The CABRI fast neutron Hodoscope: Renovation, qualification program and first results following the experimental reactor restart

Chevalier, V.; Mirotta, S.; Guillot, Jérôme; Biard, B.

doi:10.1051/epjconf/201817004003

Cited by 6 publications

(8 citation statements)

References 4 publications

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“…Analysis of the Signal over Noise Ratio of the hodoscope determined by Monte Carlo calculation  The Hodoscope, an online fuel motion measurement system, which aims at analyzing the fuel motion deduced from the detection of fast neutrons emitted by the tested rod, in real time (with a time step of 1ms) during the transient [3]. This article present the numerical model for the evaluation of the Signal over noise ratio of the hodoscope measurement system which is a fundamental parameter to observe the fuel displacement (if any) during the power excursion.…”

Section: Figure 1 -View Of the Cabri Reactor From The Topmentioning

confidence: 99%

“…The power transients are generated by the unique reactivity injection system of CABRI [2]. 96 tubes (so-called "transient rods", visible in Figure 1) located in 4 banks among the CABRI fuel rods are pressurized with 3 He gas. The very fast depressurization of this strong neutron absorber into a discharge tank, through two flow channels (low and high flow rates), is then finely adjusted to trigger the desired power pulse.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of the Signal over Noise Ratio of the hodoscope determined by Monte Carlo calculation

2021

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The CABRI experimental pulse reactor, located at the Cadarache nuclear research center, southern France, is devoted to the study of Reactivity Initiated Accidents (RIA) for the purpose of the CABRI International Program (CIP), managed by IRSN in the framework of an OECD/NEA agreement. The hodoscope equipment installed in the CABRI reactor is an almost unique online fuel motion monitoring system, thanks to the measurement of the fast neutrons emitted during a power pulse by a tested rod positioned inside a dedicated test loop reproducing PWR conditions. This system is dedicated to the analysis of fuel displacement. Hence, one of the most important parameter measured by the hodoscope detectors is the Signal over Noise Ratio (SNR), characterizing the fraction of neutrons directly coming from the test rod (“signal”) over neutrons coming from the core (“noise”). It is interesting to calculate the SNR in order to define some quantitative criterions to improve hodoscope measurements and to understand if any modification linked to the test loop may significantly change this essential parameter. Another parameter of interest is the so-called “scattering coefficient”, which corresponds to the fraction of neutrons coming from the test rod and being scattered between their birth and their detection. This parameter is used to enhance the analysis of the fuel displacement which may happen during the power transient. In this article, the method used to calculate the SNR using MCNP6.2 Monte Carlo code will be detailed. Because the hodoscope detectors are located far away from the test rod (up to 4 meters), a 2D model of CABRI core and instrumentation has been implemented. No variance reduction techniques have been used to solve this problem in order to record the place of birth of neutron which contributes to the different scores with the goal to perform a detailed analysis of the SNR. This strategy allows to access numerically to the “scattering coefficient”. Finally, the comparison between calculated and measured SNR for a case study will be carried out. A quite good agreement between the 2D simulations and experiments recently performed in the CABRI reactor has been obtained.

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Section: Figure 1 -View Of the Cabri Reactor From The Topmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of the Signal over Noise Ratio of the hodoscope determined by Monte Carlo calculation

2021

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“…These results are consistent, the new electronic works properly. These values are used in parallelizable dead time formula [3] which gives us the real count rate.…”

Section: Eqmentioning

confidence: 99%

“…From this figure it is possible to see that the counting chains including fission chambers have a linear behavior under 1.5 million cps which corresponds to~1.6 GW of CABRI power. For higher power, a dead time correction has to be taken into account, due to the behavior of the electronic chain [3].…”

Section: Figure V4 -Detectors Responses At Different Powers Of Cabrimentioning

confidence: 99%

Qualification and characterization of electronics of the fast neutron Hodoscope detectors using neutrons from CABRI core

et al. 2018

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Abstract-The study of Reactivity Initiated Accidents (RIA) is important to determine up to which limits nuclear fuels can withstand such accidents without clad failure. The CABRI International Program (CIP), conducted by IRSN under an OECD/NEA agreement, has been launched to perform representative RIA Integral Effect Tests (IET) on real irradiated fuel rods in prototypical Pressurized Water Reactors (PWR) conditions. For this purpose, the CABRI experimental pulse reactor, operated by CEA in Cadarache, France, has been strongly renovated, and equipped with a pressurized water loop. The behavior of the test rod, located in that loop in the center of the driver core, is followed in real time during the power transients thanks to the hodoscope, a unique online fuel motion monitoring system, and one of the major distinctive features of CABRI. The hodoscope measures the fast neutrons emitted by the tested rod during the power pulse with a complete set of 153 Fission Chambers and 153 Proton Recoil Counters. During the CABRI facility renovation, the electronic chain of these detectors has been upgraded. In this paper, the performance of the new system is presented describing gain calibration methodology in order to get maximal Signal/Noise ratio for amplification modules, threshold tuning methodology for the discrimination modules (old and new ones), and linear detectors response limit versus different reactor powers for the whole electronic chain.

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“…-The IRIS facility, for performing X-ray radiography and tomography imaging before and after a power transient thanks to a linear electron accelerator, as well as quantitative gamma scanning analyses; -The Hodoscope, an online fuel motion measurement system, which aims at analyzing the fuel motion deduced from the detection of fast neutrons emitted by the tested rod, in real time (with a time step of 1ms) during the transient [3]. This article presents a numerical model for the evaluation of: -The Signal-to-Noise Ratio (SNR) of the hodoscope measurement system, which is a fundamental parameter to observe the fuel displacement (if any) during the power excursion.…”

Section: Introductionmentioning

confidence: 99%

Signal-to-Noise Ratio of CABRI Hodoscope: Monte Carlo Calculation Versus Experiments

Salvo

Mirotta

Chevalier

2022

IEEE Trans. Nucl. Sci.

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The CABRI fast neutron Hodoscope: Renovation, qualification program and first results following the experimental reactor restart

Abstract: Abstract-

Cited by 6 publications

References 4 publications

Analysis of the Signal over Noise Ratio of the hodoscope determined by Monte Carlo calculation

Analysis of the Signal over Noise Ratio of the hodoscope determined by Monte Carlo calculation

Qualification and characterization of electronics of the fast neutron Hodoscope detectors using neutrons from CABRI core

Signal-to-Noise Ratio of CABRI Hodoscope: Monte Carlo Calculation Versus Experiments

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