Standard Test Method for Determination of Plutonium Isotopic Composition by Gamma-Ray Spectrometry

Importancia y uso:

4.1 The determination of plutonium isotopic composition by gamma-ray spectrometry is a nondestructive technique and when used with other nondestructive techniques, such as calorimetry (Test Method C1458) or neutron counting (Test Methods C1207, C1316, C1493, and C1500), can provide a wholly nondestructive plutonium assay necessary for material accountancy and safeguards needs.

4.2 Because gamma-ray spectrometry systems are typically automated, the routine use of the test method is fast, reliable, and is not labor intensive. The test method is nondestructive, requires no sample preparation, and does not create waste disposal problems.

4.3 This test method assumes that all plutonium in the measured item has the same isotopic distribution, often called isotopic homogeneity (see 7.2.4 and 7.2.5).

4.4 The ²⁴²Pu abundance is not measured by this test method and must be estimated from isotopic correlation techniques, stream averages, historical information, or other measurement techniques.

4.5 Americium-241 is a daughter product of  ²⁴¹Pu. The ²⁴¹Am/²³⁹Pu atom ratio can also be determined by means of this test method (assuming a homogeneous isotopic distribution of plutonium and ²⁴¹Am). The determination of the ²⁴¹Am/²³⁹Pu atom ratio is necessary for the correct interpretation of a calorimetric heat measurement.

4.6 The isotopic composition of a given batch or item of plutonium is an attribute of that item and, once determined, can be used in subsequent inventory measurements to verify the identity of an item within the measurement uncertainties.

4.7 The method can also measure the ratio of other gamma-emitting isotopes to plutonium assuming they have the same spatial distribution as the plutonium in the item. Some of these “other” gamma-emitting isotopes include isotopes of uranium, neptunium, curium, cesium, and other fission products. The same methods of this standard can be used to measure the isotopic composition of uranium in items containing only uranium (3, 4, 5, 6).

Subcomité:

C26.10

Referida por:

C1490-14R23, C1458-16, C1718-10R19, C1514-08R17, C1207-10R18, C1316-08R17, C1592_C1592M-21, C1133_C1133M-10R18, C1500-08R17, C1493-19, C1931-23

Volúmen:

12.01

Número ICS:

27.120.30 (Fissile materials and nuclear fuel technology)

Palabras clave:

americium-241; calorimetry; gamma-ray spectrometry; isotopics; neutron counting; nondestructive assay; plutonium; special nuclear material; uranium ;