Neutron Dosimetry for Fast Reactor Applications

Abstract

The status of fast reactor dosimetry is reviewed in terms of the results of recent studies in fast test reactors. Fast reactor dosimetry must provide proper spectral, flux, and fluence information for material and fuel irradiation effects programs and surveillance studies. In this review consideration is given to (1) monitor materials in current use and information needed in the data reduction of reaction product measurements to neutron interaction rates, (2) neutron flux-spectral definition from multiple foil interaction rates and comparison with results based on other methods of analysis, and (3) application of the flux-spectral data to determination of flux levels and fluences. These dosimetry techniques are applied to determine flux spectra and fluence for material irradiation programs. Such information is needed in the determination of damage functions, which relate the damage producing effectiveness of neutrons to their energy. These damage functions permit correlation of irradiation effects data in different thermal and fast reactor irradiation facilities and therefore provide a basis for setting dosimetry accuracy requirements.

LMFBR (Liquid Metal Fast Breeder Reactor) Reaction Rate and Dosimetry Quarterly Progress Report June July August 1971

“…(29)(30)(31)(32) Work in progress to improve the accuracy and consistency of these cross sections is discussed.…”

“…It is anticipated that the CFRMF test results as weTl as other work being accomplished at ANL,(1,5,6,28) HEDL, (3,4,19,20,29) and other laboratories will help to establish improved values of fission yields for the listed reaction products.…”

“…Present accuracy is in the 20 to 40% range at the 95% confidence level. (29)(30)(31)(32) This accuracy can be improved if the sources of existing inconsistencies between calculated integral averaged cross section, C1 C ' using the current evaluated energy dependent cross sections o(E) and measured values, om' can be identified and effectively eliminated. (29)(30)(31)(32)(33)(34)(35)(36)(37)44) The last Cross Section Evaluation Working Group (CSEWG) meeting at BNL included a review of the cross section needs of the FRMDC and fuels and HEDL-16 materials programs.…”

“…These needs have been discussed previously. (29)(30)(31)(32) As a result, arrangements were made with the National Neutron Cross Section Center (NNCSC) at BNL to compare the current SAND-II reference evaluated energy-dependent cross secti on 1i brary with exi s ti ng ENDF/8 data. rmcsc now has the SAND-II d(E)' S and will prepare suitable plots for making the necessary comparisons.…”

“…(29) For the CFRMF and other ILRR tests, one of the more difficult aspects of this work is the proper assignment of errors for the current SAND-II energy-dependent evaluated cross sections. (29) Two methods of error assignment have been studied to~ate.…”