Preliminary MCNP-POLIMI Simulations for the Evaluation of the ''Floor Effect'': Comparison of APSTNG and Cf Sources

Pozzi, S.A.

Oak Ridge National Laboratory

关键词: 46 Instrumentation Related To Nuclear Science And Technology;    Computerized Simulation;    07 Isotopes And Radiation Sources;    98 Nuclear Disarmament, Safeguards, And Physical Protection;    Monte Carlo Method;   

DOI  :  10.2172/814539
RP-ID  :  ORNL/TM-2002/18
RP-ID  :  AC05-00OR22725
RP-ID  :  814539

美国|英语

来源: UNT Digital Library

【 摘 要 】

The present simulations performed with the Monte Carlo code MCNP-POLIMI [1] have the scope of evaluating the associated-particle sealed tube neutron generator (APSTNG) for use as an interrogation source in the source-driven noise analysis method for the assay of nuclear materials. In the Nuclear Materials Identification System (NMIS) developed at the Oak Ridge National Laboratory, the time dependent cross-correlation of the timed neutron source and detector responses is one of the signatures acquired. Previous studies and measurements have demonstrated the sensitivity of this and other related signatures to fissile mass [2-3]. In a recent report [4], we outlined the advantages of the APSTNG interrogation source for use with NMIS when compared with the Cf-252 source. In particular, we showed that when the distance between the source and the sample and the sample and the detectors is large, the APSTNG source outperforms the Cf-252 in sensitivity to fissile mass. This is the case when performing measurements of items that are placed inside containers. The purpose of this report is to investigate the advantages of using the APSTNG source in reducing the effect of floor reflections in the signatures acquired. To this end, a large number of MCNP-POLIMI Monte Carlo simulations were performed to obtain source-detector covariance functions.