Abstract
A high-fidelity model for the first criticality of pebble-bed reactor HTR-PM is built using Monte Carlo (MC) code RMC and discrete element method (DEM) code LAMMPS. Randomly packed TRi-structural ISOtropic (TRISO) particles and fuel pebbles are modeled explicitly. A cone structure on the top of the pebble bed is also taken into account. Criticality calculation result agrees well with the experiment. Uncertainty analysis is carried out considering three inherent aspects: the randomness of MC code, the randomness of TRISO particle and pebble position, and the randomness of mixed pebbles. Results show that these factors have a significant impact on the uncertainty of effective multiplication factor (keff). And the most influential factor is expected to be the randomness of mixed pebbles. The influence of several configuration factors is studied as well. It is observed that the effects of cross-section library, the heterogeneity of TRISO particles, and the angle of pebble bed cone are nonnegligible contributors. However, the results between randomly and regularly placed TRISO particles are not noticeably different.
Highlights
As the fourth-generation nuclear power plant, high-temperature gas-cooled reactors (HTGRs) have been gaining attention because of their safety features
In order to study the influence of Monte Carlo (MC) method and mixed pebbles, 100 examples are calculated with fixed TRi-structural ISOtropic (TRISO) particle and pebble positions and randomly chosen fuel pebbles
The results suggest that the difference between randomly and regularly placed TRISO particles are insignificant, but the result using homogeneous material is unacceptable
Summary
As the fourth-generation nuclear power plant, high-temperature gas-cooled reactors (HTGRs) have been gaining attention because of their safety features. The influence of the heterogeneity of the pebble bed was studied based on HTR-PROTEUS (Auwerda et al, 2010). The influence of a cross-section library was studied based on the explicit model of the pebble bed reactor of ASTRA facility She et al (2021) studied the high-fidelity model based on deterministic code PANGU; sensitivity analysis was carried out focusing on filling fraction and uranium loading (Hao et al, 2015); uncertainty analysis on thermal features was launched using CUSA and ATHENA codes (Hao et al, 2020). This study builds a high-fidelity model of the first criticality of HTR-PM, realizing the meticulous modeling of large-scale pebble-bed reactor. The influence of cross-section library, heterogeneity of TRISO particles, and angle of pebble bed cone is studied.
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