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NEWS | Jan. 14, 2021

SWORD 7: Optimizing Radiation Detection for Homeland Security, DoD

By Paul Cage, U.S. Naval Research Laboratory Corporate Communications

Researchers at the U.S. Naval Research Laboratory (NRL) integrated an accurate and efficient model of nuclear fission into a new software suite to provide users a powerful and flexible tool to quickly and accurately model new and highly complex nuclear detection scenarios.

SoftWare for Optimization of Radiation Detectors (SWORD) is an integrated software package that offers an interface to radiation transport codes, allowing users to design and optimize radiation detectors, which results in the faster

“Our sponsors and end users are focused on preventing nuclear weapons and other radiological devices from being smuggled into the country or into areas where the Department of Defense operates,” Wade Duvall, Ph.D., an NRL research physicist said. “SWORD uses one of several standard radiation transport codes to simulate a scenario, from a medical isotope being transported to a legitimate background source.”

Program users, like the Department of Homeland Security and the Defense Threat Reduction Agency, currently evaluate complex particle interactions by Monte Carlo techniques designed to track particle types over broad ranges of energies. The Monte Carlo uses a number of simulation libraries that have a variety of adjustable parameters; however, these parameters require significant expertise to configure appropriately for the scenario to be modeled.

“These difficulties motivated us to make a tool that could be used by a person without any nuclear physics expertise to quickly build complex scenarios and simulate them,” Duvall said. “Now, with fission, SWORD 7 allows the Navy and users to model scenarios involving active interrogation, space-based and ship-based nuclear reactors and shielding.”

The SWORD implementation was a threefold effort. First, the SWORD simulation engine was updated to accommodate a new physics library and increase performance. Then, a new fission physics library was integrated into SWORD.

“The physics of particle interactions is well understood, but solving the equations gets complicated quickly,” Duvall said. “Despite using industry standard radiation transport codes, SWORD struggled to simulate fission accurately.”

After the integrated library was validated to ensure it had been properly incorporated and that fission physics was accurately modeled, Duvall said they are now working on getting SWORD 7 ready for release.

“SWORD can now model nuclear reactors and other fission sources, as well as the next-generation of fission-based detectors,” Duvall said. “This will allow SWORD to model the latest and greatest technologies being developed by the Navy and the greater defense community.”

SWORD 7 is scheduled to roll out in mid-2021 through the Radiation Safety Information Computational Center at the Oak Ridge National Laboratory at


About the U.S. Naval Research Laboratory

NRL is a scientific and engineering command dedicated to research that drives innovative advances for the U.S. Navy and Marine Corps from the seafloor to space and in the information domain. NRL is located in Washington, D.C. with major field sites in Stennis Space Center, Mississippi; Key West, Florida; Monterey, California, and employs approximately 2,500 civilian scientists, engineers and support personnel.

For more information, contact NRL Corporate Communications at (202) 480-3746 or  

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