NAAPRO, a versatile modeling tool for planning of neutron activation analysis


Vladyslav Basenko1, Andrey Berlizov, berlizov@kinr.kiev.ua1, Roy Filby2, Igor Malyuk1, and Volodymyr Tryshyn, trishin@kinr.kiev.ua1. (1) Center for Ecological Problems of Atomic Energy, Institute for Nuclear Research, 47, Prospekt Nauki, Kyiv, MSP 03680, Ukraine, (2) Department of Chemistry, Washington State University, P.O. Box 644630, Pullman, WA 99164-4630
NAAPRO (Neutron Activation Analysis PRognosis and Optimization) code has been developed for predicting results and performance characteristics (detection limits and precision) of NAA on the basis of a model gamma-ray spectrum of activation products, simulated for specified time mode, elemental composition, mass and dimensions of an analyzed sample, characteristics of irradiating neutron flux and irradiation conditions, parameters of post-irradiation radiochemical treatment procedures, measurement geometry and background conditions, as well as detector and spectrometry system parameters. Gamma-ray dose rates for different points of time after sample irradiation and input count rate of a spectrometry system are predicted also. Gamma-ray yields of activation products are calculated taking into account of burnup and buildup of both radioactive and stable isotopes under neutron exposure. The code uses extensive neutron cross-section and radionuclide data libraries, built on the basis of recent evaluated nuclear data files (ENDF/B-VI, RNAL, EAF, JENDL, CENDL, BROND, ADL, ENSDF). Integrated means for supplementing and updating of the libraries are provided. For gamma-ray spectrum modeling, an analytical and, more precise, statistical (obtained by Monte Carlo simulation) gamma-ray detector response presentations have been developed. As a result, detectors with NaI, BGO, and HPGe crystals with arbitrary dimensions, thickness of non-active layers and additional absorbers can be considered. NAAPRO has modern user interface, providing possibility for tabular and graphical output of calculation results, simulated spectrum, detector response functions, cross-section energy dependences etc. It can be applied for predicting of performance of a wide range of instrumental and radiochemical NAA techniques, utilizing reactor, isotopic source or monoenergetic neutrons. The paper will present a general overview of the NAAPRO features. Particular attention will be given to the developed detector response models and employed procedures for the activation product gamma-ray spectrum generation. The prospects for the program development will be discussed also.