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Takano, Hideki; *
JAERI-M 89-141, 78 Pages, 1989/10
no abstracts in English
; ; Nakagawa, Masayuki; ; Katsuragi, Satoru
JAERI 1255, 200 Pages, 1978/03
no abstracts in English
Katsuragi, Satoru; ; ; Nakagawa, Masayuki
JAERI 1199, 116 Pages, 1970/12
Improvements have been made for the treatments of effective cross section of heavy nuclides in the resonance energy region, and fast reactor group constants in this energy region have been produced for nuclides 
U, 
U, 
Pu, and 
Pu. These group constants are thought to be accurate compared with existing fast group constants in the following sense. (1) The resonance parameters (including those in the unresolved resonance energy region) are evaluated so as to fit measured cross sections. (2) Accurate cross sections are obtained by a calculating procedure, which uses a reasonable representation of cross sections, without waste of huge computing time. (3) The effective cross sections are obtained using exact spectra as weights, because conventional approximation methods yield less accurate results. (4) An investigation was made for the treatment of interference effects. And interference effects. And interference effects with U is taken into account for shielding factors. (5) The energy variation of 
(
/
) values and for U and Pu is properly reproduced, and an appropriate group structure is adopted taking this energy variation into consideration. For analyses and design studies of fast reactor systems, the present group constants should be used together with those listed in the report JAERI 1195.
