[Show abstract][Hide abstract] ABSTRACT: A muon scattering tomography system which uses extruded plastic scintillator bars for muon tracking and a dedicated muon spectrometer that measures scattering through steel slabs has been constructed and successfully tested. The atmospheric muon detection efficiency is measured to be 97% per plane on average and the average intrinsic hit resolution is 2.5 mm. ln addition to creating a variety of three-dimensional images of objects of interest, a quantitative study has been carried out to investigate the impact of including muon momentum measurements when attempting to detect high-density, high-Z material. As expected, the addition of momentum information improves the performance of the system. For a fixed data-taking time of 60 s and a fixed fake positive fraction, the probability to detect a target increases when momentum information is used. This is the first demonstration of the use of muon momentum information from dedicated spectrometer measurements in muon scattering tomography. Crown Copyright (C) 2015 Published by Elsevier B.V.
No preview · Article · Oct 2015 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: Here we present the development of a compact antineutrino detector for the purpose of nuclear reactor monitoring, improving upon a previously successful design. This paper will describe the design improvements of the detector which increases the antineutrino detection efficiency threefold over the previous effort. There are two main design improvements over previous generations of detectors for nuclear reactor monitoring: dual-ended optical readout and single volume detection mass. The dual-ended optical readout eliminates the need for fiducialization and increases the uniformity of the detector׳s optical response. The containment of the detection mass in a single active volume provides more target mass per detector footprint, a key design criteria for operating within a nuclear power plant. This technology could allow for real-time monitoring of the evolution of a nuclear reactor core, independent of reactor operator declarations of fuel inventories, and may be of interest to the safeguards community.
Full-text · Article · Nov 2014 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: The CRIPT Cosmic Ray Imaging and Passive Tomography system began data taking in September 2012. CRIPT is a “proof of principle” muon tomography system originally proposed to inspect cargo in shipping containers and to determine the presence of special nuclear materials. CRIPT uses 4 layers of 2 m x 2 m scintillation counter trackers, each layer measuring two coordinates. Two layers are used to track the incoming muon and two for the outgoing muon allowing the trajectories of the muon to be determined. The target volume is divided into voxels, and a Point of Closest Approach algorithm is used to determine the number of scattering events in each voxel, producing a 3D image. The system has been tested with various targets of depleted uranium, lead bricks, and tungsten rods. Data on the positional resolution has been taken and the intrinsic resolution is unfolded with the help of a simulation using GEANT4. The next steps include incorporation of data from the spectrometer section, which will assist in determining the muon's momentum and improve the determination of the density of the target.
[Show abstract][Hide abstract] ABSTRACT: A liquid scintillator (LS) based on linear alkyl benzene (LAB) solvent has been characterized using multiple radiation sources. The results confirm that boron-loaded LAB is suitable for neutron detection in a gamma ray environment. To study indirectly the LAB pulse shape discrimination (PSD) capability between neutrons and gamma rays, a dissolved 212Pb source emitting alpha and beta particles was used to emulate the conditions in a mixed radiation field for detecting neutrons in the presence of a high gamma ray background. The quenching factor depends on the alpha energy and increases from 10 to 25 as the alpha energy decreases from 10 to 1 MeV. 10B loaded LAB-based LS has been tested in a neutron beam of energy which is equal to 14.56 meV. The observed peak at 60 keVee is attributed to the absorption of neutrons. Our results show that a boron-loaded LAB-based scintillator is a sensitive medium for neutron detection in a relatively large background of gamma rays. A neutron detector could be achieved with a figure of merit (FOM) of 1.75.
Full-text · Article · Feb 2013 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: This paper explores the use of cosmic ray muons to image the contents of
shielded containers and detect high-Z special nuclear materials inside them.
Cosmic ray muons are a naturally occurring form of radiation, are highly
penetrating and exhibit large scattering angles on high Z materials.
Specifically, we investigated how radiographic and tomographic techniques can
be effective for non-invasive nuclear waste characterization and for nuclear
material accountancy of spent fuel inside dry storage containers. We show that
the tracking of individual muons, as they enter and exit a structure, can
potentially improve the accuracy and availability of data on nuclear waste and
the contents of Dry Storage Containers (DSC) used for spent fuel storage at
CANDU plants. This could be achieved in near real time, with the potential for
unattended and remotely monitored operations. We show that the expected
sensitivity, in the case of the DSC, exceeds the IAEA detection target for
nuclear material accountancy.
Full-text · Article · Oct 2012 · Annals of Nuclear Energy
[Show abstract][Hide abstract] ABSTRACT: Muons, which are produced naturally in the upper atmosphere, can be used to scan cargo for special nuclear materials (SNM). Preliminary simulated results show that detecting the presence of these materials can be accomplished by measuring the scattering of cosmic ray muons. Machine learning tools have been used on these data to classify it as SNM or not. The muon exists long enough, and is penetrating enough, that it can be used to passively scan cargo to detect SNM. By measuring the deflection angles of muons after they exit a container, one can determine whether or not SNM are present. Different detector approaches have been evaluated by considering the performance, cost, and robustness of several technologies. Simulations have been performed to help design the detectors and to determine the effectiveness of the proposed techniques. Realistic cargo containers have been simulated. Two types of techniques can be used to determine whether the cargo containers contain SNM. More traditional methods use an expert system which uses knowledge of physics to compute physical information about the cargo. The other approach is to use Machine Learning classifiers, which can be used to determine if the cargo contains SNM. These techniques include the following algorithms: decision trees, neural networks, special vector machines, and k nearest neighbours. Preliminary results from the two approaches to classification have been obtained and will be discussed in the paper.
[Show abstract][Hide abstract] ABSTRACT: Detecting antineutrinos emitted from nuclear reactors has been
previously demonstrated as a monitor of fuel content and usage. The
continuous fuel cycle of a CANDU on-load reactor presents a unique
challenge for monitoring. We present the calibration and
characterization of a detector designed for this task. The detector will
be deployed Fall 2012 at Point Lepreau Generating Station.
[Show abstract][Hide abstract] ABSTRACT: The Cosmic Ray Inspection and Passive Tomography (CRIPT) project is investigating muon scattering tomography (MST) for applications in border security, nuclear non-proliferation, and nuclear waste characterization. The construction of the full-scale prototype MST system began in the Summer of 2011 and was completed in September 2012. The CRIPT detector employs 12 layers of scintillator to track atmospheric muons before and after passage through a volume of interest, and to estimate each muon's momentum. The total height of the system is 5.5 m and its weight is 20 tonnes. Details of its construction are presented. After the integration of the custom data acquisition electronics, the commissioning of the CRIPT detector began. The first tomographic images were obtained in October 2012 and are presented here.
[Show abstract][Hide abstract] ABSTRACT: AECL has developed and deployed several high gamma radiation field measurement and profiling systems based on commercial off-the-shelf (COTS) silicon diode sensors and components. These systems have been useful in a number of applications including radiation survey of a medical radioisotope production hot-cell, liquid level measurement in a highly radioactive tank, identification of waste location inside nuclear waste storage structures, imaging of reactivity devices inside a shut-down nuclear reactor, and for scanning and imaging highly radioactive reactor components inside a hot-cell in support of an industrial surveillance project. The measurements ranged from 100 uGy/h (10 mRad/h) to 10 kGy/h (1MRad/h), which covers typical radiation fields in hazardous nuclear facilities. This paper summarizes the development and characterization of the Si-diode based detector system, and describes its performance in a variety of applications.
[Show abstract][Hide abstract] ABSTRACT: This study explores the possibility of developing a field-deployable 90Sr detector for rapid lung counting in emergency situations. The detection of beta-emitters 90Sr and its daughter 90Y inside the human lung via bremsstrahlung radiation was performed using a 3″ × 3″ NaI(Tl) crystal detector and a polyethylene-encapsulated
source to emulate human lung tissue. The simulation results show that this method is a viable technique for detecting 90Sr with a minimum detectable activity (MDA) of 1.07 × 104 Bq, using a realistic dual-shielded detector system in a 0.25-µGy h−1 background field for a 100-s scan. The MDA is sufficiently sensitive to meet the requirement for emergency lung counting
of Type S 90Sr intake. The experimental data were verified using Monte Carlo calculations, including an estimate for internal bremsstrahlung,
and an optimisation of the detector geometry was performed. Optimisations in background reduction techniques and in the electronic
acquisition systems are suggested.
Full-text · Article · Mar 2012 · Radiation Protection Dosimetry
[Show abstract][Hide abstract] ABSTRACT: In the last decade, many groups around the world have been exploring different ways to probe transport containers which may contain illicit Special Nuclear Materials such as uranium. The muon tomography technique has been proposed as a cost effective system with an acceptable accuracy. A group of Canadian institutions (see above), funded by Defence Research and Development Canada, is testing different technologies to track the cosmic muons. One candidate is the single wire Drift Chamber. With the capability of a 2D impact position measurement, two detectors will be placed above and two below the object to be probed. In order to achieve a good 3D image quality of the cargo content, a good angular resolution is required. The simulation showed that 1mrad was required implying the spatial resolution of the trackers must be in the range of 1 to 2 mm for 1 m separation. A tracking system using three prototypes has been built and tested. The spatial resolution obtained is 1.7 mm perpendicular to the wire and 3 mm along the wire.
[Show abstract][Hide abstract] ABSTRACT: The CRIPT project brings together several Canadian institutions, concerned with the detection of Special Nuclear Materials (SNM), addressing a requirement at ports-of-entry for detection of SNM in the many thousands of containers that flow into and out of Canada every day, while at the same time providing a way of monitoring the contents of nuclear waste storage containers, for waste management and non-proliferation reasons. The scale of these applications is large — typically tens of cubic metres, requiring detectors that can cover a large area at a minimum cost. The CRIPT project considered drift chambers adapted from high energy physics experience, as one of its technology choices. We report here on the performance of a full scale prototype, which covers an area of 2.4m × 1.2m with only 6 readout channels, and provides a 2D data point with accuracies (in x and z) of around 2 mm
[Show abstract][Hide abstract] ABSTRACT: The smuggling of illicit Special Nuclear Materials (SNM) and Radiological Materials (RM) is a major security concern. Current radiation detection systems for cargo are not sensitive to well-shielded nuclear materials. The Muon Scattering Tomography (MST) method that we are developing might be a solution to this problem. It is based on the measurement of multiple scattering of cosmic ray-induced muons, traversing high-Z materials such as uranium and plutonium. This is possible due to the muons' highly penetrating nature. The technique involves measuring the angular deflections of these muons with charged particle tracking detectors placed around the object to be probed. One candidate detector is the single wire drift chamber. It can measure the 2-D impact position of a muon. The CRIPT (Cosmic Ray Inspection and Passive Tomography) collaboration has performed computer simulations of detectors designed to detect SNM via MST. We have also worked on the development of image reconstruction algorithms, and simulated the performances of different muon spectrometer designs and the response of the drift chambers. In addition to these efforts, the collaboration has built three prototypes which are being tested.
No preview · Article · Oct 2010 · IEEE Nuclear Science Symposium conference record. Nuclear Science Symposium
[Show abstract][Hide abstract] ABSTRACT: A study of more than ten years of reactor trip data, following the installation of Platinum-clad In-Core Flux Detectors at the Point Lepreau Generating Station (PLGS), revealed " anomalous " detector response times. In response to the finding, a fully automated and qualified computer program was developed to analyze detector response. The program analyzes delayed detector response to neutron flux as it deviates from design expectation. The following paper discusses the issues encountered and software development processes followed to ensure adherence to Canadian Standards Association (CSA) N286.7-99.
[Show abstract][Hide abstract] ABSTRACT: An instrument based on a small and inexpensive silicon diode was developed and used to measure, for the first time, the gamma radiation exposure rate within a start-up instrumentation guide tube in a shut down CANDU® reactor undergoing refurbishment. The shape of the measured profile agreed with the expectation; however, the maximum measured exposure rate was about four times higher than the calculation. Two adjuster rods located above the core and adjacent to the guide tube, could be clearly identified from the features of the radiation profile measurement. These measurements provide confirmatory information for the creation of safe and effective radiation work plans and selection of appropriate in-core instrumentation. This technology can be used to accurately measure the positions of irradiated reactor components, such as adjuster rods, pressure tubes, calandria tubes, reactivity control absorbers and other sources of gamma radiation inside a shut down reactor.
[Show abstract][Hide abstract] ABSTRACT: A study of more than ten years of reactor trip data, following the installation of Platinum-clad In-Core Flux Detectors at the Point Lepreau Generating Station (PLGS), revealed "anomalous" detector response times. In response to the finding, a fully automated and qualified computer program was developed to analyze detector response. The program analyzes delayed detector response to neutron flux as it deviates from design expectation. The following paper discusses the issues encountered and software development processes followed to ensure adherence to Canadian Standards Association (CSA) N286.7-99.
[Show abstract][Hide abstract] ABSTRACT: The fission products Iodine-131 and Xenon-133 from medical radioisotope production waste at Atomic Energy Canada Ltd's (AECL) Chalk River Laboratories (CRL) are monitored under AECL's Environmental Protection Plan. At site, most radioactive waste monitoring is done automatically, however a portable system is being developed to gather information about possible localized emissions and support continuous improvements in the emission monitoring program. Considering the operator exposure time to radiation and measurement limitations caused by manual operations, the sampling system has been fully automated. This paper outlines the design and development of the Transportable Automated Iodine and Xenon Sampling System. This system features a fully automated instrument with configuration flexibility, sampling repeatability, reduced operator exposure time to radiation and ease of transportability.
[Show abstract][Hide abstract] ABSTRACT: The Cosmic Ray Inspection and Passive Tomography (CRIPT) project has recently started investigating the detection of illicit Special Nuclear Material in cargo using cosmic ray muon tomography and complementary neutron detectors. We are currently performing simulation studies to help with the design of small scale prototypes. Based on the prototype tests and refined simulations, we will determine whether the muon tracking system for the full scale prototype will be based on drift chambers or extruded scintillator trackers. An analysis of the operations of the Port of Montreal has determined how long muon scan times should take if all or a subset of the cargo is to be screened. As long as the throughput of the muon system(s) is equal to the rate at which containers are unloaded from ships, the impact on port operations would not be great if a muon scanning stage were required for all cargo. We also show preliminary simulation results indicating that excellent separation between Al, Fe and Pb is possible under ideal conditions. The discrimination power is reduced but still significant when realistic momentum resolution measurements are considered.