This specification covers blended uranium oxides with a 235U content of less than 5% for direct hydrogen reduction to nuclear grade uranium dioxide. For commercial-grade uranium oxide with an isotopic content of 235U between that of natural uranium and 5%, the isotopic limits shall apply. Physical and chemical requirements include: uranium content, oxygen-to-uranium ratio, impurity content, equivalent boron content, bulk density, moisture content, ability to flow, particle size, and reduction and sinterability. Maximum concentration limit is specified for impurity elements such as: aluminum, barium, beryllium, bismuth, calcium+magnesium, carbon, chlorine, chromium, cobalt, copper, fluorine, iron, lead, manganese, molybdenum, nickel, phosphorus, silicon, sodium, tantalum, thorium, tin, titanium, tungsten, vanadium, and zinc. The identity of a lot shall be retained throughout.1.1 This specification covers blended uranium trioxide (UO3), U3O8, or mixtures of the two, powders that are intended for conversion into a sinterable uranium dioxide (UO2) powder by means of a direct reduction process. The UO2 powder product of the reduction process must meet the requirements of Specification C 753 and be suitable for subsequent UO2 pellet fabrication by pressing and sintering methods. This specification applies to uranium oxides with a 235U enrichment less than 5 %.1.2 This specification includes chemical, physical, and test method requirements for uranium oxide powders as they relate to the suitability of the powder for storage, transportation, and direct reduction to UO2 powder. This specification is applicable to uranium oxide powders for such use from any source.1.3 The scope of this specification does not comprehensively cover all provisions for preventing criticality accidents, for health and safety, or for shipping. Observance of this specification does not relieve the user of the obligation to conform to all international, national, state, and local regulations for processing, shipping, or any other way of using uranium oxide powders (see 2.2 and 2.3).1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.5 The following safety hazards caveat pertains only to the test methods portion of the annexes in this specification: 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 and health practices and determine the applicability of regulatory limitations prior to use.

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5.1 Refer to Practice E261 for a general discussion of the determination of fast-neutron fluence rate with fission detectors.5.2 238U is available as metal foil, wire, or oxide powder (see Guide E844). It is usually encapsulated in a suitable container to prevent loss of, and contamination by, the 238U and its fission products.5.3 One or more fission products can be assayed. Pertinent data for relevant fission products are given in Table 1 and Table 2.(A) The lightface numbers in parentheses are the magnitude of plus or minus uncertainties in the last digit(s) listed.(B) With 137mBa (2.552 min) in equilibrium.(C) The recommended half-life and gamma emission probabilities have been taken from the Reference (3) data that was recommended at the time that the recommended fission yields were set.(D) Probability of daughter 140La decay.(E) This is the activity ratio of 140La/140Ba after reached transient equilibrium (t ≥ 19 days).(A) The JEFF-3.1/3.1.1 radioactive decay data and fission yields sub-libraries, JEFF Report 20, OECD 2009, Nuclear Energy Agency (5).(B) All yield data given as a %; RC represents a cumulative yield; RI represents an independent yield.5.3.1 137Cs-137mBa is chosen frequently for long irradiations. Radioactive products 134Cs and 136Cs may be present, which can interfere with the counting of the 0.662 MeV  137Cs-137mBa gamma rays (see Test Method E320).5.3.2 140Ba-140La is chosen frequently for short irradiations (see Test Method E393).5.3.3 95Zr can be counted directly, following chemical separation, or with its daughter 95Nb using a high-resolution gamma detector system.5.3.4 144Ce is a high-yield fission product applicable to 2- to 3-year irradiations.5.4 It is necessary to surround the 238U monitor with a thermal neutron absorber to minimize fission product production from a quantity of 235U in the 238U target and from  239Pu from (n,γ) reactions in the 238U material. Assay of the 239Pu concentration when a significant contribution is expected.5.4.1 Fission product production in a light-water reactor by neutron activation product 239Pu has been calculated to be insignificant (<2 %), compared to that from 238U(n,f), for an irradiation period of 12 years at a fast-neutron (E > 1 MeV) fluence rate of 1 × 1011 cm−2 · s−1 provided the 238U is shielded from thermal neutrons (see Fig. 2 of Guide E844).5.4.2 Fission product production from photonuclear reactions, that is, (γ,f) reactions, while negligible near-power and research-reactor cores, can be large for deep-water penetrations (6).45.5 Good agreement between neutron fluence measured by 238U fission and the 54Fe(n,p)54Mn reaction has been demonstrated (7). The reaction  238U(n,f) F.P. is useful since it is responsive to a broader range of neutron energies than most threshold detectors.5.6 The 238U fission neutron spectrum-averaged cross section in several benchmark neutron fields is given in Table 3 of Practice E261. Sources for the latest recommended cross sections are given in Guide E1018. In the case of the 238U(n,f)F.P. reaction, the recommended cross section source is the ENDF/B-VI release 8 cross section (MAT = 9237) (8). Fig. 1 shows a plot of the recommended cross section versus neutron energy for the fast-neutron reaction 238U(n,f)F.P.FIG. 1 ENDF/B-VI Cross Section Versus Energy for the 238U(n,f)F.P. ReactionNOTE 1: The data is taken from the Evaluated Nuclear Data File, ENDF/B-VI, rather than the later ENDF/B-VII. This is in accordance with Guide E1018, Section 6.1, since the later ENDF/B-VII data files do not include covariance information. Some covariance information exists for 238U in the standard sublibrary, but this is only for energies greater than 1 MeV. For more details, see Section H of Ref 9.1.1 This test method covers procedures for measuring reaction rates by assaying a fission product (F.P.) from the fission reaction 238U(n,f)F.P.1.2 The reaction is useful for measuring neutrons with energies from approximately 1.5 to 7 MeV and for irradiation times up to 30 to 40 years, provided that the analysis methods described in Practice E261 are followed.1.3 Equivalent fission neutron fluence rates as defined in Practice E261 can be determined.1.4 Detailed procedures for other fast-neutron detectors are referenced in Practice E261.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.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.

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5.1 This test method is useful for the analysis of total uranium in water following wet-ashing, as required, due to impurities or suspended materials in the water.1.1 This test method covers the determination of total uranium, by mass concentration, in water within the calibrated range of the instrument, 0.1 μg/L or greater. Samples with uranium mass concentrations above the laser phosphorimeter dynamic range are diluted to bring the concentration to a measurable level.1.2 This test method was used successfully with reagent water. It is the user’s responsibility to ensure the validity of this test method for waters of untested matrices.1.3 The values stated in SI units are to be regarded as the standard.1.4 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.1.5 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.

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5.1 Facility operators and safeguards inspectors routinely collect UF6 samples from processing lines, isotopic enrichment cascades or storage cylinders to determine uranium isotopic composition. The isotope ratio n(235U)/n(238U) is particularly important since it is used to calculate the amount of fissile 235U in the sample.5.2 Conventional sampling practices (such as Practices C1052 and C1703) collect samples of UF6, usually in quantities greater than one gram. Due to the chemical hazards of UF6 (and in some cases the high collection mass), an increasing number of air transport operators are unwilling to transport such samples. In contrast, SUDA samples are expected to be transported as excepted quantities (for example, under UN 2910 (3)), as the conversion to a less hazardous, more stable chemical species avoids the chemical hazards of UF6 similar to Practice C1880. Additionally, the decreased shipping requirement and small collection mass of SUDA samplers (less than Practice C1880) allow for multiple SUDA samples to be transported in the same shipment.5.3 For safeguards applications, isotopic measurements that fall within the 2010 International Target Value (ITV) ranges (5) have been demonstrated (1).5.4 This practice provides the following qualities:5.4.1 Fitness for purpose in verifying nuclear material declarations.5.4.2 A safe, simple and fast procedure for the sample collector that minimizes sample handling and potential for cross-contamination.5.4.3 Flexibility for use in a wide variety of facilities.5.4.4 Robustness to adapt to minor changes in facility operating parameters.5.4.5 Confidentiality for the operating facility from which the sample is collected.5.4.6 Safety in sample handling and transport since the sample is a less hazardous, more stable form (specifically, UO2F2 is more stable and less volatile than UF6 gas).5.4.7 Ease of sample preparation in the laboratory with reduced processing hazards during recovery of the uranium content (1).5.5 Samples collected using this practice are suitable for determination of uranium isotopic composition, as described in 4.5, for safeguards applications. Care must be taken to ensure cleanliness of the sampling tap to be used for SUDA samples, as any UF6 holdup in the sampling tap from previous sample collection could affect sample collection and isotopic measurements (see Section 9 for further details regarding this issue). Other applications of this practice are possible but require validation prior to use.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 zeolite in a single-use destructive assay (SUDA) sampler.1.2 This practice is based on the SUDA method developed at Pacific Northwest National Laboratory (1)2 for collection of samples of UF6 for determination of uranium isotopic content for nuclear material safeguards and other applications.1.3 The UF6 collected is converted to uranyl fluoride (UO2F2), allowing samples to be handled and categorized for transport under less stringent conditions than are required for UF6.1.4 This practice can be used to collect samples for safeguards measurements. Safeguards samples collected with this practice have been shown to provide suitable isotopic measurements (1).1.5 This practice has not been demonstrated for suitability for compliance with Specifications C787 and C996. Practices C1052 or C1703 can be used to collect samples for compliance with these specifications.1.6 The scope of this practice does not include provisions for preventing criticality.1.7 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.1.8 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.1.9 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.

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Determination of percent uranium content and 235U abundance in oxides and other materials containing high concentrations of uranium is required for special nuclear materials accountability, regulatory requirements, and process control.1.1 This test method covers a method for the determination of the uranium concentration in uranium oxides by isotope dilution mass spectrometry (IDMS). The isotopic composition of the oxide is measured simultaneously.1.2 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 and health practices and determine the applicability of regulatory limitations prior to use.

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1.1 This test method covers the semiquantitative spectrographic analysis of high-purity U3O8 for the 32 elements in the ranges indicated in Table 1. (Quantitative analyses of boron, chromium, iron, magnesium, manganese, nickel, and other impurities can be performed using densitometric methods.)1.2 The test method can be applied to those samples of uranium and uranium compounds, or both, which can be converted to the black oxide (U3O8) and which are of approximately 99.5 % purity or better.1.3 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 and health practices and determine the applicability of regulatory limitations prior to use.

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5.1 Uranium and plutonium oxides can be used as a nuclear-reactor fuel in the form of pellets. In order to be suitable for use as a nuclear fuel the starting material must meet certain specifications, such as found in Specifications C757, C833, C753, C776, C1008, or as specified by the purchaser. The uranium concentration, plutonium concentration, or both, and the isotopic abundances are measured by mass spectrometry following this test method.5.2 The separated heavy element fractions placed on mass spectrometric filaments must be very pure. The quantity required depends upon the sensitivity of the instrument detection system. If an electron multiplier detector is to be used, only a few nanograms are required. If a Faraday cup is used, a few micrograms are needed. Chemical purity of the sample becomes more important as the sample size decreases, because ion emission of the sample is suppressed by impurities.1.1 This test method covers the determination of the concentration and isotopic composition of uranium and plutonium in solutions. The purified uranium or plutonium from samples ranging from nuclear materials to environmental or bioassay matrices is loaded onto a mass spectrometric filament. The isotopic ratio is determined by thermal ionization mass spectrometry, the concentration is determined by isotope dilution.1.2 The values stated in SI units are to be regarded as the standard. Values in parentheses are for information only.1.3 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 safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.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.

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This practice is useful for the preparation of specimens of ore bodies for the analysis of uranium by X-ray emission. Two separate preparation techniques are described.1.1 This practice covers the preparation of uranium ore samples to be analyzed by X-ray emission. Two separate techniques, the glass fusion method or the pressed powder method, may be used.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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5.1 The guide is applicable to the analysis of materials to demonstrate compliance with the specifications set forth in Specifications C787 and C996. Some other specifications may be expressed in terms of mass of 232U per mass of only 238U (see ISO 21847–3:2007).1.1 This guide covers the determination of 232U in uranium hexafluoride by alpha spectrometry.1.2 The values stated in SI units are to be regarded as standard, except where the non-SI unit of molar, M, is used for the concentration of chemicals and reagents. The unit of electronvolt (eV) is outside the SI but its use with the SI is accepted by the International Committee for Weights and Measures (CIPM, Comité International des Poids et Mesures) and the U. S. National Institute of Science and Technology (NIST). No other units of measurement are included in this standard.1.3 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.1.4 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.

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4.1 The determination of  129I is not typically requested in nuclear fuel specifications however it is commonly requested for disposal of the spent fuel, or for disposal of excess uranium from national weapon complexes. This practice can provide results of sufficient quality for waste disposal repositories.1.1 This method covers the determination of iodine-129 (129I) in uranium oxide by gamma-ray spectrometry. The method could also be applicable to the determination of   129I in aqueous matrices.1.2 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 and health practices and to determine the applicability of regulatory limitations prior to use.

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4.1 The determination of uranium isotopic composition by gamma-ray spectrometry is a nondestructive technique and when used with other nondestructive techniques that quantify a single isotope, such as Test Methods C1133 (Segmented Gamma Scanning), C1221 (Solution Assay), C1455 (Holdup),and C1718 (Tomographic Gamma Scanning), can provide a wholly nondestructive assay of uranium mass necessary for material accountancy and safeguards needs. This method can be used with calorimetry (Test Method C1458) for kilogram quantities of high-enriched uranium and is also used to convert an Active-Well Coincidence Counter (4) measurement of 235U mass to total uranium mass.4.2 Because gamma-ray spectrometry systems are typically automated, the routine use of the test method is fast, reliable, and is not labor intensive. The test method is nondestructive, requires no sample preparation, and does not create waste disposal problems.4.3 The test method does not require that the system be calibrated to a specific geometry.4.4 The test method assumes that all uranium in the measured item has the same isotopic distribution. This is often termed isotopic homogeneity.4.5 The application of the test method does not depend upon the physical or chemical form of the material being analyzed.4.6 The 236U abundance is not measured by this test method and must be estimated from isotopic correlation techniques, stream averages, historical information, or other measurement techniques.4.7 The isotopic composition of a given item of uranium is an attribute of that item and, once determined, can be used in subsequent inventory measurements to verify the identity of an item within the measurement uncertainties.4.8 The method can also measure the ratio of other gamma-emitting isotopes in the measured item to uranium assuming they have the same spatial distribution as the uranium in the item. Some of these “other” gamma-emitting isotopes include daughter isotopes of uranium, cesium, and other fission products.4.9 The method can be applied to gamma and x rays in two overlapping energy regions, depending upon the nature of the measured item, its containment, and the characteristics of the detector used for data acquisition.4.9.1 60 keV to 250 keV—This energy range requires good energy resolution provided by planar or semi-planar HPGe detectors. The analysis methods must be capable of deconvoluting the x-ray peak line shapes from the gamma-ray peak shapes.4.9.2 120 keV to 1010 keV—This energy range generally requires higher efficiency detectors typified by larger coaxial detectors (> 25 % relative efficiency) or large semi-planar detectors (> 30 mm thick).4.10 Fig. 1 shows the decays that produce most of the prominent gamma and x rays that are measured in this analysis.(A) Energies and Branching Intensities from Ref (1).(B) Uncertainties in parentheses are absolute 1σ values.(C) Relative values from unweighted mean of plutonium decay data from Ref (1).1.1 This test method applies to the nondestructive determination of the isotopic abundances of uranium, typically 234U, 235U, 236U, and 238U, in isotopically homogeneous uranium-bearing materials using gamma spectrometry. The material is commonly inside a container and is measured without specimen preparation.1.2 This test method is applicable to items containing sub-gram quantities of uranium to the maximum uranium mass allowed by criticality considerations.1.3 Measurable gamma ray emissions from uranium cover the energy range from below 80 keV to above 1000 keV. K-X-ray emissions from the isotopes of uranium and their daughters are found in the energy region around 100 keV. This test method has been applied to all portions of this energy range.1.4 The isotopic abundance of 236U is usually not directly determined because its low-energy gamma rays are too weak (1)2 to be detected under normal measurement conditions. Isotopic correlation techniques have been used to estimate its relative abundance (2).1.5 This test method has been demonstrated in routine use for isotopic amount fraction (atom %) of 235U from 0.2 % to 97 %.1.6 This test method requires decay equilibrium (160 days for 99 %) between 238U and its 24.1 d half-life 234Th daughter. Corrections can be made if the date of chemical separation of the 234Th daughter is known.1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.8 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.1.9 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.

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5.1 This test method is a fast, cost-effective method that can yield limited isotopic activity levels for 238U and 234U, as well as total uranium activity. Although 232U is incorporated as a tracer, uranium recoveries for this test measured during the developmental work on this test method were usually between 95 and 105%. 5.2 The high-resolution alpha-liquid-scintillation spectrometer offers a constant (99.6 ± 0.1) % counting efficiency and instrument backgrounds as low as 0.001 counts per minute (min–1 ) over a 4 to 7 MeV energy range according to McDowell and McDowell (2). Count rates for extractive scintillator blanks and reagent blanks usually range from 0.01 min–1 to 0.1 min–1. 1.1 This test method covers determining the total soluble uranium activity in drinking water in the range of 0.037 Bq/L (1 pCi/L) or greater by selective solvent extraction and high-resolution alpha-liquid-scintillation spectrometry. The energy resolution obtainable with this technique also allows estimation of the 238U to 234U activity ratio. 1.2 This test method was tested successfully with reagent water and drinking water. It is the user's responsibility to ensure the validity of this test method for waters of untested matrices. 1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. 1.4 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 and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 9.

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5.1 This practice can be used to separate uranium or plutonium, or both, prior to the impurity analysis by various techniques. The removal of uranium and plutonium prior to quantification can improve the detection limits by minimizing the signal suppression caused by uranium or plutonium when using ICP techniques. Detection limits of ~1–10 part-per-billion (PPB) may be obtainable by matrix removal. Also, removal of the uranium and plutonium may allow the impurities analysis to be performed on a non-glove box enclosed instrument.5.2 Other test methods exist to determine impurities in uranium or plutonium. Test Method C1517 is able to determine many impurities in uranium at detection levels of ~1–10 part-per-million (ppm) by DC-Arc Spectrometry. Test Method C1287 is able to determine impurities in uranium at detection levels of ~100 ppb by ICP-MS. Test Method C1432 provides an alternative technique to remove plutonium by ion exchange prior to analysis of the impurities by ICP-AES.5.3 This practice can be used to demonstrate compliance with nuclear fuel specifications, for example, Specifications C753, C757, C776, C787, C788, and C996.1.1 This practice covers instructions for using an extraction chromatography column method for the removal of plutonium or uranium, or both, from liquid or digested oxides or metals prior to impurity measurements. Quantification of impurities can be made by techniques such as inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectrometry (ICP-AES), or atomic absorption spectrometry (AAS.)1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 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.1.4 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.

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DOE Order 5480.11 and ANSI N13.30 require that internal dose assessments be made as part of the bioassay program for nuclear facility workers. For indirect bioassay of uranium workers, the uranium isotopes must be measured along with the total uranium in urine samples. The RMDA for each uranium isotope is 0.1 pCi/L. This method is applicable for measuring 235U and 238U at the RMDA. Because of extremely low mass concentration (because of the high specific activity), 234U cannot be measured without additional sample preconcentration. Note 2—Column chromatography separations and concentration of 234U using manual or flow-injection preconcentration followed by ICP-MS isotopic determination are described in Test Methods C1310 and C1345. These methods focus on environmental soil sample analysis, but with some development, may be applicable to digested urine samples. The 234U concentration can be calculated based on an enrichment gradient for workers in uranium enrichment plants, and internal dose assessments can be made. Note 3—Use of high resolution ICP-MS may also be used to obtain lower detection limits. 1.1 This test method covers the determination of the concentration of uranium-235 and uranium-238 in urine using Inductively Coupled Plasma-Mass Spectrometry. This test method can be used to support uranium facility bioassay programs. 1.2 This method detection limits for 235U and 238U are 6 ng/L. To meet the requirements of ANSI N13.30, the minimum detectable activity (MDA) of each radionuclide measured must be at least 0.1 pCi/L (0.0037 Bq/L). The MDA translates to 47 ng/L for 235U and 300 ng/L for 238U. Uranium– 234 cannot be determined at the MDA with this test method because of its low mass concentration level equivalent to 0.1 pCi/L. 1.3 The digestion and anion separation of urine may not be necessary when uranium concentrations of more than 100 ng/L are present. 1.4 Units—The values stated in picoCurie per liter units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered 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 and health practices and determine the applicability of regulatory limitations prior to use. Note 1—Warning: The ICP-MS is a source of intense ultraviolet radiation from the radio frequency induced plasma. Protection from radio frequency radiation and UV radiation is provided by the instrument under normal operation.

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5.1 The total evaporation method is used to measure the isotopic composition of uranium, plutonium, and americium materials, and may be used to measure the elemental concentrations of these elements when employing the IDMS technique.5.2 Uranium and plutonium compounds are used as nuclear reactor fuels. In order to be suitable for use as a nuclear fuel the starting material must meet certain criteria, such as found in Specifications C757, C833, C753, C776, C787, C967, C996, or as specified by the purchaser. The uranium concentration, plutonium concentration, or both, and isotope abundances are measured by TIMS following this method.5.3 Americium-241 is the decay product of 241Pu isotope. The abundance of the 241Am isotope together with the abundance of the 241Pu parent isotope can be used to estimate radio-chronometric age of the Pu material for nuclear forensic applications Ref (6). The americium concentration and isotope abundances are measured by TIMS following this method.5.4 The total evaporation method allows for a wide range of sample loading with no significant change in precision or accuracy. The method is also suitable for trace-level loadings with some loss of precision and accuracy. The total evaporation method and modern instrumentation allow for the measurement of minor isotopes using ion counting detectors, while the major isotope(s) is(are) simultaneously measured using Faraday cup detectors.5.5 The new generation of miniaturized ion counters allow extremely small samples, in the picogram range, to be measured via the total evaporation method. The method may be employed for measuring environmental or safeguards inspection samples containing nanogram quantities of uranium or plutonium. Very small loadings require special sample handling and careful evaluation of measurement uncertainties.5.6 Typical uranium analyses are conducted using sample loadings between 50 nanograms and 800 nanograms. For uranium isotope ratios the total evaporation method had been used in several recent NBL isotopic certified reference material (CRM) characterizations (for example (2, 3)). A detailed comparison of the total evaporation data on NBL uranium CRMs analyzed by the MAT 261 and TRITONTM instruments is provided in Ref (5). For total evaporation, plutonium analyses are generally conducted using sample loads in the range of 20 to 200 nanograms of plutonium.1.1 This method describes the determination of the isotopic composition, or the concentration, or both, of uranium, plutonium, and americium as nitrate solutions by the total evaporation method using a thermal ionization mass spectrometer (TIMS) instrument. Purified uranium, plutonium, or americium nitrate solutions are deposited onto a metal filament and placed in the mass spectrometer. Under computer control, ion currents are generated by heating of the filament(s). The ion currents are continually measured until the whole deposited solution sample is exhausted. The measured ion currents are integrated over the course of the measurement and normalized to a reference isotope ion current to yield isotope ratios.1.2 In principle, the total evaporation method should yield isotope ratios that do not require mass bias correction. In practice, samples may require this bias correction. Compared to the conventional TIMS method described in Test Method C1625, the total evaporation method is approximately two times faster, improves precision of the isotope ratio measurements by a factor of two to four, and utilizes smaller sample sizes. Compared to the C1625 method, the total evaporation method provides “major” isotope ratios 235U/238U, 240Pu/239Pu, and 241Am/243Am with improved accuracy.1.3 The total evaporation method is prone to biases in the “minor” isotope ratios (233U/238U, 234U/238U, and 236U/238U ratios for uranium materials and 238Pu/239Pu, 241Pu/239Pu, 242Pu/239Pu, and 244Pu/239Pu ratios for plutonium materials) due to peak tailing from adjacent major isotopes. The magnitude of the absolute bias is dependent on measurement and instrumental characteristics. The relative bias, however, depends on the relative isotopic abundances of the sample. The use of an electron multiplier equipped with an energy filter may eliminate or diminish peak tailing effects. Measurement of the abundance sensitivity of the instrument may be used to ensure that such biases are negligible, or may be used to bias correct the minor isotope ratios.1.4 The values stated in SI units are to be regarded as standard. When non-SI units are provided in parentheses, they are for information only.1.5 This standard may involve the use of hazardous materials and equipment. This standard does not purport to address all 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 to 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.

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