Analysis of the VENUS out-of-core activation measurements using MCBEND

The Venus-1 critical assembly simulates a U02-loaded core and the internal structures from the core baffle to the neutron pad, in a generic 3-loop plant. Venus-2 contained mixed oxide Pu02-U02 fuel pins in the eight outer rows. Several out-of-core threshold activation rates (In-115, Np-237, Zn-64, Al-27, Ni-58, U-238, Rh-103) have been measured at numerous locations in water zones and steel structures. From these measurements, "equivalent fission fluxes" have been established by dividing the activation rates by cross-sections weighted by the U-235 fission spectrum. Calculations of equivalent fission fluxes have been carried out with the Monte Carlo transport programme MCBEND. The average ratio calculation/experiment (C/E) in the core barrel, with 80 dosimeters and 7 types of reactions, is 1.02 0.03 (). Further away from the core, the average C/E in the neutron pad from 13 measurements is 1.01 0.08 ().