Nuclear car wash status report, August 2005

Abstract

interrogating detector array, and bring the container to a safe stop. The container can then be returned to its initial "start" position, and the process repeated. The nominal operating parameters for the system are as follows: ß Container: standard 6.1 m length ß Container speed: nominally 20 cm/s (40 ft/min) ß Length of container travel: nominally 9.1 m total travel on 15 m long rails ß Operation: remote, from an operators station ß Positional feedback: encoder and video camera/monitor ß All operational procedures must adhere to ES&H requirements The translation design is comprised of three major subsystems: rail system, power transmission system, and container retrofit. It should be noted that this system is not intended to represent the field deployable version since, in this case, we are dealing with a floor over the neutron generator that cannot support the weight of a loaded container; and we also must address internal LLNL rules requiring substantial restraint for seismic safety so that an earthquake would not risk damage to the HEU samples that will be utilized in the experimental program. Figure 3.2.5.3-1 An overall "cut-away" view of the Cargo Container Translation System Rail System 6.1 Brief summary of accomplishments ß Identified and developed a new signature for SNM detection in thick cargo ß Defined a principal concept for implementation of this signature in a detection system. ß Assembled component testing lab for characterization of proposed system components. ß Developed a new capability for validated simulations to predict the performance of the concept with many variations in the details. ß Made absolute intensity measurements of the new signature and used those to accurately validate simulation tools. ß Defined an appropriate neutron source and detector array. ß Installed the appropriate neutron source and detector array in the cargo-scanning lab. ß Verified simulation tools with experiments employing representative cargo materials at challenging thickness in realistic geometry. ß Used a simplified error prediction analysis to show that goals can be reached within parameters currently under study in the cargo-scanning lab. 6.2 Remaining issues ß Background variations can lead to false positive errors. As cargo materials are moved and scanned the background variations are likely to be larger than those for a stable environment. Those variations must be characterized for a realistic environment. ß Component instability due to temperature variations, changes in environment, movement of materials, or other causes can lead to false alarms. These effects need to be quantified.