Two deuterium-tritium (D-T) neutron generators have been purchased from Adelphi Technology with neutron production rates up to 10 8 and 10 10 neutrons/second at 14.1 MeV, respectively. Such neutron generators hold potential for use in medical, industrial, homeland security, and fundamental nuclear science applications. Within homeland and nuclear security and related fields, these generators can be used for prompt-/delayed-gamma fast-neutron activation analysis, fast-neutron transmission spectroscopy, transmission radiography, and other neutron interrogation techniques including delayed-neutron measurements. As such, D-T neutron generators are enabling technology for nuclear nonproliferation and security, and the acquired generators will be invaluable research and development tools at Pennsylvania State University. These are being installed in the basement of the Academic Projects Building at Pennsylvania State University, but sufficient shielding to meet regulatory and safety requirements had to be designed and built first. To determine the shielding requirements, extensive Monte-Carlo simulations were conducted in Geant4 and MCNP6 using two different methods of dose determination, and three dose-level estimates at various points around the D-T generators were acquired. Multiple thicknesses of the shielding enclosure were evaluated and a combination of .61 m of concrete and 5.1 cm of polyethylene was selected as the optimal shielding. Of the different simulation methods used, the Geant4 simulations yielded higher dose estimates than MCNP6. Within the Geant4 simulations, an energy deposition-based method typically estimated higher dose levels than a fluence-based method, although different locations were impacted differently by the different methods. Based on the aforementioned simulations, the shielding structure has been constructed and the room is now ready for the installation of the D-T neutron generators.
Year
2020
Abstract