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INTRODUCTORY NOTE
The auxiliary systems, equipment and
components for a gas centrifuge enrichment plant are the systems of plant needed
to feed UF6 to the centrifuges, to link the individual centrifuges to each other
to form cascades (or stages) to allow for progressively higher enrichments and
to extract the 'product' and 'tails' UF6 fi'om
the centrifuges, together with the equipment required to drive the centrifuges
or to control the plant.
Normally UF6 is evaporated from the solid using heated autoclaves and is distributed in gaseous form to the centrifuges by way of cascade header pipework. The 'product' and 'tails' UF6 gaseous streams flowing from the centrifuges are also passed by way of cascade header pipework to cold traps (operating at about 203 K (- 70 °C)) where they are condensed prior to onward transfer into suitable containers for transportation or storage. Because an enrichment plant consists of many thousands of centrifuges arranged in cascades there are many kilometers of cascade header pipework, incorporating thousands of welds with a substantial amount of repetition of layout. The equipment, components and piping systems are fabricated to very high vacuum and cleanliness standards.
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Especially designed or prepared process
systems including:
Feed autoclaves (or stations), used for passing UF6 to the centrifuge cascades at up to 100 KPa (15 psi) and at a rate of 1 kg/h or more; Desublimers (or cold traps) used to remove UF6 from the cascades at up to 3 KPa (0.5 psi) pressure. The desublimers are capable of being chilled to 203 K (- 70 °C) and heated to 343 K (70 °C); 'Product' and 'Tails' stations used for trapping UF6 into containers. This plant, equipment and pipework is wholly made of or lined with UF6-resistant materials (see EXPLANATORY NOTE to this section) and is fabricated to very high vacuum and cleanliness standards.
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Especially designed or prepared piping systems and header systems for handling UF6 within the centrifuge cascades. The piping network is normally of the 'triple' header system with each centrifuge connected to each of the headers. There is thus a substantial amount of repetition in its form. It is wholly made of UF6-resistant materials (see EXPLANATORY NOTE to this section) and is fabricated to very high vacuum and cleanliness standards.
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Especially designed or prepared
magnetic or quadrupole mass spectrometers capable of taking 'on-line' samples of
feed, product or tails, from UF6 gas streams and having all of the following
characteristics:
1. Unit
resolution for atomic mass unit greater than 320;
2. Ion
sources constructed of or line with nichrome or monel or nickel plated;
3. Electron
bombardment ionization sources;
4. Having a collector system suitable for isotopic analysis.
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Frequency changers (also known as converters or invertors) especially designed or prepared to supply motor stators as defined under 5.1.2.(d), or parts, components and sub-assemblies of such frequency changers having all of the following characteristics