ASTM-E704 2008(Redline)

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E704-08 Standard Test Method for Measuring Reaction Rates by Radioactivation of Uranium-238 (Redline)

Published By	Publication Date	Number of Pages
ASTM	2008	5

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Categories: 27.120.30 - Fissile materials and nuclear fuel technology, ASTM

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Description

Significance and Use

Refer to Practice E 261 for a general discussion of the determination of fast-neutron fluence rate with fission detectors.

²³⁸ U is available as metal foil, wire, or oxide powder (see Guide E 844). It is usually encapsulated in a suitable container to prevent loss of, and contamination by, the ²³⁸ U and its fission products.

One or more fission products can be assayed. Pertinent data for relevant fission products are given in Table 1 and Table 2.

¹³⁷ Cs- ^137m Ba is chosen frequently for long irradiations. Radioactive products ¹³⁴ Cs and ¹³⁶ Cs may be present, which can interfere with the counting of the 0.662 MeV ¹³⁷ Cs- ¹³⁷ , Ba gamma rays (see Test Methods E 320).

¹⁴⁰ Ba- ¹⁴⁰ La is chosen frequently for short irradiations (see Test Method E 393).

⁹⁵ Zr can be counted directly, following chemical separation, or with its daughter ⁹⁵ Nb using a high-resolution gamma detector system.

¹⁴⁴ Ce is a high-yield fission product applicable to 2- to 3-year irradiations.

It is necessary to surround the ²³⁸ U monitor with a thermal neutron absorber to minimize fission product production from a quantity of ²³⁵ U in the ²³⁸ U target and from ²³⁹ Pu from (n, γ ) reactions in the ²³⁸ U material. Assay of the ²³⁹ Pu concentration when a significant contribution is expected.

Fission product production in a light-water reactor by neutron activation product ²³⁹ Pu has been calculated to be insignificant ( < 2 %), compared to that from ²³⁸ U(n,f), for an irradiation period of 12 years at a fast-neutron ( E > 1 MeV) fluence rate of 1 × 10 ¹¹ cm ^{− 2} · s ^{− 1} provided the ²³⁸ U is shielded from thermal neutrons (see Fig. 2 of Guide E 844).

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 (1) .

1. Scope

1.1 This test method covers procedures for measuring reaction rates by assaying a fission product (F.P.) from the fission reaction ²³⁸ U(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.

1.3 Equivalent fission neutron fluence rates as defined in Practice E 261 can be determined.

1.4 Detailed procedures for other fast-neutron detectors are referenced in Practice E 261.

1.5 The values stated in SI units are to be regarded as standard. No other unites 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 E320 Test Method for Cesium-137 in Nuclear Fuel Solutions by Radiochemical Analysis E393 Test Method for Measuring Reaction Rates by Analysis of Barium-140 From Fission Dosimeters 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

Neutron activation reactions; Radioactivation–fast neutron flux; Threshold detectors–1.5 to 7 MeV; Uranium; Uranium-238; Fast neutron flux/fluence; Neutron activation reactions; Radioactivation–fast neutron flux; Threshold detectors–1.5 to 7 MeV; Uranium; Uranium-238; Fast neutron flux/fluence-;

ICS Code

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

Additional information

Standard Title	E704-08 Standard Test Method for Measuring Reaction Rates by Radioactivation of Uranium-238 (Redline)
Published Code	ASTM
Publication Date	2008
Pages Count	5
ICS Codes	27.120.30 - Fissile materials and nuclear fuel technology

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ASTM-E704 2008(Redline)

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