ASTM E526 - 08(2013)

    Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Titanium

    Active Standard ASTM E526 | Developed by Subcommittee: E10.05

    Book of Standards Volume: 12.02


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    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.

    Ti(n,X)Sc Cross Section
(Normalized per Ti-46 Atom)
    FIG. 1 NatTi(n,X)46Sc Cross Section (Normalized per Ti-46 Atom)

    1. 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 1Since 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.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    E170 Terminology Relating to Radiation Measurements and Dosimetry

    E181 Test Methods for Detector Calibration and Analysis of Radionuclides

    E261 Practice for Determining Neutron Fluence, Fluence Rate, and Spectra by Radioactivation Techniques

    E262 Test Method for Determining Thermal Neutron Reaction Rates and Thermal Neutron Fluence Rates by Radioactivation Techniques

    E844 Guide for Sensor Set Design and Irradiation for Reactor Surveillance, E 706 (IIC)

    E944 Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance, E 706 (IIA)

    E1005 Test Method for Application and Analysis of Radiometric Monitors for Reactor Vessel Surveillance, E 706 (IIIA)

    E1018 Guide for Application of ASTM Evaluated Cross Section Data File, Matrix E706 (IIB)


    ICS Code

    ICS Number Code 17.240 (Radiation measurements); 27.120.30 (Fissile materials and nuclear fuel technology)

    UNSPSC Code

    UNSPSC Code 26142004(Neutron irradiators); 26142108(Nuclear reactor in core neutron flux instrumentation)


    DOI: 10.1520/E0526-08R13

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