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AN EXPERIMENTAL STUDY OF THE INTEGRAL PROPERTIES OF 235U AND 239Pu IN AN INTERMEDIATE ENERGY SPECTRUM, AND COMPARISON WITH THEORETICAL PREDICTION

Author
Fox, W. N.
Published
United Kingdom : [publisher not identified], 1969.
[Oak Ridge, Tennessee] : [U.S. Atomic Energy Commission], 1969.
Physical Description
microfiche : negative ; 11 x 15 cm
Additional Creators
King, Donald C., 1930-, MacBean, I. J., Pitcher, H. H. W., Sanders, J. E., and Small, V. G.

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Summary
Present-day methods of calculation for thermal and fast reactors involve the use of multigroup cross-section sets derived from basic nuclear data files. Since the accuracy of the calculations depends ultimately on the accuracy of these data, it is important to test them against results of 'integral experiments' in critical or sub-critical assemblies. The present report describes integral experiments designed to provide a sensitive test of the U235 and Pu239 cross-sections spectrum-averaged over the 'intermediate' energy range from about 10 eV to 10 keV. This is an area where the fissile nuclide cross-section data, particularly that for radiative capture, are still inadequately defined, as evidenced by the considerable discrepancies between various determinations. The difficulties stem from the problems of resolving and analysing the properties of closely spaced resonances and particularly in separating the fission and capture contributions. From the parameters of the resolved resonances, the distributions of the partial widths must be derived in order to provide a sound basis for the calculation of the averaged properties in the unresolved region, which constitute a significant part of the region of interest. The correct assignment of the fission and capture widths and their distributions is also necessary for the calculation of the spectrum-average capture to fission ratio (a), which has an important bearing on conversion and breeding ratios. Unlike the situation for the thermal and fast neutron regions (i.e. those below and above that considered here), where many critical and sub-critical assemblies have been made, very few integral experiments suitable for adequately testing the U235 and Pu239 data in the intermediate energy range have been reported. Hence the decision, in 1965, to undertake the work described here.
Report Numbers
AEEW-R-586
Other Subject(s)
Collection
U.S. Atomic Energy Commission depository collection.
Note
NSA number: NSA-23-052478
OSTI Identifier 4736761
Research organization: Atomic Energy Establishment, Winfrith, England (United Kingdom).
View MARC record | catkey: 37758301