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The analysis of various non-destructive methods to control fissile materials (FM) in large-size containers filled with radioactive waste (RAW) has been carried out. The difficulty of applying passive gamma-neutron monitoring FM in large containers filled with concreted RAWis shown. Selection of an active non-destructive assay technique depends on the container contents; and in case of a concrete or iron matrix with very low activity and low activity RAW the neutron radiation method appears to be more preferable as compared with the photonuclear one. [ABSTRACT FROM AUTHOR]

The paper is devoted to non-destructive control of tiny amounts of fissile materials in large-sized containers filled with radioactive waste (RAW). The aim of this work is to model an active neutron interrogation facility for detection of fissile materials inside NZK type containers with RAW and determine the minimal detectable mass of U-235 as a function of various parameters: matrix type, nonuniformity of container filling, neutron generator parameters (flux, pulse frequency, pulse duration), measurement time. As a result the dependence of minimal detectable mass on fissile materials location inside container is shown. Nonuniformity of the thermal neutron flux inside a container is the main reason of the space-heterogeneity of minimal detectable mass inside a large-sized container. Our experiments with tiny amounts of uranium-235 (<1 g) confirm the detection of fissile materials in NZK containers by using active neutron interrogation technique. [ABSTRACT FROM AUTHOR]

More than 5500 independent and cumulative yields of radioactive residual product nuclides with lifetimes ranging from 13.2 min (187Re) to 31.55 years (207Bi) are measured in 208, 207, 206, natPb and 209Bi thin targets irradiated by 0.04, 0.07, 0.10, 0.15, 0.25, 0.40, 0.60, 0.80, 1.20, 1.60, and 2.60 GeV external proton beams from the ITEP U10 accelerator. The measured yields are compared with results by the LAHET (Bertini and ISABEL options), CEM03, LAQGSM03, INCL4+ABLA, CASCADE, CASCADE-2004, CASCADO, and the LAHETO codes, in order to evaluate their predictive powers in this energy region. We found that the predictive power of the tested codes is different but is satisfactory for most of the nuclides in the spallation region, though none of the codes agree well with the data in the whole mass region of product nuclides and all should be improved further. On the whole, the predictive power of all codes for the data in the fission and fragmentation product regions and, especially, at the borders between spallation and fission and between fission and fragmentation regions is much worse than in the spallation region; therefore, development of better evaporation/fission/fragmentation models is of high priority. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]