CONTACT: Ternel Martinez, 505-665-7778 (00-034)
Researchers develop more practical dosimeter for emergency responders
LOS ALAMOS, N.M., March 15, 2000 -- Firefighters, paramedics and other emergency responders soon may wear a more practical dosimeter developed by researchers from the Department of Energy's Los Alamos National Laboratory that immediately determines if they are exposed to radiation.
The prototype dosimeter, called Radiation Litmus Paper (RLP), uses nano-scale catalysts that change the color of a chemical solution inside, signifying radiation exposure. RLP also may have applications in nonproliferation and nuclear disarmament.
"The responder community does not need sophisticated, heavy radiation detection equipment. They simply need to know if a radiological situation poses a threat to them," said project leader Benjamin Warner of Los Alamos' Chemical and Environmental Research and Development Group.
Radiation Litmus Paper is more practical for first responders than other dosimeters because it is lightweight, inexpensive and simple to use, Warner said.
Radioactive sources are commonly used to calibrate instruments or other purposes in such business sectors as medicine, construction and manufacturing. Improper disposal or abandonment of these sources has caused serious injuries and death in the United States and other countries. Radiation Litmus Paper offers an affordable means to detect radiation before it becomes a serious risk.
The inexpensive device weighs about an ounce and consists of a rugged, lightweight plastic card containing a mixed solution of two environmentally benign, nontoxic chemicals separated by a glass barrier. Similar to activating a glow-stick, the user flexes the card to activate RLP, breaking the barrier and releasing the indicating chemical solution into a chamber.
Nanocluster catalysts inside then amplify the radiation signals to which they are exposed. The cluster size is crucial to balancing the sensitivity and stability of RLP. The solution reacts with the catalysts and changes its color in correspondence to the radiation dose. Unused RLP cards remain viable for up to a year.
Currently, Radiation Litmus Paper can be set to any one level of radiation sensitivity at a time, ranging from 15 millirems to 2 rems. In addition to making Radiation Litmus Paper even smaller and lighter, Warner is developing an RLP array that will provide a wider dynamic exposure range.
"For example, picture a simple array of two units set at 20-millirem and 50-millirem sensitivity, respectively. If the 20-millirem unit changed color but the 50-millirem unit didn't, the user would have a very good idea of the radiological danger to which he or she was exposed," said Warner.
By comparison, the DOE exposure limit for workers in a radiologically controlled area is five rems (5,000 millirems) per year. The working limit at Los Alamos is much more restrictive, at two rems per year. The average Northern New Mexico resident receives about 350 millirems of normal background radiation annually.
Radiation Litmus Paper also may have nonproliferation applications. For example, RLPs attached to briefcases, luggage or containers could help deter smuggling of nuclear materials. In addition, Radiation Litmus Paper could aid disarmament by verifying the presence of pits, or fission cores, inside nuclear warheads, without divulging sensitive information about those pits.
Warner currently is conducting field tests of the Radiation Litmus Paper, which has a patent pending. Funding for its development initially came from Los Alamos' Laboratory-directed Research and Development Program and currently from DOE's Office of Nonproliferation and National Security.
The Radiation Litmus Paper Development Team includes Warner and students Deidre Johns, Kimberly Sheafe and Tony D'Alessio.
Los Alamos National Laboratory is operated by the University of California for the U.S. Department of Energy.