ASTM E705-13a
采用镎237的放射激活性测量反应速率的标准试验方法

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

被代替

标准号

ASTM E705-13a

发布

2013年

发布单位

美国材料与试验协会

替代标准

ASTM E705-18

当前最新

ASTM E705-18

 

 

引用标准

ASTM E1005 ASTM E1018 ASTM E170 ASTM E181 ASTM E261 ASTM E262 ASTM E320 ASTM E393 ASTM E704 ASTM E844 ASTM E944

适用范围

5.1 Refer to Practice E261 for a general discussion of the determination of fast-neutron fluence rate with fission detectors.

5.2 ²³⁷Np is available as metal foil, wire, or oxide powder. For further information, see Guide E844. It is usually encapsulated in a suitable container to prevent loss of, and contamination by, the 8201;²³⁷Np and its fission products.⁴

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

5.3.1 ¹³⁷Cs-^137mBa is chosen frequently for long irradiations. Radioactive products ¹³⁴Cs and 8201;¹³⁶Cs may be present, which can interfere with the counting of the 0.662 MeV 8201;¹³⁷Cs-^137mBa gamma ray (see Test Methods E320).

5.3.2 ¹⁴⁰Ba-¹⁴⁰La is chosen frequently for short irradiations (see Test Method E393).

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

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

5.4 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 8201;²³⁸Np and 8201;²³⁸Pu from (n,γ) reactions in the 8201; ²³⁷Np material. Assay of 8201;²³⁸Pu and 8201; ²³⁹Pu concentration is recommended when a significant contribution is expected.

5.4.1 Fission product production in a light-water reactor by neutron activation products 8201;²³⁸Np and 8201; ²³⁸Pu has been calculated to be insignificant (1.28201;%), compared to that from 8201;²³⁷Np(n,f), for an irradiation period of 12 years at a fast neutron (E gt; 1 MeV) fluence rate of 18201;×8201;10¹¹ cm⁻² ·s⁻¹, provided the 8201;²³⁷Np is shielded from thermal neutrons (see Fig.8201;2 of Guide E844).

5.4.2 Fission product production from photonuclear reactions, that is, (γ,f) reactions, while negligible near-power and research reactor cores, c......

<......

ASTM E705-13a相似标准

推荐