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Assessment of the MACCS Code Applicability for Nearfield Consequence Analysis

Clayton, Daniel J.; Bixler, Nathan E.

Three codes are used for comparisons in this report to evaluate the adequacy of MACCS in the nearfield, AERMOD, ARCON96 and QUIC. Test cases were developed to give a broad range of weather conditions, building dimensions and plume buoyancy. Based on the comparisons of MACCS with AERMOD, ARCON96 and QUIC across the test cases, the following observations are made: MACCS calculations configured with point-source, ground-level, nonbuoyant plumes provide nearfield results that bound the centerline, ground-level air concentrations from AERMOD, ARCON96, and QUIC. MACCS calculations with ground-level, nonbuoyant plumes that include the effects of the building wake (area source) provide nearfield results that bound the results from AERMOD and QUIC and the results from ARCON96 at distances >250 m. If using a point-source is too conservative and it is desired to bound the results from all three codes, another alternative is to use area source parameters in MACCS that are less than the standard values, i.e., an area source intermediate between the standard recommendation and a point source. All these options provide results from MACCS that are bounding for the test cases evaluated. Based on these observations, it appears that MACCS is adequate for use in nearfield calculations, given the correct parameterization.

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TYPE SAND Report YEAR 2020
DOIOSTI

Nuclear Risk Assessment 2019 Update for the Mars 2020 Mission Environmental Impact Statement

Clayton, Daniel J.; Wilkes, John; Starr, Michael J.; Ehrhart, Brian D.; Mendoza, Hector M.; Ricks, Allen J.; Villa, Daniel V.; Potter, Donald L.; Dinzl, Derek J.; Fulton, John F.; Laros, James H.; Cochran, Lainy D.; Brooks, Dusty M.

In the summer of 2020, the National Aeronautics and Space Administration (NASA) plans to launch a spacecraft as part of the Mars 2020 mission. The rover on the proposed spacecraft will use a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) to provide continuous electrical and thermal power for the mission. The MMRTG uses radioactive plutonium dioxide. NASA is preparing a Supplemental Environmental Impact Statement (SEIS) for the mission in accordance with the National Environmental Policy Act. This Nuclear Risk Assessment addresses the responses of the MMRTG option to potential accident and abort conditions during the launch opportunity for the Mars 2020 mission and the associated consequences. This information provides the technical basis for the radiological risks discussed in the SEIS.

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TYPE SAND Report YEAR 2019
DOIOSTI

Atmospheric Transport Results for Fukushima Daiichi Units 1, 2, and 3

Bixler, Nathan E.; Clayton, Daniel J.

Many of the BSAF participants provided source terms to be evaluated by Sandia National Laboratories by applying HYSPLIT [2,3,4,5] to treat atmospheric transport and dispersion (ATD). The objective was to estimate the deposition pattern that would have resulted from the predicted source term. For the participants who provided results for all three units, the overall deposition pattern can be compared with the observed deposition pattern; for the participants who submitted source terms for one or two units, the results can only be compared with each other. Atmospheric transport calculations were performed for a single isotope, Cs-137. It is the primary isotope of concern for long-term contamination and it is relatively easy to measure the strong gamma signal produced from its short-lived decay product, Ba-137m. All the atmospheric transport calculations used the actual location of each of the three units; the releases were not presumed to emanate from the same location. Also, when they were provided, release energies were accounted for in the analysis, so plume lofting was considered. Finally, aerosol size distribution data were considered for purposes of estimating deposition. In some cases, aerosol size distribution can significantly influence deposition patterns.

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TYPE Other Report YEAR 2018
DOIOSTI
Results 26–50 of 78
Results 26–50 of 78