[en] Gaussian plume model was developed and evaluated using observed Kr-85 air concentration data. The main features of the model include: segmented plumes and displaced effective source terms; reflective upper and lower boundaries; and formulations describing the effects of time-varying mixing height. The model was evaluated in terms of goodness factor, root mean square error, percentage of hits, and percentage of observed and calculated concentrations within a factor of 2 and 10. The test results show that this model predicts observed concentrations fairly well and is superior to the simpler wind rose and segmented plume models. Moreover, the prediction capability of the modified Gaussian model is also found to be insensitive to plume travel distances up to 150 kilometers

[en] This report documents the comprehensive evaluation of probability models of natural events which are applicable to Savannah River Plant. The probability curves selected for these natural events are recommended to be used by all SRP/SRL safety analysts. This will ensure a consistency in analysis methodology for postulated SAR incidents involving natural phenomena

[en] Textures in the hexagonal metals have attracted significant interest over the years because of the use of some hexagonal metals and alloys, e.g. Zircaloy cladding for nuclear reactor fuels, Ti alloys for aerospace and aircraft industry, and Mg alloys for automobile and computer, communication and consumer electronic (3C) appliances. From a mechanistic point of view, hexagonal metals are different from cubic metals due to the restricted slip systems and the activation of twinning. In this paper, a brief summary of the texture in hexagonal structural materials is carried out, mainly dealing with the deformation and recrystallization texture as well as the anisotropy of textured hexagonal materials

[en] A computer code was developed to calculate the cumulative frequency distributions of relative concentrations of an air pollutant following an accidental release from a stack or from a building penetration such as a vent. The calculations of relative concentration are based on the Gaussian plume equations. The meteorological data used for the calculation are in the form of joint frequency distributions of wind and atmospheric stability

[en] The Defense Waste Processing Facility (DWPF) for immobilizing nuclear high level waste (HLW) is scheduled to be built at the Savannah River Plant (SRP). High level waste is produced when SRP reactor components are subjected to chemical separation operations. Two candidates for immobilizing this HLW are borosilicate glass and crystalline ceramic, either being contained in weld-sealed stainless steel canisters. A number of technical analyses are being conducted to support a selection between these two waste forms. The present document compares the risks associated with the manufacture and interim storage of these two forms in the DWPF. Process information used in the risk analysis was taken primarily from a DWPF processibility analysis. The DWPF environmental analysis provided much of the necessary environmental information. To perform the comparative risk assessments, consequences of the postulated accidents are calculated in terms of: (1) the maximum dose to an off-site individual; and (2) the dose to off-site population within 80 kilometers of the DWPF, both taken in terms of the 50-year inhalation dose commitment. The consequences are then multiplied by the estimated accident probabilities to obtain the risks. The analyses indicate that the maximum exposure risk to an individual resulting from the accidents postulated for both the production and interim storage of either waste form represents only an insignificant fraction of the natural background radiation of about 90 mrem per year per person in the local area. They also show that there is no disaster potential to the off-site population. Therefore, the risks from abnormal events in the production and the interim storage of the DWPF waste forms should not be considered as a dominant factor in the selection of the final waste form

[en] In determining the source term for radiological consequence analysis of non-reactor operations, safety analysts sometimes are given a range of weight or curie fractions for the radionuclides in a process stream. Because the worst radiological dose is of most interest to safety analysts, the worst source term from the given ranges of radionuclide composition must be determined. This paper presents a methodology which can be used by safety analysts for the determining the isotopic distribution to yield the maximum radiological consequences when a range of weight or curie compositions are possible. Use of this methodology eliminates any unnecessary. safety and/or environmental concerns because safety analysts no longer have to make overly conservative assumptions to simplify the worst source term determination. The method uses a relative-dose concept which overcomes the tediousness of the traditional trial-and-error approach. Depending on the location of receptors, two relative-dose equations are derived: one for the operating personnel inside a building and the other for workers outside the building. Example problems will be used to illustrate the methodology for the determination of the worst source term

No abstract available

[en] High resolution finite difference schemes for solving the nonlinear model Boltzmann equations are presented for the computations of rarefied gas flows. The discrete ordinate method is first applied to remove the velocity space dependency of the distribution function which renders the model Boltzmann equation in phase space to a set of hyperbolic conservation laws with source terms in physical space. Then a high order essentially nonoscillatory method due to Harten et al. is adapted and extended to solve them. Explicit methods using operator splitting and implicit methods using the lower-upper factorization are described to treat multidimensional problems. The methods are tested for both steady and unsteady rarefied gas flows to illustrate its potential use. The computed results using model Boltzmann equations are found to compare well both with those using the direct simulation Monte Carlo results in the transitional regime flows and those with the continuum Navier-Stokes calculations in near continuum regime flows. 28 refs., 17 figs

No abstract available

[en] We investigate the conditions under which the Bethe-Salpeter equation with a scalar-exchange interaction (in the ladder approximation) will in the small-relative-time limit give rise to scattering states. Our results indicate that the exchange particle should be at least slightly unstable (nonzero full width GAMMA). The role of GAMMA is compared with cutoff factors occurring in nonrelativistic potential scattering