D. Szalkai

First tests of silicon-carbide semiconductors as candidate neutron detector for the ITER Test Blanket Modules

The tritium breeding blanket is an essential part of a future DT fusion power reactor. Test Blanket Modules (TBM) will be installed in the experimental reactor ITER with the aim to investigate the nuclear performance of different designs. Currently there is no qualified neutronics instrumentation for the TBMs which is able to withstand the harsh environment conditions such as high temperature and, depending on the operation scenario, intense radiation.

Radiation silicon carbide detectors based on ion implantation of boron

Radiation detectors based on radiation-hardened semiconductor such as silicon carbide (SiC), have received considerable attention in many applications such as in outer space, high energy physics experiments, gas and oil prospection, and nuclear reactors. For the first time it was demonstrated the reliability of thermal neutron detectors realized by standard ion implantation of boron layer as a neutron converter layer. Moreover, these detectors respond to thermal neutrons and gamma rays showing different counting rates at different voltages and under different types of shielding.

Detection of 14 MeV neutrons in high temperature environment up to 500 °C using 4H-SiC based diode detector

In reactor technology and industrial applications, detection of fast and thermal neutrons plays a crucial role in getting relevant information about the reactor environment and neutron yield. The inevitable elevated temperatures make neutron yield measurements problematic. Out of the currently available semiconductors 4H-SiC seems to be the most suitable neutron detector material under extreme conditions due to its high heat and radiation resistance, large band-gap and lower production cost than the competing diamond detectors. Some of future using and interesting applications of such SiC detector devices-for non-charged particles (photons and/or neutrons) are expected in the frame of non-destructive assays, nuclear reactor monitoring, safeguards, oil and gas prospections [1,2,3]. In the framework of the European I-Smart project, optimal 4H-SiC based diode geometries were developed for high temperature neutron detection. Irradiation tests were conducted with 14 MeV fast neutrons supplied by a deuterium-tritium neutron generator with an average neutron yield of 4.04 × 1010-5.25 × 1010 n/s at Neutron Laboratory of the Technical University of Dresden in Germany. In the present work, we interpret the first measurement of SiC detector irradited with fast neutrons from room temperature up to 500 degrees Celsius. These experiments are serving also the first simulation of the harsh environmental condition measurements in the tritium breeding blanket of the ITER fusion reactor, which is one of the most prominent planned location of high temperature neutron flux characterization studies in the near future.

Nuclear radiation detector based on ion implanted p-n junction in 4H-SiC

In this paper, we propose a new device detector based on ion implanted p-n junction in 4H-SiC for nuclear instrumentation. We showed the interest to use 10Boron as a Neutron Converter Layer in order to detect thermal neutrons. We present the main results obtained during irradiation tests performed in the Belgian Reactor 1. We show the capability of our detector by means of first results of the detector response at different reverse voltage biases and at different reactor power.

4H-SiC Neutron Sensors Based on Ion Implanted 10 B Neutron Converter Layer

In the framework of the I_SMART project the main aim is to develop an innovative radiation detection system based on silicon carbide technology in view to detect neutrons (thermal and fast) and photons for harsh environments. In the present work two geometries have been realized based on ion implantation of boron. In the first geometry, 10B ions have been implanted into the Al metallic contact of a p-n diode to create the neutron converter layer. In the second geometry one single process has been used to realize both the p+-layer and the neutron converter layer. The technological processes followed to fabricate these detectors, with a study of their electrical behavior and their responses under thermal neutron irradiations are addressed in this paper.

Optimization of thermal neutron converter in SiC sensors for spectral measurements of thermal and fast neutron flux

Optimization of the neutron converter in SiC sensors is presented. The sensors are used for spectral radiation measurements of thermal and fast neutrons and optionally gamma ray at elevated temperature in harsh radiation environment. The neutron converter, which is based on 10B, allows to detect thermal neutrons by means of neutron capture reaction. Two construction of the sensors were used to measure radiation in experiments. Sensor responses collected in experiments have been reproduced by the computer tool created by authors, it allows to validate the tool. The tool creates the response matrix function describing the characteristic of the sensors and it was used for detailed analyses of the sensor responses. Obtained results help to optimize the neutron converter in order to increase thermal neutron detection. Several enhanced construction of the sensors, which includes the neutron converter based on 10B or 6Li, were proposed.

SiC-based neutron detector in quasi-realistic working conditions: Efficiency and stability at room and high temperature under fast neutron irradiations

In the framework of the European I_SMART project, we have designed and made new SiC-based nuclear radiation detectors able to operate in harsh environments and to detect both fast and thermal neutrons. In this paper, we report experimental results of fast neutron irradiation campaign at high temperature (106 °C) in quasi-realistic working conditions. Our device does not suffer from high temperature, and spectra do show strong stability, preserving features. These experiments, as well as others in progress, show the I_SMART SiC-based device skills to operate in harsh environments, whereas other materials would strongly suffer from degradation. Work is still demanded to test our device at higher temperatures and to enhance efficiency in order to make our device fully exploitable from an industrial point of view.

Instrumentation for Neutron Flux and Tritium Production Rate Monitoring in the European TBM in ITER

Test blanket modules (TBMs) will be installed in the ITER with the aim to investigate the nuclear performance of different breeding blanket designs for fusion power reactors. Here, we present an overview of our ongoing work on three types of neutron flux monitors under development at Karlsruhe Institute of Technology (KIT) for the TBMs. A foil activation system with pneumatic sample transport was constructed by KIT utilizing the intense DT neutron generator of Technical University of Dresden. It is used as a test bench for the development of a neutron activation system for the TBMs. Self-powered neutron detectors (SPNDs) are widely applied in fission reactor monitoring, and the commercially available SPNDs are sensitive to thermal neutrons. We are investigating novel materials for SPND which would be sensitive also to the fast neutron flux expected in the TBMs. Within the I_SMART project, funded by KIC InnoEnergy, KIT is developing an online detector based on silicon carbide electronics for the TBMs.

Neutron measurement instrumentation development at KIT for the European ITER TBM

We present an overview of ongoing work on three types of neutron flux monitors under investigation and development for the two European ITER Test Blanket Modules: 1) a neutron activation system, 2) silicon carbide diodes, 3) self-powered neutron detectors for fast neutrons. A pneumatic test system for neutronics tests for a TBM-NAS was constructed at the DT neutron generator laboratory of Technical University of Dresden. Several irradiations have been performed with focus on the simultaneous measurement of the extracted activated probes. Furthermore, an engineering assessment in the conceptual design phase has been done which considered issues of design requirements and integration. Within the I_SMART project, KIT is investigating the suitability of an online detector based on silicon carbide semiconductor material and associated electronics for the TBMs. Detectors of several designs have been already irradiated with DT neutrons. Irradiation tests at elevated temperatures have been done and further tests are currently underway. Self-powered neutron detectors (SPND) with novel materials sensitive also to the fast neutron flux expected in the TBMs are under investigation. Simulations with the European Activation System EASY and neutron flux spectra which were calculated with MCNP for the HCPB TBM. Preliminary tests with commercial SPND in a fast reactor were performed. Test detectors are under preparation for testing with DT neutron generators.

Neutronics instrumentation for the European TBM in ITER

Test Blanket Modules (TBM) will be installed in the ITER with the aim to investigate the nuclear performance of different breeding blanket designs for fusion power reactors. Here we present an overview of our ongoing work on three types of neutron flux monitors under development at KIT for the TBMs. A foil activation system with pneumatic sample transport was constructed by KIT utilizing the intense DT neutron generator of Technical University of Dresden. It is used as a test bench for the development of a neutron activation system for the TBMs. Self-powered neutron detectors (SPND) are widely applied in fission reactor monitoring, and the commercially available SPNDs are sensitive to thermal neutrons. We are investigating novel materials for SPND which would be sensitive also to the fast neutron flux expected in the TBMs. Within the I_SMART project, funded by KIC InnoEnergy, KIT is developing an online detector based on silicon carbide electronics for the TBMs.