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RASCAL 3.0.5: Description of
Models and Methods (NUREG-1887)
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Publication Information
Manuscript Completed: August 2007
Date Published: August 2007
Prepared by
S.A. McGuirea
J.V. Ramsdell, Jr.b
G.F. Atheyc
aOffice of Nuclear Security and Incident Response
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001
bPacific Northwest National Laboratory
P.O. Box 999
Richland, WA 99352
cAthey Consulting
P.O. Box 178
Charles Town WV 25414-0178
Prepared for
Office of Nuclear Security and Incident Response
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001
Availability
Notice
Abstract
The code currently used by NRC's emergency operations center for making dose projections for
atmospheric releases during radiological emergencies is RASCAL version 3.0.5 (Radiological Assessment System for Consequence AnaLysis). This code was developed by NRC. The first version was
created about 20 years ago. Since then the code has been undergoing continual improvement to expand
its capabilities and to update the models used in its calculations. This report describes the models and
calculational methods used in RASCAL 3.0.5. This report updates and supercedes the information in
NUREG-1741, "RASCAL 3.0: Description of Models and Methods," 2001.
RASCAL 3.0.5 evaluates releases from: nuclear power plants, spent fuel storage pools and casks, fuel
cycle facilities, and radioactive material handling facilities.
While RASCAL 3.0.5 operates as a single piece of software, it is really a set of inter-linked modules each
with a different function. These are:
- Source term: this module calculates a time-dependent source term, which for nuclear power
plants, is composed of about 50 radionuclides including parents and daughters. This module is
unique in the world for its ability to model a wide variety of accidents based on plant conditions
for many different facility types.
- Meteorological data processor: this module inputs weather observations and forecasts along with
local topography to generate time-dependent wind fields that will transport the plume.
- Atmospheric transport and diffusion: this module uses the wind fields with a two-dimensional
Gaussian puff model to transport the plume downwind and to calculate concentrations of each
radionuclide as a function of time and location.
- Dose calculator: this module calculates various types of doses resulting from airborne releases
(TEDE, thyroid, acute, etc.) to individuals at each location from three dose pathways - inhalation,
cloudshine, and groundshine. It also calculates the longer-term intermediate phase doses from
deposited radionuclides. The calculations are completely consistent with the EPA protective
action guide manual and the methods adopted by the Federal Radiological Monitoring and
Assessment Center (FRMAC).
- Display of results: this module allows the user to display a wide variety of calculated results as
either a picture of the plume footprint on a map background for each of the result types or as
numeric table.
- Uranium hexafluoride module: for uranium hexafluoride releases, RASCAL contains a heavy gas
model to account for the exothermic reaction with air and gravitational slumping of the plume.
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