A HYBRID MONTE-CARLO-DETERMINISTIC METHOD FOR AP1000 EX-CORE DETECTOR RESPONSE SIMULATION

The ex-core detector-response calculation is a typical deep-penetration problem, which is challenging for the Monte Carlo method. The response of the ex-core detector is an important parameter for the safe operation of the nuclear power plants. Meanwhile, evaluation of the ex-core detector response during each step of fuel-loading is used to guide the fuel-loading sequence. The response can also be used to reconstruct core-power distribution for online monitoring of long-term power. The detector used for the ex-core response is the source-range detector which is sensitive to thermal neutrons. For a Monte Carlo shielding calculation of the above detector response, the thermal flux under 0.625eV is needed, which is too small to be tallied by traditional Monte Carlo simulations. In practice, the tally results are close to zero in the detector region under direct Monte Carlo calculation. Even if the number of particles is increased to a significant amount, the statistical variance is still very large. The high variance along with a significant calculation time leads to a small Figure Of Merit (FOM). In order to solve this problem and to improve the tally efficiency of the ex-core detector response, a hybrid Monte-Carlo-deterministic method is employed in this study, and an in-house hybrid Monte-Carlo-deterministic particle transport code, NECP-MCX, is developed in this paper. The method takes the space-energy-dependent adjoint fluxes to generate importance parameters for the mesh-based weight window in the Monte Carlo calculation. Simultaneously, the mesh-based source biasing is performed with the consistent importance parameters to make the starting weight of neutrons matching with the survival weight of the weight windows. As the mesh used in the hybrid Monte-Carlo-deterministic method is superimposed, the mesh of the weight window will not be affected by the complex geometry model. The adjoint flux is obtained by the efficient SN method with the multi-group cross-section data. The whole toolset is convenient to use with single set of the modelling data for both Monte Carlo and deterministic simulations. Compared with the direct Monte Carlo simulation, the hybrid Monte-Carlo-deterministic method has a higher efficiency for a typical deep-penetration problem such as the AP1000 ex-core detector-response simulation.

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Path integral hybrid Monte Carlo calculation of the bosonic oscillators

Journal of Molecular Liquids ◽

10.1016/s0167-7322(00)00176-8 ◽

2001 ◽

Vol 90 (1-3) ◽

pp. 21-28

Author(s):

Shinichi Miura ◽

Susumu Okazaki

Keyword(s):

Monte Carlo ◽

Path Integral ◽

Monte Carlo Calculation ◽

Hybrid Monte Carlo

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Monte Carlo Calculation of X-Rays Deposited Energy in CdZnTe Detector

Materials Science Forum ◽

10.4028/www.scientific.net/msf.555.141 ◽

2007 ◽

Vol 555 ◽

pp. 141-146 ◽

Cited By ~ 2

Author(s):

Srboljub J. Stanković ◽

M. Petrović ◽

M. Kovačević ◽

A. Vasić ◽

P. Osmokrović ◽

...

Keyword(s):

Monte Carlo ◽

Monte Carlo Calculation ◽

Absorbed Dose ◽

Detector Response ◽

X Rays ◽

X Ray ◽

Cdznte Detector ◽

Deposited Energy ◽

Photon Direction ◽

Cdznte Detectors

CdZnTe detectors have been employed in diagnostic X-ray spectroscopy. This paper presents the Monte Carlo calculation of X-ray deposited energy in a CdZnTe detector for different energies of photon beam. In incident photon direction, the distribution of absorbed dose as deposited energy in detector is determined. Based on the dependence of the detector response on the thickness and different Zn fractions, some conclusions about changes of the material characteristics could be drawn. Results of numerical simulation suggest that the CdZnTe detector could be suitable for X-ray low energy.

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PERFORMANCE STUDY OF GLOBAL WEIGHT WINDOW GENERATOR BASED ON PARTICLE DENSITY UNIFORMITY

EPJ Web of Conferences ◽

10.1051/epjconf/202124718005 ◽

2021 ◽

Vol 247 ◽

pp. 18005

Author(s):

Peng He ◽

Bin Wu ◽

Lijuan Hao ◽

Guangyao Sun ◽

Bin Li ◽

...

Keyword(s):

Monte Carlo ◽

Variance Reduction ◽

Particle Density ◽

Complex Model ◽

Deep Penetration ◽

Detailed Calculation ◽

Performance Study ◽

Global Weight ◽

Weight Window ◽

Calculation Results

The variance reduction techniques are necessary for Monte Carlo calculations in which obtaining a detailed calculation result for a large and complex model is required. The GVR method named as global weight window generator (GWWG) was proposed by the FDS team. In this paper, two typical calculation examples, ISPRA-Fe benchmark in SINBAD (Shielding Integral Benchmark Archive Database) and TF Coils (Toroidal Field coils) of European HCPB DEMO (Helium Cooled Pebble Bed demonstration fusion plant), are used to study the performance of GWWG method. It can be seen from the calculation results that the GWWG method has a significant effect in accelerating the Monte Carlo calculation. Especially when the global convergence calculation results are needed, the acceleration effect (FOMG) can reach 105 or more. It proves that the GWWG method is an effective tool for deep-penetration simulations using Monte Carlo method.

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