Parameter Values for Estimation of Internal Doses from Ingestion of Radioactive Fallout from Nuclear Detonations

Abstract

This paper suggests values or probability distributions for a variety of parameters used in estimating internal doses from radioactive fallout due to ingestion of food. Parameters include those needed to assess the interception and initial retention of radionuclides by vegetation, translocation of deposited radionuclides to edible plant parts, root uptake by plants, transfer of radionuclides from vegetation into milk and meat, transfer of radionuclides into non-agricultural plants and wildlife, and transfer from food and drinking water to mother's milk (human breast milk). The paper includes discussions of the weathering half-life for contamination on plant surfaces, biological half-lives of organisms, food processing (culinary factors), and contamination of drinking water. As appropriate, and as information exists, parameter values or distributions are specific for elements, chemical forms, plant types, or other relevant characteristics. Information has been obtained from the open literature and from publications of the International Atomic Energy Agency. These values and probability distributions are intended to be generic; they should be reviewed for applicability to a given location, time period, or season of the year, as appropriate. In particular, agricultural practices and dietary habits may vary considerably both with geography and over time in a given location.

A Method for Estimating the Deposition Density of Fallout on the Ground and on Vegetation from a Low-yield, Low-altitude Nuclear Detonation

“…Thus, we have assumed that the initial fraction of activity intercepted by a given area of vegetation will not vary significantly with type of vegetation or climate. However, as discussed in Anspaugh et al (2022) and Thiessen et al (2022) , the biomass (kg per unit area of ground surface) and thus the total activity on vegetation per unit area of ground surface will be greater in more temperate environs.…”

“…f dry is a unit-less parameter that describes the fraction of the deposition density initially retained on the vegetation for a specific radionuclide and vegetation type as a function of particle size Thiessen et al (2022) .…”

“…Equation 2 requires an estimate of the total beta activity rather than the total radioactivity because, as discussed in Appendix B, the model is based on regression fits to post-detonation measurements of the fraction of total beta activity on particles <50 μm in diameter. Recommendations on how best to use the activity of nuclide i deposited and initially retained on vegetation (eqn 2) to estimate the potential internal exposure and dose for a particular radionuclide deposited on vegetation is discussed in the papers by Thiessen et al (2022) and Anspaugh et al (2022) . As seen in Fig.…”

“…Calculate DD i-veg at TOA for each nuclide of interest from X˙(12) , TOA, the estimated R / V and an appropriate estimate of f dry from Anspaugh et al (2022) and Thiessen et al (2022) .…”

“…First, because rain-out and wash-out will likely increase the probability of more of the smaller particles in the air and cloud being deposited at an earlier time, the average R / V at the site will likely be reduced, and the fraction of total activity on < 50 μm particles will likely be greater. However, the fraction of that activity initially intercepted and retained on vegetation may be smaller than for dry fallout ( Hoffman et al 1992 ; Thiessen et al 2022 ). The fallout depositing on some surfaces such as road surfaces, roofs, etc., may be intercepted but immediately be redistributed in a manner that may change the relative nuclide activity.…”