1. Scope

1.1 This test method describes two procedures for the measurement of reaction rates by determining the amount of the fission product ¹⁴⁰ Ba produced by the non-threshold reactions ²³⁵ U (n, f), ²⁴¹ Am (n, f), and ²³⁹ Pu (n, f), and by the threshold reactions ²³⁸ U (n, f), ²³⁷ Np (n, f), and ²³² Th (n, f).

1.2 These reactions produce many fission products, among which is ¹⁴⁰ Ba, having a half-life of 12.752 days. ¹⁴⁰ Ba emits gamma rays of several energies; however, these are not easily detected in the presence of other fission products. Competing activity from other fission products requires that a chemical separation be employed or that the ¹⁴⁰ Ba activity be determined indirectly by counting its daughter product ¹⁴⁰ La. This test method describes both procedure ( a ), the nondestructive determination of ¹⁴⁰ Ba by the direct counting of ¹⁴⁰ La several days after irradiation, and procedure ( b ), the chemical separation of ¹⁴⁰ Ba and the subsequent counting of ¹⁴⁰ Ba or its daughter ¹⁴⁰ La.

1.3 With suitable techniques, fission neutron fluence rates can be measured in the range from 10 ⁷ n (neutrons) cm ² s ¹ to approximately 10 ¹⁵ n cm ² s ¹ .

1.4 The measurement of time-integrated reaction rates with fission dosimeters by ¹⁴⁰ Ba analysis is limited by the half-life of ¹⁴⁰ Ba to irradiation times up to about six weeks.

1.5 The values stated in SI units are to be regarded as 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

C697 Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Plutonium Dioxide Powders and Pellets

D1193 Specification for Reagent Water

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

E704 Test Method for Measuring Reaction Rates by Radioactivation of Uranium-238

E705 Test Method for Measuring Reaction Rates by Radioactivation of Neptunium-237

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)

Keywords

Barium-140; fission dosimeter; fission product; fission reaction rates;

ICS Code

ICS Number Code 17.240 (Radiation measurements)

DOI: 10.1520/E0393-96R02

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