ASTM C1880-19

5.1 Facility operators and safeguards inspectors routinely take UF₆ samples from processing lines, isotopic enrichment cascades or storage cylinders to determine its U isotopic composition, most important the n(²³⁵U)/n(²³⁸U) isotope ratio, needed to calculate the amount of the fissile ²³⁵U in the sample. The current version of the “International Target Values for Measurement Uncertainties in Safeguarding Nuclear Materials” 5.2 The conventional sampling practice collects UF_{5.3 This sampling practice was developed to meet the following requirements:}

5.4 This sampling practice offers significant advantages over the conventional sampling practice because it allows handling non-reactive, non-volatile, solid UO₂F₂ instead of highly reactive and volatile UF₆.

5.5 A smaller UO₂F₂ sample can be transported with lower radioactivity level and reduced radiological problems in case of accident. Additionally, there is no risk of airborne uranium particle and HF release.

5.6 The U isotope ratios measured in UF_{5.7 It is strongly recommended to discard used P-10 tubes to avoid the possibility of isotopic cross contamination, mainly because this practice is associated with the processing of very small amounts of U.}

5.8 In case recycled P-10 tubes are used, a very efficient and reliable cleaning procedure must be employed to assure a complete removal of U from the P-10 tube inner surfaces.

5.9 This practice provides guidance to obtain samples for determining the U composition for material nuclear safeguards as well as other applications. Such samples should not be used for determining compliance with Specifications C787 and C996. For these cases, the recommendations of Practices C1052 or C1703 must be followed.

5.10 The test methods describing procedures for subsampling, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of uranium hexafluoride are presented in Test Methods C761. Most of them are routinely used to determine the compliance with Specifications C787 and C996.

1.1 This practice is applicable to sampling gaseous uranium hexafluoride (UF₆) from processing facilities, isotope enrichment cascades or storage cylinders, using the sorbent properties of aluminum oxide (Al₂O₃).

1.2 It is based on the ‘ABACC-Cristallini Method’ 1.3 The application of this practice assures the resulting sample vessel contains no UF₆ and hydrogen fluoride (HF); therefore, it may be handled and categorized for transport under less stringent constraints.

1.4 The scope of this practice does not include provisions for preventing criticality.

1.5 Units—The values stated in SI units are to be regarded as the standard. When non-SI units are provided, they are for information only.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7 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.