The ORNL researchers conducted a test in which they sprayed the scintillating phosphor on simulated debris material marked with technetium-99.
An image intensified camera system captured an image of the simulated debris material in dark conditions.
OAK RIDGE, Tenn. – Oak Ridge National Laboratory (ORNL) researchers have developed a new technology to determine the extent of contamination in Cold War facilities that could replace costly and time-consuming traditional survey methods used by EM.
The innovative process is simple but effective: spray scintillating phosphor on the surface, and if it lights up, it’s a hotspot of radioactivity.
“Frankly, it works surprisingly well from our perspective,” said David Glasgow, a researcher at the laboratory. “Use of phosphor in this work is completely new and the detection limits we have achieved are exemplary for work of this kind.”
EM's Office of Deactivation & Decommissioning and Facilities Engineering (D&D/FE) Director Andrew Szilagyi challenged the researchers to find an efficient, effective way to determine the extent of elevated levels of low-energy beta emitting isotopes, such as technetium-99, in aging facilities in EM’s nuclear cleanup program. Technetium-99 is a slow-decaying radioactive isotope present in the remaining portion of Oak Ridge’s K-25 superstructure and the large gaseous diffusion plants scheduled for future decommissioning at EM's Portsmouth, Ohio, and Paducah, Ky. sites.
Szilagyi wanted to depart from the traditional methods that rely on large crews to survey, characterize, sample and analyze, all of which is especially costly in hazardous conditions. What’s more, high dose rates may prevent traditional survey devices from detecting contamination, forcing the longer process of sampling and analysis.
The commercially available spray is water-based and nonhazardous, and the scintillator coating can be removed easily without impeding decontamination efforts. The scintillator becomes energetically excited in contact with ionizing radiation, releasing excess energy through fluorescence, or light emission.
While radiological control technicians may take hours to assess contamination in an entire room using field survey instruments, the spray safely brings results in minutes.
“If we can assess larger areas more quickly, it would reduce the amount of time people have to be in those areas,” Glasgow said.
A camera, night vision device and optical filter can capture the images of the contamination, but the green color of the scintillator emission can be viewed by the naked eye when contamination is at a high level.
Szilagyi said EM is currently investigating use of the spray in the nuclear cleanup program.