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Analysis and extension of the SAND-II code in damage function unfolding applications. [BWR; PWR]

Conference ·
OSTI ID:6563725
A way has been found to include a-priori information about the expected energy dependence of the damage function (together with uncertainties) as part of the data input of the SAND-II code in damage function unfolding procedures. Damage function analysis is useful when it is necessary to predict property change in a spectrum that is different from the spectra which were used to develop information about the degradation characteristics of the material. If the damage is a non-linear function of fluence, it is sometimes necessary to define an intermediate degradation parameter which is linear in the fluence. The integral equations can then be replaced by a set of linear equations with finite widths for the energy groups and a fixed number of groups. The inclusion of the a-priori information about the damage function causes the linear equations set to be overdetermined. If this overdetermined set is regarded as a least squares problem in log-normal statistics, then a solution can be obtained by a method of steepest descent. The steepest descent solution-algorithm is similar but not identical to the basic algorithm of the SAND-II code. In an overdetermined case, the basic SAND-II algorithm is shown to iterate towards a solution which is identical to the log-normal least squares solution.
Research Organization:
Westinghouse Hanford Co., Richland, WA (USA)
DOE Contract Number:
EY-76-C-14-2170
OSTI ID:
6563725
Report Number(s):
HEDL-SA-1475; CONF-780722-5
Country of Publication:
United States
Language:
English