Naslov
Severe accident gamma dose distribution through NPP Krško containment and auxiliary building calculated using SCALE6/MAVRIC sequence

Autori
Matijević, Mario ; Grgić, Davor ; Pevec, Dubravko

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

Izvornik
Proceedings of the 24th International Conference Nuclear Energy for New Europe / Jenčič, Igor - Ljubljana : Nuclear Society of Slovenia, 2015, 411.1-411.13

ISBN
978-961-6207-38-6

Skup
24th International Conference Nuclear Energy for New Europe - NENE 2015

Mjesto i datum
Portorož, Slovenija, 14.09.2015. - 17.09.2015

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
SCALE6; FW-CADIS; shielding; PWR; variance reduction; Monte Carlo; MAVRIC; ORIGEN; RADTRAD

Sažetak
The ORNL SCALE6.2b4 code package was used for the Monte Carlo model preparation of the NPP Krško corresponding to reactor, primary loop components, containment and adjoining buildings. A fairly detailed model of the reactor with concrete compartments housing primary pumps and steam generators was developed using as-built dimensions. Auxiliary buildings (AB) were modeled as empty in this work, taking into account the bulk dimensions of concrete walls and floors. An analysis of gamma dose distribution in the case of hypothetical SBO accident was performed using hybrid deterministic-stochastic FW-CADIS methodology of the MAVRIC shielding sequence. Preparation of the gamma source was done using isotopic concentrations calculated with RADTRAD code and 18-groups ORIGEN energy structure. The source is homogenous and distributed over all air regions in the containment. The influence of melted material in reactor cavity is not taken into account. Under such conditions the aim was to calculate gamma dose rates through different floors, sections and buildings, posing significant shielding problem. Special attention was given to gamma doses in the containment and in AB rooms close to the containment. For that purpose, the integrated discrete ordinates code Denovo, based on the adjoint transport theory, was used for calculation of variance reduction parameters (weight windows and biased source) over the XYZ meshes covering the problem domain. Denovo utilizes Koch-Baker-Alcouffe parallel transport sweep algorithm and Krylov iteration on multigroup equations giving space-energy dependent fluxes and variance reduction parameters. These variance reduction parameters, that work in tandem, are automatically transferred to the functional module Monaco for the final, optimized Monte Carlo transport. Different adjoint source locations were investigated, giving optimized dose rates over localized or distributed phase-space regions.

Izvorni jezik
Engleski

Znanstvena područja
Elektrotehnika

POVEZANOST RADA