Homeland Security Graphic
This simulated image of the SoftWare for Optimization of Radiation Detectors (SWORD) illustrates a detected radiation dispersal device inside a vehicle crossing the San Ysidro, California Port of Entry’s radiation portal monitor. (Photo by U.S. Naval Research Laboratory)

Researchers at the U.S. Naval Research Laboratory (NRL) integrated an accurate and efficient model of nuclear fission into a new software suite to give 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 development and evaluation of radiation detection equipment.

“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. 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.