VALUE-BASED MODELING TECHNIQUE FOR REACTOR PHYSICS SIMULATIONS OF DEEP PENETRATION AND DETECTION USING THE "PRIZMA" CODE
O. V. Zatsepin, Ya. Z. Kandiev
VANT. Ser.: Mat. Mod. Fiz. Proc 2015. Вып.1. С. 30-36.
PRIZMA is a code that has been developed at RFNC-VNIITF for Monte-Carlo ionizing radiation transport simulations for more than thirty years. The code enables simulations of both separate and joint transport of neutrons, photons, electrons, positrons and ions in the 1D, 2D and 3D geometry. Functionals are calculated using visiting estimates, i.e. the estimates, the contributions to which are non-zero only for the particle paths intersecting the integration region/surface. To improve efficiency, the code uses value-based modeling for deeper penetration and detection simulations. Consideration of reactor physics problems belonging to these classes revealed special features that required special modeling schemes and revision of the existing value-based modeling technique.
This paper provides an overview of the methods for deep penetration and detection simulations using the PRIZMA code and describes specific features of some reactor physics problems belonging to these classes and requiring the development of the value-based modeling technique. To prove the validity of the improved technique, the paper presents solutions of a number of test and applied problems. The solutions are shown to agree with asymptotic solutions, if available, or, in the other cases, with solutions obtained by the analog modeling method or using other codes. Applied simulations to estimate signals of out-of-core detectors from neutron sources located in the core of VVER-1 000 and in-core detectors of VVER-1 000 are considered. Keywords: particle transport, Monte Carlo method, value-based modeling, deep penetration, detection, PRIZMA code, VVER-1 000.
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