Sandia LabNews

Radiation detection on the high seas


George Lasche (6418) never imagined his career as a physicist would take him into the shipping business. On Oct. 6, 2006, he stood on the Golden Gate Bridge and watched proudly as the SS Lurline of Matson Lines passed underneath. On the ship were four containers prominently marked with the Sandia thunderbird logo.

“The captain and crew waved when they saw me on the bridge and saluted with a long blast of the horn,” George recalls. “I saluted back. It was gorgeous, a wonderful moment.”

This departure was the first of eight planned round-trip voyages for a project testing the Experimental Limits for In-Transit Detection of Radiological Materials, funded by the Domestic Nuclear Detection Office within the Department of Homeland Security.

The goal of the project is to determine if it would be feasible to deploy on-ship systems that can reliably detect radiological/nuclear materials while at sea with an extremely low probability of a false alarm.

“These two goals require that we learn as much as possible about the environment in which these systems are being designed and deployed,” says George.

The approach is to ship a selected variety of advanced radiation detection equipment amongst a large sampling of actual cargo in container ships while at sea. These include high-purity germanium (HPGe) gamma-ray detectors, bonner-spheres neutron spectrometers, a fission meter multiplicity detector, muon-neutron correlation detection suites, and environmental detection suites.

In some shipments, selected radiation sources also are shipped to characterize radiation transmission through cargo at a range of energies spanning the natural radiation spectrum.

Radiation detection at sea is, in a sense, uncharted territory. While much research has been done detecting radiation on land, the sea presents an entirely different environment — one with significantly less background noise.

Challenges of detection at sea unique

Detection at sea is also unique because constraints on size and weight may not apply. Land-based detection systems are typically embedded into some physical aspect of a port, such as a drive-through portal or crane. A detector enclosed in a container could weigh up to 40,000 pounds.

Time is another factor. While land-based detection usually happens within a few seconds, ship-based detection has days in which to seek out a source. The project uses the longest domestic route available, from Oakland to Honolulu, which takes four days.

“The ability to detect and interdict nuclear material on ships could keep such threats from ever reaching our shores,” says Bill Ballard (8100), Radiological/Nuclear Countermeasures Program manager. “We don’t know if this is the final answer — this project is examining the feasibility of such detection on a large scale.”

This project is a collaboration on many levels. Though Sandia leads the project, the detectors come from Sandia, Lawrence Livermore National Laboratory (LLNL), Pacific Northwest National Laboratory (PNNL), Los Alamos National Laboratory (LANL), and the Environmental Measurements Laboratory.

The equipment, George says, is far more costly than anyone could afford to deploy in regular commerce. But using such sophisticated, highly sensitive equipment will enable the researchers to characterize the radiation environment at sea and properly design less expensive detectors.

At the same time, LLNL and PNNL are using data collected by Sandia to develop and test computer models for radiation detection at sea.

“Few people believe computer models until they have been proven. If we get similar answers using two different approaches, it will build confidence,” says George.

He recently launched the seventh round-trip voyage of his special containers. Each voyage begins at the high bay at Sandia/California’s Micro and Nano Technologies Laboratories (MANTL), which last year was retrofitted to accommodate up to six 40-foot shipping containers and everything being loaded into them. Once loaded, the containers are trucked 30 minutes west to the Port of Oakland.

So far the project has run extremely smoothly with very intriguing results, George says. He attributes a good part of that success to the strong partnership with the shipping company.

‘A wholehearted commitment’

“Matson Shipping Lines responded with a wholehearted commitment all the way from the vice presidents to ship electricians in the spirit of helping us solve our problems, instead of just figuring out how to deal with them,” he says.

Every ship’s captain volunteered to carry GPS equipment in the bridge, allowing the researchers to coordinate where the ships were at every moment in time. Those locations could then be correlated with any phenomena shown in experiments.

George recalls that one captain was so concerned the GPS equipment had failed that he had his first mate write down by hand every position recorded during the voyage.

This data on location proved invaluable when all of the detectors registered a gain drift. On the voyage west to Hawaii, the line of potassium moved slightly up and then fell slightly on the return trip.

According to George, his team determined the gain drift was driven by temperature. As a result, any instrument deployed would have to be calibrated enroute. If done computationally, this is feasible because measurements were taken every 15 minutes and the gain drift showed itself over a longer period of time.

The significance of this project lies in the fact that all experiments are conducted in a real shipping environment.

“We’re testing among what people actually ship, which is not always what one would expect to see,” says George. “A lot of manifests simply read FAK, for Freight of All Kinds.”

For example, a huge signature of potassium 40 was detected on one of the more recent shipments. With the help of Matson, the Sandia researchers discovered that the detector picking up the signature was nestled between two containers filled with fertilizer composed of potassium nitrite.

Another surprise was the detection of a weak signature of uranium in all of the first shipments. George says the uranium signal was so pure it appeared to be inside Sandia’s own containers. It turns out the background environment at sea is so quiet compared with that of land that the detectors were sensing the minute amount of natural uranium found in most aluminum.

“We’ve gotten rid of the aluminum in our containers, so now I expect we’ll see all the uranium in beer cans traveling from Oakland to Hawaii,” says George. “Any instrument in a real deployment must be able to discriminate innocent uranium from threatening uranium.”

Originally eight round-trips were planned, but the Department of Homeland Security (DHS) has added several more trips so that a neutron scatter camera can be included with the experiments. This is a testament to the success of the project and the value of the neutron scatter camera, which was developed at Sandia/California.

“It’s so good to be out with the public doing something for the national defense — working with real instruments in real environments is a refreshing change from office work,” George says. “This is one of the most rewarding projects of my life.”

Sandia’s ‘micro’ terminal processes shipping containers for tests

About two years ago the high bay in Building 942 at the California site, in the group of buildings known as the Micro and Nano Technologies Laboratories (MANTL), faced an uncertain future.

The building’s interior was demolished in preparation to become a facility for LIGA (a lithography, electroplating, and molding technique). When the LIGA project was canceled abruptly, the space lay empty for quite some time.

Early last year, John Didlake (8229) began looking at the space for Work for Others projects such as SNIFFER and the Explosives Detection System. Then in June 2006, George Lasche (6418) won funding from the Defense Nuclear Detection Office for an in-transit radiation detection project that would require a lot of space.

A perfect fit

George needed to load and unload up to eight 40-foot shipping containers for a total of eight round-trip journeys from Oakland, Calif., to Honolulu. Originally, he considered renting space close to the Port of Oakland, which is what is done in Hawaii.

John saw a perfect fit between the empty building and George’s containers. The space is unique in that it is a large indoor space in an unclassified area and close to a major port.

“This would be a difficult project to do outside in someone else’s parking lot,” says John. “We have the space to accommodate the containers and are located 30 minutes from Oakland.”

In about July 2006, discussions began about changing the purpose of the MANTL high bay into Sandia/California Container Terminal (SCCT). At that point the building had no electricity and mothballed cranes with a 6-ton capacity, which is only adequate to lift empty containers.

John describes the process of transforming the SCCT into a port of call as a “just-in-time” endeavor. The electricity was restored on a Saturday, the retrofitted 10-ton cranes were certified on Monday, and container assemblies began on Tuesday.

With a lot of coordination and teamwork led by Scott Keith (85141), Lynn McClellan (8523), Terry Spraggins (8523), Grace Miranda (8523), and the receiving staff, George was able to hit his Oct. 6, 2006, deadline for the first shipment. The project has been extended to at least two more shipments beyond the original eight.

Nicholas Mascarenhas (8132) has a neutron scatter project funded by the Department of Homeland Security (DHS) that will be on later shipments. John is hopeful DHS will continue using the SCCT for container research projects.

The irony of a facility filled with 40-foot shipping containers in a site known for micro- and nano-scale work is not lost on John. “Actually, we are 1.8 x 10-6 the size of the Port of Singapore,” he says. “So we really are a micro terminal in comparison with a real port.”