Atmospheric dispersion and deposition of iodine-131 released from the Hanford Site

Conference · Wed Jun 01 00:00:00 EDT 1994

OSTI ID:10184135

Ramsdell, J V; Simonen, C A; Burk, K W; Stage, S A

Approximately 2.6x10{sup 4} TBq (700,000 curies) of iodine-131 were released to the air from reactor fuel processing plants on the Hanford Site in southcentral Washington State from December 1944 through December 1949. The Hanford Environmental Dose Reconstruction (HEDR) Project developed a suite of codes to estimate the doses that might have resulted from these releases. The Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET) computer code is part of this suite. The RATCHET code implements a Lagrangian-trajectory, Gaussian-puff dispersion model that uses hourly meteorological and release rate data to estimate daily time-integrated air concentrations and surface contamination for use in dose estimates. In this model, iodine is treated as a mixture of three species (nominally, inorganic gases, organic gases, and particles). Model deposition parameters are functions of the mixture and meteorological conditions. A resistance model is used to calculate dry deposition velocities. Equilibrium between concentrations in the precipitation and the air near the ground is assumed in calculating wet deposition of gases, and irreversible washout of the particles is assumed. RATCHET explicitly treats the uncertainties in model parameters and meteorological conditions. Uncertainties in iodine-131 release rates and partitioning among the nominal species are treated by varying model input. The results of 100 model runs for December 1944 through December 1949 indicate that monthly average air concentrations and deposition have uncertainties ranging from a factor of two near the center of the time-integrated plume to more than an order of magnitude near the edge. These results indicate that -10% of the iodine-131 released to the atmosphere decayed during transit in the study area, -56% was deposited within the study area, and the remaining 34% was transported out of the study area while still in the air.

• Research Organization: Pacific Northwest Lab., Richland, WA (United States)
• Sponsoring Organization: Department of Health and Human Services, Washington, DC (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 10184135
• Report Number(s): PNWD-SA-3972-HEDR; CONF-9406210-7; ON: DE94018921; CNN: Contract 200-92-0503(CDC)/18620(BNW); TRN: 94:018984
• Resource Relation: Conference: Health Physics Society annual meeting,San Francisco, CA (United States),27-30 Jun 1994; Other Information: PBD: Jun 1994
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
HANFORD RESERVATION
FUEL REPROCESSING PLANTS
IODINE 131
DIFFUSION
DEPOSITION
ECOLOGICAL CONCENTRATION
GASEOUS WASTES
MATHEMATICAL MODELS
R CODES
SURFACE CONTAMINATION
540130
053000
RADIOACTIVE MATERIALS MONITORING AND TRANSPORT
ENVIRONMENTAL ASPECTS