Canadian Technology Demonstration Of The Passive Techniques: Muon, Neutron, And Gamma-rays For Nuclear Disarmament Verification

Canada is an active participant of the International Partnership for Nuclear Disarmament Verification (IPNDV), providing both financial and expert support. One of the IPNDV’s mandates is to demonstrate technologies and procedures to verify nuclear weapons reductions without the transfer of sensitive information. To this end, Canadian Nuclear Laboratories (CNL) completed a technological demonstration of the use of muon scattering tomography (MST) to map volumes of very high density/high atomic number materials inside containers as well as measuring the neutrons and gamma-rays signatures of a mock-up nuclear warhead specifically designed for this study. The potential of the three passive technologies is high, however a technology demonstration is required to show the techniques’ limitations, and their ability to reliably distinguish between actinides and other heavy metals without revealing the exact shape, constituents, and mass of the fissile core; a concept known as “the information barrier”. The strengths and limitations of the three techniques were demonstrated experimentally at CNL by using a simple cubical model of a nuclear warhead. Although each technique investigated here presents its own strengths and limitations, the complementary use of three of them together appear to be the most appropriate approach in nuclear disarmament verification (NDV). Examples where results of each technique, if used solely, are not conclusive for NDV include the scenario where a nuclear core is surrounded by heavy shielding such as lead. If the MST technique is capable of determining the presence of a high-density and high-Z core, it does not provide information on the nature of the material, which leaves the possibility of swapping a nuclear weapon core with heavy metal such as tungsten. Similarly, detecting neutrons/gamma-rays via gross counting or mid-resolution spectra does not necessarily imply the presence of the nuclear core inside the black box under investigation. In this talk we will discuss scenarios that show the importance of fusing MST data and neutron/gamma emission rates for an effective and conclusive nuclear disarmament verification.