Abstract
The evaluation of radiation damage in stainless-steel reactor pressure vessels requires reliable iron cross sections. However, cross sections in general, and those of iron in particular, in even the more recent evaluated-cross-section libraries (e.g. ENDF/B-VI r) are not yet reliable enough to satisfy the needs of the dosimetry as well as those of other user communities. Even if the uncertainties due to the approximations involved in the calculational models and numerical schemes are negligible, the uncertainties in calculated responses - due to the uncertainties in the given cross sections - generally are such as to make these responses rather doubtful. Speaking of cross-section (limited) reliability, we refer not only to their nominal values, but also to the uncertainties (collective noun for variance and covariance) in these values. In the analysis of any problem, involving the calculation of physical quantities which are functions of certain cross sections, an essential element is the evaluation of the partial derivatives, i.e. the sensitivities of each response to every parameter. The sensitivities are, first of all, necessary to determine the uncertainties in the calculated responses, and for a given response the sensitivities serve to find the `snore important` parameters. As the geometry of an assembly
More>>
Citation Formats
Oerel, R L, Wagschall, J J, and Yeivin, Y.
Analysis of fission-rate-ratio measurements in the NIST iron sphere field.
Israel: N. p.,
1996.
Web.
Oerel, R L, Wagschall, J J, & Yeivin, Y.
Analysis of fission-rate-ratio measurements in the NIST iron sphere field.
Israel.
Oerel, R L, Wagschall, J J, and Yeivin, Y.
1996.
"Analysis of fission-rate-ratio measurements in the NIST iron sphere field."
Israel.
@misc{etde_475944,
title = {Analysis of fission-rate-ratio measurements in the NIST iron sphere field}
author = {Oerel, R L, Wagschall, J J, and Yeivin, Y}
abstractNote = {The evaluation of radiation damage in stainless-steel reactor pressure vessels requires reliable iron cross sections. However, cross sections in general, and those of iron in particular, in even the more recent evaluated-cross-section libraries (e.g. ENDF/B-VI r) are not yet reliable enough to satisfy the needs of the dosimetry as well as those of other user communities. Even if the uncertainties due to the approximations involved in the calculational models and numerical schemes are negligible, the uncertainties in calculated responses - due to the uncertainties in the given cross sections - generally are such as to make these responses rather doubtful. Speaking of cross-section (limited) reliability, we refer not only to their nominal values, but also to the uncertainties (collective noun for variance and covariance) in these values. In the analysis of any problem, involving the calculation of physical quantities which are functions of certain cross sections, an essential element is the evaluation of the partial derivatives, i.e. the sensitivities of each response to every parameter. The sensitivities are, first of all, necessary to determine the uncertainties in the calculated responses, and for a given response the sensitivities serve to find the `snore important` parameters. As the geometry of an assembly becomes even moderately complex, if time-dependent solutions are required, or when point, rather than multi-group, cross sections are called for. then deterministic calculations become unacceptably time consuming. To overcome these difficulties we turn to MC calculation of the responses and their sensitivities. Then the geometry poses no serious problems, time-dependent problems are as easy to solve as stationary ones and, surprisingly, the differential-operator method, facilitates the evaluation of all the sensitivities of all the responses in the one MC run that calculates the responses. (authors).}
place = {Israel}
year = {1996}
month = {Dec}
}
title = {Analysis of fission-rate-ratio measurements in the NIST iron sphere field}
author = {Oerel, R L, Wagschall, J J, and Yeivin, Y}
abstractNote = {The evaluation of radiation damage in stainless-steel reactor pressure vessels requires reliable iron cross sections. However, cross sections in general, and those of iron in particular, in even the more recent evaluated-cross-section libraries (e.g. ENDF/B-VI r) are not yet reliable enough to satisfy the needs of the dosimetry as well as those of other user communities. Even if the uncertainties due to the approximations involved in the calculational models and numerical schemes are negligible, the uncertainties in calculated responses - due to the uncertainties in the given cross sections - generally are such as to make these responses rather doubtful. Speaking of cross-section (limited) reliability, we refer not only to their nominal values, but also to the uncertainties (collective noun for variance and covariance) in these values. In the analysis of any problem, involving the calculation of physical quantities which are functions of certain cross sections, an essential element is the evaluation of the partial derivatives, i.e. the sensitivities of each response to every parameter. The sensitivities are, first of all, necessary to determine the uncertainties in the calculated responses, and for a given response the sensitivities serve to find the `snore important` parameters. As the geometry of an assembly becomes even moderately complex, if time-dependent solutions are required, or when point, rather than multi-group, cross sections are called for. then deterministic calculations become unacceptably time consuming. To overcome these difficulties we turn to MC calculation of the responses and their sensitivities. Then the geometry poses no serious problems, time-dependent problems are as easy to solve as stationary ones and, surprisingly, the differential-operator method, facilitates the evaluation of all the sensitivities of all the responses in the one MC run that calculates the responses. (authors).}
place = {Israel}
year = {1996}
month = {Dec}
}