Technical methods employed for the On-Site Inspection

In the paper, the technical methods to be used for the on-site inspection (OSI) are reviewed. The main purpose of the OSI is to find evidences of a nuclear explosion conducted anyplace in the world, however, the technical methods described in the paper might be employed for a suspected underground explosion. Various technical methods are described but they can be classified into two categories, namely, technical methods, 1) to identify fission products, and 2) to identify underground evidences. Fission products can be identified by conventional gamma spectrum analysis, however, for the OSI, radioactive Xe and Ar are important nuclides since they are supposed to leak to the ground surface even when the explosion is conducted in deep underground. The seismic and various other technical methods, which might be commonly used by mining industry, can identify the underground evidences, such as a cavity. However, these technical methods might be necessary to be verified to confirm the applicability and effectiveness to OSI objectives.