Analyse des effets mecaniques d'une depressurisation brutale dans un circuit de refroidissement d'un reacteur nucleaire

SIGLEINIST T 77214 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Simulation of photo-neutron induced activation gamma rays for copper characterization in scrap metal

International audienc

The Self-Powered Detector Simulation ‘MATiSSe’ Toolbox applied to SPNDs for severe accident monitoring in PWRs

International audienceIn the framework of the French National Research Agency program on nuclear safety and radioprotection, the ‘DIstributed Sensing for COrium Monitoring and Safety’ project aims at developing innovative instrumentation for corium monitoring in case of severe accident in a Pressurized Water nuclear Reactor. Among others, a new under-vessel instrumentation based on Self-Powered Neutron Detectors is developed using a numerical simulation toolbox, named ‘MATiSSe’. The CEA Instrumentation Sensors and Dosimetry Lab developed MATiSSe since 2010 for Self-Powered Neutron Detectors material selection and geometry design, as well as for their respective partial neutron and gamma sensitivity calculations. MATiSSe is based on a comprehensive model of neutron and gamma interactions which take place in Selfpowered neutron detector components using the MCNP6 Monte Carlo code. As member of the project consortium, the THERMOCOAX SAS Company is currently manufacturing some instrumented pole prototypes to be tested in 2017. The full severe accident monitoring equipment, including the standalone low current acquisition system, will be tested during a joined CEA-THERMOCOAX experimental campaign in some realistic irradiation conditions, in the Slovenian TRIGA Mark II research reacto

The Self-Powered Detector Simulation ‘MATiSSe’ Toolbox applied to SPNDs for severe accident monitoring in PWRs

In the framework of the French National Research Agency program on nuclear safety and radioprotection, the ‘DIstributed Sensing for COrium Monitoring and Safety’ project aims at developing innovative instrumentation for corium monitoring in case of severe accident in a Pressurized Water nuclear Reactor. Among others, a new under-vessel instrumentation based on Self-Powered Neutron Detectors is developed using a numerical simulation toolbox, named ‘MATiSSe’. The CEA Instrumentation Sensors and Dosimetry Lab developed MATiSSe since 2010 for Self-Powered Neutron Detectors material selection and geometry design, as well as for their respective partial neutron and gamma sensitivity calculations. MATiSSe is based on a comprehensive model of neutron and gamma interactions which take place in Selfpowered neutron detector components using the MCNP6 Monte Carlo code. As member of the project consortium, the THERMOCOAX SAS Company is currently manufacturing some instrumented pole prototypes to be tested in 2017. The full severe accident monitoring equipment, including the standalone low current acquisition system, will be tested during a joined CEA-THERMOCOAX experimental campaign in some realistic irradiation conditions, in the Slovenian TRIGA Mark II research reactor

Evaluation of linac-based delayed gamma neutron activation technique for copper characterization in scrap metal by means of Monte Carlo modeling

International audienceDelayed gamma rays following neutron activation, induced by a 6 MeV linear electron accelerator (linac) coupled to a deuterium oxide photo-neutron conversion target, are simulated with MCNP6.1. The 1039 keV copper activation gamma peak is detected with a 33 % relative efficiency hyper pure germanium detector. Two copper distributions were assessed for a 2-hour irradiation followed by a 2-hour counting configuration. Homogeneously distributed copper in a planar scrap metal matrix shows 65Cu detection limits of 10.01 g. A solid copper sample, modeled at five distinct positions in the planar scrap metal matrix, exhibits detection limits from 8.27 to 14.27 grams

Detection and quantification of copper in scrap metal by linac-based neutron activation analysis

International audienceThis paper presents the investigation carried out by CEA List and ArcelorMittal R&D in order to assess the potential of linac-based neutron activation analysis to detect and quantify copper in scrap metal. Performances are evaluated using MCNP6 and then validated experimentally using a 6 MeV linac coupled with heavy water. It is shown that (γ, n) reaction cross-sections for deuterium are likely to be undervalued in ENDF/B-VII and suggested that photoneutron production algorithms in Monte Carlo codes should be reexamined

Temperature ramps for severe accident instrumentation in nuclear reactor cavity concrete

International audienceDistributed Optical Fiber Sensing and Self-Powered Nuclear Detectors are potential innovative instrumentation for the management of severe accidents. The former can monitor temperature, strain, and/or presence of hot melt while the latter is more dedicated to gamma radiation measurements and can also be coupled to thermocouples for temperature measurement purpose. These sensors could be installed in the basement concrete to monitor corium progression (arriving in lower head, later on in the reactor pit, reaching a predefined level in concrete before melt through…). In order to assess the temperature evolution that these sensors may experience, thermal conduction in concrete structures was modelled coupled with TOLBIAC-ICB calculation results for several typical scenarios. This confirmed that, due to concrete low thermal conductivity, ablation progresses more rapidly than conduction, except in a small zone close to the ablation front. Therefore experimental temperature profiles from prototypic corium-concrete interaction experiments can be used to specify the temperature profiles that sensors inserted in the reactor cavity can withstand during such severe accident. A first experiment, VULCANO VB-U10, has been carried out to study the behavior of 5 distributed optical fiber sensors that were installed inside a concrete crucible experiencing ablation by prototypic corium. These instruments have been used in this test to monitor the concrete temperature and/or its ablation. During this test, 50 kg of prototypic uranium-containing corium have interacted for 98 minutes with a lime-siliceous concrete leading to an axial ablation of 25 mm and a radial ablation of 80 mm. Optical fiber length measurements with Rayleigh OFDR technique have been found to be coherent with data from thermocouples installed in the concrete as in previous VULCANO experiments. Raman DTS measurements provided satisfactory temperature evolution results. This good performance of the distributed temperature measurement has been validated in conditions representative of a severe accident

The Potential of Photon Activation and Neutron Activation Techniques for Fast Soil Characterization

In the frame of a partnership between CEA and VINCI, various measurement techniques are applied to soil analysis and tested in different laboratories located at CEA Saclay (France). This paper deals with two nuclear measurement techniques assessed in this project. More specifically, this paper presents the feasibility study carried out for two non-destructive active methods: photon activation and neutron activation. First, some atomic nuclides are activated either by photons or neutrons. Secondly, gamma-rays of specific energies are emitted by activated nuclides and gamma-ray spectrometry enables to identify these activated nuclides. Calibration of the full measurement system with reference samples would enable to quantify the mass of activated nuclides. Irradiations performed for photon activation measurements were conducted using a linear electron accelerator (linac) as the latter enables to generate high-energy photons by Bremsstrahlung thanks to its conversion target. Furthermore, irradiations performed for neutron activation measurements were also conducted with a linac. Indeed, photons may be converted to neutrons by photonuclear reactions using a secondary target. In the frame of this project, experiments were carried out at the SAPHIR platform (CEA Saclay) with a Linatron-M9 VARIAN linac. The electron energy was either 6 or 9 MeV. For neutron activation measurements, a secondary target made of heavy water has been used as neutron source and a polyethylene cell enabled to thermalize neutrons and increase the number of reactions of interest. In this paper, we present the different experimental setups and the measurement protocols established for this feasibility study. We show experimental results obtained with raw material samples coming from three construction sites

The Potential of Photon Activation and Neutron Activation Techniques for Fast Soil Characterization

In the frame of a partnership between CEA and VINCI, various measurement techniques are applied to soil analysis and tested in different laboratories located at CEA Saclay (France). This paper deals with two nuclear measurement techniques assessed in this project. More specifically, this paper presents the feasibility study carried out for two non-destructive active methods: photon activation and neutron activation. First, some atomic nuclides are activated either by photons or neutrons. Secondly, gamma-rays of specific energies are emitted by activated nuclides and gamma-ray spectrometry enables to identify these activated nuclides. Calibration of the full measurement system with reference samples would enable to quantify the mass of activated nuclides. Irradiations performed for photon activation measurements were conducted using a linear electron accelerator (linac) as the latter enables to generate high-energy photons by Bremsstrahlung thanks to its conversion target. Furthermore, irradiations performed for neutron activation measurements were also conducted with a linac. Indeed, photons may be converted to neutrons by photonuclear reactions using a secondary target. In the frame of this project, experiments were carried out at the SAPHIR platform (CEA Saclay) with a Linatron-M9 VARIAN linac. The electron energy was either 6 or 9 MeV. For neutron activation measurements, a secondary target made of heavy water has been used as neutron source and a polyethylene cell enabled to thermalize neutrons and increase the number of reactions of interest. In this paper, we present the different experimental setups and the measurement protocols established for this feasibility study. We show experimental results obtained with raw material samples coming from three construction sites