Dispersion Modeling and Consequence Assessment.

DOE-STD-3014-96

APPENDIX D

development of ARF/ARR/RF distributions based on the experimental

data for the purpose of statistical sampling.

During the measurement of ARFs and RFs, precise correspondence

between event conditions and experimental conditions is not generally

found. For conservative analysis, the data are applicable if the

measurement conditions exceed those calculated for the event (e.g., if

the fall distances for spilled powders or liquids with characteristics like the

materials used in the experiments are equal to or less than the

experimental distance). In most cases, extrapolation beyond the domain

of experimental data is valid to a limited extent (a factor of 2 to 5,

depending on the slope of the experimental data and the range of

conditions covered in the experimental study). Models are available for

the calculation of ARFs, ARRs, and RFs for some phenomena. Care

should be used in any extrapolation, however, to avoid producing

inappropriate results.

LPFij - The use of leakpath factors is generally most advantageous when

taking credit for deposition within a building under quasi-static conditions,

such as after an earthquake that causes cracks in the structure and a

loss of ventilation. For aircraft impact, the leakpath factor is 1.0 for all

affected material, given the possible extent of facility structural damage.

D.1.2 Dispersion Modeling and Consequence Assessment. Once the source term has

been developed, it is necessary to translate the quantity of hazardous material

released into dose to the maximally exposed individual at the site boundary. The

specifics of the calculation will depend upon the definition of the evaluation

guidelines, in terms of the precise parameter being measured and the conditions

(e.g., meteorological) under which the evaluation guidelines are developed. In

general, however, the modeling of material transport from the source to the

receptor is necessary, and should be performed at a calculational level of detail

commensurate with the balance of the analysis. In most cases, it should be

possible to demonstrate that the evaluation guidelines have been met using

D-3