M.S. Thesis Presentation by Adam Nielson
Tuesday, May 26, 1998

(Dr. Nolan Hertel, advisor)

"A Health Risk Assessment for the Decommisssioning of the Georgia Insitute of Technology Research Reactor"

Abstract

Calculations of fluence-to-dose coefficients for neutrons above MeV have been performed using Monte Carlo computer simulations. the LAHET 2.8 (Los Alamos High-Energy Transport) code was used in conjunction with HMCNP4A to perform the dosimetric calculations. The ICRU sphere was bombarded with parallel beams of monenergetic neutrons ranging in energy from 25 MeV to 2 GeV. Primary neutrons were transported down to 20 MeV by the LAHET 2.8 code system. The code HMCNP4a was used to transport the neutrons from 20 MeV down thermal energies and calculate the neutronvkerma. Absorbed dose contributions from secondary particles produced by neutrons above 20 MeV were calculated using LAHET 2.8 Quality factors were assigned to charged secondary particles using the ICRP-60 Q-L relationship. Pions and muons are produced as part of the extra-nuclear cascade process. At energies in the GeV range, it was found that pions become significant absorbed dose contributors. Gamma rays emitted from the decay of neutral pions were also significant absorbed dose contributors.