Alpha characterization inside pipes using ion-transport technology

摘要

Many DOE facilities have several miles of waste pipe systems that are internally contaminated with various and often undetermined radio nuclides. Unfortunately, currently acceptable alpha detection technologies are inefficient, time consuming, and do not address the problems presented by small diameter or curved pipes. In general, the problem of detecting alpha contamination on the inside surface of pipes is complicated by the fact that alphas do not penetrate the pipe walls. Unlike their conventional counterparts, alpha detectors based on ion transport technology sense alpha particles by collecting the ions created in ambient air as the particle loses its kinetic energy. The ions inside the pipe are transported by a fan-generated air current to an electrode inside the detector, which is attached to one end of the pipe. The collected charge at the electrode is proportional to the number of ions created inside the pipe, which in turn is proportional to the number of alphas emitted. Typically, monitoring for alpha contamination inside pipes or ductwork involves disrupting the operation to access as much surface area as possible for standard alpha monitoring. The detector based on ion transport technology effectively minimizes such disruption and in many circumstances will allow for in situ monitoring of a system that might otherwise not be practically accessible to standard methods.