Calculating Expected and Observed Risks in an Advanced Transparency Framework

Proliferation resistance features that reduce the likelihood of diversion from the civilian nuclear power fuel cycle are critical for a global nuclear future. A framework that monitors process information continuously can demonstrate the ability to resist proliferation by measuring and reducing diversion risk, thus ensuring the legitimate use of the nuclear fuel cycle. Sandia National Laboratories (SNL) and the Japan Atomic Energy Agency (JAEA) are working in cooperation to develop an advanced transparency framework capable of assessing diversion risk in support of overall plant transparency. The “diversion risk” quantifies the probability and consequence of a host nation diverting nuclear materials from a civilian fuel cycle facility. This paper introduces the details of the comparison of expected and observed diversion risk. A real-time comparison between expected and observed operations provides the foundation for the calculation of diversion risk. The “expected risk” is the risk introduced by the existence of the facility based on planned and declared operations. This risk represents the normal baseline risk and is dependent upon plant design and processing capabilities. The plant design should have the goal of making this amount as small as possible. The “observed risk” is measured in real-time when the plant is operating and is based on the signals transmitted by sensors during the completion of declared operations. Observed risk is calculated at every process step via a comparison of actual operations to planned and declared operations (the foundation for expected risk).