Successful Deployments

One of Pacific Northwest National Laboratory's goals is to move its technologies out of the laboratory and into commercial applications where they can solve critical problems for industry and society. PNNL's Radiation Detection and Nuclear Sciences group has excelled in transferring technology developed by its researchers to government and industry. These technologies include:

ARSA/RASA

Since the first nuclear test in the years following World War II, the world has been living under the threat of nuclear attacks. The Comprehensive Nuclear-Test-Ban Treaty (CTBT), which was adopted in 1996 by the United Nations' General Assembly, signed by 150 nations and ratified by more than 60, requires a network of 80 radionuclide monitoring stations covering the globe. Many monitors are in place to ensure the success of the treaty.

This subject is just as crucial today as it was during the heyday of U.S. testing in the 50's. The provocative nuclear testing undertaken by India and Pakistan in 1998 showed that testing can escalate international tensions and could possibly result in a disastrous nuclear war in which many millions of innocents die.

The RASA and ARSA nuclear explosion identification devices are fast becoming part of the monitoring arsenal to verify international compliance with the CTBT. The RASA and ARSA represent a quantum leap beyond previous monitoring devices, with greater sensitivity, full automation, near-real time reporting, and novel nuclear radiation detectors. Radionuclide detection is unique-it is the only method to provide absolute proof of a nuclear explosion. RASA and ARSA can definitely prove it was a nuclear explosion, while other technologies cannot.

The technologies moved from concept to commercialization in only six years. Because they are reliable, can collect large sample volumes without requiring human labor, and inexpensive, RASA and ARSA have been chosen by the U.S. and a growing number of other countries to be part of the monitoring regime to verify international compliance with the CTBT.

The RASA detects fission products in the form of particulate debris from atmospheric nuclear explosions. It filters a huge volume of air each day to check for evidence of fission products from a nuclear explosion that attach to dust particles. The automated system draws air through a series of filters, which remove practically all of the atmospheric particles. The filters are sealed, bar coded, and then passed to a radiation detection system. Radiation from weapons debris is then registered and translated to prove a violation of the treaty. Researchers at PNNL have created the most sensitive automated system-more than 100 times as sensitive as the best previous commercial technology.

The ARSA analyzes air samples for radioactive xenon, or radioxenon, that seeps from underground nuclear explosions, the most common testing method today but the most difficult to detect. ARSA can detect xenon with a sensitivity nearly 100 times greater than other systems being used, and is the only automatic system available. ARSA collects air samples, and processes them to trap the radioactive xenon on cold charcoal. The system purifies the radioactive xenon, and transfers it to a nuclear counting system. The different isotopes of xenon are automatically measured, and the results are automatically passed to a data center by communication link. Both the ARSA and RASA can be completely monitored, controlled, and programmed remotely to lower operating costs.

PUMA

Plutonium Measurement and Analysis, or PUMA, is a revolutionary radiation monitoring system that uses glass fibers to detect the presence of radionuclides, such as plutonium. This flexible, lightweight, low-power detection system can be used to monitor an inventory of nuclear materials and has significant potential in countering the threat of nuclear terrorism.

PUMA was successfully commercialized. Early in its development stages, researchers at PNNL saw the potential of the Fiber Optic Neutron and Gamma-Ray sensor as a nuclear weapons deterrent, for environmental cleanup, and as a valuable tool in nuclear medicine. The technology has been licensed for a range of fields of use.

The innovative use of glass fibers is a breakthrough in the field of radiation detectors. Glass fibers offer substantial flexibility over conventional neutron sensor technologies, most of which use rigid helium-filled tubes. Glass fibers are much more flexible than conventional sensor technologies; for example, the fibers can be wrapped around a drum to assay its contents or installed in an asphalt road to detect the transport of nuclear materials. In medicine, the sensor can be used with boron neutron capture therapy, a promising method for treating cancer patients. The sensor can monitor real-time dose to provide the exact dose prescribed and prevent overexposure to radiation. One of the biggest potential applications for the new sensor is monitoring plutonium in spent fuel rods.

PUMA's glass fibers contain lithium-6 atoms and cerium ions that detect the presence of radionuclides such as plutonium. The neutrons react with the lithium isotope to leave an ionization trail through the glass matrix, which results in light emission from the cerium. The fiber is coated with a low refractive index silicone polymer, which maximizes the amount of light captured in the glass fiber. The trapped light travels down the fiber and is detected at the ends using photomultiplier tubes. Each fiber can detect from one to millions of neutrons and gamma rays per second. The researchers have developed glass compositions specifically for fiber drawing and manufacturing processes that enable fiber to be produced in useful lengths of more than 200 cm (2 meters).

Timed Neutron Detector

There are, depending on the source, 110 to 200 million land mines currently in place throughout the world. To this total, mines are being added at a rate 20 times higher than the rate at which mines are being located and neutralized. UNICEF estimates that in the 9 most-contaminated countries (Bosnia and Herzegovina, Cambodia, Croatia, Egypt, Iraq, Afghanistan, Angola, Iran, Rwanda), there are more than 90 million mines on more than 1.3 billion acres. Five of these countries, estimated to contain about 75 million mines distributed over nearly 2 million square miles of contaminated land, are mostly desert or steppe lands.

The United States aims to greatly accelerate global humanitarian demining operations and assistance efforts to end the plague of landmines posing threats to civilians through the U.S. led Demining 2010 Initiative to develop, marshal and commit the resources necessary to accomplish this goal in cooperation with other nations by the year 2010. Since 1998, the United States has spent more than $400 million in all aspects of humanitarian demining activity, including a substantial amount on research and development for mine detection and mine clearance.

In June 1999, two PNNL researchers attended a conference on Crete at which several land mine detection schemes were presented. Over lunch, they said to one another, "We can come up with something better." Upon their return to PNNL, they modeled the effects of timing on the detection of hydrogenous materials, and found that it could provide significant signal-to-noise improvement. They then constructed a prototype from commercial off-the-shelf components and a time-tagged source, and in subsequent laboratory and field experiments confirmed their findings.

The Timed Neutron Detector (TND) appears similar to a metal detector yet applies physics to discover signs indicative of a landmine's presence. Specifically, the system detects hydrogen, which is present in the casings and explosives found in plastic and metal landmines.

The TND system consists of a neutron source about the size of a personal pager and a detector built into a man portable system that can be swept over the ground, much like a metal detector. The radiation exposure to the operator from this source is smaller than the variation in natural radiation exposure across the United States, and smaller than the occupational radiation exposure experienced by an airline pilot.

http://www.technet.pnl.gov/sensors/macro/projects/es4lndmn-nuc.stm

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Updated: February 2008