1,721,854 research outputs found
Benchmarking of the FENDL-3 neutron cross-section data starter library for fusion applications
No full textThis paper summarizes the benchmark analyses performed in a joint effort of ENEA (Italy), JAEA (Japan), KIT (Germany), and the University of Wisconsin (USA) on a computational ITER benchmark and a series of 14 MeV neutron benchmark experiments. The computational benchmark revealed a modest increase of the neutron flux levels in the deep penetration regions and a substantial increase of the gas production in steel components. The comparison to experimental results showed good agreement with no substantial differences between FENDL-3.0 and FENDL-2.1 for most of the responses. In general, FENDL-3 shows an improved performance for fusion neutronics applications. © 2014 Elsevier Inc
Instrumentation for neutron flux and tritium production rate monitoring in the European TBM in ITER
No full textTest 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
No full textWe 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. © 2015 IEEE
Preliminary engineering assessment of the HCLL and HCPB Neutron Activation System
No full textThe Neutron Activation System (NAS) is one of the four types of neutronics sensors considered for the testing of the HCLL and HCPB Test Blanket Module (TBM) in ITER. It measures the absolute neutron flux intensity with information on the neutron spectrum in selected positions of the TBM. The working principle of the NAS is as follows: the system moves small activation probes (capsules) into selected positions in the TBM (irradiation ends) by means of pneumatic transport with pressurized helium gas; the capsules are irradiated for a selected period, depending on their materials composition (several tens of seconds up to the full plasma pulse length); immediately after the irradiation they are extracted and transported to a gamma spectrometer by means of the same pneumatic transport system; the gamma spectrometer determines the induced gamma activity; the neutron flux and neutron fluence is calculated from the measured gamma activity and the known activation cross section of the materials in the activation probe; after the measurement the capsule is sent either to a disposal or storage (for later measurement). This paper summarizes the results of the feasibility assessment of the TBM NAS in the conceptual design phase, including design justification, identification of requirements based on the expected operating conditions in ITER and preliminary engineering assessment of the activation materials, irradiation ends integration in the modules design and the counting station. © 2015 IEEE
Status and verification strategy for ITER neutronics
No full textThe paper summarizes the current status of neutronics at ITER and a first set of proposals for experimental programmes to be conducted in the early operational life-time of ITER are described for the more crucial areas. These include a TF coils heating benchmark, a streaming benchmark and streaming measurements by activation on ITER itself. Also on ITER the measurement of activated water from triton burn-up should be planned and performed. This will require the measurement of triton burn-up in DD phase. Measurements of neutron flux in the tokamak building during DD operations should also be carried out. The use of JET for verification of shut down dose rate estimates is desirable. Other facilities to examine the production and behaviour of activated corrosion products and the shielding properties of concretes to high energy (6 MeV) gamma-rays are recommended. © 2014 Published by Elsevier B.V
Benchmarking and validation activities within JEFF project
No full textThe challenge for any nuclear data evaluation project is to periodically release a revised, fully consistent and complete library, with all needed data and covariances, and ensure that it is robust and reliable for a variety of applications. Within an evaluation effort, benchmarking activities play an important role in validating proposed libraries. The Joint Evaluated Fission and Fusion (JEFF) Project aims to provide such a nuclear data library, and thus, requires a coherent and efficient benchmarking process. The aim of this paper is to present the activities carried out by the new JEFF Benchmarking and Validation Working Group, and to describe the role of the NEA Data Bank in this context. The paper will also review the status of preliminary benchmarking for the next JEFF-3.3 candidate cross-section files. © The Authors, published by EDP Sciences, 2017
Neutronics instrumentation for the European TBM in ITER
No full textTest 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. © 2013 IEEE
Experimental Assessment of a Flat Sandwich-Like Self-Powered Detector for Nuclear Measurements in ITER Test Blanket Modules
No full textNeutron and gamma flux measurements in designated positions in the test blanket modules (TBMs) of ITER will be important tasks during its campaigns. Investigations on self-powered detectors (SPDs), a class of reactor flux monitors are undertaken in the framework of an ongoing project on development of nuclear instrumentation for European ITER TBMs. This paper reports the findings of experiments performed with an SPD in flat sandwich-like geometry. A detector with vanadium emitter is chosen for preliminary studies. Its irradiation in a thermal neutron field gives a proof of the principle of flat SPDs. It is further irradiated in the mixed neutron-gamma field of a 14-MeV neutron generator and a bremsstrahlung photon field. The test SPD signals are proportional to the incident fluxes, deeming it suitable for flux monitoring. Whereas both neutrons and gammas can be detected with appropriate optimization of geometries, materials, and sizes of the components, the present design is more sensitive to gammas than fast neutrons. Based on the measured sensitivities of the SPD, its response under TBM conditions is predicted. © 2018 IEEE
Soil geochemistry and pedological processes. The case study of the quaternary soils of the montagnola senese (central Italy)
No full textThe role of soil as an environmental filter is widely acknowledged, although not fully understood in all the processes involved. Unfortunately in the monitoring of some environmental parameters indicative of soil quality, such as heavy metals, we can observe a general tendency to simplify the issue. In fact, data refer only to a part of soil, i.e. the uppermost part, or the plow layer, while characteristics and processes which occur in the lower parts of the profile are neglected. On the other hand many soils, like Paleosols, which are quite widespread in Italy, have a very thick and complex profile, in which a significant elemental concentration can take place as a result of natural, pedological processes. This stresses the importance of in-depth investigation when the object of laboratory analysis is to provide advice for specific land uses. Aim of this work was to study the role played by soil forming processes in addressing element behaviour in some soils of the Montagnola Senese territory. Results of this work show an accumulation of many elements with respect to parent material. However this trend was not uniform in all cases, pointing out that their re-distribution in soil horizons can be related to different pedogenetic processes. The accumulation of some elements in soils can be to some extent related to organic matter content, pH and cation exchange capacity, but mainly in the upper horizons, while clay richness seems to play a more important role in determining the element concentration in all soil horizons: correlation coefficients with high level of significance have been found between clay and Ti, K and Cr, but also Fe, Zn and Pb are correlated with clay content, with the exception of those horizons, which are affected by element redistribution caused by oxidative-reductive processes. Several elements show a time dependent concentration process. Ti, K, Na and Mn seem to increase through time from the Holocene, to the Upper and Middle Pleistocene; Cr, Pb and Zn, similarly to Fe, from Holocene up to the Lower Pleistocene. The accumulation process proceeds along with clay neo-genesis and illuviation, but it can be affected by clay impoverishment, due to ferrolysis, together with the element mobilisation produced by reducing conditions. If clay impoverishment is characteristic of eluvial horizons and bleached streaks of fragipan and glossic horizons, mobilisation of Fe, Zn and Pb is manifested in the reduced parts of almost all the horizons with bad drainage
Development of a spectrometer to measure photon and electron decay heat from radionuclides
No full textNeutron activation of elements gives rise to an energy release during the subsequent radioactive decay. This paper deals with the development of a large, almost 4π, spectrometer for accurate and efficient measurements of photon and electrondecay heat of neutron activated elements. The spectrometer consists of a well-type 22.8 x 22.8 cm cylindrical CsI(Tl) scintillator (for photon detection) and a small plastic electron detector inserted in the well. The spectrometer was designed to have manyexcellent features such as the possibility to measure simultaneously the total activity of the sample and its electron and photon decay heat separately with high sensitivity and wide dynamic range. To demonstrate the feasibility of decay heat measurements with our spectrometer, we have irradiated twelve samples of different materials using the 14 MeV neutron generator FNG. The measurements have been compared with the prediction of the activation system EASY-99 and the results in term of the C/E (calculationvs. Experiment) are presented. While most of the C/E values are, within the uncertainties, equal to one, discrepancies for one radionuclide was found and are discussed in the paper. © 2014 Atomic Energy Society of Japan
- …
