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MILDOS Software

The MILDOS computer code (MILDOS 4) is used to estimate the radiological impacts from airborne emissions from uranium milling facilities. It provides the capability to consider both conventional uranium ore operations and operations associated with in-situ recovery (ISR) facilities. The code is used by license applicants and U.S. Nuclear Regulatory Commission staff to perform routine radiological impact and compliance evaluations for various uranium recovery operations.

MILDOS screen shot

MILDOS 4 is maintained at Argonne National Laboratory for the Office of Nuclear Regulatory Research at the U.S. Nuclear Regulatory Commission under the Radiation Protection Computer Code Analysis and Maintenance Program (RAMP).

Source Types

The airborne release of radon and particulates from eight different source types can be analyzed:

  1. Point sources [stacks, vents]
  2. Area sources [ore pads, tailing areas]
  3. New well field sources (ISR-specific)
  4. Well field sources (ISR-specific)
  5. Purge sources (ISR-specific)
  6. Ion-exchange sources (ISR-specific)
  7. Drying and packaging sources
  8. Land application sources
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Scenarios Considered

Plume rise is considered for point, drying and packaging, purge, and ion-exchange sources. A wind-blown dust (erosion) model is available for area sources to address ore pads and tailings piles. Downwind air concentrations are estimated using a Gaussian plume model with dry and wet deposition to estimate ground concentrations for particulates. The ground concentrations are used in turn to estimate resuspended air concentrations and plant uptake with subsequent consumption by humans and animals. Dose to humans is calculated for the following pathways — inhalation of downwind and resuspended radionuclide air concentrations, external exposure from contaminated ground and air concentrations, and ingestion of plants, meat, and milk.

Releases of particulates explicitly considered are limited to the radionuclides U-238, Th-230, Ra-226, and Pb-210 for the U-series decay chain and Th-232, Ra-228, and Th-228 for the Th-series decay chain. Other radionuclides in these series are implicitly accounted for under the secular equilibrium assumption. Gaseous releases are limited to consideration of Rn-222 and Rn-220 plus in growth of decay products.


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As of version 4, the code was revised to run natively on Windows 7 to 10. Updates include an improved user interface, support for uranium ores containing Th‑232 and its daughter radionuclides, a revised area source model, revised ISR models, and the ability to perform sensitivity analysis on specific input parameters.

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The improved user interface includes geographic information system (GIS) functionality to aid in visualization of the scenario to be assessed, including the proper consideration of area source shapes and positioning of receptors and sources.

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Meteorological Data

Use current local meteorological data provided by the National Centers for Environmental Information. A pre‑processor was added to import recent meteorological data (for the U.S. and abroad) for use in air dispersion calculations.

Register at the RAMP web site to download MILDOS 4.

Version History

4.21September 2020Parallel programming algorithms in the area source dispersion calculations and the population dose calculations are used to realize a reduction in calculation times to a small extent. The reduction in calculation times will be dependent on the executing machine’s CPU and memory configuration as well as the problem under study. Problems with larger area sources will benefit more when the full area source calculation is performed. Standard report generation at the end of runs that include population calculations is now faster due to a separate upgrade.
4.2April 2020A population wheel generator is now available in MILDOS4 for input into population calculations. Based on U.S. Census estimates for 2016, users can generate an 80-km population distribution for any location within the United States. In addition, the custom output table interface was augmented to allow users to also specify custom output graphs in a variety of formats (column, scatter, and radar) to review results.
4.1April 2019The ISR models have been revised. The new well field source type is now treated as an area source and the production and restoration well field (point) source types have been replaced by the well field (area) source type. The release of radon from well field purge (bleed) operations and from ion exchange operations are now accounted for by the purge and ion exchange source types which are treated as point source releases. A shielding/infiltration factor has been added to the dose calculations for individual receptor indoor inhalation exposure and is available as a user input parameter. Additional model parameters are accessible. Users are now able to modify food transfer factors as well as particulate deposition velocities and densities. Users can specify custom output tables in a variety of formats to review and summarize results.
4.02April 2018Incremental release. MILDOS has gone from a 32-bit to a 64-bit application. As a 64-bit application, version 4.02 allows for a greater number of source terms, receptors, and time steps and eliminates most of the previous issues associated with the use of larger map files. Added features include the ability to re-project raster map data, a map ruler, sorting of meteorological joint frequency data, and additional output of intermediate calculated values such as source – receptor distance and outdoor radon equilibrium fractions.
4.01September 2016Maintenance release. Fixed a number of user interface issues. Faster report generation at the end of a run.
4.0March 2016Last major release


Related Documentation

Contact Us

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Nuclear Regulatory Commission

Casper Sun
Office of Nuclear Regulatory Research
Mail Stop T-10B58
U.S. Nuclear Regulatory Commission
Washington DC 20555


[email protected]

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Argonne National Laboratory

Dave LePoire
Environmental Science Division
9700 S. Cass Ave
Argonne IL 60439


[email protected]

For technical support, send questions or comments to [email protected].