Cross-Talk Characterization in Passive Neutron Coincidence Counting of Radioactive Waste Drums With Plastic Scintillators

This paper reports on a numerical feasibility study of a passive neutron coincidence counting system for radioactive waste drums with plastic scintillators. The motivation is to replace 3 He gas counters generally used for this type of measurement. Indeed, plastic scintillators present several advan...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on nuclear science 2016-06, Vol.63 (3), p.1513-1519
Main Authors: Simony, B., Deyglun, C., Perot, B., Carasco, C., Saurel, N., Colas, S., Collot, J.
Format: Article
Language:English
Subjects:
Detectors
Feasibility studies
Gamma rays
Glass
Instrumentation and Detectors
Lead
Neutrons
Physics
Plastics
Sensors
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:This paper reports on a numerical feasibility study of a passive neutron coincidence counting system for radioactive waste drums with plastic scintillators. The motivation is to replace 3 He gas counters generally used for this type of measurement. Indeed, plastic scintillators present several advantages for the measurement of neutron coincidences such as a good efficiency for detecting fast neutrons, short detection time, and low cost comparatively to 3 He. However, unlike 3 He counters, their high sensitivity to gamma rays and cross talk constitutes a drawback as parasite random and true coincidences are detected together with the useful signal of plutonium. Simulations are performed using the Monte Carlo transport code MCNPX-PoliMi v2.0 coupled to data processing algorithms developed with ROOT data analysis software. Performances of the coincidence counting system are studied for the case of a vitrified waste drum containing Pu and 241 Am, focusing particularly on multiplicity 1 and 2, i.e., 2 or 3 pulses recorded in a short time gate in different detectors. Cross talk induced by neutrons and gamma rays has been characterized in terms of time and distance between detectors, and strategies to limit this phenomenon are reported, consisting of ignoring neighboring detectors signal. A significant improvement of the Pu to 241 Am ratio for multiplicity 2 coincidences has thus been obtained, at the expense of counting statistics. Alternative case studies with organic and metallic matrixes of technological wastes are also reported, for which the part of useful signal of plutonium is significantly higher, showing the feasibility of the measurement method.
ISSN:0018-9499
1558-1578
DOI:10.1109/TNS.2016.2542290