Fall 2023 - Flipbook - Page 8
Simulating Radionuclide Transport in the Environment
Ryan Hupfer, P.G., and Olivia Warren, Drummond Carpenter, PLLC., Orlando, FL
In modern society, humans are exposed to low levels of radiation every day from natural and man-made materials
and processes (sunlight, radon in rocks, medical and industrial applications, electronics). Generally, human health
is not affected by daily radiation due to the shielding that soil and buildings provide and strict regulation of medical
and industrial machinery that uses radiation; however, when humans receive elevated doses of radiation over a long
period of time, they can experience adverse health effects (U.S. Environmental Protection Agency 2012). Since the
mid-20th century, radioactive materials have been extracted for use in medical and industrial applications and
power generation, among other things. These processes have produced waste (mine tailings, spent radioactive
material, contaminated buildings, etc.) that can have high concentrations of radionuclides. Additionally, excavation
of native materials for commercial and residential development in areas with naturally occurring radioactive
materials could concentrate radionuclides in debris and tailings. Proper management of these types of waste is
important, as release of radionuclides to the environment from these sources can be detrimental to human health.
To help protect the public from
exposure to high levels of radiation,
both proprietary and publicly
available computer codes have been
developed to simulate radionuclide
transport and evaluate the dose
received from accumulation in the
environment. The current industry
standard for performing these
evaluations is the RESRAD family of
codes developed by Argonne
National laboratory (available for free
at: http://resrad.evs.anl.gov/), which
have been used for dose
evaluations across the globe
including at the well-known Fukushima Figure 1. Depiction of the radionuclide transport and exposure pathways simulated in RESRAD-OFFSITE, from User’s Manual for RESRAD-OFFSITE Version 2, Yu et al. 2007
and Chernobyl sites. RESRAD-OFFSITE, a member of the RESRAD family, was developed for scientists and engineers to predict environmental
concentrations and radioactive dose to an individual exposed while within or outside of an area contaminated
with radioactive materials (Yu et al. 2007). The code calculates radionuclide release from a source area to the
atmosphere (as contaminated dust), surface runoff, and groundwater and computes accumulation in hypothetical
receptors (agricultural areas, pastures, a dwelling, a groundwater well, and a surface water body). Radionuclide
accumulation in the hypothetical receptors is used to calculate the dose to an individual from nine different internal
and external exposure pathways, which include: direct exposure from contaminated soil, inhalation of particulates,
inhalation of radon, ingestion of plant food (fruits, grains, and vegetables), ingestion of meat, ingestion of milk, ingestion of aquatic foods (fish and crustacea), ingestion of water, and incidental ingestion of soil (Yu et al. 2007). A
depiction of the release and exposure pathways simulated in RESRAD-OFFSITE is provided in Figure 1.
www.asce.org/ewri • EWRI Currents • Volume 21, Number 4 • Fall 2019
