ASTM C787-20

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C787 − 15 C787 − 20
Standard Specification for
Uranium Hexafluoride for Enrichment
This standard is issued under the fixed designation C787; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers uranium hexafluoride (UF ) intended for feeding to an enrichment plant. Included are
specifications for UF derived from unirradiated natural uranium and UF derived from irradiated uranium that has been
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reprocessed and converted to UF for enrichment and subsequent reuse. The objectives of this specification are twofold: (1) Toto
define the impurity and uranium isotope limits for Commercial Natural UF feedstock;feedstock, and (2) Toto define additional
limits for Reprocessed UF (or any mixture of Reprocessed UF and Commercial Natural UF ). For such UF , special provisions
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may be needed to ensure that no extra hazard arises to the work force, process equipment, or the environment.
1.2 The scope of this specification does not comprehensively cover all provisions for preventing criticality accidents or
requirements for health and safety or for shipping. Observance of this specification does not relieve the user of the obligation to
conform to all international, federal, state, and local regulations for processing, shipping, or in any other way using UF (see, for
(for example, see TID-7016, DP-532, ORNL-NUREG-CSD-6, and DOE O 474.1).
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.after
SI units are provided for information only and are not considered standard.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C761 Test Methods for Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical Analysis of Uranium
Hexafluoride
C859 Terminology Relating to Nuclear Materials
C996 Specification for Uranium Hexafluoride Enriched to Less Than 5 % U
C1052 Practice for Bulk Sampling of Liquid Uranium Hexafluoride
C1295 Test Method for Gamma Energy Emission from Fission and Decay Products in Uranium Hexafluoride and Uranyl Nitrate
Solution
C1703 Practice for Sampling of Gaseous Uranium Hexafluoride for Enrichment
2.2 ANSI Standard:
N14.1 Packaging of Uranium Hexafluoride for Transport
2.3 U.S. Government Documents:
Inspection, Weighing, and Sampling of Uranium Hexafluoride Cylinders, Procedures for Handling and Analysis of Uranium
Hexafluoride, Vol. 1,ORO-671-1 Department of Energy Report ORO-671-1, latest revisionInspection, Weighing, and
Sampling of Uranium Hexafluoride Cylinders, Procedures for Handling and Analysis of Uranium Hexafluoride, Vol. 1, latest
revision
This specification is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.02 on Fuel and Fertile
Material Specifications.
Current edition approved July 1, 2015March 1, 2020. Published July 2015April 2020. Originally approved in 1976. Last previous edition approved in 20112015 as
C787 – 11.C787 – 15. DOI: 10.1520/C0787-15.10.1520/C0787-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute, 11 W. 42nd St., 13thInstitute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.10036, http://www.ansi.org.
Available from Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.Superintendent of Documents, 732 N. Capitol St., NW,
Washington, DC 20401-0001, http://www.access.gpo.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C787 − 20
The UF Manual: Good Handling Practices for Uranium Hexafluoride, United States Enrichment Corporation Report
USEC-651, latest revision
Nuclear Safety Guide, U.S. Nuclear Regulatory Commission Report TID-7016,TID-7016 (ORNL-NUREG-CSD-6) Rev. 2,
1978, and ORNL-NUREG-CSD-6Nuclear Safety Guide, Rev. 2
Clarke, H. K., Handbook of Nuclear Safety, Department of Energy Report DP-532 Handbook of Nuclear Safety
Control and Accountability of Nuclear Materials, DOE Directive DOE O 474.1 Control and Accountability of Nuclear Materials,
DOE Directive
2.4 Other Document:
USEC-651 The UF Manual: Good Handling Practices for Uranium Hexafluoride United States Enrichment Corporation Report,
latest revision
3. Terminology
3.1 Definitions:
3.1.1 Terms shall be defined in accordance with Terminology C859, except for the terms listed below.
3.2 Definitions of Terms Specific to This Standard:
3.1.1 Terms shall be defined in accordance with Terminology C859, except for the following:
3.2.1 Commercial Natural UF —, n—UF from natural unirradiated uranium (containing 0.711 6 0.004 g U per 100 g U).
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3.2.1.1 Discussion—
It is recognized that some contamination with reprocessed uranium may occur during routine processing. This is acceptable
provided that the UF meets the requirements for Commercial Natural UF .
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3.2.2 Reprocessed UF —, n—any UF made from uranium that has been exposed in a neutron irradiation facility and
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subsequently chemically separated from the fission products and transuranic isotopes so generated.
3.2.2.1 Discussion—
The requirements for Reprocessed UF given in this specification are intended to be typical of reprocessed spent fuel that has
achieved burnup levels of up to 50 000 Megawattmegawatt days per tonneton of uranium in light water reactors and has been
cooled for ten years after discharge. It is recognized that different limits would be necessary to accommodate different fuel
histories.
4. Safety, Health Physics, and Criticality Requirements
4.1 The UF concentration shall be not less than 99.5 g UF per 100 g of sample in order to limit the potential hydrogen content
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for nuclear criticality safety.
4.2 The total absolute vapor pressure shall not exceed the values given following values:
380 kPa at 80 °C (55 psia at 176 °F), or
517 kPa at 93 °C (75 psia at 200 °F), or
862 kPa at 112 °C (125 psia at 235 °F)
below:
380 kPa at 80°C (55 psia at 176°F), or
517 kPa at 93°C (75 psia at 200°F), or
862 kPa at 112°C (125 psia at 235°F)
Additionally, if a measurement is taken over solid UF , then the vapor pressure shall not exceed the values given following
values:
50 kPa at 20 °C (7 psia at 68 °F), or
69 kPa at 35 °C (10 psia at 95 °F)
below:
50 kPa at 20°C (7 psia at 68°F), or
69 kPa at 35°C (10 psia at 95°F)
The purpose of the pressure check is to limit the hydrogen fluoride, air, or other volatile components that might cause
overpressure when heating the shipping container to obtain a liquid sample or withdraw the contents.
4.2.1 If the temperature differs from 20°C20 or 35°C,35 °C, a temperature correction must be performed which takes the change
in vapor pressure of UF into account. For example, an acceptable correction would be that the pressure must remain below
P (T) + 39.3 kPa, where P (T) is the vapor pressure of pure UF over solid at temperature T and P (T) is given according
UF6 UF6 6 UF6
Available from United States Enrichment Corporation, 6903Centrus Energy Corporation, 6901 Rockledge Drive, Bethesda, MD 20817.
C787 − 20
to in accordance with Log P = 12.77 – (2562.46/T), with P in Pascal and T in K. Other methods or equations to assure that
UF6
the pressure limits above are met are acceptable provided that validated temperature compensation is made.
4.3 The total hydrocarbon, chlorocarbon, and partially substituted halohydrocarbon content shall not exceed 0.01 mol % of the
UF . The reason for the exclusion of these materials is to prevent a vigorous reaction with UF upon heating or with
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stronger-fluorinating agents which may be present in enrichment plants. It is essential that contamination of the UF containers,
such as by vacuum pump oil, be prevented since it is not practical to obtain a sample without heating the UF . For fully substituted
chlorofluorocarbons a maximum limit may be agreed upon between the parties concerned.
4.3.1 Measures should be taken to minimize contamination by hydrocarbons, chlorocarbons, and partially substituted
halohydrocarbons in the receiving cylinder before filling and it is good practice to minimize such contact during UF processing.
4.3.2 If UF has been liquefied, either during filling or during sampling of the final shipping container, compliance can be
assumed. If the UF has not been liquefied, compliance must be demonstrated. An alternative means of demonstrating compliance
with this requirement, other than by direct measurement, may be agreed upon between the parties concerned.
4.4 For Reprocessed UF the gamma radiation from fission products shall not exceed 1.1 × 10 MeV MeV Bq/kgU
(1.1 × 10 MeV MeV/sec ⁄s kgU). The measurements are made in accordance with Test Method C1295 or equivalent. The purpose
of this requirement is to limit the gamma dose from fission products to which plant workers might be exposed to a level less than
20 % of the gamma dose from aged natural uranium, and to limit the quantity of fission products in effluent from enrichment and
fuel fabrication plants.
4.5 For Reprocessed UF , the alpha activity from neptunium (Np) and plutonium (Pu) isotopes may be specified in either of two
ways as agreed upon between the parties concerned:
4.5.1 The total alpha activity from Np and Pu in the cylinder shall be limited to 25 000 Bq/kgU (1.5 × 10 disintegrations per
minute per kilogram of uranium). This criterion is concerned with both the volatile components and those that remain on the inner
surfaces and in the heel, so it can be measured practically only by sampling from the inflow during the filling of the shipping
container; or
4.5.2 The volatile alpha activity from Np and Pu in the liquid sample from the shipping container shall be limited to 3300
Bq/kgU (0.2 × 10 disintegrations per minute per kilogram of uranium). To prevent nonvolatile particles from being included in
this measurement, the liquid sample must be filtered through a porous nickel filter as described in Test Methods C761.
5. Chemical, Physical, and Isotopic Requirements
5.1 Plants preparing UF will have to control the purity of process chemicals and also employ low corrosion equipment to be
successful in meeting the specifications for most impurities. Both Commercial Natural UF and Reproce
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