Multiphysics coupled calculations using OpenFOAM, Serpent, and external heat conduction solver in high-temperature engineering test reactor HTTR : master’s thesis

Abulawi, Zaid (author), Rintala, Ville (mentor), Tiselj, Iztok (co-mentor), Suikkanen, Heikki (co-mentor)

Adequate safety analysis is needed for generation IV Gas Cooled Reactors (GCRs), as nuclear reactor safety is challenged by the complexity of the different physical phenomena. High-fidelity modeling is achieved by a comprehensive coupling of these phenomena. This master’s thesis provides a neutronics/thermal-hydraulics coupling approach to model GCRs using Serpent, OpenFOAM, and an external heat conduction solver. The approach provides a way to model GCRs without explicitly simulating the TRISO fuel particles, instead a homogeneous fuel region is simulated in OpenFOAM, and then the homogeneous fuel temperature is used as a boundary condition in the heat conduction solver to analytically resolve the layers and kernel temperatures. The data exchange between the solvers is conducted through a type 8 Serpent coupling interface and a modified chtMultiRegionSimpleFOAM solver to retrieve the volumetric power produced in Serpent. Convergence in the coupling process is determined by assessing the volumetric power values from Serpent. The coupling approach is applied to a single fuel rod and a fuel block in High-Temperature Engineering Test Reactor (HTTR). Given that both simulations have similar volumetric power, it is observed that there is a notable discrepancy in solid region temperatures, in contrast to a pronounced agreement in the fluid region properties.

• Language: English
• Keywords: multiphysics, coupled simulations, CFD-neutronics, HTTR, OpenFOAM, Serpent, thermal-hydraulics, Monte Carlo
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FMF - Faculty of Mathematics and Physics
• Place of publishing: Lappeenranta
• Publisher: Z. Abulawi
• Year: 2023
• Number of pages: 1 spletni vir (1 datoteka PDF ([100] str.))
• PID: 20.500.12556/RUL-152560
• UDC: 621.039.5
• COBISS.SI-ID: 173965315
• Publication date in RUL: 28.11.2023

Secondary language

• Language: Slovenian
• Title: Sklopitev računalniških programov OpenFOAM, Serpent in analitičnega modela prenosa toplote v simulacijah visokotemperaturnega plinsko hlajenega reaktorja : magistrsko delo

Abstract

Varnostne analize plinsko hlajenih reaktorjev IV. generacije zahtevajo sklopljeno obravnavo različnih vrst fizikalnih pojavov, saj lahko le na ta način dosežemo primerno natančnost. To magistrsko delo opisuje sklopitev nevtronskih in termo-hidravličnih pojavov v plinsko hlajenem reaktorju z uporabo računalniških programov Serpent za nevtronske preračune in OpenFOAM za termo-hidravlične preračune. V okviru sklopitve smo uporabili še dodaten program za simulacije prevajanja toplote v trdni snovi. Predlagan pristop omogoča modeliranje plinsko hlajenega reaktorja brez eksplicitne simulacije goriva TRISO, ki se nahaja v obliki drobnih kroglic v grafitni matriki. Namesto tega v OpenFOAM-u simuliramo gorivo kot homogeno zmes, nato pa se homogena temperatura goriva uporabi kot robni pogoj za analitičen izračun temperaturnih profilov v TRISO kroglicah. Izmenjava podatkov med računalniškimi programi poteka prek povezovalnega, vmesnika programa Serpent in nadgrajenega podprograma chtMultiRegionSimpleFOAM, ki prebere gostoto moči, ki jo izračuna Serpent. Konvergenca v procesu sklopitve je določena z oceno polja gostote moči. ki jo napove program Serpent. Sklopitev smo uporabili za dva ločena primera: eno samo gorivno palico in za gorivni blok v visokotemperaturnem testnem reaktorju (HTTR). Glede na to, da imata obe simulaciji podobno gostoto moč, opazimo znatno razliko v temperaturah sredice v trdnem agregatnem stanju, ter dobro ujemanje napovedi v območjih, ki jih zaseda tekočina.

• Keywords: sklopljene simulacije, računska dinamika tekočin, nevtronski preračuni, HTTR reaktor, OpenFOAM, Serpent, Monte Carlo simulacije