Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: A high temperature reactor (HTR) generates heat inside of the reactor core through
nuclear fission, from where the heat is transferred through the core and heats up the reactor pressure vessel (RPV). The heat from the RPV is transported passively through the
reactor cavity, where it is cooled by the reactor cavity cooling system (RCCS), through
the concrete confinement structure and ultimately into the environment. The concrete
confinement structure can withstand temperatures of up to 65°C for normal operating
conditions and temperatures of up to 125°C during an emergency. This project endeavours to research the heat transfer between an HTR’s RPV and the outside of the
concrete confinement structure by utilising three investigative approaches: experimental,
computational fluid dynamics (CFD) and analytical.
The first approach, an experimental analysis, required the development of an experi-
mental model. The model was used to perform experiments and gather temperature data
that could be used to verify the accuracy of the CFD simulations. The second approach
was a CFD analysis of the experimental model, and the external concrete temperatures
from the simulation were compared with the temperatures measured with the experimen-
tal model. Finally, an analytical analysis was performed in order to better understand
CFD and how CFD solves natural convection-type problems. The experiments were performed successfully and the measurements taken were com-
pared with the CFD results. The CFD results are in good agreement with the Dry
experiments, but not with the Charged experiments. It was identified that the inaccurate
results for the CFD simulations of the Charged experiments arose due to convective heat
leakage through gaps in the heat shield and between the heat shield and the sides of the
experimental model. A computer program was developed for the analytical analysis and
it was established that the program could successfully solve the natural convection in a
square cavity - as required. / AFRIKAANSE OPSOMMING: ’n Hoë temperatuur reaktor (HTR) genereer hitte binne die reaktor kern deur kernsplyting en die hitte word dan deur die kern versprei en verhit die reaktor se drukvat. Die hitte
van die reaktor drukvat word dan passief deur die reaktorholte versprei, waar dit deur
die reaktorholte se verkoelingstelsel afgekoel word, en deur die beton beskermingstruktuur gelei word en uiteindelik die omgewing bereik. Die beton beskermingstruktuur kan
temperature van tot 65°C onder normale operasietoestande van die reaktor weerstaan, en
temperature van tot 125°C tydens ’n noodgeval. Hierdie projek poog om die hitte-oordrag
tussen ’n HTR-reaktor drukvat en die buitekant van die beton beskermingstruktuur te on-
dersoek deur gebruik te maak van drie ondersoekbenaderings: eksperimenteel, numeriese
vloei dinamika (NVD) en analities. Die eerste benadering, ’n eksperimentele analise, het die ontwikkeling van ’n eksper-
imentele model vereis. Die model is gebruik om eksperimente uit te voer en temperatu-
urmetings te neem wat gebruik kon word om die akkuraatheid van die NVD simulasies
te bevestig. Die tweede benadering was ’n NVD-analise van die eksperimentele model,
en die eksterne betontemperature verkry van die simulasies is vergelyk met die gemete
temperature van die eksperimente. Uiteindelik is ’n analitiese analise uitgevoer ten einde
NVD beter te verstaan en hoe NVD natuurlike konveksie-tipe probleme sal oplos.
Die eksperimente is suksesvol uitgevoer en die metings is gebruik om die NVD resultate
mee te vergelyk. Die NVD resultate van die Droë eksperimente het goeie akkuraatheid
getoon. Dit was nie die geval vir die Gelaaide eksperimente nie. Daar is geïdentifiseer dat
die verskille in resultate tussen die NVD en die eksperimente aan natuurlike konveksie
hitte verliese deur gapings in die hitteskuld en tussen die hitteskuld en die kante van
die eksperimentele model toegeskryf kan word. ’n Rekenaarprogram is geskryf vir die
analitiese ontleding en die program kon suksesvol die natuurlike konveksie in ’n vierkantige
ruimte oplos.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/71796 |
| Date | 12 1900 |
| Creators | Van der Merwe, David-John |
| Contributors | Dobson, R. T., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 122 p. : ill. |
| Rights | Stellenbosch Univesity |
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