Researchers at ORAU are working to make radiation dose reconstruction more accurate by removing the limit built in to the coding used to made dose calculations.
“Our project reconstructs worker doses,” explained Roger Halsey, a health physicist at ORAU. “We go back and look at the records and see what people were exposed to in their workplace.”
One of the tools ORAU uses to calculate radiation exposure is MCNP, a software package for simulating nuclear processes and exposure that was developed by Los Alamos National Laboratory in the late 1950s and has seen numerous updates. MCNP calculates radiation doses by modeling the room, the source of the exposure, the person in the room and the dose to the person.
“A few years ago I was running a calculation for neutron radiation,” Halsey said. He was using SOURCES-4C, a code to calculate neutron spectrums for MCNP. “When I ran the calculation I found that it had a built-in limit,” meaning it couldn’t calculate the impact from higher energy particles.
Halsey has wanted to improve the accuracy of the dose calculations, even if just slightly, “so when we had the opportunity for a student to work on it I suggested this as her project,” he said.
Enter Mairead Montague, who is pursuing her PhD in nuclear engineering at the University of Tennessee, Knoxville.
She is working to remove that built-in limit in the code, allowing it to handle the higher energy alpha particles Halsey referenced.
The limit, she says, “was put into the code to make the code a little bit easier to work, but it doesn’t exist in reality. So I have been removing the cap and adding more data in order to make it more realistic.”
“While it shouldn’t make too big of a difference, ultimately it would be helpful to have a better understanding of the dose calculations,” Montague said.
It’s a small but important change that results in higher quality, more accurate data.
“The legislation that set up our project is specific in that we have to use the latest and greatest of any method to calculate exposures,” Halsey said. “By improving the code, Mairead is giving us a tool to improve the calculation of these exposures.”
The project is funded through ORAU’s Visiting Faculty Research Program, now in its second year. The VFRP creates teams to tackle research projects of interest to the organization. Teams are comprised of faculty from an ORAU university consortium member institution, a student intern and an ORAU subject matter expert.