A combined radiographic and time-of-flight method for zero-knowledge warhead verification

Abstract

A novel means of combined spectroscopic and radiographic zero-knowledge warhead verification has been developed and investigated using Monte Carlo simulations. This verification approach, henceforth called "epi-ZK," uses time-structured beams of epithermal neutrons to verify weapon isotopics and geometry without creating or transmitting meaningful information about the device design. This method seeks to remedy information security and hoax resistance issues inherent in previously proposed zero-knowledge verification methods such as fast neutron radiography with preloaded detector arrays and NRF based methods. By using a combination of epithermal neutron radiography and time-of-flight analysis, the epi-ZK method achieves sensitivity to subtle isotopic and geometric hoaxes, while preserving a high level of information security. Results using a MCNP5¹ model of the verification setup on the "Black Sea Object" pit geometry as well as a speculative HEU implosion weapons design indicate that the method would be highly effective, even using existing research reactor or accelerator neutron sources. This method of verification therefore presents a viable means of verification for weapons previously excluded from treaties such as ST ART due to a lack of information-secure means of assuring device authenticity.