Nuclear Related Items Subject to Regulatory Control - Specific Regulation

1- Nuclear Reactors and Especially Designed or Prepared Equipment and Components Therefor

NOTE

Various types of nuclear reactors may be characterized by the moderator used (e.g., graphite, heavy water, light water, none), the spectrum of neutrons therein (e.g., thermal, fast), the type of coolant used (e.g., water, liquid metal, molten salt, gas), or by their function or type (e.g., power reactors, research reactors, test reactors). It is intended that all of these types of nuclear reactors are within scope of this entry and all of its sub-entries where applicable. This entry does not control fusion reactors.

1-1 Complete nuclear reactors

Nuclear reactors capable of operation so as to maintain a controlled self-sustaining fission chain reaction.

NOTE

A nuclear reactor basically includes the items within or attached directly to the reactor vessel, the equipment which controls the level of power in the core, and the components which normally contain or come in direct contact with or control the primary coolant of the reactor core. 

According to the procedures of the Guidelines are listed in paragraphs 1.2. to 1.11, the Commission reserves to itself the right to apply the procedures of the Guidelines to other items within the functionally defined boundary.

1-2 Nuclear reactor vessels

Metal vessels, or major shop-fabricated parts therefor, especially designed or prepared to contain the core of a nuclear reactor as defined in paragraph 1.1. above, as well as relevant reactor internals as defined in paragraph 1.8. below.

NOTE

Item 1.2. covers nuclear reactor vessels regardless of pressure rating and includes reactor pressure vessels and calandrias. The reactor vessel head is covered by item 1.2. as a major shop-fabricated part of a reactor vessel.

1-3 Nuclear reactor fuel charging and discharging machines

Manipulative equipment especially designed or prepared for inserting or removing fuel in a nuclear reactor as defined in paragraph 1.1. above.

NOTE

The items noted above are capable of on-load operation or at employing technically sophisticated positioning or alignment features to allow complex off-load fueling operations such as those in which direct viewing of or access to the fuel is not normally available.

1-4 Nuclear reactor control rods and equipment

Especially designed or prepared rods, support, or suspension structures therefor, rod drive mechanisms or rod guide tubes to control the fission process in a nuclear reactor as defined in paragraph 1.1. above.

1-5 Nuclear reactor pressure tubes

Tubes which are especially designed or prepared to contain both fuel elements and the primary coolant in a reactor as defined in paragraph 1.1. above.

NOTE

Pressure tubes are parts of fuel channels designed to operate at elevated pressure, sometimes in excess of 5 MPa.

1-6 Nuclear fuel cladding

Zirconium metal tubes or zirconium alloy tubes (or assemblies of tubes) especially designed or prepared for use as fuel cladding in a reactor as defined in paragraph 1.1. above, and in quantities exceeding 10 kg.

NOTE:

For zirconium pressure tubes see 1.5. For calandria tubes see 1.8.

Zirconium metal tubes or zirconium alloy tubes for use in a nuclear reactor consist of zirconium in which the relation of hafnium to zirconium is typically less than 1:500 parts by weight.

1-7 Primary coolant pumps or circulators

Pumps or circulators especially designed or prepared for circulating the primary coolant for nuclear reactors as defined in paragraph 1.1. above.

NOTE

Especially designed or prepared pumps or circulators include pumps for water-cooled reactors, circulators for gas-cooled reactors, and electromagnetic and mechanical pumps for liquid-metal-cooled reactors. This equipment may include pumps with elaborate sealed or multi-sealed systems to prevent leakage of primary coolant, canned-driven pumps, and pumps with inertial mass systems. This definition encompasses pumps certified to Section III, Division I, Subsection NB (Class 1 components) of the American Society of Mechanical Engineers (ASME) Code, or equivalent standards.

1-8 Nuclear reactor internals

Nuclear reactor internals especially designed or prepared for use in a nuclear reactor as defined in paragraph 1.1. above. This includes, for example, support columns for the core, fuel channels, calandria tubes, thermal shields, baffles, core grid plates, and diffuser plates.

NOTE

Nuclear reactor internals are major structures within a reactor vessel which have one or more functions such as supporting the core, maintaining fuel alignment, directing primary coolant flow, providing radiation shields for the reactor vessel, and guiding in-core instrumentation.

1-9 Heat exchangers

A. Steam generators especially designed or prepared for the primary or intermediate coolant circuit of a nuclear reactor as defined in paragraph 1.1. above.

B. Other heat exchangers especially designed or prepared for use in the primary coolant circuit of a nuclear reactor as defined in paragraph 1.1. above.

NOTE

Steam generators are especially designed or prepared to transfer the heat generated in the reactor to the feed water for steam generation. In the case of a fast reactor for which an intermediate coolant loop is also present, the steam generator is in the intermediate circuit.

In a gas-cooled reactor, a heat exchanger may be utilized to transfer heat to a secondary gas loop that drives a gas turbine.

The scope of control for this entry does not include heat exchangers for the supporting systems of the reactor (e.g., the emergency cooling system or the decay heat cooling system).

1-10 Neutron detectors

Especially designed or prepared neutron detectors for determining neutron flux levels within the core of a reactor as defined in paragraph 1.1. above.

NOTE

The scope of this entry encompasses in-core and ex-core detectors which measure flux levels in a wide range, typically from 104 neutrons per cm2 per second or more. Ex-core refers to those instruments outside the core of a reactor as defined in paragraph 1.1. above, but located within the biological shielding.

1-11 External thermal shields

External thermal shields especially designed or prepared for use in a nuclear reactor as defined in paragraph 1.1. for reduction of heat loss and also for containment vessel protection.

NOTE

External thermal shields are major structures placed over the reactor vessel which reduce heat loss from the reactor and reduce temperature within the containment vessel.

2- Non-Nuclear Materials for Reactors

2-1 Deuterium and heavy water

Deuterium, heavy water (deuterium oxide) and any other deuterium compound in which the ratio of deuterium to hydrogen atoms exceeds 1:5000 for use in a nuclear reactor as defined in paragraph 1.1. above in quantities exceeding 200 kg of deuterium atoms for any one recipient country within a period of one calendar year (1 Jan – 31 Dec).

2-2 Nuclear grade graphite

Graphite having a purity level better than 5 ppm (parts per million) boron equivalent and with a density greater than 1.50 g/cm3 for use in a nuclear reactor as defined in paragraph 1.1. above, in quantities exceeding 1 kg.

NOTE:

For the purpose of export and import control, the Commission will determine whether or not the exports and imports of graphite meeting the above specifications are for nuclear reactor use. Graphite having a purity level better than 5 ppm (parts per million) boron equivalent and with a density greater than 1.50 g/cm3 not for use in a nuclear reactor as defined in paragraph 1.1. above is not covered by this paragraph.

Boron Equivalent (BE) may be determined experimentally or is calculated as the sum of BEz for impurities (excluding BEcarbon since carbon is not considered an impurity) including boron, where:

BEz ppm = CF x concentration of element Z (in ppm);

CF is the conversion factor: (σz x AB) divided by (σB x Az);

σB and σz are the thermal neutron capture cross sections (in barns) for naturally occurring boron and element Z respectively; and

AB and Az are the atomic masses of naturally occurring boron and element Z respectively. 

3- Plants for the Reprocessing of Irradiated Fuel Elements, and Equipment Especially Designed or Prepared Therefor

Reprocessing irradiated nuclear fuel separates plutonium and uranium from intensely radioactive fission products and other transuranic elements. Different technical processes can accomplish this separation. However, over the years Purex has become the most commonly used and accepted process. Purex involves the dissolution of irradiated nuclear fuel in nitric acid, followed by separation of the uranium, plutonium, and fission products by solvent extraction using a mixture of tributyl phosphate in an organic diluent.

Purex facilities have process functions similar to each other, including irradiated fuel element decladding and/or chopping, fuel dissolution, solvent extraction, and process liquor storage. There may also be equipment for thermal denitration of uranium nitrate, conversion of plutonium nitrate to oxide or metal, and treatment of fission product waste liquor to a form suitable for long term storage or disposal. However, the specific type and configuration of the equipment performing these functions may differ between Purex facilities for several reasons, including the type and quantity of irradiated nuclear fuel to be reprocessed and the intended disposition of the recovered materials, and the safety and maintenance philosophy incorporated into the design of the facility.

A plant for the reprocessing of irradiated fuel elements includes the equipment and components which normally come in direct contact with and directly control the irradiated fuel and the major nuclear material and fission product processing streams.

These processes, including the complete systems for plutonium conversion and plutonium metal production, may be identified by the measures taken to avoid criticality (e.g., by geometry), radiation exposure (e.g., by shielding), and toxicity hazards (e.g., by containment).

Items of equipment that are considered to fall within the meaning of the phrase “and equipment especially designed or prepared” for the reprocessing of irradiated fuel elements include: 

3-1 Irradiated fuel element de cladding equipment and chopping machines

Remotely operated equipment especially designed or prepared for use in a reprocessing plant as identified above and intended to expose or prepare the irradiated nuclear material in fuel assemblies, bundles, or rods for processing.

NOTE:

This equipment cuts, chops, shears, or otherwise breaches the cladding of the fuel to expose the irradiated nuclear material for processing or prepares the fuel for processing. Especially designed cutting shears are most commonly employed, although advanced equipment, such as lasers, peeling machines, or other techniques, may be used. Decladding involves removing the cladding of the irradiated nuclear fuel prior to its dissolution.

3-2 Dissolvers

Dissolver vessels or dissolvers employing mechanical devices especially designed or prepared for use in a reprocessing plant as identified above, intended for dissolution of irradiated nuclear fuel and which are capable of withstanding hot, highly corrosive liquid, and which can be remotely loaded, operated, and maintained.

NOTE:

Dissolvers normally receive the solid, irradiated nuclear fuel. Nuclear fuels with cladding made of material including zirconium, stainless steel, or alloys of such materials must be decladded and/or sheared or chopped prior to being charged to the dissolver to allow the acid to reach the fuel matrix. The irradiated nuclear fuel is typically dissolved in strong mineral acids, such as nitric acid, and any undissolved cladding removed. While certain design features, such as small diameter, annular, or slab tanks, may be used to ensure criticality safety, they are not a necessity. Administrative controls, such as small batch size or low fissile material content, may be used instead. Dissolver vessels and dissolvers employing mechanical devices are normally fabricated of material such as low carbon stainless steel, titanium or zirconium, or other high-quality materials. Dissolvers may include systems for the removal of cladding or cladding waste and systems for the control and treatment of radioactive off-gases. These dissolvers may have features for remote placement since they are normally loaded, operated, and maintained behind thick shielding.

3-3 Solvent extractors and solvent extraction equipment

Especially designed or prepared solvent extractors (such as packed or pulse columns, mixer settlers or centrifugal contactors) for use in a plant for the reprocessing of irradiated fuel. Solvent extractors must be resistant to the corrosive effect of nitric acid. Solvent extractors are normally fabricated to extremely high standards (including special welding and inspection and quality assurance and quality control techniques) out of low carbon stainless steels, titanium, zirconium, or other high quality materials. 

NOTE:

Solvent extractors both receive the solution of irradiated fuel from the dissolvers and the organic solution which separates the uranium, plutonium, and fission products. Solvent extraction equipment is normally designed to meet strict operating parameters, such as long operating lifetimes with no maintenance requirements or adaptability to easy replacement, simplicity of operation and control, and flexibility for variations in process conditions.

3-4 Chemical holding or storage vessels

Especially designed or prepared holding or storage vessels for use in a plant for the reprocessing of irradiated fuel. The holding or storage vessels must be resistant to the corrosive effect of nitric acid. The holding or storage vessels are normally fabricated of materials such as low carbon stainless steels, titanium or zirconium, or other high quality materials. Holding or storage vessels may be designed for remote operation and maintenance and may have the following features for control of nuclear criticality:

1. Walls or internal structures with a boron equivalent of at least 2%;

2. A maximum diameter of 175 mm for cylindrical vessels; or

3. A maximum width of 75 mm for either a slab or annular vessel.

NOTE:

Three main process liquor streams result from the solvent extraction step. Holding or storage vessels are used in the further processing of all three streams, as follows:

A. The pure uranium nitrate solution is concentrated by evaporation and passed to a denitration process where it is converted to uranium oxide. This oxide is re-used in the nuclear fuel cycle.

B. The intensely radioactive fission products solution is normally concentrated by evaporation and stored as a liquor concentrate. This concentrate may be subsequently evaporated and converted to a form suitable for storage or disposal.

C. The pure plutonium nitrate solution is concentrated and stored pending its transfer to further process steps. In particular, holding or storage vessels for plutonium solutions are designed to avoid criticality problems resulting from changes in concentration and form of this stream.

3-5 Neutron measurement systems for process control

Neutron measurement systems especially designed or prepared for integration and use with automated process control systems in a plant for the reprocessing of irradiated fuel elements.

NOTE:

These systems involve the capability of active and passive neutron measurement and discrimination in order to determine the fissile material quantity and composition. The complete system is composed of a neutron generator, a neutron detector, amplifiers, and signal processing electronics. 

The scope of this entry does not include neutron detection and measurement instruments that are designed for nuclear material accountancy and safeguarding, or any other application not related to integration and use with automated process control systems in a plant for the reprocessing of irradiated fuel elements.

 

4- Plants for the Fabrication of Nuclear Reactor Fuel Elements, and Equipment Especially Designed or Prepared Therefor

NOTE:

Nuclear fuel elements are manufactured from one or more of the source or special fissionable materials mentioned in MATERIAL AND EQUIPMENT of this annex. For oxide fuels, the most common type of fuel, equipment for pressing pellets, sintering, grinding, and grading will be present. Mixed oxide fuels are handled in glove boxes (or equivalent containment) until they are sealed in the cladding. In all cases, the fuel is hermetically sealed inside a suitable cladding which is designed to be the primary envelope encasing the fuel so as to provide suitable performance and safety during reactor operation. Also, in all cases, precise control of processes, procedures and equipment to extremely high standards is necessary in order to ensure predictable and safe fuel performance.

Items of equipment that are considered to fall within the meaning of the phrase “and equipment especially designed or prepared” for the fabrication of fuel elements include equipment which:

A. normally comes in direct contact with, or directly processes, or controls, the production flow of nuclear material;

B. seals the nuclear material within the cladding;

C. checks the integrity of the cladding or the seal;

D. checks the finish treatment of the sealed fuel; or

E. is used for assembling reactor fuel elements.

Such equipment or systems of equipment may include, for example:

1. Fully automatic pellet inspection stations especially designed or prepared for checking final dimensions and surface defects of the fuel pellets;

2. Automatic welding machines especially designed or prepared for welding end caps onto the fuel pins (or rods);

3. Automatic test and inspection stations especially designed or prepared for checking the integrity of completed fuel pins (or rods);

4. Systems especially designed or prepared to manufacture nuclear fuel cladding.

Item 3 typically includes equipment for:

A. X-ray examination of pin (or rod) end cap welds;

B. Helium leak detection from pressurized pins (or rods);

C. Gamma-ray scanning of the pins (or rods) to check for correct loading of the fuel pellets inside.

5- Plants for the Separation of Isotopes of Natural Uranium, Depleted Uranium or Special Fissionable Material and Equipment, other than Analytical Instruments, Especially Designed or Prepared Therefor

NOTE:

Plants, equipment, and technology for the separation of uranium isotopes have, in many instances, a close relationship to plants, equipment and technology for isotope separation of “other elements”. In particular cases, the controls under section 5 also apply to plants and equipment that are intended for isotope separation of “other elements”. These controls of plants and equipment for isotope separation of “other elements” are complementary to controls on plants and equipment especially designed or prepared for the processing, use or production of special fissionable material covered by the Nuclear Related Items List. These complementary section 5 controls for uses involving “other elements” do not apply to the electromagnetic isotope separation process, which is addressed under Annex C.

Processes for which the controls in section 5 equally apply whether the intended use is uranium isotope separation or isotope separation of “other elements” are: gas centrifuge, gaseous diffusion, the plasma separation process, and aerodynamic processes.

For some processes, the relationship to uranium isotope separation depends on the element being separated. These processes are: laser-based processes (e.g., molecular laser isotope separation and atomic vapor laser isotope separation), chemical exchange, and ion exchange. For this purpose, export and import regulations will be applied based on these processes on a case-by-case basis to apply section 5 controls for uses involving “other elements” accordingly.

Items of equipment that are considered to fall within the meaning of the phrase “equipment, other than analytical instruments, especially designed or prepared” for the separation of isotopes of uranium include:

5-1 Gas centrifuges and assemblies and components especially designed or prepared for use in gas centrifuges 

NOTE:

The gas centrifuge normally consists of a thin-walled cylinder of between 75 mm and 650 mm diameter contained in a vacuum environment and spun at high peripheral speed of the order of 300 m/s or more with its central axis vertical. In order to achieve high speed the materials of construction for the rotating components have to be of a high strength to density ratio and the rotor assembly, and hence its individual components, have to be manufactured to very close tolerances in order to minimize the unbalance. In contrast to other centrifuges, the gas centrifuge for uranium enrichment is characterized by having within the rotor chamber a rotating disc-shaped baffle (or baffles) and a stationary tube arrangement for feeding and extracting the uranium hexafluoride (UF6) gas and featuring at least three separate channels, of which two are connected to scoops extending from the rotor axis towards the periphery of the rotor chamber. Also contained within the vacuum environment are a number of critical items which do not rotate and, which although they are especially designed, are not difficult to fabricate nor are they fabricated out of unique materials. A centrifuge facility however requires a large number of these components, so that quantities can provide an important indication of end use.

5-1-1 Rotating components

A. Complete rotor assemblies:

Thin-walled cylinders, or a number of interconnected thin-walled cylinders, manufactured from one or more of the high strength to density ratio materials described in the NOTE to this section. If interconnected, the cylinders are joined together by flexible bellows or rings as described in section 5.1.1.(c) following. The rotor is fitted with an internal baffle (or baffles) and end caps, as described in section 5.1.1.(d) and (e) following, if in final form. However, the complete assembly may be delivered only partly assembled.

B. Rotor tubes:

Especially designed or prepared thin-walled cylinders with thickness of 12 mm or less, a diameter of between 75 mm and 650 mm, and manufactured from one or more of the high strength to density ratio materials described in the NOTE to this section.

C. Rings or Bellows:

Components especially designed or prepared to give localized support to the rotor tube or to join together a number of rotor tubes. The bellows is a short cylinder of wall thickness 3 mm or less, a diameter of between 75 mm and 650 mm, having a convolute, and manufactured from one of the high strength to density ratio materials described in the NOTE to this section.

D. Baffles:

Disc-shaped components of between 75 mm and 650 mm diameter especially designed or prepared to be mounted inside the centrifuge rotor tube, in order to isolate the take-off chamber from the main separation chamber and, in some cases, to assist the UF6 gas circulation within the main separation chamber of the rotor tube and manufactured from one of the high strength to density ratio materials described in the NOTE to this section.

E. Top caps/Bottom caps:

Disc-shaped components of between 75 mm and 650 mm diameter especially designed or prepared to fit to the ends of the rotor tube, and so contain the UF6 within the rotor tube, and in some cases to support, retain or contain as an integrated part an element of the upper bearing (top cap) or to carry the rotating elements of the motor and lower bearing (bottom cap), and manufactured from one of the high strength to density ratio materials described in the NOTE to this section.

NOTE:

The materials used for centrifuge rotating components include the following:

A. Maraging steel capable of an ultimate tensile strength of 1.95 GPa or more;

B. Aluminum alloys capable of an ultimate tensile strength of 0.46 GPa or more;

C. Filamentary materials suitable for use in composite structures and having a specific modulus of 3.18x106 m or greater and a specific ultimate tensile strength of 7.62x104 m or greater.

(‘Specific Modulus’ is the Young’s Modulus in N/m2 divided by the specific weight in N/m3; ‘Specific Ultimate Tensile Strength’ is the ultimate tensile strength in N/m2 divided by the specific weight in N/m3).

5-1-2 Static components

A. Magnetic suspension bearings:

1. Especially designed or prepared bearing assemblies consisting of an annular magnet suspended within a housing containing a damping medium. The housing will be manufactured from a UF6-resistant material (see NOTE to section 5.2.). The magnet couples with a pole piece or a second magnet fitted to the top cap described in section 5.1.1.(e). The magnet may be ring- shaped with a relation between outer and inner diameter smaller or equal to 1.6:1. The magnet may be in a form having an initial permeability of 0.15 H/m or more, or a remanence of 98.5% or more, or an energy product of greater than 80 kJ/m3. In addition to the usual material properties, it is a prerequisite that the deviation of the magnetic axes from the geometrical axes is limited to very small tolerances (lower than 0.1 mm) or that homogeneity of the material of the magnet is specially called for.

2. Active magnetic bearings especially designed or prepared for use in gas centrifuges.

NOTE:

These bearings usually have the following characteristics:

- Designed to keep centered a rotor spinning at 600 Hz or more; and

- Associated to a reliable electrical power supply and/or to an uninterruptible power supply (UPS) unit in order to function for more than one hour.

B. Bearings/Dampers:

Especially designed or prepared bearings comprising a pivot/cup assembly mounted on a damper. The pivot is normally a hardened steel shaft with a hemisphere at one end with a means of attachment to the bottom cap described in section 5.1.1.(e) at the other. The shaft may however have a hydrodynamic bearing attached. The cup is pellet-shaped with a hemispherical indentation in one surface. These components are often supplied separately to the damper.

C. Molecular pumps:

Especially designed or prepared cylinders having internally machined or extruded helical grooves and internally machined bores. Typical dimensions are as follows: 75 mm to 650 mm internal diameter, 10 mm or more wall thickness, with the length equal to or greater than the diameter. The grooves are typically rectangular in cross-section and 2 mm or more in depth.

D. Motor stators:

Especially designed or prepared ring-shaped stators for high speed multiphase AC hysteresis (or reluctance) motors for synchronous operation within a vacuum at a frequency of 600 Hz or greater and a power of 40 VA or greater. The stators may consist of multi-phase windings on a laminated low loss iron core comprised of thin layers typically 2 mm thick or less.

E. Centrifuge housing/recipients:

Components especially designed or prepared to contain the rotor tube assembly of a gas centrifuge. The housing consists of a rigid cylinder of wall thickness up to 30 mm with precision machined ends to locate the bearings and with one or more flanges for mounting. The machined ends are parallel to each other and perpendicular to the cylinder’s longitudinal axis to within 0.05° or less. The housing may also be a honeycomb type structure to accommodate several rotor assemblies.

F. Scoops:

Especially designed or prepared tubes for the extraction of UF6 gas from within the rotor tube by a Pitot tube action (that is, with an aperture facing into the circumferential gas flow within the rotor tube, for example by bending the end of a radially disposed tube) and capable of being fixed to the central gas extraction system.

5-2 Especially designed or prepared auxiliary systems, equipment and components for gas centrifuge enrichment plants

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 from 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 gas 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.

Some of the items listed below either come into direct contact with the UF6 process gas or directly control the centrifuges and the passage of the gas from centrifuge to centrifuge and cascade to cascade. Materials resistant to corrosion by UF6 include copper, copper alloys, stainless steel, aluminum, aluminum oxide, aluminum alloys, nickel or alloys containing 60% by weight or more nickel and fluorinated hydrocarbon polymers.

5-2-1 Feed systems/product and tails withdrawal system 

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, cold traps or pumps 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.

5-2-2 Machine header piping systems

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 or protected by UF6-resistant materials (see NOTE to this section) and is fabricated to very high vacuum and cleanliness standards.

5-2-3 Special shut-off and control valves

A. Shut-off valves especially designed or prepared to act on the feed, product, or tails UF6 gas streams of an individual gas centrifuge.

B. Bellows-sealed valves, manual or automated, shut-off or control, made of or protected by materials resistant to corrosion by UF6, with an inside diameter of 10 to 160 mm, especially designed or prepared for use in main or auxiliary systems of gas centrifuge enrichment plants.

NOTE:

Typical especially designed or prepared valves include bellow-sealed valves, fast acting closure-types, fast acting valves, and others.

5-2-4 UF6 mass spectrometers/Ion sources

Especially designed or prepared mass spectrometers capable of taking on-line samples from UF6 gas streams and having all of the following characteristics:

- Capable of measuring ions of 320 atomic mass units or greater and having a resolution of better than 1 part in 320;

- Ion sources constructed of or protected by nickel, nickel-copper alloys with a nickel content of 60% by weight or more, or nickel-chrome alloys;

- Electron bombardment ionization sources; and

- Having a collector system suitable for isotopic analysis.

5-2-5 Frequency changers

Frequency changers (also known as converters or inverters) 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 both of the following characteristics:

- A multiphase frequency output of 600 Hz or greater; and

- High stability (with frequency control better than 0.2%).

5-3 Especially designed or prepared assemblies and components for use in gaseous diffusion enrichment

NOTE:

In the gaseous diffusion method of uranium isotope separation, the main technological assembly is a special porous gaseous diffusion barrier, heat exchanger for cooling the gas (which is heated by the process of compression), seal valves and control valves, and pipelines. Inasmuch as gaseous diffusion technology uses 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. A gaseous diffusion facility requires a number of these assemblies, so that quantities can provide an important indication of end use.

5-3-1 Gaseous diffusion barriers and barrier materials

A. Especially designed or prepared thin, porous filters, with a pore size of 10 - 100 nm, a thickness of 5 mm or less, and for tubular forms, a diameter of 25 mm or less, made of metallic, polymer or ceramic materials resistant to corrosion by UF6 (see NOTE to section 5-4).

B. Especially prepared compounds or powders for the manufacture of such filters. Such compounds and powders include nickel or alloys containing 60% by weight or more nickel, aluminum oxide, or UF6-resistant fully fluorinated hydrocarbon polymers having a purity of 99.9% by weight or more, a particle size less than 10 µm, and a high degree of particle size uniformity, which are especially prepared for the manufacture of gaseous diffusion barriers.

5-3-2 Diffuser housings 

Especially designed or prepared hermetically sealed vessels for containing the gaseous diffusion barrier, made of or protected by UF6-resistant materials (see NOTE to section 5-4).

5-3-3 Compressors and gas blowers

Especially designed or prepared compressors or gas blowers with a suction volume capacity of 1 m3 per minute or more of UF6, with a discharge pressure of up to 500 kPa, and designed for long-term operation in the UF6 environment, as well as separate assemblies of such compressors and gas blowers. These compressors and gas blowers have a pressure ratio of 10:1 or less and are made of, or protected by, materials resistant to UF6 (see NOTE to section 5-4.).

5-3-4 Rotary shaft seals

Especially designed or prepared vacuum seals, with seal feed and seal exhaust connections, for sealing the shaft connecting the compressor or the gas blower rotor with the driver motor so as to ensure a reliable seal against in-leaking of air into the inner chamber of the compressor or gas blower which is filled with UF6. Such seals are normally designed for a buffer gas in-leakage rate of less than 1000 cm3 per minute.

5-3-5 Heat exchangers for cooling UF6

Especially designed or prepared heat exchangers made of or protected by UF6-resistant materials (see NOTE to section 5.4) and intended for a leakage pressure change rate of less than 10 Pa/h under a pressure difference of 100 kPa.

5-4 Especially designed or prepared auxiliary systems, equipment and components for use in gaseous diffusion enrichment

NOTE:

The auxiliary systems, equipment and components for gaseous diffusion enrichment plants are the systems of plant needed to feed UF6 to the gaseous diffusion assembly, to link the individual assemblies to each other to form cascades (or stages) to allow for progressively higher enrichments and to extract the ‘product’ and ‘tails’ UF6 from the diffusion cascades. Because of the high inertial properties of diffusion cascades, any interruption in their operation, and especially their shut-down, leads to serious consequences. Therefore, a strict and constant maintenance of vacuum in all technological systems, automatic protection from accidents, and precise automated regulation of the gas flow is of importance in a gaseous diffusion plant. All this leads to a need to equip the plant with a large number of special measuring, regulating and controlling systems.

Normally UF6 is evaporated from cylinders placed within autoclaves and is distribute d in gaseous form to the entry point by way of cascade header pipework. The ‘product’ and ‘tails’ UF6 gas streams flowing from exit points are passed by way of cascade header pipework to either cold traps or to compression stations where the UF6 gas is liquefied prior to onward transfer into suitable containers for transportation or storage. Because a gaseous diffusion enrichment plant consists of a large number of gaseous diffusion assemblies arranged in cascades, there are many kilometers of cascade header pipework, incorporating thousands of welds with substantial amounts of repetition of layout. The equipment, components and piping systems are fabricated to very high vacuum and cleanliness standards.

The items listed below either come into direct contact with the UF6 process gas or directly control the flow within the cascade. Materials resistant to corrosion by UF6 include copper, copper alloys, stainless steel, aluminum, aluminum oxide, aluminum alloys, nickel or alloys containing 60% by weight or more nickel and fluorinated hydrocarbon polymers.

5-4-1 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, cold traps or pumps 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. 

5-4-2 Header piping systems

Especially designed or prepared piping systems and header systems for handling UF6 within the gaseous diffusion cascades.

NOTE:

This piping network is normally of the ‘double’ header system with each cell connected to each of the headers.

5-4-3 Vacuum systems

A. Especially designed or prepared vacuum manifolds, vacuum headers and vacuum pumps having a suction capacity of 5 m3/min or more.

B. Vacuum pumps especially designed for service in UF6-bearing atmospheres made of, or protected by, materials resistant to corrosion by UF6 (see NOTE to this section). These pumps may be either rotary or positive, may have displacement and fluorocarbon seals, and may have special working fluids present.

5-4-4 Special shut-off and control valves

Especially designed or prepared bellows-sealed valves, manual or automated, shut-off or control, made of or protected by materials resistant to corrosion by UF6, for installation in main and auxiliary systems of gaseous diffusion enrichment plants.

5-4-5 UF6 mass spectrometers/Ion sources

Especially designed or prepared mass spectrometers capable of taking on-line samples from UF6 gas streams and having all of the following:

- Capable of measuring ions of 320 atomic mass units or greater and having a resolution of better than 1 part in 320;

- Ion sources constructed of or protected by nickel, nickel-copper alloys with a nickel content of 60% by weight or more, or nickel-chrome alloys;

- Electron bombardment ionization sources; and 

- Having a collector system suitable for isotopic analysis.

5-5 Especially designed or prepared systems, equipment, and components for use in aerodynamic enrichment plants

NOTE:

In aerodynamic enrichment processes, a mixture of gaseous UF6 and light gas (hydrogen or 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 or protected by materials that remain stable in contact with UF6.

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 purposes of the section relating to aerodynamic enrichment items, the materials resistant to corrosion by UF6 include copper, copper alloys, stainless steel, aluminum, aluminum oxide, aluminum alloys, nickel or alloys containing 60% by weight or more nickel and 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, 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 tube s

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, and with one or more tangential inlets. The tubes may be equipped with nozzle- type appendages at either or both ends.

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 compressors or gas blowers made of or protected by materials resistant to corrosion by the UF6/carrier gas (hydrogen or helium) mixture.

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.

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 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 bellows-sealed valves, manual or automated, shut-off or control, made of or protected by materials resistant to corrosion by UF6, with a diameter of 40 mm or greater, for installation in main and auxiliary systems of aerodynamic enrichment plants.

5-5-11 UF6 mass spectrometers/ion  sources

Especially designed or prepared mass spectrometers capable of taking on-line samples from UF6 gas streams and having all of the following:

- Capable of measuring ions of 320 atomic mass units or greater and having a resolution of better than 1 part in 320;

- Ion sources constructed of or protected by nickel, nickel-copper alloys with a nickel content of 60% by weight or more, or nickel-chrome alloys;

- Electron bombardment ionization sources; and

- Having a collector system suitable for isotopic analysis.

5-5-12 UF6/carrier gas separation systems

Especially designed or prepared process systems for separating UF6 from carrier gas (hydrogen or helium).

NOTE:

These systems are designed to reduce the UF6 content in the carrier gas to 1 ppm or less and may incorporate equipment such as:

- Cryogenic heat exchangers and cryoseparators capable of temperatures of 153 K (-120°C) or less.

- Cryogenic refrigeration units capable of temperatures of 153 K (-120°C) or less.

- Separation nozzle or vortex tube units for the separation of UF6 from carrier gas.

- UF6 cold traps capable of freezing out UF6. 

5-6 Especially designed or prepared systems, equipment, and components for use in chemical exchange or ion exchange enrichment plants

NOTE:

The slight difference in mass between the isotopes of uranium causes small changes in chemical reaction equilibria that can be used as a basis for separation of the isotopes. Two processes have been successfully developed: liquid-liquid chemical exchange and solid-liquid ion exchange.

In the liquid-liquid chemical exchange process, immiscible liquid phases (aqueous and organic) are counter currently contacted to give the cascading effect of thousands of separation stages. The aqueous phase consists of uranium chloride in hydrochloric acid solution; the organic phase consists of an extractant containing uranium chloride in an organic solvent. The contactors employed in the separation cascade can be liquid-liquid exchange columns (such as pulsed columns with sieve plates) or liquid centrifugal contactors. Chemical conversions (oxidation and reduction) are required at both ends of the separation cascade in order to provide for the reflux requirements at each end. A major design concern is to avoid contamination of the process streams with certain metal ions. Plastic, plastic-lined (including use of fluorocarbon polymers) and/or glass- lined columns and piping are therefore used.

In the solid-liquid ion-exchange process, enrichment is accomplished by uranium adsorption/desorption on a special, very fast-acting, ion-exchange resin or adsorbent. A solution of uranium in hydrochloric acid and other chemical agents is passed through cylindrical enrichment columns containing packed beds of the adsorbent. For a continuous process, a reflux system is necessary to release the uranium from the adsorbent back into the liquid flow so that ‘product’ and ‘tails’ can be collected. This is accomplished with the use of suitable reduction/oxidation chemical agents that are fully regenerated in separate external circuits and that may be partially regenerated within the isotopic separation columns themselves. The presence of hot concentrated hydrochloric acid solutions in the process requires that the equipment be made of or protected by special corrosion-resistant materials.

5-6-1 Liquid-liquid exchange columns (Chemical exchange)

Countercurrent liquid-liquid exchange columns having mechanical power input, especially designed or prepared for uranium enrichment using the chemical exchange process. For corrosion resistance to concentrated hydrochloric acid solutions, these columns and their internals are normally made of or protected by suitable plastic materials (such as fluorinated hydrocarbon polymers) or glass. The stage residence time of the columns is normally designed to be 30 s or less.

5-6-2 Liquid-liquid centrifugal contactors (Chemical exchange )

Liquid-liquid centrifugal contactors especially designed or prepared for uranium enrichment using the chemical exchange process. Such contactors use rotation to achieve dispersion of the organic and aqueous streams and then centrifugal force to separate the phases. For corrosion resistance to concentrated hydrochloric acid solutions, the contactors are normally made of or protected by suitable plastic materials (such as fluorinated hydrocarbon polymers) or glass. The stage residence time of the centrifugal contactors is normally designed to be 30 s or less.

5-6-3 Uranium re duction systems and equipment  (Chemical exchange )

A. Especially designed or prepared electrochemical reduction cells to reduce uranium from one valence State to another for uranium enrichment using the chemical exchange process. The cell materials in contact with process solutions must be corrosion resistant to concentrated hydrochloric acid solutions.

NOTE:

The cell cathodic compartment must be designed to prevent re-oxidation of uranium to its higher valence State. To keep the uranium in the cathodic compartment, the cell may have an impervious diaphragm membrane constructed of special cation exchange material. The cathode consists of a suitable solid conductor such as graphite.

B. Especially designed or prepared systems at the product end of the cascade for taking the U+4 out of the organic stream, adjusting the acid concentration and feeding to the electrochemical reduction cells.

NOTE:

These systems consist of solvent extraction equipment for stripping the U+4 from the organic stream into an aqueous solution, evaporation and/or other equipment to accomplish solution pH adjustment and control, and pumps or other transfer devices for feeding to the electrochemical reduction cells. A major design concern is to avoid contamination of the aqueous stream with certain metal ions. Consequently, for those parts in contact with the process stream, the system is constructed of equipment made of or protected by suitable materials (such as glass, fluorocarbon polymers, polyphenol sulphate, polyether sulphone, and resin-impregnated graphite).

5-6-4 Feed preparation systems (Chemical exchange )

Especially designed or prepared systems for producing high-purity uranium chloride feed solutions for chemical exchange uranium isotope separation plants.

NOTE:

These systems consist of dissolution, solvent extraction and/or ion exchange equipment for purification and electrolytic cells for reducing the uranium U+6 or U+4 to U+3. These systems produce uranium chloride solutions having only a few parts per million of metallic impurities such as chromium, iron, vanadium, molybdenum and other bivalent or higher multi-valent cations. Materials of construction for portions of the system processing high-purity U+3 include glass, fluorinated hydrocarbon polymers, polyphenol sulphate or polyether sulphone plastic-lined and resin-impregnated graphite. 

5-6-5 Uranium oxidation systems (Chemical exchange)

Especially designed or prepared systems for oxidation of U+3 to U+4 for return to the uranium isotope separation cascade in the chemical exchange enrichment process.

NOTE:

These systems may incorporate equipment such as:

A. Equipment for contacting chlorine and oxygen with the aqueous effluent from the isotope separation equipment and extracting the resultant U+4 into the stripped organic stream returning from the product end of the cascade.

B. Equipment that separates water from hydrochloric acid so that the water and the concentrated hydrochloric acid may be reintroduced to the process at the proper locations.

5-6-6 Fast-reacting ion exchange resins/adsorbents (Ion exchange)

Fast-reacting ion exchange resins or adsorbents especially designed or prepared for uranium enrichment using the ion exchange process, including porous macroreticular resins, and/or pellicular structures in which the active chemical exchange groups are limited to a coating on the surface of an inactive porous support structure, and other composite structures in any suitable form including particles or fibers. These ion exchange resins/adsorbents have diameters of 0.2 mm or less and must be chemically resistant to concentrated hydrochloric acid solutions as well as physically strong enough so as not to degrade in the exchange columns. The resins/adsorbents are especially designed to achieve very fast uranium isotope exchange kinetics (exchange rate half-time of less than 10 s) and are capable of operating at a temperature in the range of 373 K (100°C) to 473 K (200°C).

5-6-7 Ion exchange columns (Ion exchange)

Cylindrical columns greater than 1000 mm in diameter for containing and supporting packed beds of ion exchange resin/adsorbent, especially designed or prepared for uranium enrichment using the ion exchange process. These columns are made of or protected by materials (such as titanium or fluorocarbon plastics) resistant to corrosion by concentrated hydrochloric acid solutions and are capable of operating at a temperature in the range of 373 K (100°C) to 473 K (200°C) and pressures above 0.7 MPa.

5-6-8 Ion exchange reflux systems (Ion exchange)

A. Especially designed or prepared chemical or electrochemical reduction systems for regeneration of the chemical reducing agent used in ion exchange uranium enrichment cascades.

B. Especially designed or prepared chemical or electrochemical oxidation systems for regeneration of the chemical oxidizing agent (agents) used in ion exchange uranium enrichment cascades.

NOTE:

The ion exchange enrichment process may use, for example, trivalent titanium (Ti+3) as a reducing cation in which case the reduction system would regenerate Ti+3 by reducing Ti+4.

The process may use, for example, trivalent iron (Fe+3) as an oxidant in which case the oxidation system would regenerate Fe+3 by oxidizing Fe+2.

5-7 Especially designed or prepared systems, equipment, and components for use in laser-based enrichment plants

NOTE:

Present systems for enrichment processes using lasers fall into two categories: those in which the process medium is atomic uranium vapor and those in which the process medium is the vapor of a uranium compound, sometimes mixed with another gas or gases. Common nomenclature for such processes include:

First category - atomic vapor laser isotope separation.

Second category - molecular laser isotope separation, including chemical reaction by isotope selective laser activation.

The systems, equipment and components for laser enrichment plants include:

A. Devices to feed uranium-metal vapor (for selective photo-ionization) or devices to feed the vapor of a uranium compound (for selective photo-dissociation or selective excitation/activation).

B. Devices to collect enriched and depleted uranium metal as ‘product’ and ‘tails’ in the first category, and devices to collect enriched and depleted uranium compounds as ‘product’ and ‘tails’ in the second category.

C. Process laser systems to selectively excite the uranium-235 (235U) species.

D. Feed preparation and product conversion equipment. The complexity of the spectroscopy of uranium atoms and compounds may require incorporation of any of a number of available laser and laser optics technologies.

Many of the items listed in this section come into direct contact with uranium metal vapor or liquid or with process gas consisting of UF6 or a mixture of UF6 and other gases. All surfaces that come into direct contact with the uranium or UF6 are wholly made of or protected by corrosion-resistant materials. For the purposes of the section relating to laser-based enrichment items, the materials resistant to corrosion by the vapor or liquid of uranium metal or uranium alloys include yttria-coated graphite and tantalum; and the materials resistant to corrosion by UF6 include copper, copper alloys, stainless steel, aluminum, aluminum oxide, aluminum alloys, nickel or alloys containing 60% by weight or more nickel and fluorinated hydrocarbon polymers.

5-7-1 Uranium vaporization systems (atomic vapor based methods)

Especially designed or prepared uranium metal vaporization systems for use in laser enrichment.

NOTE:

These systems may contain electron beam guns and are designed to achieve a delivered power (1 kW or greater) on the target sufficient to generate uranium metal vapor at a rate required for the laser enrichment function.

5-7-2 Liquid or vapor uranium metal handling systems and components (atomic vapor based methods)

Especially designed or prepared systems for handling molten uranium, molten uranium alloys or uranium metal vapor for use in laser enrichment, or especially designed or prepared components therefor.

NOTE:

The liquid uranium metal handling systems may consist of crucibles and cooling equipment for the crucibles. The crucibles and other parts of this system that come into contact with molten uranium, molten uranium alloys or uranium metal vapor are made of or protected by materials of suitable corrosion and heat resistance. Suitable materials may include tantalum, yttria-coated graphite, graphite coated with other rare earth oxides (see Annex C) or mixtures thereof.

5-7-3 Uranium metal ‘product’ and ‘tails’ collector assemblies (atomic vapor based methods)

Especially designed or prepared ‘product’ and ‘tails’ collector assemblies for collecting uranium metal in liquid or solid form.

NOTE:

Components for these assemblies are made of or protected by materials resistant to the heat and corrosion of uranium metal vapor or liquid (such as yttria-coated graphite or tantalum) and may include pipes, valves, fittings, gutters, feed-throughs, heat exchangers and collector plates for magnetic, electrostatic or other separation methods.

5-7-4 Separator module housings (atomic vapor based methods)

Especially designed or prepared cylindrical or rectangular vessels for containing the uranium metal vapor source, the electron beam gun, and the ‘product’ and ‘tails’ collectors.

NOTE:

These housings have multiplicity of ports for electrical and water feed-throughs, laser beam windows, vacuum pump connections and instrumentation diagnostics and monitoring. They have provisions for opening and closing to allow refurbishment of internal components.

5-7-5 Supersonic expansion nozzles (molecular based methods)

Especially designed or prepared supersonic expansion nozzles for cooling mixtures of UF6 and carrier gas to 150 K (-123°C) or less and which are corrosion resistant to UF6.

5-7-6 ‘Product’ or ‘tails’ collectors (molecular based methods)

Especially designed or prepared components or devices for collecting uranium product material or uranium tails material following illumination with laser light.

NOTE:

In one example of molecular laser isotope separation, the product collectors serve to collect enriched uranium pentafluoride (UF5) solid material. The product collectors may consist of filter, impact, or cyclone-type collectors, or combinations thereof, and must be corrosion resistant to the UF5/ UF6 environment.

5-7-7 UF6/carrier gas compressors (molecular based methods)

Especially designed or prepared compressors for UF6/carrier gas mixtures, designed for long term operation in a UF6 environment. The components of these compressors that come into contact with process gas are made of or protected by materials resistant to corrosion by UF6.

5-7-8 Rotary shaft seals (molecular based methods)

Especially designed or prepared rotary shaft seals, with seal feed and seal exhaust connections, for sealing the shaft connecting the compressor 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 which is filled with a UF6/carrier gas mixture.

5-7-9 Fluorination systems (molecular based methods)

Especially designed or prepared systems for fluorinating UF5 (solid) to UF6 (gas). 

NOTE:

These systems are designed to fluorinate the collected UF5 powder to UF6 for subsequent collection in product containers or for transfer as feed for additional enrichment. In one approach, the fluorination reaction may be accomplished within the isotope separation system to react and recover directly off the ‘product’ collectors. In another approach, the UF5 powder may be removed/transferred from the ‘product’ collectors into a suitable reaction vessel (e.g., fluidized-bed reactor, screw reactor or flame tower) for fluorination. In both approaches, equipment for storage and transfer of fluorine (or other suitable fluorinating agents) and for collection and transfer of UF6 are used.

5-7-10 UF6 mass spectrometers/ion sources (molecular based methods)

Especially designed or prepared mass spectrometers capable of taking on-line samples from UF6 gas streams and having all of the following:

- Capable of measuring ions of 320 atomic mass units or greater and having a resolution of better than 1 part in 320;

- Ion sources constructed of or protected by nickel, nickel-copper alloys with a nickel content of 60% by weight or more, or nickel-chrome alloys;

- Electron bombardment ionization sources; and 

- Having a collector system suitable for isotopic analysis.

5-7-11 Feed systems/product and tails withdrawal systems (molecular based methods)

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.

5-7-12 UF6/carrier gas separation systems (molecular based methods)

Especially designed or prepared process systems for separating UF6 from carrier gas. 

NOTE:

These systems may incorporate equipment such as:

A. Cryogenic heat exchangers or cryoseparators capable of temperatures of 153 K (-120°C) or less.

B. Cryogenic refrigeration units capable of temperatures of 153 K (-120°C) or less.

C. UF6 cold traps capable of freezing out UF6.

The carrier gas may be nitrogen, argon, or other gas. 

5-7-13 Laser systems

Lasers or laser systems especially designed or prepared for the separation of uranium isotopes.

NOTE:

The lasers and laser components of importance in laser-based enrichment processes include those identified in (Annex C) as amended. The laser system typically contains both optical and electronic components for the management of the laser beam (or beams) and the transmission to the isotope separation chamber. The laser system for atomic vapor based methods usually consists of tunable dye lasers pumped by another type of laser (e.g., copper vapor lasers or certain solid-State lasers). The laser system for molecular based methods may consist of carbon dioxide lasers or excimer lasers and a multi-pass optical cell. Lasers or laser systems for both methods require spectrum frequency stabilization for operation over extended periods of time.

5-8 Especially designed or prepared systems, equipment, and components for use in plasma separation enrichment plants

NOTE:

In the plasma separation process, a plasma of uranium ions passes through an electric field tuned to the 235U ion resonance frequency so that they preferentially absorb energy and increase the diameter of their corkscrew-like orbits. Ions with a large-diameter path are trapped to produce a product enriched in 235U. The plasma, which is made by ionizing uranium vapor, is contained in a vacuum chamber with a high-strength magnetic field produced by a superconducting magnet. The main technological systems of the process include the uranium plasma generation system, the separator module with superconducting magnet in (Annex C), and metal removal systems for the collection of ‘product’ and ‘tails’.

5-8-1 Microwave power source s and antennae

Especially designed or prepared microwave power sources and antennae for producing or accelerating ions and having the following characteristics: greater than 30 GHz frequency and greater than 50 kW mean power output for ion production.

5-8-2 Ion excitation coils

Especially designed or prepared radio frequency ion excitation coils for frequencies of more than 100 kHz and capable of handling more than 40 kW mean power.

5-8-3 Uranium plasma generation systems

Especially designed or prepared systems for the generation of uranium plasma for use in plasma separation plants.

5-8-4 Uranium metal ‘product’ and ‘tails’ collector assemblies

Especially designed or prepared ‘product’ and ‘tails’ collector assemblies for uranium metal in solid form. These collector assemblies are made of or protected by materials resistant to the heat and corrosion of uranium metal vapor, such as yttria-coated graphite or tantalum.

5-8-5 Separator module housings

Cylindrical vessels especially designed or prepared for use in plasma separation enrichment plants for containing the uranium plasma source, radio-frequency drive coil and the ‘product’ and ‘tails’ collectors.

NOTE:

These housings have a multiplicity of ports for electrical feed-throughs, diffusion pump connections and instrumentation diagnostics and monitoring. They have provisions for opening and closing to allow for refurbishment of internal components and are constructed of a suitable non-magnetic material such as stainless steel.

5-9 Especially designed or prepared systems, equipment, and components for use in electromagnetic enrichment plants

NOTE:

In the electromagnetic process, uranium metal ions produced by ionization of a salt feed material (typically uranium tetrachloride (UCl4)) are accelerated and passed through a magnetic field that has the effect of causing the ions of different isotopes to follow different paths. The major components of an electromagnetic isotope separator include: a magnetic field for ion-beam diversion/separation of the isotopes, an ion source with its acceleration system, and a collection system for the separated ions. Auxiliary systems for the process include the magnet power supply system, the ion source high-voltage power supply system, the vacuum system, and extensive chemical handling systems for recovery of product and cleaning/recycling of components.

5-9-1 Electromagnetic isotope separators

Electromagnetic isotope separators especially designed or prepared for the separation of uranium isotopes, and equipment and components therefor, including:

A. Ion sources:

Especially designed or prepared single or multiple uranium ion sources consisting of a vapor source, ionizer, and beam accelerator, constructed of suitable materials such as graphite, stainless steel, or copper, and capable of providing a total ion beam current of 50 mA or greater.

B. Ion collectors:

Collector plates consisting of two or more slits and pockets especially designed or prepared for collection of enriched and depleted uranium ion beams and constructed of suitable materials such as graphite or stainless steel.

C. Vacuum housings:

Especially designed or prepared vacuum housings for uranium electromagnetic separators, constructed of suitable non-magnetic materials such as stainless steel and designed for operation at pressures of 0.1 Pa or lower.

NOTE:

The housings are specially designed to contain the ion sources, collector plates and water-cooled liners and have provision for diffusion pump connections and opening and closing for removal and reinstallation of these components.

D. Magnet pole pieces:

Especially designed or prepared magnet pole pieces having a diameter greater than 2 m and used to maintain a constant magnetic field within an electromagnetic isotope separator and to transfer the magnetic field between adjoining separators.

5-9-2 High voltage power supplies

Especially designed or prepared high-voltage power supplies for ion sources, having both of the following characteristics:

- Capable of continuous operation, output voltage of 20,000 V or greater, output current of 1 A or greater; and 

- Voltage regulation of better than 0.01% over a time period of 8 h.

5-9-3 Magnet power supplies

Especially designed or prepared high-power, direct current magnet power supplies having both of the following characteristics:

- Capable of continuously producing a current output of 500 A or greater at a voltage of 100 V or greater; and

- Current or voltage regulation better than 0.01% over a time period of 8 h. 

 

6- Plants for the Production or Concentration of Heavy Water, Deuterium and Deuterium Compounds and Equipment Especially Designed or Prepared Therefor

NOTE:

Heavy water can be produced by a variety of processes. However, the two processes that have proven to be commercially viable are the water-hydrogen sulfide exchange process (GS process) and the ammonia-hydrogen exchange process.

The GS process is based upon the exchange of hydrogen and deuterium between water and hydrogen sulfide within a series of towers which are operated with the top section cold and the bottom section hot. Water flows down the towers while the hydrogen sulfide gas circulates from the bottom to the top of the towers. A series of perforated trays are used to promote mixing between the gas and the water. Deuterium migrates to the water at low temperatures and to the hydrogen sulfide at high temperatures. Gas or water, enriched in deuterium, is removed from the first stage towers at the junction of the hot and cold sections and the process is repeated in subsequent stage towers. The product of the last stage, water enriched up to 30% by weight in deuterium, is sent to a distillation unit to produce reactor grade heavy water; i.e., 99.75% by weight deuterium oxide (D2O).

The ammonia-hydrogen exchange process can extract deuterium from synthesis gas through contact with liquid ammonia (NH3) in the presence of a catalyst. The synthesis gas is fed into exchange towers and to an ammonia converter. Inside the towers the gas flows from the bottom to the top while the liquid NH3 flows from the top to the bottom. The deuterium is stripped from the hydrogen in the synthesis gas and concentrated in the NH3. The NH3 then flows into an ammonia cracker at the bottom of the tower while the gas flows into an ammonia converter at the top. Further enrichment takes place in subsequent stages and reactor grade heavy water is produced through final distillation. The synthesis gas feed can be provided by an ammonia plant that, in turn, can be constructed in association with a heavy water ammonia-hydrogen exchange plant. The ammonia-hydrogen exchange process can also use ordinary water as a feed source of deuterium.

Many of the key equipment items for heavy water production plants using GS or the ammonia-hydrogen exchange processes are common to several segments of the chemical and petroleum industries. This is particularly so for small plants using the GS process. The GS and ammonia- hydrogen processes require the handling of large quantities of flammable, corrosive and toxic fluids at elevated pressures. Accordingly, in establishing the design and operating standards for plants and equipment using these processes, careful attention to the materials selection and specifications is required to ensure long service life with high safety and reliability factors. The choice of scale is primarily a function of economics and need. 

Finally, it should be noted that, in both the GS and the ammonia-hydrogen exchange processes, items of equipment which individually are not especially designed or prepared for heavy water production can be assembled into systems which are especially designed or prepared for producing heavy water. The catalyst production system used in the ammonia-hydrogen exchange process and water distillation systems used for the final concentration of heavy water to reactor-grade in either process are examples of such systems.

 The items of equipment which are especially designed or prepared for the production of heavy water utilizing either the water-hydrogen sulfide exchange process or the ammonia-hydrogen exchange process include the following: 

6-1 Water-hydrogen sulphide exchange towers

Exchange towers with diameters of 1.5 m or greater and capable of operating at pressures greater than or equal to 2 MPa, especially designed or prepared for heavy water production utilizing the water-hydrogen sulfide exchange process.

6-2 Blowers and compressors

Single stage, low head (i.e., 0.2 MPa) centrifugal blowers or compressors for hydrogen- sulfide gas circulation (i.e., gas containing more than 70% by weight hydrogen sulfide, H2S) especially designed or prepared for heavy water production utilizing the water-hydrogen sulfide exchange process. These blowers or compressors have a throughput capacity greater than or equal to 56 m3/s while operating at pressures greater than or equal to 1.8 MPa suction and have seals designed for wet H2S service.

6-3 Ammonia-hydrogen exchange towers

Ammonia-hydrogen exchange towers greater than or equal to 35 m in height with diameters of 1.5 m to 2.5 m capable of operating at pressures greater than 15 MPa especially designed or prepared for heavy water production utilizing the ammonia- hydrogen exchange process. These towers also have at least one flanged, axial opening of the same diameter as the cylindrical part through which the tower internals can be inserted or withdrawn.

6-4 Tower internals and stage sumps

Tower internals and stage pumps especially designed or prepared for towers for heavy water production utilizing the ammonia-hydrogen exchange process. Tower interna ls include especially designed stage contactors which promote intimate gas/liquid contact. Stage pumps include especially designed submersible pumps for circulation of liquid NH3 within a contacting stage internal to the stage towers.

6-5 NH3 crackers

NH3 crackers with operating pressures greater than or equal to 3 MPa especially designed or prepared for heavy water production utilizing the ammonia-hydrogen exchange process.

6-6 Infrared absorption analyzers

Infrared absorption analyzers capable of on-line hydrogen/deuterium ratio analysis where deuterium concentrations are equal to or greater than 90% by weight.

6-7 Catalytic burners

Catalytic burners for the conversion of enriched deuterium gas into heavy water especially designed or prepared for heavy water production utilizing the ammonia-hydrogen exchange process.

6-8 Complete heavy water upgrade systems or columns therefor

Complete heavy water upgrade systems, or columns therefor, especially designed or prepared for the upgrade of heavy water to reactor-grade deuterium concentration.

NOTE:

These systems, which usually employ water distillation to separate heavy water from light water, are especially designed or prepared to produce reactor-grade heavy water (i.e., typically 99.75% by weight D2O) from heavy water feedstock of lesser concentration.

6-9 NH3 synthesis converters or synthesis units

NH3 synthesis converters or synthesis units especially designed or prepared for heavy water production utilizing the ammonia-hydrogen exchange process.

NOTE:

These converters or units take synthesis gas (nitrogen and hydrogen) from an NH3/hydrogen high-pressure exchange column (or columns), and the synthesized NH3 is returned to the exchange column (or columns).

 

7- Plants for The Conversion of Uranium and Plutonium for Use in The Fabrication of Fuel Elements and The Separation of Uranium Isotopes as Defined in Sections 4 and 5 Respectively, and Equipment Especially Designed or Prepared Therefor

7-1 Plants for the conversion of uranium and equipment especially designed or prepared therefor

NOTE:

Uranium conversion plants and systems may perform one or more transformations from one uranium chemical species to another, including: conversion of uranium ore concentrates to uranium trioxide (UO3), conversion of UO3 to uranium dioxide (UO2), conversion of uranium oxides to uranium tetrafluoride (UF4), UF6, or UCl4, conversion of UF4 to UF6, conversion of UF6 to UF4, conversion of UF4 to uranium metal, and conversion of uranium fluorides to UO2. Many of the key equipment items for uranium conversion plants are common to several segments of the chemical process industry. For example, the types of equipment employed in these processes may include: furnaces, rotary kilns, fluidized bed reactors, flame tower reactors, liquid centrifuges, distillation columns and liquid-liquid extraction columns. most would be prepared according to the requirements and specifications of the customer. In some instances, special design and construction considerations are required to address the corrosive properties of some of the chemicals handled (hydrogen fluoride (HF), fluorine (F2), chlorine trifluoride (ClF3), and uranium fluorides) as well as nuclear criticality concerns. Finally, it should be noted that, in all of the uranium conversion processes, items of equipment which individually are not especially designed or prepared for uranium conversion can be assembled into systems which are especially designed or prepared for use in uranium conversion.

7-1-1 Especially designed or prepared systems for the conversion of uranium ore concentrates to UO3

NOTE:

Conversion of uranium ore concentrates to UO3 can be performed by first dissolving the ore in nitric acid and extracting purified uranyl nitrate (UO2(NO3)2)using a solvent such as tributyl phosphate (TBP). Next, the uranyl nitrate is converted to UO3 either by concentration and denitration or by neutralization with gaseous NH3 to produce ammonium diuranate with subsequent filtering, drying, and calcining.

7-1-2 Especially designed or prepared systems for the conversion of UO3 to UF6

NOTE:

Conversion of UO3 to UF6 can be performed directly by fluorination. The process requires a source of F2 or ClF3.

7-1-3 Especially designed or prepared systems for the conversion of UO3 to UO2

NOTE:

Conversion of UO3 to UO2 can be performed through reduction of UO3 with cracked gaseous NH3 or hydrogen.

7-1-4 Especially designed or prepared systems for the conversion of UO2 to UF4

NOTE:

Conversion of UO2 to UF4 can be performed by reacting UO2 with gaseous HF at 573-773 K (300-500°C).

7-1-5 Especially designed or prepared systems for the conversion of UF4 to UF6

NOTE:

Conversion of UF4 to UF6 is performed by exothermic reaction with fluorine in a tower reactor. UF6 is condensed from the hot effluent gases by passing the effluent stream through a cold trap cooled to 263 K (-10°C). The process requires a source of gaseous F2.

7-1-6 Especially designed or prepared systems for the conversion of UF4 to uranium metal

NOTE:

Conversion of UF4 to uranium metal is performed by reduction with magnesium (large batches) or calcium (small batches). The reaction is carried out at temperatures above the melting point of uranium (1403 K (1130°C)).

7-1-7 Especially designed or prepared systems for the conversion of UF6 to UO2

NOTE:

Conversion of UF6 to UO2 can be performed by one of three processes. In the first, UF6 is reduced and hydrolyzed to UO2 using hydrogen and steam. In the second, UF6 is hydrolyzed by solution in water, NH3 is added to precipitate ammonium diuranate, and the diuranate is reduced to UO2 with hydrogen at 1093 K (820°C). In the third process, gaseous UF6, CO2, and NH3 are combined in water, precipitating ammonium uranyl carbonate. The ammonium uranyl carbonate is combined with steam and hydrogen at 773-873 K (500-600°C) to yield UO2. UF6 to UO2 conversion is often performed as the first stage of a fuel fabrication plant.

7-1-8 Especially designed or prepared systems for the conversion of UF6 to UF4

NOTE:

Conversion of UF6 to UF4 is performed by reduction with hydrogen.

7-1-9 Especially designed or prepared systems for the conversion of UO2 to UCl4

NOTE:

Conversion of UO2 to UCl4 can be performed by one of two processes. In the first, UO2 is reacted with carbon tetrachloride (CCl4) at approximately 673 K (400°C).

 In the second, UO2 is reacted at approximately 973 K (700°C) in the presence of carbon black (CAS 1333-86-4), carbon monoxide, and chlorine to yield UCl4.

7-2 Plants for the conversion of plutonium and equipment especially designed or prepared therefor

NOTE:

Plutonium conversion plants and systems perform one or more transformations from one plutonium chemical species to another, including: conversion of plutonium nitrate (PuN) to plutonium dioxide (PuO2), conversion of PuO2 to plutonium tetrafluoride (PuF4), and conversion of PuF4 to plutonium metal. Plutonium conversion plants are usually associated with reprocessing facilities, but may also be associated with plutonium fuel fabrication facilities. Many of the key equipment items for plutonium conversion plants are common to several segments of the chemical process industry. For example, the types of equipment employed in these processes may include furnaces, rotary kilns, fluidized bed reactors, flame tower reactors, liquid centrifuges, distillation columns and liquid-liquid extraction columns. Hot cells, glove boxes and remote manipulators may also be required. most would be prepared according to the requirements and specifications of the customer. Particular care in designing for the special radiological, toxicity and criticality hazards associated with plutonium is essential. In some instances, special design and construction considerations are required to address the corrosive properties of some of the chemicals handled (e.g., HF).

7-2-1 Especially designed or prepared systems for the conversion of plutonium nitrate to oxide

NOTE:

The main functions involved in this process are: process feed storage and adjustment, precipitation and solid/liquor separation, calcination, product handling, ventilation, waste management, and process control. The process systems are particularly adapted so as to avoid criticality and radiation effects and to minimize toxicity hazards. In most reprocessing facilities, this process involves the conversion of PuN to PuO2. Other processes can involve the precipitation of plutonium oxalate or plutonium peroxide.

7-2-2 Especially designed or prepared systems for plutonium metal production

NOTE:

This process usually involves the fluorination of PuO2, normally with highly corrosive HF, to produce plutonium fluoride which is subsequently reduced using high purity calcium metal to produce metallic plutonium and a calcium fluoride slag. The main functions involved in this process are fluorination (e.g., involving equipment fabricated or lined with a precious metal), metal reduction (e.g., employing ceramic crucibles), slag recovery, product handling, ventilation, waste management and process control. The process systems are particularly adapted so as to avoid criticality and radiation effects and to minimize toxicity hazards. Other processes include the fluorination of plutonium oxalate or plutonium peroxide followed by a reduction to metal.

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