Cold neutron tomography of annular coolant flow in a double subchannel model of a boiling water reactor

Kickhofel, John; Zboray, Robert; Damsohn, Manuel; Kaestner, Anders; Lehmann, Eberhard; Prasser, Horst-Michael

doi:10.1016/j.nima.2011.01.062

Cited by 22 publications

(8 citation statements)

References 10 publications

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“…However, the usage of NT on thermal-hydraulic flows has to this date only been applied at NT laboratories, where neutron beam lines are available from research reactors or spallation sources, 13,14 Since such sources are stationary, they cannot be used at dedicated large-scale thermal-hydraulic test loops. Therefore, this paper explores the feasibility of NT on stationary thermal-hydraulic test loops using portable neutron generators, where we focus on Deuterium-Tritium neutron generators emitting neutrons at an energy of 14 MeV.…”

Section: B Fast Neutrons For Transmission Tomography Of Void Distribmentioning

confidence: 99%

Neutron tomography of axially symmetric objects using 14 MeV neutrons from a portable neutron generator

Andersson

Andersson-Sundén

Sjöstrand

et al. 2014

Review of Scientific Instruments

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In nuclear boiling water reactor cores, the distribution of water and steam (void) is essential for both safety and efficiency reasons. In order to enhance predictive capabilities, void distribution assessment is performed in two-phase test-loops under reactor-relevant conditions. This article proposes the novel technique of fast-neutron tomography using a portable deuterium-tritium neutron generator to determine the time-averaged void distribution in these loops. Fast neutrons have the advantage of high transmission through the metallic structures and pipes typically concealing a thermal-hydraulic test loop, while still being fairly sensitive to the water/void content. However, commercially available fast-neutron generators also have the disadvantage of a relatively low yield and fast-neutron detection also suffers from relatively low detection efficiency. Fortunately, some loops are axially symmetric, a property which can be exploited to reduce the amount of data needed for tomographic measurement, thus limiting the interrogation time needed. In this article, three axially symmetric test objects depicting a thermal-hydraulic test loop have been examined; steel pipes with outer diameter 24 mm, thickness 1.5 mm, and with three different distributions of the plastic material POM inside the pipes. Data recorded with the FANTOM fast-neutron tomography instrument have been used to perform tomographic reconstructions to assess their radial material distribution. Here, a dedicated tomographic algorithm that exploits the symmetry of these objects has been applied, which is described in the paper. Results are demonstrated in 20 rixel (radial pixel) reconstructions of the interior constitution and 2D visualization of the pipe interior is demonstrated. The local POM attenuation coefficients in the rixels were measured with errors (RMS) of 0.025, 0.020, and 0.022 cm(-1), solid POM attenuation coefficient. The accuracy and precision is high enough to provide a useful indication on the flow mode, and a visualization of the radial material distribution can be obtained. A benefit of this system is its potential to be mounted at any axial height of a two-phase test section without requirements for pre-fabricated entrances or windows. This could mean a significant increase in flexibility of the void distribution assessment capability at many existing two-phase test loops.

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Section: B Fast Neutrons For Transmission Tomography Of Void Distribmentioning

confidence: 99%

Neutron tomography of axially symmetric objects using 14 MeV neutrons from a portable neutron generator

Andersson

Andersson-Sundén

Sjöstrand

et al. 2014

Review of Scientific Instruments

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“…The converter layer was glued on a 3 mm thick aluminum electrode and mounted above the first THGEM cascade as is shown in Figure 1. When an incident neutron interacts with 10 B, an alpha ( 4 He) particle and a lithium-7 ( 7 Li) ion are released according to 10 B + n → 4 He (1.47 MeV)…”

Section: Detector Setupmentioning

confidence: 99%

“…Schematic drawing of the detector configurations: the THGEMbased readout was coupled to a 1-μm thick 10B layer deposited on an Al support for neutron-to-charged particle conversion. 10 B + n → 4 He (1.79 MeV)…”

Section: Detector Setupmentioning

confidence: 99%

“…This is due to an ever-growing availability of strong neutron sources and to the developments of novel imaging detector technologies. Potential applications range from fundamental research to industry, including material test and quality-control inspection in metallurgy, 4 fuel cells research, 5 study of objects from cultural heritage, 6,7 geoscience and soil physics, 8,9 investigation of thermal hydraulic phenomena, 10,11 homeland security, 3 and imaging of biological specimens. 3 Unlike charged particles (electrons, protons, alpha particles, etc.)…”

Section: Introductionmentioning

confidence: 99%

“…17 We develop various high-resolution instrumentation and measurement techniques for investigating various relevant industrial processes, like dynamic gas-liquid two-phase flows. 18,19 As part of these activities, we have recently initiated an extensive study of two-phase flows in nuclear fuel bundle models by cold-neutron imaging at the Imaging with COld Neutrons (ICON) beam line on the SINQ spallation source, 10,11 using an optical cold-neutron imaging system that includes a scintillator plate, a mirror, and a CCD camera. 20 Though the optical system is capable of providing an excellent spatial resolution (around hundred micrometers), it is relatively an expensive device and it does not allow high-frame rates (kHz) at large field of views (>20 × 20 cm 2 ).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Development of a cold-neutron imaging detector based on thick gaseous electron multiplier

Cortesi

Zboray

Kaestner

et al. 2013

Review of Scientific Instruments

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We present the results of our recent studies on a cold-neutron imaging detector prototype based on THick Gaseous Electron Multiplier (THGEM). The detector consists of a thin Boron layer, for neutron-to-charged particle conversion, coupled to two THGEM electrodes in cascade for charge amplification and a position-sensitive charge-readout anode. The detector operates in Ne∕(5%)CF4, at atmospheric pressure, in a stable condition at a gain of around 10(4). Due to the geometrical structure of the detector elements (THGEM geometry and charge read-out anode), the image of detector active area shows a large inhomogeneity, corrected using a dedicated flat-filed correction algorithm. The prototype provides a detection efficiency of 5% and an effective spatial resolution of the order of 1.3 mm.

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Two-dimensional mapping of falling water film thickness with near-infrared attenuation

2015

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We have developed an optical technique for the two-dimensional mapping of water film thickness. The technique is based on infrared light absorption. A nearinfrared camera is used to capture the radiation returning from a surface illuminated by a halogen lamp. The attenuation of the back-scattered radiation is used as a measure for the thickness of the water film covering the surface. The method was calibrated using well-defined liquid films between a glass plate and the surface. Series of instantaneous, two-dimensional thickness profiles of wavy turbulent free-falling films along a vertical wall were measured at a frame rate of 200 Hz. The evolution of complex flow patterns with three-dimensional instabilities such as long waves and capillary waves was observed under isothermal conditions. For the validation of the method, simultaneous independent measurements were taken together with an electrical high-speed liquid film sensor.

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Cold neutron tomography of annular coolant flow in a double subchannel model of a boiling water reactor

Cited by 22 publications

References 10 publications

Neutron tomography of axially symmetric objects using 14 MeV neutrons from a portable neutron generator

Neutron tomography of axially symmetric objects using 14 MeV neutrons from a portable neutron generator

Development of a cold-neutron imaging detector based on thick gaseous electron multiplier

Two-dimensional mapping of falling water film thickness with near-infrared attenuation

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