http://www.engineeringnews.co.za
  SEARCH
Login
R/€ = 13.14Change: -0.15
R/$ = 12.05Change: -0.20
Au 1200.03 $/ozChange: -6.12
Pt 1139.50 $/ozChange: -16.00
 
 
Note: Search is limited to the most recent 250 articles. Set date range to access earlier articles.
Where? With... When?








Start
 
End
 
 
And must exclude these words...
Close Main Search
Close Main Login
My Profile News Alerts Newsletters Logout Close Main Profile
 
Agriculture   Automotive   Chemicals   Competition Policy   Construction   Defence   Economy   Electricity   Energy   Environment   ICT   Metals   Mining   Science and Technology   Services   Trade   Transport & Logistics   Water  
What's On Press Office Tenders Suppliers Directory Research Jobs Announcements Letters Contact Us
 
 
 
RSS Feed
Article   Comments   Other News   Research   Magazine  
 
 
Aug 10, 2007

Fuel for thought - PBMR fuel set for year-end production

Back
Expertise|Africa|CoAL|Design|Nuclear|Storage|Water|Africa|Energy|Equipment|Manufacturing|Nuclear|Products|Power|Water
Expertise|Africa|CoAL|Design|Nuclear|Storage|Water|Africa|Energy|Equipment|Manufacturing|Nuclear|Products|Power|Water
expertise|africa-company|coal|design|nuclear-company|storage|water-company|africa|energy|equipment|manufacturing|nuclear-industry-term|products|power|water
© Reuse this



The first pebble-bed modular reactor (PBMR) fuel containing uranium is expected to be produced toward the end of the year at the company’s fuel development laboratories at Pelindaba. The South African nuclear energy corporation (Necsa) will assist PBMR in certain phases of the manu- facturing.

PBMR chief technology officer Dr Johan Slabber states that the first uranium-containing batch will be irradiated in test reactors in Russia and Holland, to provide early proof of performance. He points out that the PBMR fuel is based on a proven, high-quality German fuel design, consisting of low-enriched uranium triple-coated isotropic particles contained in a moulded graphite sphere.

“Our objective is to emulate the German fuel,” says Slabber, “because its reliability was tested and proven in Germany over 21 years.” He says the results from the test reactors will provide confirmation that a fuel equivalent to the German fuel can be manufactured in South Africa, and that German high- temperature reactor fuel manufactur- ing and quality control technology has been successfully transferred to South Africa.

Slabber states that a number of successful runs have been com- pleted on the coater of the PBMR fuel development laboratories, using simulated kernel materials instead of uranium. The coater was commissioned early this year. “The next step is to obtain a licence from the national nuclear regulator for the manufacturing of fuel containing uranium.”

Under the umbrella of development laboratories falls a host of laboratory-scale facilities with the prime purpose of developing the expertise required to manufacture the PBMR fuel, namely the kernel laboratory for uranium dioxide kernels, the coating laboratory for coating kernels, the fuel sphere laboratory for PBMR spherical fuel elements, and the quality control laboratory to perform the prescribed chemical, physical, and dimensional tests.

While the kernel laboratory has produced kernels with depleted and natural uranium, the coater facility has only produced zirconia- and alumina-coated particles. The graphite laboratory has produced fuel spheres containing alumina kernels, alumina- coated particles, zirconia-coated particles, and depleted uraniumcoated particles.

The initial laboratory work for the laboratory fuel started in 2002, with preparations and planning for the actual fuel plant at Necsa starting in early 2006. This means that the layout and design for the fuel laboratories went hand in hand with the sourcing of equipment and the establishment of protocols to ensure the orderly development of quality controls.

Slabber explains that a solution of uranyl nitrate is sprayed to form microspheres, which are then gelled and calcined to produce uranium dioxide kernels. The kernels are run through a chemical vapour deposition oven, in which layers of specific chemicals can be added with extreme precision.

First to be deposited on the kernel is a porous carbon layer, which allows fission products to collect without overpressurising the coated fuel particles. This is followed by a thin coating of pyrolitic carbon, which is a very dense form of heat-treated carbon. A thin layer of silicon carbide, which is a strong refractory material, and another layer of pyrolitic carbon, follow.

The porous carbon accommodates any mechanical deformation that the uranium dioxide kernel may undergo during the lifetime of the fuel, as well as gaseous fission products diffusing out of the kernel. The pyrolitic carbon and silicon carbide layers provide an impene-trable barrier, designed to contain the fuel and radioactive fission products resulting from nuclear reactions in the kernel.

About 15 000 of these coated kernels, each of which is now about 1 mm in diameter, are mixed with graphite powder and a phenolic resin, which is then pressed into the shape of a 50-mm-diameter ball. A 5-mm layer of pure carbon is then added to form a nonfuel zone, and the resulting spheres are carbonised and annealed to make them hard and durable.

The spherical fuel pebbles are machined to a diameter of 60 mm, about the size of a billiard ball. Each fuel pebble contains 9 g of uranium, and Slabber says this holds enough generation capacity to sustain a family of four, for a year. “Five tons of coal and up to 23 000 8467 of water will be required to generate one pebble’s energy.”

During normal operation, the PBMR core contains a load of 456 000 pebbles and can generate about 165 MW of electricity. A graphite column is located at the centre of the core, and the fuel pebbles in the annulus around it. Graphite is used owing to its structural characteristics, and its ability to slow down neutrons to the speed required for the nuclear reaction to take place. This geometry also limits the peak temperature in the fuel, in the unlikely event of a loss of active cooling.

The reactor is continuously replenished with fresh or reusable fuel from the top, while used fuel is removed from the bottom of the reactor. After each pass through the reactor core, the fuel pebbles are measured to determine the amount of fissionable material left. If the pebble still contains a usable amount, it is returned to the top of the reactor for a further cycle.

Each cycle takes about six months, and each pebble passes through the reactor about six times, and lasts about three years before it is spent. This means that a reactor will use 12 total fuel loads in its 40-year design lifetime.

The extent to which the enriched uranium is consumed during the lifetime of a fuel pebble, is much greater in the PBMR than in con-ventional power reactors, states Slabber. There is, therefore, minimal fissionable material that could be extracted from spent PBMR fuel. This, coupled with the level of technology required to break down the barriers surrounding the spent fuel particles, protects the PBMR fuel against the possibility of nuclear proliferation, or other covert uses.

A 165-MW PMBR will generate around 32 t/y of spent pebbles, of which about 1 t will be uranium. The spent fuel storage consists of ten tanks, each of which can store up to 600 000 pebbles. After the 40-year life cycle of the fuel plant has ended, the spent fuel can be safely stored on site, for another 40 years, before being sent to a final repository.

Edited by: Laura Tyrer
© Reuse this Comment Guidelines (150 word limit)
 
 
 
 
 
 
 
 
Other Nuclear News
Russian State-owned nuclear group Rosatom has confirmed that it is in talks with Nigeria about the construction of nuclear power plants (NPPs) in that country, but has denied that any agreement has been signed. This follows a recent report in the Nigerian media that...
Today’s organisations execute projects within increasingly complex environments – particularly in the engineering sector. The ability to successfully execute these projects is what drives the realisation of successful projects and, ultimately, the achievement of...
Public opinion is an essential element in any nuclear programme. This was highlighted last month by World Nuclear Association chairperson Jean-Jacques Gautrot. "Public acceptance is essential to develop the environment in which nuclear development can take place," he...
More
 
 
Latest News
Two influential US senators, central to the so-called ‘chicken war’, have announced their intention to pursue amendments to the African Growth and Opportunity Act (Agoa) to secure greater access for US poultry into the SA market. “We believe passionately in Agoa’s...
The Independent Communications Authority of South Africa (Icasa) on Friday published the findings of a discussion document on South Africa’s television and radio local content environment. Icasa last year requested industry input as it reviewed and revamped...
Buying the catering unit of cash-strapped state airline South African Airways (SAA) could work for Bidvest Group, its chief executive said on Friday. SAA is considering selling some of its units including its inflight and airport lounge catering business, Air Chefs,...
More
 
 
Recent Research Reports
Steel 2015: A review of South Africa's steel sector (PDF Report)
Creamer Media’s Steel 2015 report provides an overview of the key developments in the global steel industry and particularly of South Africa’s steel sector over the past year, including details of production and consumption, as well as the country's primary carbon...
Projects in Progress 2015 - First Edition (PDF Report)
In fact, this edition of Creamer Media’s Projects in Progress 2015 supplement tracks developments taking place under the Renewable Energy Independent Power Producer Procurement Programme, which has had four bidding rounds. It appears to remain a shining light on the...
Electricity 2015: A review of South Africa's electricity sector (PDF Report)
Creamer Media’s Electricity 2015 report provides an overview of State-owned power utility Eskom and independent power producers, as well as electricity planning, transmission, distribution and the theft thereof, besides other issues.
Construction 2015: A review of South Africa’s construction sector (PDF Report)
Creamer Media’s Construction 2015 Report examines South Africa’s construction industry over the past 12 months. The report provides insight into the business environment; the key participants in the sector; local construction demand; geographic diversification;...
Liquid Fuels 2014 - A review of South Africa's Liquid Fuels sector (PDF Report)
Creamer Media’s Liquid Fuels 2014 Report examines these issues, focusing on the business environment, oil and gas exploration, the country’s feedstock supplies, the development of South Africa’s biofuels industry, fuel pricing, competition in the sector, the...
Water 2014: A review of South Africa's water sector (PDF Report)
Creamer Media’s Water 2014 report considers the aforementioned issues, not only in the South African context, but also in the African and global context, and examines the issues of water and sanitation, water quality and the demand for water, among others.
 
 
 
 
 
This Week's Magazine
Today’s organisations execute projects within increasingly complex environments – particularly in the engineering sector. The ability to successfully execute these projects is what drives the realisation of successful projects and, ultimately, the achievement of...
SMART DISTRIBUTION Providing funds to introduce smart grid technologies in the absence of a clearly defined strategy will not result in the desired outcome
South Africa’s distribution grid is a twentieth-century relic, which must be changed to serve the country’s modern electricity needs, says South African National Energy Development Institute (Sanedi) Smart Grid Programme manager Dr Minnesh Bipath. “What we are...
There is a disparity in government funding provided to integrated transport networks – bus rapid transit (BRT) networks ¬¬– and that given to conventional bus services, says Putco executive director Thys Heyns. “We have neglected and strangled conventional bus...
The Johannesburg Social Housing Company (Joshco) is building 502 rental housing units, valued at R200-million, in Dobsonville, Soweto, which are scheduled for completion in June 2016.
Automotive component manufacturer and distributor Metair is centralising its research and development (R&D) work in Turkey, in an attempt to bolster the company’s ability to produce affordable start/stop batteries. The new R&D centre is part of an expansion plan in...
 
 
 
 
 
 
 
 
 
Alert Close
Embed Code Close
content
Research Reports Close
Research Reports are a product of the
Research Channel Africa. Reports can be bought individually or you can gain full access to all reports as part of a Research Channel Africa subscription.
Find Out More Buy Report
 
 
Close
Engineering News
Completely Re-Engineered
Experience it now. Click here
*website to launch in a few weeks
Subscribe Now for $96 Close
Subscribe Now for $96