ASTM E705-08
Standard Test Method for Measuring Reaction Rates by Radioactivation of Neptunium-237
- Standard No.
- ASTM E705-08
- Release Date
- 2008
- Published By
- American Society for Testing and Materials (ASTM)
- Status
- Replace By
- ASTM E705-13
- Latest
- ASTM E705-18
- Scope
Refer to Practice E 261
for a general discussion of the determination of fast-neutron fluence rate with fission detectors. 237Np is available as metal foil, wire, or oxide powder. For further information, see Guide E 844
. It is usually encapsulated in a suitable container to prevent loss of, and contamination by, the 237Np 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.
137Cs-137mBa is chosen frequently for long irradiations. Radioactive products 134Cs and 136Cs may be present, which can interfere with the counting of the 0.662 MeV 137Cs-137mBa gamma ray (see Test Methods E 320
). 140Ba-140La is chosen frequently for short irradiations (see Test Method E 393
). 95Zr can be counted directly, following chemical separation, or with its daughter 95Nb, using a high-resolution gamma detector system.
144Ce is a high-yield fission product applicable to 2- to 3-year irradiations.
It is necessary to surround the 237Np monitor with a thermal neutron absorber to minimize fission product production from trace quantities of fissionable nuclides in the 237Np target and from 238Np and 238Pu from (n,γ) reactions in the 237Np material. Assay of 238Pu and 239Pu concentration is recommended when a significant contribution is expected.
Fission product production in a light-water reactor by neutron activation products 238Np and 238Pu has been calculated to be insignificant (1.2 %), compared to that from 237Np(n,f), for an irradiation period of 12 years at a fast neutron (E > 1 MeV) fluence rate of 1 × 1011 cm−2·s−1, provided the 237Np 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 researchreactor cores, can be large for deep-water penetrations (1).
Good agreement between neutron fluence measured by 237Np fission and the 54Fe(n,p)54Mn reaction has been demonstrated (2). The reaction 237Np(n,f) F.P. is useful since it is responsive to a broader range of neutron energies than most threshold detectors.
The 237Np fission neutron spectrum-averaged cross section in several benchmark neutron fields are given in Table 3 of Practice E 261
. Sources for the latest recommended cross sections are given in Guide E 1018 . In the case of the 237Np(n,f)F.P. reaction, the recommended cross section source is the ENDF/B-VI cross section (MAT = 9346) revision 1 (3). Fig. 1 shows a plot of the recommended cross section versus neutron energy for the fast-neutron reaction 237Np(n,f)F.P. Note 18212;The data are taken from the Evaluated Nuclear Data file, ENDF/B-VI, rather than the later ENDF/B-VII. This is in accordance with Guide E 1018
Guide for Application of ASTM Evaluated Cross Section Data File, 6.1. since the later ENDF/B-VII data files do not include covariance information. For more details s......<......
ASTM E705-08 Referenced Document
- ASTM E1005 Standard Test Method for Application and Analysis of Radiometric Monitors for Reactor Vessel Surveillance, E 706(IIIA)
- ASTM E1018 Standard Guide for Application of ASTM Evaluated Cross Section Data File, Matrix E 706 (IIB)
- ASTM E170 Standard Terminology Relating to Radiation Measurements and Dosimetry
- ASTM E181 Standard Test Methods for Detector Calibration and Analysis of Radionuclides
- ASTM E261 Standard Practice for Determining Neutron Fluence, Fluence Rate, and Spectra by Radioactivation Techniques
- ASTM E262 Standard Method for Determining Thermal Neutron Reaction and Fluence Rates by Radioactivation Techniques
- ASTM E320 Test Method for Cesium-137 in Nuclear Fuel Solutions by Radiochemical Analysis
- ASTM E393 Standard Test Method for Measuring Reaction Rates by Analysis of Barium-140 From Fission Dosimeters
- ASTM E704 Standard Test Method for Measuring Reaction Rates by Radioactivation of Uranium-238
- ASTM E844 Standard Guide for Sensor Set Design and Irradiation for Reactor Surveillance, E 706(IIC)
- ASTM E944 Standard Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance, (IIA)
ASTM E705-08 history
- 2018 ASTM E705-18 Standard Test Method for Measuring Reaction Rates by Radioactivation of Neptunium-237
- 2013 ASTM E705-13a Standard Test Method for Measuring Reaction Rates by Radioactivation of Neptunium-237
- 2013 ASTM E705-13 Standard Test Method for Measuring Reaction Rates by Radioactivation of Neptunium-237
- 2008 ASTM E705-08 Standard Test Method for Measuring Reaction Rates by Radioactivation of Neptunium-237
- 1996 ASTM E705-96(2002) Standard Test Method for Measuring Reaction Rates by Radioactivation of Neptunium-237
- 1996 ASTM E705-96 Standard Test Method for Measuring Reaction Rates by Radioactivation of Neptunium-237
