Integral measurements for higher actinides in CFRMF

To improve upon the lack of fast integral data for higher actinides, an effort is underway to measure integral capture and fission cross sections for 242Pu, 241Am and 243Am in the fast neutron zone of the Couple Fast Reactivity Measurements Facility (CFRMF). Fission cross sections are determined based on the Ge(Li) gamma spectrometric measurements of the absolute emission rates of the 537-keV and/or 1596-keV lines in the 140Ba - 140La decay. The capture rate for 242Pu is based on the measurement of the absolute emission rate of the 84.0 keV line in the 243Pu β- decay. Although the capture cross sections for 241Am and 243Am are not obtained directly, the cross sections for production of 242Cm and 244Cm are based on the quantitative alpha spectrometry and total alpha counting. Measured integral and capture cross sections for 242Pu are 357 mb +- 10% and 146 mb +- 15%. Corresponding spectral averaged cross sections calculated using ENDF/B-IV data and 489 mb and 238 mb, respectively. For 241Am fission and capture the measured cross sections are 504 mb +- 12% and 1.01 b +- 3%, respectively. For 243Am fission and capture, the measure cross sections are 0.352 b and .10 b, respectively. 19 references