Full Description

1.1This test method describes the nondestructive assay of plutonium in forms such as metal, oxide, scrap, residue, or waste using passive neutron multiplicity counting. This test method provides results that are usually more accurate than conventional neutron coincidence counting. The method can be applied to a large variety of plutonium items in various containers including cans, 208-L drums, or 1900-L Standard Waste Boxes. It has been used to assay items whose plutonium content ranges from 1 g to 1000s of g.

1.2There are several electronics or mathematical approaches available for multiplicity analysis, including the multiplicity shift register, the Euratom Time Correlation Analyzer, and the List Mode Module, as described briefly in Ref. (1).2

1.3This test method is primarily intended to address the assay of²⁴⁰Pu-effective by moments-based multiplicity analysis using shift register electronics (1, 2, 3) and high efficiency neutron counters specifically designed for multiplicity analysis.

1.4This test method requires knowledge of the relative abundances of the plutonium isotopes to determine the total plutonium mass (See Test Method C1030).

1.5This test method may also be applied to modified neutron coincidence counters (4) which were not specifically designed as multiplicity counters (that is, HLNCC, AWCC, etc), with a corresponding degradation of results.

1.6The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.7This 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.