The US and the Russian Federation are currently engaged in negotiating or implementing several nuclear arms and nuclear material control agreements. These involve placing nuclear material in specially designed containers within controlled facilities. Some of the agreements require the removal of nuclear components from stockpile weapons. These components are placed in steel containers that are then sealed and tagged. Current strategies for monitoring the agreements involve taking neutron and gamma radiation measurements of components in their containers to monitor the presence, mass, and composition of plutonium or highly enriched uranium, as well as other attributes that indicate the use of the material in a weapon. If accurate enough to be useful, these measurements will yield data containing information about the design of the weapon being monitored. In each case, the design data are considered sensitive by one or both parties to the agreement. To prevent the disclosure of this information in a bilateral or trilateral inspection scenario, so-called information barriers have evolved. These barriers combine hardware, software, and procedural safeguards to contain the sensitive data within a protected volume, presenting to the inspector only the processed results needed for verification. Interlocks and volatile memory guard against disclosure in case of failure. Implementing these safeguards requires innovation in radiation measurement instruments and data security. Demonstrating their reliability requires independent testing to uncover any flaws in design. This study discusses the general problem and gives a proposed solution for a high resolution gamma ray detection system. It uses historical examples to illustrate the evolution of other successful systems.
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