Search results for "nuclear energy"
showing 10 items of 614 documents
Radiation stability of long-term annealed bi-phasic advanced ceramic breeder pebbles
2019
Abstract Advanced ceramic breeder pebbles consisting of Li4SiO4 and additions of Li2TiO3 were tested regarding their long-term thermal and to their radiation stability. As-prepared and long-term annealed pebbles were irradiated with accelerated electrons (up to 6 MGy) to investigate the formation of radiation-induced defects and radiolysis products caused by ionizing radiation. By using Raman spectroscopy the formation of significant amounts of radiolysis products can be excluded. Electron spin resonance spectrometry revealed several paramagnetic radiation-induced defects, such as HC2 centres ( SiO 4 3 - and TiO 3 - ), E’ centres ( SiO 3 3 - and TiO 3 3 - ), Ti 3 + centres and peroxide radi…
Thermoluminescence study of irradiated lithium orthosilicate
1998
Abstract The thermoluminescental investigations of neutron and gamma irradiated lithium orthosilicate pellets were carried out. It has been shown that the addition of Cr 3+ and Fe 3+ ions with the total concentration up to 2.0 wt.% during preparation of lithium orthosilicate pellets, significantly reduces the formation of radiation defects in irradiated matrix. This phenomena can be explained by the reducing of the formation of primary radiation defects during irradiation due to stimulating the recombination processes by the ions of impurities. Several ion concentration combinations were studied. The thermoluminescental investigations of fast neutron irradiated lithium orthosilicate pellets…
Study of tritium and helium generation and release from lead-lithium eutectics Li15.7Pb under neutron irradiation
2019
Abstract This paper describes the experiments on study of tritium and helium generation and release processes from lead-lithium eutectics Li15.7Pb. The irradiation was performed at the IVG.1M research reactor at 6 MW of thermal power. The irradiation temperature increased step by step from 225 to 550 °C. A qualitative assessment of the experimental results showed that as the temperature rises above 390 °C, the tritium flux from the sample consisting of T2 and HT molecules decreases. It was concluded that the observed effect is similar to the previously observed one for lead-lithium eutectics with Li17Pb83 composition.
Effects of external energetic factors on tritium release from the EXOTIC 8-3/13 neutron-irradiated beryllium pebbles
2009
Abstract Tritium release from samples of 9–13 mg of the EXOTIC 8-3/13 neutron-irradiated beryllium pebbles under the separate and simultaneous action of temperature 490–770 K, 5 MeV fast-electron radiation 14 MGy h−1 for 3 h and magnetic field (MF) of 1.7 T was investigated. The pebbles were found to be very dissimilar with respect to their total tritium content—2.5–9 MBq g−1. The batch contained also some coarse agglomerates of the pebbles containing 10–19 MBq g−1 of tritium having also a high tritium release. For the pebbles having the total tritium 2.5–5.3 MBq g−1, the electron radiation for 3 h caused the fractional tritium release 17–26% (B = 0) and 21–29% (B = 1.7 T), the temperature …
Radiation effects on stress evolution and dimensional stability of large fusion energy structures
2021
Abstract We assess the effects of neutron irradiation on the deformation and stress evolution of large-scale fusion energy structures. This is accomplished through non-linear finite element structural analysis of the coupled thermal and mechanical fields at the Beginning-Of-Life (BOL), at 45 dpa, and at 90 dpa. Radiation effects include volumetric swelling and the influence of radiation on the mechanical properties. The system studied here is a large section of a full inboard module of an integrated structure comprising the First Wall and Blanket (FW/B) of a Dual Cooled Lithium-Lead (DCLL) energy conversion unit in the Fusion Nuclear Science Facility (FNSF). The structural material is the f…
On the thermal-hydraulic performances of the DEMO divertor cassette body cooling circuit equipped with a liner
2020
Abstract In the framework of the Work Package DIV 1 - “Divertor Cassette Design and Integration” of the EUROfusion action, a research campaign has been jointly carried out by University of Palermo and ENEA to investigate the steady-state thermal-hydraulic performances of the DEMO divertor cassette cooling system. The research activity has been focussed onto the most recent design of the Cassette Body (CB) cooling circuit, consistent with the DEMO baseline 2017 and equipped with a liner, whose main function is to protect the underlying vacuum pump CB opening from plasma radiation. The research campaign has been carried out following a theoretical-computational approach based on the finite vo…
Thermal-hydraulic study of the DEMO divertor cassette body cooling circuit equipped with a liner and two reflector plates
2021
Abstract In the framework of the Work Package DIV 1 – “Divertor Cassette Design and Integration” of the EUROfusion action, a research campaign has been jointly carried out by University of Palermo and ENEA to investigate the steady-state thermal-hydraulic performances of the DEMO divertor cassette cooling system. The research activity has been focussed onto the most recent design of the Cassette Body (CB) cooling circuit, consistent with the DEMO baseline 2017 and equipped with a liner and two Reflector Plates (RPs), whose main functions are to protect the underlying vacuum pump hole from the radiation arising from plasma and shield the PFCs inlet distributors, respectively. The research ca…
A Comprehensive Model for the Auto-Ignition Prediction in Spark Ignition Engines Fueled With Mixtures of Gasoline and Methane-Based Fuel
2018
The introduction of natural gas (NG) in the road transport market is proceeding through bifuel vehicles, which, endowed of a double-injection system, can run either with gasoline or with NG. A third possibility is the simultaneous combustion of NG and gasoline, called double-fuel (DF) combustion: the addition of methane to gasoline allows to run the engine with stoichiometric air even at full load, without knocking phenomena, increasing engine efficiency of about 26% and cutting pollutant emissions by 90%. The introduction of DF combustion into series production vehicles requires, however, proper engine calibration (i.e., determination of DF injection and spark timing maps), a process which…
Thermal optimization of the Helium-Cooled Lithium Lead breeding zone layout design regarding TBR enhancement
2017
Abstract Within the framework of EUROfusion R&D activities, CEA-Saclay has carried out an investigation of the thermal and mechanical performances of alternative designs intended to enhance the Tritium Breeding Ratio (TBR) of the Helium-Cooled Lithium Lead (HCLL) Breeding Blanket (BB) for DEMO. Neutronic calculations performed on the 2014 DEMO HCLL baseline predicted a value of TBR equal to 1.07, lower than the required value of 1.1, necessary to ensure the tritium self-sufficiency of the breeding blanket taking into account uncertainties. In order to reach the TBR target, the strategy of the steel amount reduction inside the HCLL module breeding zone (BZ) has been followed by suppressing s…
On the effect of stiffening plates configuration on the DEMO Water Cooled Lithium Lead Breeding Blanket module thermo-mechanical behaviour
2019
Abstract Within the framework of the pre-conceptual design of the EU-DEMO Breeding Blanket (BB) supported by EUROfusion action, results of the research activities carried out in the last years have highlighted that changes in the proposed Water Cooled Lithium Lead (WCLL) BB design have to be considered, especially as to the liquid breeder circulation path within the BB module. Therefore, in view of the definition of a final WCLL BB module layout, a parametric campaign of numerical analyses has been carried out at the University of Palermo in order to assess the impact of different SPs configurations on the module thermo-mechanical performances. To this purpose, attention has been focussed o…