Evaluation of special nuclear material monitoring instruments

A statistical method to protect against the loss of strategic special nuclear material (SSNM) is presented. A simplified step by step approach to the test procedure is described. Strategic special nuclear material (SSNM) is protected using several layers of physical and administrative controls. In a facility having both enriched and depleted uranium, extensive control is exercised to prevent a diversion of the SSNM, but assurance must also be provided that depleted material is not being removed inasmuch as its low would indicate the possible loss of SSNM through surreptitious substitution. One option for identifying loss of material is to place walkthrough monitors at the pedestrian exits leaving the perimeter of the security boundary enclosing the uranium processing area. Within this security perimeter are the SSNM areas having tight control and restricted access. The monitors for the SSNM are within buildings and are in the benign environment of a working area. Perimeter monitors on the other hand are located at the boundary rotogates and are subject to the ambient conditions varying with the seasons