OBSERVED PRACTICES THAT CAN ADVERSELY AFFECT AN MC&A PROGRAM

This paper describes practices observed by the authors that can undermine the effectiveness of a program intended to control and account for nuclear material. Included are practices that have long been acknowledged as adversely affecting material control and accounting programs, such as the use of \"by-difference\" accounting (where unmeasured side streams are estimated by subtracting output from input) and the extensive use of measurement methods that lack precision. It also covers practices that adversely affect new MC&A methodologies. For example, process monitoring is affected when manufacturing processes undergo frequent change and lack stability, and both process monitoring and item monitoring are affected when data is entered incorrectly in the computer systems used to account for material.