Nuclear Engineering ETDs

Publication Date

Spring 5-16-2026

Abstract

This research numerically investigates the helium-air mixing in HTGR containment cavities during the blowdown phase of a simulated DLOFC accident. The results of the performed CFD simulation analyses, using the commercial code STAR-CCM+, are compared with reported measurements from an experiment conducted at CCNY. The analyses investigate the effects of the RANS and LES turbulence models, numerical mesh refinement, time-step size, and flow rate and temperature of the injected hot helium into the scaled reactor cavity. Calculated parameters analyzed include the pressure and spatial distributions of temperature and oxygen concentration in the simulated reactor and steam generator cavities. CFD oxygen concentration predictions agree well with experimental measurements early in the transient but diverge later. Temperature comparisons show good agreement during the middle of the transient, with overprediction early and underprediction late. The LES model resolves significantly more small-scale eddies, producing more uniform helium-air mixing than the RANS model.

Keywords

HTGR, CFD, DLOFC, LES, RCTF, Blowdown

Document Type

Thesis

Language

English

Degree Name

Nuclear Engineering

Level of Degree

Masters

Department Name

Nuclear Engineering

First Committee Member (Chair)

Mohamed S. El-Genk

Second Committee Member

Svetlana V. Poroseva

Third Committee Member

Eric Lang

Fourth Committee Member

Timothy M. Schriener

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