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Author: Wenkai Fu Publisher: ISBN: Category : Languages : en Pages :
Book Description
The Transient REActor Test (TREAT) facility was restarted and will be used to test accident-tolerant fuels to improve nuclear reactor safety. In this work, alternative neutron detectors for use in core and with the hodoscope at the TREAT facility were modeled and simulated using different computational tools to understand the underlying physics. The Hornyak button scintillation detector used in the original TREAT hodoscope to detect fast neutrons and its variants were evaluated using Geant4 to simulate the coupled nuclear and optical physics. The Hornyak-button model predicted an intrinsic efficiency of 0.35% for mono-directional fission neutrons and strong gamma-induced Cherenkov noise, which agree relatively well with the reported experimental observations. The proposed variants use silicon photomultipliers to reduce Cherenkov noise and have optimized layered or homogenized scintillation volumes. The layered and homogenized variants with 5-cm length were predicted to achieve neutron-detection efficiencies of 3.3% and 1.3%, respectively, at a signal-to-noise ratio of 100. Another candidate devices for the hodoscope are the actinide and hydrogenous microstructured semiconductor neutron detectors (MSNDs) evaluated using Geant4 and MCNP. With a sufficient rejection of the gamma noises, the U235 -filled and the hydrogenous MSNDs were predicted to yield neutron-detection efficiencies of 1.2% and 2.5%, respectively, at the length of 2 cm. The micro-pocket fission detectors (MPFDs) were developed to detect in-core neutrons, and the electron collection process in such devices was evaluated using Garfield++-based computational routine. The high-performance Garfield++ application was developed using the built-in, optimized element-search techniques and a hydrid MPI and OpenMP parallelization scheme. The preliminary results indicated that the averaged deposited energy per fission fragment was 7.15 MeV, and the induced current occured within 400 ns.
Author: Wenkai Fu Publisher: ISBN: Category : Languages : en Pages :
Book Description
The Transient REActor Test (TREAT) facility was restarted and will be used to test accident-tolerant fuels to improve nuclear reactor safety. In this work, alternative neutron detectors for use in core and with the hodoscope at the TREAT facility were modeled and simulated using different computational tools to understand the underlying physics. The Hornyak button scintillation detector used in the original TREAT hodoscope to detect fast neutrons and its variants were evaluated using Geant4 to simulate the coupled nuclear and optical physics. The Hornyak-button model predicted an intrinsic efficiency of 0.35% for mono-directional fission neutrons and strong gamma-induced Cherenkov noise, which agree relatively well with the reported experimental observations. The proposed variants use silicon photomultipliers to reduce Cherenkov noise and have optimized layered or homogenized scintillation volumes. The layered and homogenized variants with 5-cm length were predicted to achieve neutron-detection efficiencies of 3.3% and 1.3%, respectively, at a signal-to-noise ratio of 100. Another candidate devices for the hodoscope are the actinide and hydrogenous microstructured semiconductor neutron detectors (MSNDs) evaluated using Geant4 and MCNP. With a sufficient rejection of the gamma noises, the U235 -filled and the hydrogenous MSNDs were predicted to yield neutron-detection efficiencies of 1.2% and 2.5%, respectively, at the length of 2 cm. The micro-pocket fission detectors (MPFDs) were developed to detect in-core neutrons, and the electron collection process in such devices was evaluated using Garfield++-based computational routine. The high-performance Garfield++ application was developed using the built-in, optimized element-search techniques and a hydrid MPI and OpenMP parallelization scheme. The preliminary results indicated that the averaged deposited energy per fission fragment was 7.15 MeV, and the induced current occured within 400 ns.
Author: Publisher: ISBN: Category : Languages : en Pages : 34
Book Description
Accurate determinations of fusion neutron yields on the TFTR require that the neutron detectors be absolutely calibrated in-situ, using neutron sources of known strengths. For such calibrations, numerical simulations of neutron transport can be powerful tools in the design of experiments and the study of measurement results. On the TFTR, numerical calibration experiments' have been frequently used to complement actual detector calibrations. We present calculational approaches and transport models used in these numerical simulations, and summarize the results from simulating the calibration of 235U fission detectors carried out in December 1988. 12 refs., 9 figs., 6 tabs.
Author: Sophit Pongpun Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
This thesis focuses on designing, building, and analyzing a neutron detection system to measure neutron fluxes of a TRIGA reactor at Texas A&M University to verify newly developed simulation codes. Such a system must be designed to cover a wide range of neutron fluxes in transient power surges (up to 1015 neutrons/cm2/s, lasting 20 to 50 ms) and in steady-state operations (1013 neutrons/cm2/s at full power of one megawatt). The size of the detector is limited to a maximum of 9.525 mm outer diameter including housing. The detection system consisted of slow neutron detectors, associated electronics, data acquisition and storage equipment, and an analysis software. The detector used boron- 10 to capture slow neutrons, generating charged particles within an ionization chamber filled with air. Due to the low Q-value of the reaction, a high gain charge-sensitive preamplifier, which was a part of a miniature 16.9 mm x 298.5 mm electronic package, was placed within 1.7 m of the detector to minimize noise level. The preamplifier was designed to offer pulse mode, current mode, and high voltage current mode of operation. Experimental data were acquired at 20 MHz using a solid-state drive for data storage and were subjected to 250 MHz for up to eight-hour continuous operation using an array of five three-TB hard drives. Data analysis software was programmed using MATLAB. In addition to analysis using the shaping amplifier's output, an algorithm to generate a radiation pulse from the directly digitized preamplifier signal was proposed and tested with test pulses simulating neutron events. The detection system was tested with isotopic sources and in a dry tube located near the TRIGA reactor. The latter showed an increase in the number of gamma events with the reactor power, whereas the number of neutron events was also proportional to the power. In addition, a trial run of in-core measurements was performed. The results suggested that high gamma radiation present in the core interfered with the neutron signal. Suggestions was made for modification of the mechanical assembly of the system, compensation for gamma signals, and additional tests to improve analysis of the neutron signal.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The Advanced Test Reactor (ATR) and the ATR Critical (ATRC) facilities lack real-time methods for detecting thermal neutron flux and fission reaction rates for irradiation capsules. Direct measurements of the actual power deposited into a test are now possible without resorting to complicated correction factors. In addition, it is possible to directly measure minor actinide fission reaction rates and to provide time-dependent monitoring of the fission reaction rate or fast/thermal flux during transient testing. A joint Idaho State University /Idaho National Laboratory ATR National Scientific User Facility (ATR NSUF) project was recently initiated to evaluate new real-time state-of-the-art in-pile flux detection sensors. Initially, the project is comparing the accuracy, response time, and long duration performance of French Atomic Energy Commission (CEA)-developed miniature fission chambers, specialized self-powered neutron detectors (SPNDs) by the Argentinean National Energy Commission (CNEA), specially developed commercial SPNDs, and back-to-back fission (BTB) chambers developed by Argonne National Laboratory (ANL). As discussed in this paper, specialized fixturing and software was developed by INL to facilitate these joint ISU/INL evaluations. Calculations were performed by ISU to assess the performance of and reduce uncertainties in flux detection sensors and compare data obtained from these sensors with existing integral methods employed at the ATRC. Ultimately, project results will be used to select the detector that can provide the best online regional ATRC power measurement. It is anticipated that project results may offer the potential to increase the ATRC's current power limit and its ability to perform low-level irradiation experiments. In addition, results from this effort will provide insights about the viability of using these detectors in the ATR. Hence, this effort complements current activities to improve ATR software tools, computational protocols and in-core instrumentation under the ATR Modeling, Simulation and V & V Upgrade initiative, as well as the work to replace nuclear instrumentation under the ATR Life Extension Project (LEP) and provide support to the ATR NSUF.
Author: J-P Trapp Publisher: ISBN: Category : Miniature fission chamber Languages : en Pages : 8
Book Description
The Reactor Measurement Systems Laboratory (LSMR) of the CEA/Cadarache, is specialized in the development, design, modeling and manufacturing of neutron detectors, especially miniature fission chambers.
Author: Yacouba Diawara Publisher: Springer Nature ISBN: 3031365461 Category : Science Languages : en Pages : 257
Book Description
This book covers the most common neutron detectors used in neutron scattering facilities and all of those in use at Oak Ridge National Lab. It starts describing the facilities, instruments and the critical detector parameters needed by various instruments. Then the key components of the 3He-based linear position-sensitive detectors as well as on their electronics, which require particular attention to signal processing and noise reduction, are introduced. One chapter is dedicated to the 3He alternatives where scintillators play a critical role. It also covers emerging neutron detection technologies including semiconductors, vacuum-based devices and their associated readouts, which will be required in the future for high rate and high-resolution neutron detectors. The authors explain the logic behind the choice of materials as well as the various constraints that neutron detectors must respect to be useful. Some of these constraints, such as efficiency and gamma-ray sensitivity are common to all neutron counters while others, like timing resolution, dynamic range, and peak counting rate, depend on the applications. The book guides experts, the nuclear science community, and young scholars through the physical processes and the required electronics in a way that is accessible for those not professionally involved in designing detector’s components and electronic circuits.
Author: Wenkai Fu
Author: Wenkai Fu
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Author: 
Author: Sophit Pongpun
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Author: J-P Trapp
Author: Yacouba Diawara
Author: R. W. Albrecht
Author: A. Chesavage
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