Publication: Magyar Közlöny
Issue: MK-2006-137 (Year: 2006, Number: 137)
Era: 2004-2010
Section: 
Paragraph Index: 311

4. collector system suitable for isotopic analysis. Explanatory note The items listed above either come into direct contact with the UF6 process gas or directly control the flow within the cascade. All surfaces which come into contact with the process gas are wholly made of, or lined with, UF6-resistant materials. For the purposes of the sections relating to gaseous diffusion items the materials resistant to corrosion by UF6 include stainless steel, aluminium, aluminium alloys, aluminium oxide, nickel or alloys containing 60% or more nickel and UF6-resistant fully fluorinated hydrocarbon polymers. 5.5. Especially designed or prepared systems, equipment and components for use in aerodynamic enrichment plants Introductory note In aerodynamic enrichment processes, a mixture of gaseous UF6 and light gas (hydrogen of helium) is compressed and then passed through separating elements wherein isotopic separation is accomplished by the generation of high centrifugal forces over a curved-wall geometry. Two processes of this type have been successfully developed: the separation nozzle process and the vortex tube process. For both processes the main components of a separation stage include cylindrical vessels housing the special separation elements (nozzles or vortex tubes), gas compressors and heat exchangers to remove the heat of compression. An aerodynamic plant requires a number of these stages, so that quantities can provide an important indication of end use. Since aerodynamic processes use UF6 all equipment, pipeline and instrumentation surfaces (that come in contact with the gas) must be made of materials that remain stable in contact with UF6. 2006/137. szám Explanatory note The items listed in this section either come into direct contact with the UF6 process gas or directly control the flow within the cascade. All surfaces which come into contact with the process gas are wholly made of or protected by UF6-resistant materials. For the purpose of the section relating to aerodynamic enrichments items, the materials resistant to corrosion by UF6 include copper, stainless steel, aluminium, aluminium alloys, nickel or alloys containing 60% or more nickel and UF6-resistant fully fluorinated hydrocarbon polymers. 5.5.1. Separation nozzles Especially designed or prepared separation nozzles and assemblies thereof. The separation nozzles consist of slit-shaped, curved channels having a radius of curvature less than 1 mm (typically 0,1 to 0,05 mm), resistant to corrosion by UF6 and having a knife-edge within the nozzle that separates the gas flowing through the nozzle into two fractions. 5.5.2. Vortex tubes Especially designed or prepared vortex tubes and assemblies thereof. The vortex tubes are cylindrical or tapered, made of or protected by materials resistant to corrosion by UF6, having a diameter of between 0,5 cm and 4 cm, a length to diameter ratio of 20:1 or less and with one or more tangential inlets. The tubes may be equipped with nozzle-type appendages at either or both ends. Explanatory note The feed gas enters the vortex tube tangentially at one end or through swirl vanes or at numerous tangential positions along the periphery of the tube. 5.5.3. Compressors and gas blowers Especially designed or prepared axial, centrifugal or positive displacement compressors or gas blowers made of or protected by materials resistant to corrosion by UF6 and with a suction volume capacity of 2 m3/min. or more of UF6/carrier gas (hydrogen or helium) mixture. Explanatory note These compressors and gas blowers typically have a pressure ratio between 1,2:1 and 6:1. 5.5.4. Rotary shaft seals Especially designed or prepared rotary shaft seals, with seal feed and seal exhaust connections, for sealing the shaft connecting the compressor rotor or the gas blower rotor with the driver motor so as to ensure a reliable seal against out-leakage of process gas or in-leakage of air or seal gas into the inner chamber of the compressor or gas blower which is filled with a UF6/carrier gas mixture. 5.5.5. Heat exchangers for gas cooling Especially designed or prepared heat exchangers made of or protected by materials resistant to corrosion by UF6. 5.5.6. Separation element housings Especially designed or prepared separation element housings, made of or protected by materials resistant to corrosion by UF6, for containing vortex tubes or separation nozzles. Explanatory note These housings may be cylindrical vessels greater than 300 mm in diameter and greater than 900 mm in length, or may be rectangular vessels of comparable dimensions, and may be designed for horizontal or vertical installation. 5.5.7. Feed systems/product and tails withdrawal systems Especially designed or prepared process systems or equipment for enrichment plants made of or protected by materials resistant to corrosion by UF6, including: (a) feed autoclaves, ovens, or systems used for passing UF6 to the enrichment process; (b) desublimers (or cold traps) used to remove UF6 from the enrichment process for subsequent transfer upon heating; (c) solidification or liquefaction stations used to remove UF6 from the enrichment process by compressing and converting UF6 to a liquid or solid form; (d) *product* or *tails* stations used for transferring UF6 into containers. 5.5.8. Header piping systems Especially designed or prepared header piping systems, made of or protected by materials resistant to corrosion by UF6 for handling UF6 within the aerodynamic cascades. This piping network is normally of the *double* header design with each stage or group of stages connected to each of the headers. 5.5.9. Vacuum systems and pumps (a) Especially designed or prepared vacuum systems having a suction capacity of 5 m3/min or more, consisting of vacuum manifolds, vacuum headers and vacuum pumps, and designed for service in UF6-bearing atmospheres. (b) Vacuum pumps especially designed or prepared for service in UF6-bearing atmospheres and made of or protected by materials resistant to corrosion by UF6. These pumps may use fluorocarbon seals and special working fluids. 5.5.10. Special shut-off and control valves Especially designed or prepared manual or automated shut-off and control bellows valves made of or protected by materials resistant to corrosion by UF6 with a diameter of 40 to 1500 mm for installation in main and auxiliary systems of aerodynamic enrichment plants. 5.5.11. UF6 mass spectrometers/ion sources 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:

Source: https://magyarkozlony.hu/hivatalos-lapok/b6608ce0ee5111440d921bbbc22c7b417c236810/dokumentumok/167d9c7f6b19ca1b6bf4028ed0980858645ecec4/letoltes