High-temperature reactor code package thermo-fluid dynamics development

  • Hochtemperaturreaktor Code Package Thermofluiddynamik Entwicklung

Trabadela Ramirez, Alfonso; Allelein, Hans-Josef (Thesis advisor); Macián-Juan, Rafael (Thesis advisor); Olivier, Herbert (Thesis advisor)

Aachen : RWTH Aachen University (2020, 2021)
Dissertation / PhD Thesis

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2020

Abstract

The High Temperature Reactor Code Package (HCP) is a code environment tailored to the simulation of high temperature reactors (HTR). The prediction of stationary and transient reactor behaviour under normal operation as well as during contingencies and accidents necessitates reliable reactor dynamic simulation capabilities. These simulation capabilities require a code environment that couples the feedback loop of neutronics and thermo-fluid dynamics. This coupling is the essential building block of the HCP. Licensing procedures of nuclear power plants mandates the simulation of design basis and beyond design basis accidents. Such simulations necessitate thoroughly validated tools. The thorough validation ensures the documentation of the up-to-date knowledge obtained on physical, chemical, and structure-mechanical parameters during accidents withing the expected pressure and temperature ranges – among other parameters. The centrepiece of this thesis comprises the integration of MGT-FD and MGT-N in HCP. MGT-3D is a multi-energy-group 3D reactor dynamics code for high temperature reactors. Before integrating it, the code was restructured and subdivided into two modules: MGT-FD (thermo-fluid dynamics) and MGT-N (neutronics). Each separate module was coupled to the HCP-platform. The thus extended HCP was verified and validated and its suitability for the simulation of HTR-accident scenarios for the HTR MODUL-concept was demonstrated. The success of the coupling was ascertained by exactly reproducing results of MGT 3D as an independent software suite. The HCP thermo-fluid dynamical capabilities including graphite corrosion modelling were compared to the data obtained from reference codes and validated with experimental data. New reactor dynamic capabilities, such as the simulation of a simplified transient, could be proven. HCP now is a highly integrated platform capable of simulating steady-states as well as accident scenarios in high temperature reactors. The restructuring of some HCP modules and their respective analyses have contributed significantly to the understanding of high temperature reactor dynamics. In tandem with improvements in coding on the cutting edge of technology this has led to a version of HCP which currently is the most comprehensive code environment for the analysis of high temperature reactor dynamics currently available; thus, it provides the bedrock for future development increments. An extensive developer-independent validation of the HCP at some point in the future is mandatory.

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