RESRAD-BIOTA is used to evaluate radiation exposures of nonhuman biota, including flora and fauna, in a terrestrial or aquatic ecosystem.

Objectives

RESRAD-BIOTA implements the U.S. Department of Energy's graded approach methodology for evaluating radiation doses to aquatic and terrestrial biota (DOE-STD-1153-2002). It calculates absorbed radiation doses to various biota organisms, default or user-created, from contaminated environmental media, as well as derives Biota Concentration Guides (BCGs) in terms of medium concentration levels, corresponding to a specific biota absorbed dose limit.

Modeling Approach

Radiation exposures to biota in a terrestrial or aquatic ecosystem are considered to result from contaminated soil, water, and sediment, which subsequently result in contamination in air and in different food sources. A graded approach that consists of three tiers of analysis is implemented in the RESRAD-BIOTA code. At Level 1, screening BCGs for contaminated soil, water, and sediment that were pre-developed by DOE considering four default categories of organisms—terrestrial animal, terrestrial plant, riparian animal, and aquatic animal—are used for comparison with input environmental media concentrations, to determine the potential that the recommended biota dose limit could be exceeded. At Levels 2 and 3, more site- and organism-specific input data are accepted to perform a more realistic dose calculation for comparison with a specified dose limit. Both external radiation and internal radiation are considered in the dose calculation.

The external dose is calculated considering the time fractions an organism spends close to or in the contaminated media. For internal dose calculation, three options are provided, with measured tissue concentrations, with a lumped medium-to-tissue concentration ratio, or with allometric equations that estimate the maximum tissue concentration considering the inhalation and food intake rate, biological and radiological decay, body weight, and life-time of the organism. To account for the influence of body size, eight different ellipsoidal geometries each with its own set of dose coefficients are provided for selection.

Features

A user-friendly interface facilitates data entry, performing calculations, displaying calculation results, and accessing general and context-specific help. RESRAD-BIOTA has provisions for specifying food sources reflecting hierarchy relationship in a food chain network. It is equipped with an organism wizard in Level 3 analysis for creating new organisms for dose calculation, and allows the export of organism data. Both deterministic and probabilistic sensitivity analyses can be conducted on most of the input parameters.

Use and Applications

The RESRAD-BIOTA code is widely used by DOE sites and programs and by federal and several state environmental agencies. It has been used to participate in the International Atomic Energy Agency's Environmental Modeling for Radiation Safety (EMRAS) program for model comparison.

Learn more about the use and applications of RESRAD-BIOTA at a training workshop at Argonne National Laboratory.