. We present here the application of the MST technique to investigate two types of nuclear waste packages, a small-steel drum and a large nuclear waste cask, namely, a CASTOR V/52. We have developed a quantitative method using the contrast-to-noise ratio (CNR) to evaluate the performance of an MST detector system in differentiating between high-, medium-, and low-Z materials inside nuclear waste packages with different shielding types. The density maps of the investigated volume are reconstructed with three different algorithms: Point of Closest Approach (PoCA), Binned Clustering (BC) and Angle Statistics Reconstruction (ASR). This study reveals that our MST detector system is able to differentiate between a (10 × 10 × 10 cm 3 ) copper cube, embedded within a concrete matrix inside the small-steel drum, and regions of background signal in four days of muon exposure time with a CNR value of 3.9±0.22 when using the ASR method. During our investigation of the highly-shielded cask, the reconstructed images of the cask contents by the ASR algorithm indicated the ability of our system to detect irregular baskets, such as empty baskets, with a CNR value of 5.0±0.3 after 30 days of muon exposure.

Mountain Muon Tomography Using a Liquid Scintillator Detector

“…Extensive research has shown that MT has a wide range of applications, including the imaging of volcanoes [1,2], pyramids [3,4], hidden underground structures [5,6], nuclear reactors [7,8], high-Z materials [9], high-Z and medium-Z materials [10], and bedrock sculpting beneath an alpine glacier [11]. The imaging techniques used in MT are often based on plastic scintillators [12,13], emulsion [14], and gas [15] detectors.…”