ASTM C 1133 : 1996

1.1 This test method covers the nondestructive assay of gamma-ray emitting special nuclear materials (SNMs) in low-density scrap or waste, packaged in cylindrical containers (with measured transmission values greater than 1%). High resolution gamma-ray spectroscopy is used to detect and measure the nuclides of interest and to measure and correct for average gamma-ray attenuation in discrete vertical segments of the container. Corrections are also made for counting losses occasioned by signal processing characteristics (1-3).

1.2 Two conditions must be met to optimize assay results as follows:

1.2.1 The particles containing the nuclides of interest must be small to minimize self absorption of emitted gamma radiation.

1.2.2 The mixture of material within a package segment must be reasonably uniform in order to apply an attenuation correction factor, computed from a single measurement of item transmission through the segment.

1.3 The assay technique may be applicable to loadings of from one to several hundred grams of nuclide with more restricted ranges to be applicable, depending on specific packaging and counting equipment considerations. Measured transmission values must be greater than 1% to permit valid attenuation corrections.

1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.5 This standard may involve hazardous materials, operations, and equipment. 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. Specific precautionary statements are given in Section 9.