Nuclear Proliferation TechnologyTrends Analysis - International ...

PNNL -14480
The bottom bearing must support the weight of the rotor, efficiently supply a
“frictionless’ surface area, and have an extended lifetime. With a design lifetime of 10
years, a high rotational speed (1200 rpm or more), and the small bearing size, it is an
important and critical component.
Table 6 lists important components used in centrifuge enrichment, and associated
technical issues.
3.2.2.2 Changes/improvements in technology
Seven countries have successfully developed and utilized centrifuge technology over the
last fifty years. Two primary approaches have been used, a great many relatively low
enrichment sub-critical centrifuges or a lesser number of super-critical centrifuges that
pass at least the first centrifuge critical speed. A variety of improvements and
evolutionary changes have occurred in materials used, electronic speed control, bearing
design, and internal improvements.
1. Critical speeds
Two basic approaches are taken to overcome the critical speed issue. The Soviets, the
first to use centrifuge technology, selected the sub-critical approach. They used
aluminum alloys and built machines about 50 cm tall and 50 mm in diameter. The
original throughput was small, approximately 1 swu/yr or less. Accordingly, it took
many thousands of centrifuges to meet production requirements.
The second approach is to build ‘super-critical’ machines. Two approaches (sometimes
combined) are taken here. In the first approach, flexible joints, called bellows, are built
into the rotor, so it could bend freely with the dynamic forces and adopt new shapes as it
accelerated through each critical speed. In the second approach, new materials, primarily
carbon fiber, are used. These have a much higher tensile strength (almost twice that of
aluminum alloys) and can spin at much higher speeds.
2. Manufacturing processes
Modern computer numerically-controlled machine tools in specially constructed "clean
rooms” must be used. This ensures that the large quantity of high-precision parts needed
to produce components for high-speed centrifuges are of sufficient quality to ensure longterm
successful operation.
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