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Impact of advanced systems on LMFBR accident analysis code development

Description: In order to investigate the ability of an advanced computer, using currently available software, to handle large LMFBR accident analysis codes, the SAS3D code has been run on the NCAR CRAY-1. SAS3D is a large code (56,000 Fortran cards) using many different physical models and numerical algorithms, no one of which dominates the computing time. Even though SAS3D was developed on IBM computers, remarkably little effort was required to run it on the CRAY-1. Making limited use of the CRAY-1 vector capabilities, it runs a factor of 2.5 to 4 times faster on the NCAR CRAY-1 than on the ANL IBM 370-195. With minor modifications, an additional 20 to 30% speed improvement on the CRAY-1 is achieved. In the current process of completely re-writing SAS3D to make SAS4A, much of the coding is being vectorized for the CRAY-1 without sacrificing IBM, CDC 7600, or UNIVAC performance and portability. An initial SAS4A test case runs a factor of 7.1 faster on the CRAY-1 than on the IBM 370-195.
Date: January 1, 1979
Creator: Dunn, F.E. & Kyser, J.M.
Partner: UNT Libraries Government Documents Department

PROSA-1 : a Probabilistic Response-Surface Analysis Code

Description: Techniques for probabilistic response-surface analysis have been developed to obtain the probability distributions of the consequences of postulated nuclear-reactor accidents. The uncertainties of the consequences are caused by the variability of the system and model input parameters used in the accident analysis. Probability distributions are assigned to the input parameters, and parameter values are systematically chosen from these distributions. These input parameters are then used in deterministic consequence analyses performed by mechanistic accident-analysis codes. The results of these deterministic consequence analyses are used to generate the coefficients for analytical functions that approximate the consequences in terms of the selected input parameters. These approximating functions are used to generate the probability distributions of the consequences with random sampling being used to obtain values for the accident parameters from their distributions. A computer code PROSA has been developed for implementing the probabilistic response-surface technique. Special features of the code generate or treat sensitivities, statistical moments of the input and output variables, region-wise response surfaces, correlated input parameters, and conditional distributions. The code can also be used for calculating important distributions of the input parameters. The use of the code is illustrated in conjunction with the fast-running accident-analysis code SACO to provide probability studies of LMFBR hypothetical core-disruptive accidents. However, the methods and the programming are general and not limited to such applications.
Date: June 1978
Creator: Vaurio, J. K.; Mueller, C.; Kyser, J. M. & Sciaudone, D.
Partner: UNT Libraries Government Documents Department