The garage-sized device, called a Crated Waste Assay Monitor (CWAM), uses a neutron-activation system to "look" into 4- by 4- by 6-foot steel boxes that contain a variety of nuclear-weapons factory wastes.
Once its 5-ton door slides closed over the box-analysis area, CWAM fires neutrons into the waste and reflects the resulting signal from arrays on all six sides of the waste crate, a technique known as active interrogation. The radioactive contents of an entire box can be analyzed in 30 minutes with the technique. Sensitive detector arrays, combined with specialized software packages, determine the source, matrix type and source location in the crate from the returned neutron signal.
The process, called the Differential Die-away Technique, allows operators to determine the amount of uranium or plutonium inside each box, despite a potentially dense matrix of scrap metal, baled debris and other waste materials. In its new home at Y-12, it will be used primarily for uranium detection.
The device's developer, Sheila Melton of Los Alamos' Nonproliferation and International Security Division, says CWAM can find the radioactive equivalent of half a packet of sugar sprinkled into the waste crate.
"Correcting for the dense matrix of other materials is one of the key advances in this technology," Melton said. "The operator can confidently determine from the readings an amazing amount of detail. For example, CWAM can distinguish a large, shielded piece of uranium in the center of the box from several smaller pieces of the metal near the edges, information needed to correctly categorize the waste for efficient, legal disposal."
With that level of detail, Y-12 technicians can safely analyze approximately 1,000 crates per year that await disposal at the facility, and they can determine which are below the regulatory limit. Boxes containing less than one ten-billionth of a Curie of uranium per gram of waste can be disposed of at the Y-12 site landfill. Without the CWAM measurement, the waste would have to travel to an off-site radioactive waste facility at considerably greater cost.
Including transportation, disposal, container, and characterization costs, the annual savings to the public is $3.7M (assuming a throughput of 1000 boxes/year). Thus, CWAM's effective differentiation of waste bound for onsite versus offsite disposal has a significant financial impact.
The CWAM device is owned by the Department of Energy and will be operated by Canberra Industries, a nuclear systems and instrument company based in Meriden, Conn. The system was developed with the support of DOE's Office of Nonproliferation and National Security, under program manager Michael Sparks in the Office of Security and Emergency Operations, Technology Development Program (SO-212.4), as well as Canberra Industries. The system will serve as the prototype for another combined neutron and gamma ray measurement system designed to assay low-level and transuranic nuclear waste. The next-generation instrument, called the Integrated Box Interrogation System, can be used at nuclear facilities nationwide that require accurate analyses of radioactive waste.
"This new generation of detector package can perform real-time analysis at reduced cost, with improved accuracy and with greater safety from contamination," said Joseph Wachter, senior applications manager for Nondestructive Assay Systems at Canberra.
NOTE: Photographs and videotapes of the CWAM device are available.
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and the Washington Division of URS for the Department of Energy's National Nuclear Security Administration.
Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.