Highly enriched uranium
Of highly enriched uranium (engl. Highly enriched uranium , HEU ) is when in a uranium containing material, the content of the easily cleavable isotope 235 U exceeds a certain percentage. According to the definition used in the European Community, highly enriched uranium contains at least 20% 235 U; this definition can also be found in an IAEA glossary and other sources. Another IAEA glossary gives 80%.
In natural uranium, 235 U occurs only with a frequency of 0.7%. For use in light water reactors , the uranium must be enriched to a 3–3.5% 235 U content ( reactor grade ). The uranium enrichment can be done by various methods. The degree of enrichment achieved basically only depends on the number of cascades (similar process steps) that the material passes through one after the other. HEU can therefore be produced with all enrichment processes. The various processes differ, however, clearly in how easily and inconspicuously the respective plant can be converted from the production of large quantities with low enrichment (for reactor power plants) to small amounts with high enrichment (for weapons).
In principle, uranium enriched to 20% could already be used in nuclear weapons , but such an explosive device would require large quantities of uranium and would be very inefficient. Therefore, one speaks of weapon-grade only from an enrichment level of 85% . The Little Boy bomb, which was dropped on Hiroshima on August 6, 1945, contained just under 60 kg of 93% enriched HEU. The fuel element in the Heinz Maier-Leibnitz research neutron source (Research Reactor Munich II), which went into operation in 2004, also contains 93% HEU, so that its commissioning was initially very controversial.
As part of the Atoms for Peace project initiated by US President Dwight D. Eisenhower , the US, which initially had a monopoly on uranium enrichment in the western world, exported it to states that had committed to using it exclusively for research purposes and for energy generation . To do this, the degree of enrichment had to be reduced again by mixing the HEU (degree of enrichment 93%) with natural uranium.
At the end of 2009, Germany reported an inventory totaling 0.92 t of highly enriched uranium to the IAEA . Of this, 0.19 t was in the fuel of research reactors, 0.73 t of irradiated, highly enriched uranium was in storage and 0.03 t was stored elsewhere.
Table of HEU stocks by country
The table reflects the status as of December 31, 2016 and is largely based on data transmitted to the IAEA.
| Country | Stock of HEU |
|---|---|
| Russia | 695 t |
| United States | 604 t |
| France | 31 t |
| United Kingdom | 21.2 t |
| China | 16 t |
| Pakistan | 3 t |
| India | 0.8 t |
| Israel | 0.3 t |
| Other | 15 t |
Individual evidence
- ↑ Wolf-Georg Schärf: European nuclear law. de Gruyter, Berlin 2008, ISBN 978-3-89949449-5 , p. 135.
- ↑ IAEA Safety Glossary
- ↑ Report 2013 of the International Panel on Fissile Materials
- ^ Glossary of the Federation of American Scientists
- ↑ Definition in the INISML thesaurus
- ↑ Valentin Crastan : Electrical energy supply. Volume 2: Energy and electricity industry, power plant technology, alternative electricity generation, dynamics, regulation and stability, operational planning and management. Springer, Berlin et al. 2004, ISBN 3-540-41326-X , p. 246; ISBN 3-540-41326-X .
- ^ Leonhard Müller: Handbook of the electricity industry. Technical, economic and legal basics. 2nd Edition. Springer, Berlin et al. 2001, ISBN 3-540-67637-6 , p. 219.
- ↑ Roland Kollert: The politics of latent proliferation. Military use of “peaceful” nuclear technology in Western Europe. DUV - Deutscher Universitäts-Verlag 1994, ISBN 3-8244-4156-X , p. 521ff.
- ↑ Germany declared its 2009 plutonium and HEU holdings - International Panel on Fissile Materials Blog
- ↑ International Panel on Fissile Materials - Fissile material stocks