Process Accountability Flow Diagrams at the Los Alamos National Laboratory Plutonium Facility

We began implementing process accountability flow diagrams (PAFDs) at the Los Alamos National Laboratory Plutonium Facility in response to a 1983 DOE request for documentation of the flow of nuclear materials within the facility. Simple diagrams of each of the one-hundredplus unit processes have evolved into complex accountability “road maps” for each process. Here, we present the steps for constructing and modifying a PAFD, including details on accountability measurements points, process steps and item names, materials management information, and authorization/information block content. We also discuss the benefits of using PAFDs, particularly as a way to isolate process losses and gains for the rapid evaluation of inventory differences.