Eventos Anais de eventos
ENCIT 2020
18th Brazilian Congress of Thermal Sciences and Engineering
Simulation of Dispersed Flow Film Boiling in LOCA Conditions Considering Steam Flow Deviation Due to Clad Ballooning
Submission Author:
Arthur Vieira da Silva Oliveira , SP
Co-Authors:
Arthur Vieira da Silva Oliveira, Alexandre Labergue, Michel Gradeck, Juan Esteban LUNA VALENCIA, glantz tony, Georges Repetto
Presenter: Arthur Vieira da Silva Oliveira
doi://10.26678/ABCM.ENCIT2020.CIT20-0075
Abstract
During a loss of coolant accident (LOCA), the water in a pressurized water reactor (PWR) evaporates and, consequently, the fuel assemblies temperature increases substantially. This process may lead to clad swelling, resulting in a partial or complete blockage of some sub-channels of the flow. This leads to the steam flow deviation from these more resistant sub-channels, although inertial droplet tend to continue in their path straight to the blocked sub-channel. This paper presents a simulation of dispersed flow film boiling using the code NECTAR to evaluate the effect of the steam flow deviation on the coolability of blocked sub-channels by comparing with a simulation without flow deviation (Venturi effect). The heat dissipation with flow deviation is highly decreased because of the degraded wall-to-steam convection. Furthermore, droplets impact onto the heated wall to the heat dissipation, which is negligible in the Venturi effect, contributes by 26% to the heat dissipation when there is flow deviation. Finally, droplets breakup does not occur with flow deviation for the tested case.
Keywords
LOCA, NECTAR, thermal hydraulics, nuclear reactor, Droplets impact
