Naslov
SCALE6 Hybrid Deterministic-Stochastic Shielding Methodology for PWR Containment Calculations

Autori
Matijević, Mario ; Pevec, Dubravko ; Trontl, Krešimir

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Proceedings of the 10th International Conference on Nuclear Option in Countries with Small and Medium Electricity Grids / Čavlina, Nikola ; Grgić, Davor ; Pevec, Dubravko - Zagreb : Croatian Nuclear Society, 2014, 100-1

ISBN
978-953-55224-6-1

Skup
10th International Conference on Nuclear Option in Countries with Small and Medium Electricity Grids

Mjesto i datum
Zadar, Hrvatska, 01.06.2014. - 04.06.2014

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Monte Carlo; SCALE6; shielding; hybrid methodology; FW-CADIS; CADIS; variance reduction

Sažetak
The capabilities and limitations of SCALE6/MAVRIC hybrid deterministic-stochastic shielding methodology (CADIS and FW-CADIS) are demonstrated when applied to a realistic deep penetration Monte Carlo (MC) shielding problem of full-scale PWR containment model. The ultimate goal of such automatic variance reduction (VR) techniques is to achieve acceptable precision for the MC simulation in reasonable time by preparation of phase-space VR parameters via deterministic transport theory methods (discrete ordinates SN) by generating space-energy mesh-based adjoint function distribution. The hybrid methodology generates VR parameters that work in tandem (biased source distribution and importance map) in automated fashion which is paramount step for MC simulation of complex models with fairly uniform mesh tally uncertainties. The aim in this paper was determination of neutron-gamma dose rate distribution (radiation field) over large portions of PWR containment phase-space with uniform MC uncertainties. The sources of ionizing radiation included fission neutrons and gammas (reactor core) and gammas from activated two-loop coolant. Special attention was given to focused adjoint source definition which gave improved MC statistics in selected materials and/or regions of complex model. We investigated benefits and differences of FW-CADIS over CADIS and manual (i.e. analog) MC simulation of particle transport. Computer memory consumption by deterministic part of hybrid methodology represents main obstacle when using meshes with millions of cells together with high SN/PN parameters, so optimization of control and numerical parameters of deterministic module plays important role for computer memory management. We investigated the possibility of using deterministic module (memory intense) with broad group library v7_27n19g opposed to fine group library v7_200n47g used with MC module to fully take effect of low energy particle transport and secondary gamma emission. Compared with CADIS and also analog MC simulations, the FW-CADIS drastically improved MC dose rate calculations in quality as well in quantity. Large shielding problems such as portions and complete PWR facility require not only extensive computational resources but also understanding of the underlying physics, which is inevitable in interpreting results of hybrid deterministic-stochastic methodology.

Izvorni jezik
Engleski

Znanstvena područja
Elektrotehnika

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