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1.1 This test method covers the measurement of gamma energy emitted from fission products in uranium hexafluoride (UF₆) and uranyl nitrate solution. This test method may also be used to measure the concentration of some uranium decay products. It is intended to provide a method for demonstrating compliance with UF₆ Specifications C787 and C996, uranyl nitrate Specification C788, and uranium ore concentrate Specification C967.

1.2 The lower limit of detection is estimated at 5000 MeV Bq/kg (MeV kg^-1/s^-1) of uranium and is the square root of the sum of the squares of the individual reporting limits of the nuclides to be measured. The limit of detection was determined on a pure, aged natural uranium (ANU) solution. The value is dependent upon the detector efficiency and background that can be achieved.

1.3 The fission product nuclides to be measured are ¹⁰⁶Ru/¹⁰⁶Rh, ¹⁰³Ru, ¹³⁷Cs, ¹⁴⁴Ce, ¹⁴⁴Pr, ¹⁴¹Ce, ⁹⁵Zr, ⁹⁵Nb, and ¹²⁵Sb. Among the uranium decay product nuclides that may be measured is ²³¹Pa. Other gamma energy-emitting fission and uranium decay nuclides present in the spectrum at detectable levels should be identified and quantified as required by the data quality objectives.

1.4 The values stated in SI units are to be regarded as standard. Additionally, the non-SI units of kiloelectron volts and megaelectron volts are to be regarded as standard. No other units of measurement are included in this standard.

1.5 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.

1.6 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.

5.1 Specific gamma-ray emitting radionuclides in UF₆ are identified and quantified using a high-resolution gamma-ray energy analysis system, which includes a high-resolution germanium detector. This test method shall be used to meet the health and safety specifications of C787, C788, and C996 regarding applicable fission products in reprocessed uranium solutions. This test method may also be used to provide information to parties such as conversion facilities on the level of uranium decay products in such materials. Pa-231 is a specific uranium decay product that may be present in uranium ore concentrate and is amenable to analysis by gamma spectrometry.