Using Real-Time Radiography (RTR) as an Inspection Tool for Low-Level Nuclear Waste

Because of support of multiple on-going research and programmatic activities at Los Alamos’ Chemistry and Metallurgy Research (CMR) Facility, large quantities of lowlevel nuclear waste materials are constantly being generated. These materials must be continually moved along their proper disposition paths and out of the facility in as timely and economically feasible manner as possible. Low-level waste, consisting primarily of low-density, combustible-type items such as paper products, light rubber gloves and plastics, and rags, is accumulated in the various laboratory rooms and packaged in plastic bags which are further placed in 1 x 1 x 2 ft cardboard boxes. Prior to counting these boxes on a low-level waste (LLW) instrument, they must be opened and inspected to ensure that no prohibited items such as metal, aerosol cans, and glass were inadvertently introduced. A radiological control technician (RCT) who monitors for potential contamination must accompany this procedure. Thus, the inspection process is not only time consuming and costly but also risky. In addition, a further risk potential exists for physical injury from hazardous items such as broken glass and sharp pieces of metal. Clearly, a method for non-invasively inspecting these boxes would be very desirable. We have a large industrial X-ray system in place at the Waste Assay Laboratory in the CMR Facility capable of supplying real-time imaging. This instrument produces X-rays ranging from very low energies to a maximum output of 320 keV at 10mA. Also, the instrument has a large rotating and translating platform capable of holding multiple boxes. Because of the motion of the platform and varying beam energy and intensity, identifying liquids and metals is a relatively simple process. The intent of this paper is to describe and evaluate the various imaging techniques and to present data on cost and time savings. While we still have to process the boxes where the X-ray unit indicates suspicious items, this should be considerably less time consuming, costly, and risky than our current practices.