Development and evaluation of a list mode neutron coincidence collar for spatial response measurements of fresh fuel assemblies

A. S. Moore, L. G. Worrall, C. Britton, S. Croft, K. Dayman, M. N. Ericson, R. D. McElroy, A. D. Nicholson, G. Nutter, R. B. Warmack, J. P. Hayward

Research output: Contribution to journalArticlepeer-review

Abstract

The capabilities of current safeguards neutron instrumentation can be expanded by acquiring and analyzing data in new ways. A new List Mode Collar (LMCL) was created by retrofitting a traditional safeguards neutron coincidence counting system, the Neutron Coincidence Collar, with newly developed preamplifiers on each of its 18 3He tubes in active interrogation mode. By applying list mode data acquisition (LMDA) and analysis, a signal from each 3He tube can now be recorded and analyzed to determine the neutron count rate measured in each individual 3He tube. Further, the count rate distribution across all 3He tube locations in the system can be determined. This is the first time that a full list mode method has been implemented using a traditional neutron coincidence collar and spatial response data has been obtained. The objective of this research was to develop and evaluate a laboratory demonstration list mode neutron coincidence collar (LMCL) that can extract a greater number of useful signatures than are currently generated using the current collar. A new analysis method called the “List Mode Response Matrix” has also been developed for use in combination with these measurements to improve the detection of missing fuel pins (partial defects) during the nondestructive assay of fresh nuclear fuel assemblies, although analysis algorithms will be reported separately from this experimental evaluation. In this paper, 18 channel spatial response data are presented for a 252Cf source moving within the LMCL detector cavity. LMDA, combined with the addition of multiple preamplifiers, facilitates this capability by increasing the number of signals that can be measured simultaneously; allowing for in-depth analysis of neutron coincidence events to determine the location and distribution of nuclear material within the measurement geometry. This approach enables a spatial response measurement to form a “pattern” or item signature unique to the fissioning source's distribution; in the case of the LMCL, the distribution of fresh low-enriched uranium fuel within the assembly. A major benefit provided by LMDA is that this can all be achieved from a single measurement pulse train in offline analysis. To experimentally demonstrate this concept, a Mirion Technologies (Canberra) model JCC-71 Neutron Coincidence Collar has been retrofitted with new electronics designed at Oak Ridge National Laboratory. This paper presents the results from the experimental evaluation of the laboratory demonstration system. The results indicate equivalent performance of the LMCL to the original collar in addition to improved spatial response capabilities, while maintaining the original system footprint.

Funding

This material is based upon work supported by the United States Department of Energy (DOE), National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (DNN) Research and Development (R&D) under the project OR16-List Mode for Collar-PD1La “List Mode Response Matrix for Advanced Correlated Neutron Analysis for Nuclear Safeguards”. Funding support was also provided through the Nuclear Science and Security Consortium under Award Number DE-NA0003180 and DE-NA0000979. This paper was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or limited, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. This material is based upon work supported by the United States Department of Energy (DOE) , National Nuclear Security Administration (NNSA) , Office of Defense Nuclear Nonproliferation (DNN) Research and Development (R&D) under the project OR16-List Mode for Collar-PD1La “List Mode Response Matrix for Advanced Correlated Neutron Analysis for Nuclear Safeguards”. Funding support was also provided through the Nuclear Science and Security Consortium under Award Number DE-NA0003180 and DE-NA0000979 .

Keywords

  • List mode data acquisition
  • Multichannel analysis
  • Neutron coincidence collar
  • Neutron coincidence counter
  • Safeguards
  • Spatial response

Fingerprint

Dive into the research topics of 'Development and evaluation of a list mode neutron coincidence collar for spatial response measurements of fresh fuel assemblies'. Together they form a unique fingerprint.

Cite this