Abstract: | A study was made of the distribution of the ratio of radiation capture and fission cross sections for Pu239 with respect to height in the BR-5 reactor. The distribution of neutron capture reactions was measured by determining the concentration of Pu240 from the rate of spontaneous fissions in plutonium samples irradiated in the reactor with an integral flux of 1021 to 1022 neutrons/cm2. As initial material for irradiation, almost isotopically pure Pu239 (Pu240 content 5·10–3% was used. The values of obtained rose from 0.1 to 0.8 on moving away from the center of the reactor. The data corresponding to equilibrium neutron spectra in the active zone and the outer region of the reflector agree with the results of measuring
and
f
in monoenergetic neutrons.Translated from Atomnaya Énergiya, Vol. 16, No. 6, pp. 497–500, June, 1964 |