Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Production of graphite dust inside the Pebble Bed Modular Reactor (PBMR)
influences the reactor operation negatively. Graphite is used as a moderator in the
reactor core and the formation and transportation of graphite dust away from the
reactor core decreases the amount of moderator which in turn has a negative
impact on the reactor operation. High levels of radioactive dust may also
contaminate reactor components which may pose a health risk to maintenance
personnel.
In this study a pressure vessel was designed and used to measure the wear of a
graphite pebble in helium at elevated temperatures. By means of a multi-linear
regression analysis a proper mathematical function was established in order to
relate graphite wear to certain tribological parameters. These parameters were
identified through a literature study.
Discrete Element Modelling (DEM) was used to simulate the gravitational flow of
graphite pebbles through the reactor core. The experimentally determined
mathematical function was incorporated into the DEM simulation to estimate the
annual mass of graphite dust to be produced by the PBMR pebble bed as a result
of pebble-pebble interaction and pebble-wall interaction during refuelling. / AFRIKAANSE OPSOMMING: Die vorming van grafiet stof binne die korrelbed-modulêre reaktor (PBMR)
beïnvloed die werking daarvan negatief. Grafiet word gebruik as 'n moderator in
die reaktor kern en die vorming en vervoer van grafietstof weg van die reaktor
kern lei tot 'n afname in die hoeveelheid moderator en dit het 'n negatiewe impak
op die werking van die reaktor. Hoë vlakke van radioaktiewe grafietstof
kontamineer ook reaktorkomponente wat 'n gesondheidsrisiko vir onderhoudspersoneel
inhou.
In hierdie studie was 'n drukvat ontwerp en gebruik om die slytasie van 'n grafietkorrel
in helium by verhoogde temperature te meet. 'n Multi-lineêre regressie
analise is dan gebruik om 'n wiskundige funksie daar te stel wat die verband
tussen grafietslytasie en die eksperimentele parameters vas stel. Hierdie
parameters was met behulp van 'n literatuurstudie geïdentifiseer.
Diskrete Element Modellering (DEM) was gebruik om die gravitasionele vloei
van grafietkorrels in die reaktor te modelleer. Die eksperimenteel bepaalde
wiskundige funksie word in die DEM simulasie ge-inkorporeer om 'n skatting te
maak van die jaarlikse massa grafietstof wat gevorm sal word in die PBMR
korrelbed as 'n gevolg van korrel-korrel interaksie en korrel-wand interaksie
gedurende hersirkulasie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/80211 |
| Date | 03 1900 |
| Creators | Wilke, Charel Daniel |
| Contributors | Coetzee, C. J., 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 | x, 122 p. : ill. |
| Rights | Stellenbosch University |
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