1.1 This test method describes the nondestructive assay of scrap or waste for plutonium content using passive thermal-neutron coincidence counting. This test method provides rapid results and can be applied to a variety of carefully sorted materials in containers as large as 208-L drums. The test method applies to measurements of ²³⁸Pu, ²⁴⁰Pu, and ²⁴²Pu and has been used to assay items whose total plutonium content ranges from 0.01 to 6000 g (1).

1.2 This test method requires knowledge of the relative abundances of the plutonium isotopes to determine the total plutonium mass.

1.3 This test method may not be applicable to the assay of scrap or waste containing other spontaneously fissioning nuclides.

1.3.1 This test method may give biased results for measurements of containers that include large amounts of hydrogenous materials.

1.3.2 The techniques described in this test method have been applied to materials other than scrap and waste (2, 3).

1.4 This test method assumes the use of shift-register-based coincidence technology (4).

1.5 Several other techniques that are related to passive neutron coincidence counting exist These include neutron multiplicity counting (5,6), add-a-source analysis (7), and cosmic-ray rejection (8). Discussions of these techniques are not included in this method.

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.