Year
2006
Abstract
CANBERRA has recently supplied Nucleco SpA with a new Passive/Active Neutron Waste Assay System (PANWAS) for use at their waste management facility in Casaccia, Italy. The system has already completed its first major measurement campaign in which it was used, in conjunction with two existing CANBERRA high resolution gamma spectrometry waste assay systems, to carry out the physical inventory taking of safeguarded nuclear material contained in approximately 700 drums of waste held at the Nucleco facility. A review of the system performance following installation on the Casaccia site identified a number of potential modifications to the PANWAS that could bring about improvements to the system's detection limits for fissile material that would be necessary for future, more demanding, measurement applications. As a result of this work, a number of these modifications have now been implemented and have been found to deliver worthwhile improvements to the system's sensitivity to fissile material. This paper describes the main characteristics of the PANWAS and the process used to identify and select the most practicable modifications that were likely to provide the greatest improvements in measurement sensitivity in both its passive and active modes of operation. It describes how these modifications were carried out and how their impact on the system calibration was determined so that the necessary changes to the system calibration parameters could be made and the system performance evaluated before bringing the PANWAS back into service ready for a new measurement campaign starting in 2006.