1、Designation: C1842 16Standard Test Method forThe Analysis of Boron and Silicon in Uranium Hexfluoridevia Fourier-Transform Infrared (FTIR) Spectroscopy1This standard is issued under the fixed designation C1842; the number immediately following the designation indicates the year oforiginal adoption o
2、r, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is suitable for determining boron andsilicon impurities as BF
3、3and SiF4in uranium hexafluoride.This test method is an alternative to those described in TestMethods C761 and C1771.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesaf
4、ety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C761 Test Methods for Chemical,
5、 Mass Spectrometric,Spectrochemical, Nuclear, and RadiochemicalAnalysis ofUranium HexafluorideC787 Specification for Uranium Hexafluoride for Enrich-mentC859 Terminology Relating to Nuclear MaterialsC996 Specification for Uranium Hexafluoride Enriched toLess Than 5 %235UC1052 Practice for Bulk Sampl
6、ing of Liquid UraniumHexafluorideC1703 Practice for Sampling of Gaseous UraniumHexafluorideC1771 Test Method for Determination of Boron, Silicon,and Technetium in Hydrolyzed Uranium Hexafluoride byInductively Coupled PlasmaMass Spectrometer AfterRemoval of Uranium by Solid Phase Extraction2.2 Other
7、Documents:ANSI N14.1 Nuclear Materials Uranium Hexfluo-ride Packaging for Transport3ISO 7195 Nuclear Energy Packaging of UraniumHexafluoride (UF6) for Transport43. Terminology3.1 Except as otherwise defined herein, definitions of termsare as given in Terminology C859.3.2 Definitions of Terms Specifi
8、c to This Standard:3.2.1 detection limit, nbased on the minimum absorbanceobtainable at a given pressure to yield a meaningful result. Inaccordance with Terminology C859, a low concentration levelcould be achieved with these methods.3.2.2 FTIR, nFourier-transform infrared spectroscopy.3.2.3 K, ninfr
9、ared absorbance constant in pressure units1/Pa, K = OD/Pressure.3.2.4 “1S” container, na nickel or Monel container asdescribed in ANSI N14.1.4. Summary of Test Method4.1 To perform the Fourier-Transform Infrared (FTIR) spec-troscopic analysis of boron and silicon impurities in uraniumhexafluoride, a
10、 sample must be collected in a “1S” container orequivalent with the methods described in Practices C1052 orC1703.4.2 The bottle is kept at room temperature. The manifoldand the sample cell are maintained at 50C. In these conditions,UF6is mainly in solid phase in the bottle and boron and siliconare p
11、resent in the gaseous phase of manifold. In this medium,the boron and silicon chemical forms are respectively BF3andSiF4.4.3 The test method is based on the analysis in the gasphase. The gas phase is analyzed at 50C by FTIR spectrom-etry to determine the B and Si concentration in uraniumhexafluoride
12、.1This test method is under the jurisdiction ofASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved June 1, 2016. Published July 2016. DOI: 10.1520/C1842-16.2For referenced ASTM standards, visit the ASTM website, w
13、ww.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.
14、ansi.org.4Available from International Organization for Standardization (ISO), ISOCentral Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,Geneva, Switzerland, http:/www.iso.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Unit
15、ed States14.4 The manifold and sample cell are filled at the vaporpressure of UF6at room temperature (near 12 kPa).4.5 After a screening, if the spectrum is the UF6spectrum,this test method can be used to check the compliance of UF6asspecified in Specifications C787 and C996.4.6 The boron and silico
16、n determinations are done on thegaseous phase. The concentration and the limits of detectionare in units of g/g U.4.7 There are no spectral interferences from uraniumhexafluorides infrared absorbences.5. Significance and Use5.1 This test method utilizes FTIR spectroscopy to deter-mine the boron and
17、silicon concentration in uranium hexafluo-ride.5.2 These detection limits are low and very effective tocheck the compliance of UF6with Specifications C787 andC996.6. Hazards6.1 Uranium hexafluoride is a hazardous material. It is ahighly reactive and toxic substance in addition to its radioac-tive pr
18、operties. It must be handled as a gas in containers andmanifolds using materials of construction that are inert tofluorine-bearing gases, such as nickel, Monel, copper, oraluminum.7. Apparatus7.1 Fourier-Transform Infrared Spectrophotometer, with aresolution of 60.5 cm-1or better. The scanning range
19、 dependson the equipment being used, but at minimum shall be 600 to1550 cm-1.7.2 A Manifold System, built with materials of constructioninert to fluorine-bearing gases. The manifold system shall beconditioned and passivated with an appropriate fluorinatingagent.7.3 A Sample Cell, windows are made of
20、 material(s) inert tofluorine-bearing gases, for example, zinc selenide (ZnSe). Acell path length of more than 150 mm was found to besufficient for the required LOD. The cell is heated at 50C.7.4 A Pressure Gauge, which can be read to 1 Pa isnecessary.7.5 Absorbence Data, or OD optical density, can
21、be deter-mined to 0.001 units.8. Calibration and Standardization8.1 Calibration:8.1.1 BF3and SiF4are calibrated between 15 and 150 Pa.The cell temperature is maintained at 50C. Different pressuresof pure BF3or pure SiF4are introduced between 15 and 150Pa. The maximum of absorbance and the scans are
22、recorded.The response of absorbance as a function of pressure is linear.The slope of this line is K. The slope is constant from near zeroabsorbance to about 0.8 absorbance units.8.1.2 The K value are measured at 1441 cm-1for BF3and1029 cm-1for SiF4(see Fig. 1 and Fig. 2).8.1.3 The operating experien
23、ce of each laboratory for pre-cision calculations of impurities are critical to the success ofthe method. Each laboratory shall determine the “K” valuesspecific to its instrumentation: K = OD/ Pressure.8.2 Calibration of Pressure Gauge and FTIR InstrumentPressure gauges and the FTIR instruments are
24、very stable overtime. Annual calibration is recommended.FIG. 1 BF3Spectrum in Pure MediumC1842 1628.3 Calibration ChecksThe calibration of the gaugeshould be checked before analyzing a UF6standard. After thecheck of the gauge calibration, 10 kPa of UF6standard areintroduced and the maximum of absorb
25、ance at 625 cm-1isrecorded. These calibration checks should be performed eachday that the instrument is used. If the difference on the OD isabove 1 %, the pressure gauge should be recalibrated. If thewavelength difference is greather than 0.5 cm-1, then the FTIRinstrument should be recalibrated9. Pr
26、ocedure9.1 Acquire a Sample Scan:9.1.1 Weigh the empty bottle (M1).9.1.2 Withdraw a sample in a 1S bottle with the processdefined in Practices C1052 or C1703.9.1.3 Weigh the bottle to determine the UF6mass in thebottle (M2).9.1.4 Evacuate manifold system until readout on gaugedisplays a value of les
27、s than 10 Pa.9.1.5 Verify the digital manometer for zero and full scalereadings.9.1.6 Obtain an infrared background spectrum on the FTIRto check that the manifold is clean.9.1.7 Connect the sample 1S bottle on the manifold andcontrol the tightness.9.1.8 Open the bottle valve on the manifold. Wait un
28、til thepressure is stabilized and close the valve. Record the samplepressure (P).9.1.9 Obtain the infrared spectrum.The spectrum will be theresult of ten scans.9.2 Interpret Spectrum:9.2.1 Record the absorbance maxima (OD BF3and ODSiF4) and the infrared spectrum (see Fig. 3).FIG. 2 SiF4Spectrum in P
29、ure MediumFIG. 3 SiF4Spectrum in UF6MediumC1842 1639.3 Representativity of the Sample:9.3.1 The representativity of the sample is validated by thefollowing process. Control the concentration of UF6in the gasphase. If the UF6concentration is above 80 %, the sample isvalidated and the boron and silico
30、n concentration could bedetermined. If the UF6concentration is under 80 %, a resam-pling is necessary.9.3.2 To determine the concentration of UF6in the gasphase, perform a UF6calibration introducing a pressure of pureUF6(PUF6) and record the UF6absorbance (ODUF6)tocalculate KUF6(KUF6= ODUF6/ PUF6).
31、Record the UF6absorbance on the infrared spectrum of the sample andcalculate the UF6pressure with the K value. To calculate theconcentration of UF6in the gas phase, divide the UF6pressureby the sample pressure (%UF6= PUF6/ Psample).9.4 Evacuation of the Manifold System:9.4.1 Open the cold trap.9.4.2
32、 Continue the total evacuation until the pressure gaugereads below 10 Pa.NOTE 1The manifold system must be passivated with an appropriatefluorinating agent to generate high quality analytical results.10. Calculation of Boron and Silicon Concentration inUF610.1 Calculation of K Value:10.1.1 The calcu
33、lation for K is as follows:Ideal Gas Law PV 5 nRTwhere:P = pressure,V = volume,n = moles,R = gas constant, andT = absolute temperatureandBeers Law OD 5 Cwhere:OD = absorbance, = extinction coefficient, = cell pathlength, andC = concentration.C 5 n/V 5 P/RT and C 5 OD/P/RT 5 OD/K 5 RT 5 OD/Pmole % 5
34、OD/PKK 5 1Kmole % 5 OD 3 K!P and K 5 mole % 3 P!OD10.1.2 Use of a known standard gas (for example, BF3andSiF4) enables the mole % to be known. The actual gas pressurethat produces the absorbance maximum peak (at 1441 wave-numbers or 1029 wavenumbers, respectively) provides three ofthe numbers. With
35、the other three numbers known, K can becalculated.10.2 Calculation of Concentration in UF6:10.2.1 Calculate the partial pressure of BF3(PBF3) and SiF4(PSiF4).PBF35 ODBF3KBF3; PSiF45 OD SiF4K SiF410.2.2 Calculate the mass of UF6(MUF6) by the differenceof bottle mass empty (M1) and after the sampling
36、(M2).MUF6 5 M2 2 M110.2.3 Multiply the mass of UF6by 0.6761 to calculate themass of uranium (MU).MU 5 MUF630.676110.2.4 Divide the mass of UF6by the volumetric mass ofUF6to obtain the volume of UF6(VUF6).VUF65 MUF635.0910.2.5 Subtract the UF6volume from the volume bottle(VB) to calculate the free vo
37、lume (VFB).VFB 5 VB 2 VUF610.2.6 Add the free volume of the bottle, the manifoldvolume (VM) and the cell volume (VC) to have the volume(V).V 5 VFB1VM1VC10.2.7 With the partial pressure and the total volume calcu-late the number of moles of BF3and SiF4.nBF35 PBF33V/RT ; nSiF45 PSiF43V/RT ;10.2.8 Mult
38、iply the number of moles by the molar mass ofB or Si to obtain the mass of B (MB) and the mass of Si (MSi).MB 5 nBF3310.81; MSi 5 nSiF4328.08610.2.9 Divide the mass of B and Si by the U mass to havethe quantity of impurities in g B/g U and g Si/g U.B# 5 MB/MU ;Si# 5 MSi/MU10.2.10 See results for B a
39、nd Si in Table 1 and Table 2.10.2.11 The units used are Pa for pressure, kg for mass, m3for volume, and Kelvin for temperature.11. Precision and Bias11.1 Within the different stages of the nuclear fuel cyclemany challenges lead to the inability to perform interlaboratorystudies for precision and bia
40、s. These challenges may includevariability of matrices of material tested, lack of suitablereference or calibration materials, limited laboratories perform-ing testing, shipment of materials to be tested, and regulatoryconstraints. Because of this each individual laboratory utilizingTABLE 1 Result o
41、f Boron Concentration in UF6Analysis pressure (kPa) 12BF3pressure (Pa) 0,16Mass of UF6(g) 400Volume of UF6(mL) 78,43Bottle volume (mL) 150Empty volume in the bottle (mL) 71,57Total volume (mL) 2021,57Mol number of BF31,30.10-7Mass of BF3(g) 1,41Mass of U (g) 270,44B concentration (g/gU) 0,0052C1842
42、164this test method should develop their own precision and bias aspart of their quality assurance program.11.2 Precision:11.2.1 The precision has been determined to be about 1 %(average over ten measures).11.2.2 The precision is determined by the following equa-tion:P 5tsx=n*100where:t = student coe
43、fficient at 95 % confidence,s = standard deviation,x = average of measurements, andn = number of measurements.11.2.3 The precision has been determined after ten measure-ments at 100 Pa: (1) the BF3precision (P) is 0.7 % in the rangeof 0 to 150 Pa (cf Table 3), (2) the SiF4precision (P) is 0.4 %in th
44、e range of 0 to 150 Pa (cf Table 4).11.3 Limit of Quantification:11.3.1 Perform ten measurements with the empty cell torecord the blank measure. Fig. 4 shows the background.Record the max and min values of OD (cf Table 5 and Table 6)and calculate the blank OD (OD max OD min).11.3.2 The limit of quan
45、tification (LOQ) is determined bythe following equation:LOQ 510 BlankKwhere:10 Blank = 10 standard deviation of blank, andK = infrared absorbance constant in pressure units1/Pa, K = OD/Pressure.11.3.3 The limits of quantification are reported in Table 7.11.4 Correction of Impurities in the Solid Pha
46、se:11.4.1 At equilibrium, the amount of impurity in the solidphase depends on the vapor pressure of the compounds, thefree volume (volume occupied by the gas phase inside thebottle) and the temperature.11.4.2 For example, in Table 8, the repartition of BF3between the solid and gas phases is presente
47、d at four tempera-tures for a free volume of 92 % of the total volume. The alphacoefficient corresponds to the ratio of BF3concentration in thegas phase divided by concentration in the solid phase. 5 BF3in the gas phase ppm/U! /BF3in the solid phase ppm/U!11.4.3 Alpha can be calculated theoretically
48、, using the ratioof vapor pressures of BF3and UF6. It can also be measuredexperimentally.11.4.4 When the free volume decreases, the proportion ofBF3in the solid phase increases. It reaches a maximum for theminimum permissible volume in a 1S bottle, as seen in Table9.11.4.5 Having quantified the amou
49、nt of impurity in the gasphase using Section 10, it is the responsibility of the user tomake the correction for the impurity in the solid phase. Table10 presents the typical correction of SiF4and BF3. For SiF4,the correction is limited and SiF4in the gas phase representsmore than 94 % of the total.11.4.6 If the bottle has been filled during sampling withliquid UF6and cooled down to room temperature to solidifyUF6, the question of when we reach the thermodynamicequilibrium can be raised due to low diffusion coeff
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