Uranium Development 25 Years

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This cover is postmarked on 08-10-1977 at Wes-Rand. It marks twenty five years of South African uranium development, with the accompanying text explaining the physics of uranium fission and noting the country's development of a new uranium enrichment method that led to the pilot plant built at Valindaba. At the time of issue, government had approved a full-scale commercial enrichment plant in principle, though decisions on its capacity were still pending, with full production expected only by 1986.

Description of the Cachet

The cachet is a bold, minimal atomic diagram, an orange rectangular nucleus at the centre orbited by curving electron paths and small solid dots representing electrons, all set against the plain cream envelope. "Uranium development 25 years / Uraanontwikkeling 25 jaar" runs beneath the diagram in plain bilingual type. A small numbered diamond marker sits in the top left corner. The single stamp shows a stylised atom in orbit beside a mine headgear structure against a starfield background, linking the abstract science of uranium fission to its physical extraction from South African mines. The Wes-Rand postmark uses a cluster of black and white circles arranged to suggest an atomic nucleus, echoing the cachet's own diagram. This is a purely conceptual, diagram based design, well suited to the technical and industrial subject matter of a uranium enrichment milestone rather than any single event or place.

Information Card

URAAN Die element uraan, waarvan die naam van die planeet Uranus se naam afgelei is, is die swaarste van die 92 elemente wat vry in die natuur voorkom. Dit het 'n atoommassa van nagenoeg 238 teenoor bv. die 1 van waterstof, 16 van suurstof en 197 van goud. Natuurlike uraan het 14 isotope wat almal in 'n mindere of meerdere mate radioaktief is, dit wil sê hulle straal energie in die vorm van alfa-, beta- en/of gammastrale uit. Die grootste energiepotensiaal van uraan lê daarin dat een van sy onstabiele isotope, nl. U 235, maklik kloofbaar is. Indien 'n termiese neutron deur die kern gevang word, word die kern in twee gekloof en hierdie kernreaksie stel 'n groot hoeveelheid energie vry wat uitgedruk word as die beroemde vergelyking van Einstein, E = mc², waar m die massa materiaal is wat gedurende klowing vernietig word en c die snelheid van lig is. Wanneer een kilogram U 235 gekloof word, lewer dit nagenoeg dieselfde hoeveelheid energie wat uit die verbranding van ongeveer 3 000 ton steenkool verkry word. Voornoemde isotoop van uraan maak slegs 'n geringe persentasie van natuurlike uraan uit (0,71 %) en aangesien die chemiese eienskappe van al die isotope dieselfde is en daar slegs 'n klein massaverskil tussen hulle is, is skeiding van die isotope 'n besonder moeilike proses. Die lae gehalte van Suid-Afrikaanse uraanerts het die toepassing van hoogs gespesialiseerde tegnieke vereis, en as gevolg daarvan het hierdie land 'n wêreldleier met betrekking tot die bewerking van sodanige ertse geword. Die belangrikste prestasie was egter die ontwikkeling van 'n nuwe metode om uraan te verryk, wat gelei het tot die multimiljoenrand-aanvooraanleg wat by Valindaba gebou is. Die Regering het reeds die oprigting van 'n volskaalse kommersiële uraanverrykingsaanleg in beginsel goedgekeur, maar daar sal eers in 1978 oor die vermoë en ander besonderhede besluit word. Die aanleg sal waarskynlik in 1986 in volle produksie wees. P.T. **English:** URANIUM The element uranium, the name of which is derived from the name of the planet Uranus, is the heaviest of the 92 elements that occur free in nature. It has an atomic mass of about 238 compared for example with the 1 of hydrogen, 16 of oxygen and 197 of gold. Natural uranium has 14 isotopes, all of which are radioactive to a greater or lesser degree, that is to say, they radiate energy in the form of alpha, beta and/or gamma rays. The greatest energy potential of uranium lies in the fact that one of its unstable isotopes, namely U 235, is readily fissionable. If a thermal neutron is captured by the nucleus, the latter is split in two and this nuclear reaction releases a large amount of energy that is expressed as Einstein's famous equation, i.e. E = mc², where m is the mass of the material destroyed during fission and c is the velocity of light. When one kilogram of U 235 is split it produces approximately the same amount of energy obtained from burning about 3 000 tons of coal. The above-mentioned isotope of uranium accounts for only a very small percentage (0,71 %) of natural uranium and because the chemical properties of all the isotopes are the same and as there is only a small difference in mass between them, isolation of the isotopes is an exceptionally difficult process. The low grade of South African uranium ore has required the application of highly specialized techniques, with the result that this country has become a world leader with regard to the processing of such ores. The most significant achievement, however, has been the development of a new method of enriching uranium, which has led to the multi-million rand pilot plant being built at Valindaba. The Government has already approved in principle the erection of a full-scale commercial uranium-enrichment plant, but decisions about its capacity and other details will only be taken in 1978. The plant will probably be in full production by 1986.

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