ASTM E526-08(2013)
(Test Method)Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Titanium
Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Titanium
SIGNIFICANCE AND USE
5.1 Refer to Guide E844 for the selection, irradiation, and quality control of neutron dosimeters.
5.2 Refer to Test Method E261 for a general discussion of the determination of fast-neutron fluence rate with threshold detectors.
5.3 Titanium has good physical strength, is easily fabricated, has excellent corrosion resistance, has a melting temperature of 1675°C, and can be obtained with satisfactory purity.
5.4 46Sc has a half-life of 83.79 days.3 The 46Sc decay4 emits a 0.8893 MeV gamma 99.984 % of the time and a second gamma with an energy of 1.1205 MeV 99.987 % of the time.
5.5 The isotopic content of natural titanium recommended for 46Ti is 8.25 %.3
5.6 The radioactive products of the neutron reactions 47Ti(n,p)47Sc (τ1/2 = 3.3492 d) and 48Ti(n,p)48Sc (τ1/2 = 43.67 h), might interfere with the analysis of 46Sc.
5.7 Contaminant activities (for example, 65Zn and 182Ta) might interfere with the analysis of 46Sc. See Sections 7.1.2 and 7.1.3 for more details on the 182Ta and 65Zn interference.
5.8 46Ti and 46Sc have cross sections for thermal neutrons of 0.59 and 8 barns, respectively5; therefore, when an irradiation exceeds a thermal-neutron fluence greater than about 2 × 1021 cm–2, provisions should be made to either use a thermal-neutron shield to prevent burn-up of 46Sc or measure the thermal-neutron fluence rate and calculate the burn-up.
5.9 Fig. 1 shows a plot of cross section versus neutron energy for the fast-neutron reactions of titanium which produce 46Sc [that is, NatTi(n,X)46Sc]. Included in the plot is the 46Ti(n,p) reaction6 and the 47Ti(n,np) contribution to the 46Sc production,7 normalized (at 14.7 MeV)8 per 46Ti atom. This figure is for illustrative purposes only to indicate the range of response of the 46Ti(n,p) reaction. Refer to Guide E1018 for descriptions of recommended tabulated dosimetry cross sections.
FIG. 1 NatTi(n,X)46Sc Cross Section (Normalized per Ti-46 Atom)
SCOPE
1.1 This test method covers procedures for measuring reaction rates by the activation reactions 46Ti(n,p) 46Sc + 47Ti(n, np)46Sc.Note 1—Since the cross section for the (n,np) reaction is relatively small for energies less than 12 MeV and is not easily distinguished from that of the (n,p) reaction, this test method will refer to the (n,p) reaction only.
1.2 The reaction is useful for measuring neutrons with energies above approximately 4.4 MeV and for irradiation times up to about 250 days (for longer irradiations, see Practice E261).
1.3 With suitable techniques, fission-neutron fluence rates above 109 cm–2·s–1 can be determined. However, in the presence of a high thermal-neutron fluence rate, 46Sc depletion should be investigated.
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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E526 − 08 (Reapproved 2013)
Standard Test Method for
Measuring Fast-Neutron Reaction Rates by Radioactivation
of Titanium
This standard is issued under the fixed designation E526; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E181Test Methods for Detector Calibration andAnalysis of
Radionuclides
1.1 This test method covers procedures for measuring reac-
46 46 47 E261Practice for Determining Neutron Fluence, Fluence
tion rates by the activation reactions Ti(n,p) Sc + Ti(n,
Rate, and Spectra by Radioactivation Techniques
np) Sc.
E262Test Method for Determining Thermal Neutron Reac-
NOTE 1—Since the cross section for the (n,np) reaction is relatively
tion Rates and Thermal Neutron Fluence Rates by Radio-
small for energies less than 12 MeV and is not easily distinguished from
activation Techniques
that of the (n,p) reaction, this test method will refer to the (n,p) reaction
E844Guide for Sensor Set Design and Irradiation for
only.
Reactor Surveillance, E 706 (IIC)
1.2 The reaction is useful for measuring neutrons with
E944Guide for Application of Neutron Spectrum Adjust-
energies above approximately 4.4 MeV and for irradiation
ment Methods in Reactor Surveillance, E 706 (IIA)
timesuptoabout250days(forlongerirradiations,seePractice
E1005Test Method for Application and Analysis of Radio-
E261).
metric Monitors for Reactor Vessel Surveillance, E 706
1.3 With suitable techniques, fission-neutron fluence rates
(IIIA)
9 –2 –1
above 10 cm ·s can be determined. However, in the pres-
E1018Guide for Application of ASTM Evaluated Cross
ence of a high thermal-neutron fluence rate, Sc depletion
Section Data File, Matrix E706 (IIB)
should be investigated.
1.4 Detailed procedures for other fast-neutron detectors are
3. Terminology
referenced in Practice E261.
3.1 Definitions:
1.5 The values stated in SI units are to be regarded as
3.1.1 Refer to Terminology E170.
standard. No other units of measurement are included in this
standard.
4. Summary of Test Method
1.6 This standard does not purport to address all of the
4.1 High-purity titanium is irradiated in a fast-neutron field,
safety concerns, if any, associated with its use. It is the
46 46 46
thereby producing radioactive Sc from the Ti(n,p) Sc
responsibility of the user of this standard to establish appro-
activation reaction.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4.2 The gamma rays emitted by the radioactive decay of
Sc are counted in accordance with Methods E181 and the
2. Referenced Documents
reaction rate, as defined by Test Method E261, is calculated
2.1 ASTM Standards:
from the decay rate and the irradiation conditions.
E170Terminology Relating to Radiation Measurements and
4.3 The neutron fluence rate above about 4.4 MeV can then
Dosimetry
be calculated from the spectral-weighted neutron activation
cross section as defined by Test Method E261.
ThistestmethodisunderthejurisdictionofASTMCommitteeE10onNuclear
Technology and Applicationsand is the direct responsibility of Subcommittee
5. Significance and Use
E10.05 on Nuclear Radiation Metrology.
Current edition approved Jan. 1, 2013. Published January 2013. Originally
5.1 Refer to Guide E844 for the selection, irradiation, and
approved in 1976. Last previous edition approved in 2008 as E526–08. DOI:
quality control of neutron dosimeters.
10.1520/E0526-08R13.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.2 Refer to Test Method E261 for a general discussion of
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
the determination of fast-neutron fluence rate with threshold
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. detectors.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E526 − 08 (2013)
7 8 46
5.3 Titanium has good physical strength, is easily production, normalized (at 14.7 MeV) per Ti atom. This
fabricated, has excellent corrosion resistance, has a melting figure is for illustrative purposes only to indicate the range of
temperature of 1675°C, and can be obtained with satisfactory response of the Ti(n,p) reaction. Refer to Guide E1018 for
purity. descriptions of recommended tabulated dosimetry cross sec-
46 3 46 4 tions.
5.4 Sc has a half-life of 83.79 days. The Sc decay
emitsa0.8893MeVgamma99.984%ofthetimeandasecond
6. Apparatus
gamma with an energy of 1.1205 MeV 99.987% of the time.
6.1 NaI(Tl) or High Resolution Gamma-Ray Spectrometer.
5.5 The isotopic content of natural titanium recommended
46 3
Because of its high resolution, the germanium detector is
for Ti is 8.25%.
useful when contaminant activities are present. See Methods
5.6 The radioactive products of the neutron reactions
E181 and E1005.
47 47 48 48
Ti(n,p) Sc (τ = 3.3492 d) and Ti(n,p) Sc (τ = 43.67
1/2 1/2
6.2 Precision Balance, able to achieve the required accu-
h), might interfere with the analysis of Sc.
racy.
65 182
5.7 Contaminant activities (for example, Zn and Ta)
6.3 Digital Computer, useful for data analysis (optional).
might interfere with the analysis of Sc. See Sections 7.1.2
182 65
and 7.1.3 for more details on the Ta and Zn interference.
7. Materials
46 46
5.8 Ti and Sc have cross sections for thermal neutrons
7.1 Titanium Metal—High-puritytitaniummetalintheform
of 0.59 and 8 barns, respectively ; therefore, when an irradia-
of wire or foil is available.
tion exceeds a thermal-neutron fluence greater than about 2 ×
21 –2
7.1.1 Themetalshouldbetestedforimpuritiesbyaneutron
10 cm , provisions should be made to either use a thermal-
activation technique. If the measurement is to be made in a
neutron shield to prevent burn-up of Sc or measure the
thermal-neutron environment, scandium impurity must be low
thermal-neutron fluence rate and calculate the burn-up.
45 46
because of the reaction, Sc(n,γ) Sc. To reduce this
5.9 Fig. 1 shows a plot of cross section versus neutron
interference, the use of a thermal-neutron shield during irra-
energyforthefast-neutronreactionsoftitaniumwhichproduce
diation would be advisable if scandium impurity is suspected.
46 Nat 46
Sc [that is, Ti(n,X) Sc]. Included in the plot is the
As an example, when a titanium sample containing 6 ppm
46 6 47 46
Ti(n,p)reaction andthe Ti(n,np)contributiontothe Sc
scandium has been irradiated in a neutron field with equal
thermalandfast-neutronfluenceratesabout1%ofthe Scin
45 46
Nuclear Wallet Cards, National Nuclear Data Center, prepared by Jagdish K. the sample is due to the reaction Sc(n,γ) Sc.
Tuli, April 2005.
7.1.2 Tantalum impurities can also cause a problem. The
Evaluated Nuclear Structure Data File (ENSDF), maintained by the National 181 182
low-energy response of the Ta(n,γ) Ta reaction produces
Nuclear Data Center (NNDC), Brookhaven National Laboratory, on behalf of the
gamma activity that interferes with the measurement of Sc
International Network for Nuclear Structure Data Evaluation.
46 46
Nuclear Data retrieval program NUDAT, a computer file of evaluated nuclear
radioactivity produced from the Ti(n,p) Sc high-energy
structure and radioactive decay data, which is maintained by the National Nuclear
threshold reaction. The radioactive Ta isotope has a
Data Center (NNDC), Brookhaven National Laboratory (BNL), on behalf of the
half-life of τ = 114.43 d and emits a 1121.302 keV photon
1/2
InternationalNetworkforNuclearStructureDataEvaluation,whichfunctionsunder
34.7% of the time. This photon is very close in energy to one
theauspicesoftheNuclearDataSectionoftheInternationalAtomicEnergyAgency
(IAEA). The URL is http://www.nndc.bnl.gov/nudat2/indx_sigma.jsp.
of the two photons emitted by Sc (889.3 keV and 1120.5
“International Reactor Dosime
...
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