Meteorological modeling of arrival and deposition of fallout at intermediate distances downwind of the Nevada Test Site

Journal Article · Thu Nov 01 04:00:00 EST 1990 · Health Physics; (USA)

DOI:https://doi.org/10.1097/00004032-199011000-00010· OSTI ID:6286360

Cederwall, R T; Peterson, K R ^[1]

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1. Lawrence Livermore National Laboratory, CA (USA)

A three-dimensional atmospheric transport and diffusion model is used to calculate the arrival and deposition of fallout from 13 selected nuclear tests at the Nevada Test Site (NTS) in the 1950s. Results are used to extend NTS fallout patterns to intermediate downwind distances (300 to 1200 km). The radioactive cloud is represented in the model by a population of Lagrangian marker particles, with concentrations calculated on an Eulerian grid. Use of marker particles, with fall velocities dependent on particle size, provides a realistic simulation of fallout as the debris cloud travels downwind. The three-dimensional wind field is derived from observed data, adjusted for mass consistency. Terrain is represented in the grid, which extends up to 1200 km downwind of NTS and has 32-km horizontal resolution and 1-km vertical resolution. Ground deposition is calculated by a deposition-velocity approach. Source terms and relationships between deposition and exposure rate are based on work by Hicks. Uncertainty in particle size and vertical distributions within the debris cloud (and stem) allow for some model tuning to better match measured ground-deposition values. Particle trajectories representing different sizes and starting heights above ground zero are used to guide source specification. An hourly time history of the modeled fallout pattern as the debris cloud moves downwind provides estimates of fallout arrival times. Results for event HARRY illustrate the methodology. The composite deposition pattern for all 13 tests is characterized by two lobes extending out to the north-northeast and east-northeast, respectively, at intermediate distances from NTS. Arrival estimates, along with modeled deposition values, augment measured deposition data in the development of data bases at the county level.

• OSTI ID: 6286360
• Journal Information: Health Physics; (USA), Journal Name: Health Physics; (USA) Vol. 59:5; ISSN 0017-9078; ISSN HLTPA
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540130* -- Environment
Atmospheric-- Radioactive Materials Monitoring & Transport-- (1990-)
AEROSOLS
CLOUDS
COLLOIDS
COMPUTERIZED SIMULATION
DEPOSITION
DISPERSIONS
ECOLOGICAL CONCENTRATION
ENVIRONMENTAL TRANSPORT
EXPLOSIONS
FALLOUT
MASS TRANSFER
MATHEMATICAL MODELS
METEOROLOGY
MONITORING
NATIONAL ORGANIZATIONS
NEVADA TEST SITE
NUCLEAR EXPLOSIONS
PARTICLE SIZE
RADIATION MONITORING
RADIOACTIVE AEROSOLS
RADIOACTIVE CLOUDS
RADIOECOLOGICAL CONCENTRATION
SIMULATION
SIZE
SOLS
US DOE
US ORGANIZATIONS