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Title: Dry Deposition Velocity Estimation for the Savannah River Site: Part 1 – Parametric Analysis

Abstract

Values for the dry deposition velocity of airborne particles were estimated with the GENII Version 2.10 computer code for the Savannah River site using assumptions about surface roughness parameters and particle size and density. Use of the GENII code is recommended by the U.S. Department of Energy for this purpose. Meteorological conditions evaluated include atmospheric stability classes D, E, and F and wind speeds of 0.5, 1.0, 1.5, and 3.0 m/s. Local surface roughness values ranging from 0.03 to 2 meters were evaluated. Particles with mass mean diameters of 1, 5, and 10 microns and densities of 1, 3, and 5 g/cm3 were evaluated.

Authors:
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1037964
Report Number(s):
PNNL-21144
830403000; TRN: US1201776
DOE Contract Number:
AC05-76RL01830
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; COMPUTER CODES; DEPOSITION; METERS; PARAMETRIC ANALYSIS; PARTICLE SIZE; PARTICULATES; ROUGHNESS; SAVANNAH RIVER PLANT; STABILITY; VELOCITY; Dry Deposition Velocity; GENII Version 2.10

Citation Formats

Napier, Bruce A. Dry Deposition Velocity Estimation for the Savannah River Site: Part 1 – Parametric Analysis. United States: N. p., 2012. Web. doi:10.2172/1037964.
Napier, Bruce A. Dry Deposition Velocity Estimation for the Savannah River Site: Part 1 – Parametric Analysis. United States. doi:10.2172/1037964.
Napier, Bruce A. 2012. "Dry Deposition Velocity Estimation for the Savannah River Site: Part 1 – Parametric Analysis". United States. doi:10.2172/1037964. https://www.osti.gov/servlets/purl/1037964.
@article{osti_1037964,
title = {Dry Deposition Velocity Estimation for the Savannah River Site: Part 1 – Parametric Analysis},
author = {Napier, Bruce A.},
abstractNote = {Values for the dry deposition velocity of airborne particles were estimated with the GENII Version 2.10 computer code for the Savannah River site using assumptions about surface roughness parameters and particle size and density. Use of the GENII code is recommended by the U.S. Department of Energy for this purpose. Meteorological conditions evaluated include atmospheric stability classes D, E, and F and wind speeds of 0.5, 1.0, 1.5, and 3.0 m/s. Local surface roughness values ranging from 0.03 to 2 meters were evaluated. Particles with mass mean diameters of 1, 5, and 10 microns and densities of 1, 3, and 5 g/cm3 were evaluated.},
doi = {10.2172/1037964},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2012,
month = 1
}

Technical Report:

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  • Values for the dry deposition velocity of airborne particles were estimated with the GENII Version 2.10.1 computer code for the Savannah River site using assumptions about surface roughness parameters and particle size and density. Use of the GENII code is recommended by the U.S. Department of Energy for this purpose. Meteorological conditions evaluated include atmospheric stability classes D, E, and F and wind speeds of 0.5, 1.0, 1.5, and 2.0 m/s. Local surface roughness values ranging from 0.03 to 2 meters were evaluated. Particles with mass mean diameters of 1, 5, and 10 microns and densities of 1, 3, 4,more » and 5 g/cm3 were evaluated. Site specific meteorology was used to predict deposition velocity for Savannah River conditions for a range of distances from 670 to 11,500 meters.« less
  • The Defense Nuclear Facilities Safety Board (DNFSB) has recently questioned the appropriate value for tritium deposition velocity used in the MELCOR Accident Consequence Code System Ver. 2 (Chanin and Young 1998) code when estimating bounding dose (95th percentile) for safety analysis (DNFSB 2011). The purpose of this paper is to provide appropriate, defensible values of the tritium deposition velocity for use in Savannah River Site (SRS) safety analyses. To accomplish this, consideration must be given to the re-emission of tritium after deposition. Approximately 85% of the surface area of the SRS is forested. The majority of the forests are pinemore » plantations, 68%. The remaining forest area is 6% mixed pine and hardwood and 26% swamp hardwood. Most of the path from potential release points to the site boundary is through forested land. A search of published studies indicate daylight, tritiated water (HTO) vapor deposition velocities in forest vegetation can range from 0.07 to 2.8 cm/s. Analysis of the results of studies done on an SRS pine plantation and climatological data from the SRS meteorological network indicate that the average deposition velocity during daylight periods is around 0.42 cm/s. The minimum deposition velocity was determined to be about 0.1 cm/s, which is the recommended bounding value. Deposition velocity and residence time (half-life) of HTO in vegetation are related by the leaf area and leaf water volume in the forest. For the characteristics of the pine plantation at SRS the residence time corresponding to the average, daylight deposition velocity is 0.4 hours. The residence time corresponding to the night-time deposition velocity of 0.1 cm/s is around 2 hours. A simple dispersion model which accounts for deposition and re-emission of HTO vapor was used to evaluate the impact on exposure to the maximally exposed offsite individual (MOI) at the SRS boundary (Viner 2012). Under conditions that produce the bounding, 95th percentile MOI exposure, i.e., low wind speed, weak turbulence, night, low deposition velocity, the effect of deposition and re-emission on MOI exposure was found to be very small. The exposure over the two hour period following arrival of the plume was found to be decreased by less than 0.05 %. Furthermore the sensitivity to deposition velocity was low. Increasing deposition velocity to 0.5 cm/s reduced exposure to 0.3 %. After a 24 hour period, an MOI would have been exposed to all of the released material. Based on the low sensitivity of MOI exposure to the value of deposition velocity when re-emission is considered, it is appropriately conservative to use a 0.0 cm/s effective deposition velocity for safety analysis in the MACCS2 code.« less
  • This report documents the results of examining the deposition velocity of water to forests, the residence time of HTO in forests, and the relation between deposition velocity and residence time with specific consideration given to the topography and experimental work performed at SRS. A simple mechanistic model is used to obtain plausible deposition velocity and residence time values where experimental data are not available and recommendations are made for practical application in a safety analysis model.
  • This report discusses the experimental program conducted at ANL to study the performance of in-situ-formed magnetite for the removal of Sr, Pu, Np, U, Am, and Cs from the Savannah River Site (SRS) tank waste. The boundaries for the experimental work were defined based on the operational envelope developed earlier in collaboration with SRS. In situ formed ''magnetite'' is actually a mixture of Fe(II) and Fe(III) oxides and hydroxides, including magnetite. Decontamination factor (DF) values were measured for both magnetite and monosodium titanate (MST). Magnetite DF values were found to be superior to MST for all isotopes studied. DF valuesmore » for Pu, Np, and Sr, achieved within 30 minutes of magnetite formation were orders of magnitude larger than the needed values. DF values for U and Am were less than the former three but still acceptable, and greater than MST. DF values for Cs were very low. Conditions were found under which magnetite filtered rapidly and faster than MST. Further tests are needed to make concrete conclusions on the magnetite performance relative to MST in a cross-flow filtration setup.« less
  • In essence, this study was envisioned as the ``combination`` of existing accident dose and risk calculations from safety analyses of individual facilities. However, because of the extended time period over which the safety analyses were prepared, calculational assumptions and methodologies differed between the analyses. The scope of this study therefore included the standardization of assumptions and calculations as necessary to insure that the analytical logic was consistent for all the facilities. Each of the nonseismic external events considered in the analyses are addressed in individual sections in this report. In Section 2, extreme straight-line winds are examined. Section 3 addressesmore » tornadoes, and Section 4 addresses other external events [floods, other extreme weather events (lightning, hail, and extremes in temperature or precipitation), vehicle impact, accidents involving adjacent facilities, aircraft impact, and meteorite impact]. Section 5 provides a summary of the general conclusions of the report.« less