ASTM E704-13
用铀的放射性活化测量反应速度的标准试验方法

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

被代替

标准号

ASTM E704-13

发布

2013年

发布单位

美国材料与试验协会

替代标准

ASTM E704-19

当前最新

ASTM E704-19

 

 

引用标准

ASTM E1005 ASTM E1018 ASTM E170 ASTM E181 ASTM E261 ASTM E262 ASTM E320 ASTM E393 ASTM E705 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 ²³⁸U is available as metal foil, wire, or oxide powder (see Guide E844). It is usually encapsulated in a suitable container to prevent loss of, and contamination by, the8201;²³⁸U and its fission products.

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 products8201;¹³⁴Cs and8201;¹³⁶Cs may be present, which can interfere with the counting of the 0.662 MeV8201; ¹³⁷Cs-^137mBa gamma rays (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 daughter8201;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 the8201;²³⁸U monitor with a thermal neutron absorber to minimize fission product production from a quantity of8201;²³⁵U in the8201;²³⁸U target and from8201; ²³⁹Pu from (n,γ) reactions in the8201;²³⁸U material. Assay of the8201;²³⁹Pu concentration when a significant contribution is expected.

5.4.1 Fission product production in a light-water reactor by neutron activation product8201;²³⁹Pu has been calculated to be insignificant (lt;28201;%), compared to that from8201;²³⁸U(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 the8201;²³⁸U is shielded from thermal neutrons (see Fig. 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, can be large for deep-water penetrations <......

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