ULTRAFINE GRAINED AND NANOSTRUCTURED MATERIALS FOR ADVANCED ENERGY APPLICATIONS

2008 ◽  
Vol 22 (18n19) ◽  
pp. 2887-2895 ◽  
Author(s):  
CONSTANTIN POLITIS
Keyword(s):  
Ball Milling ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Fission Products ◽  
High Energy ◽  
Interfacial Behavior ◽  
First Wall ◽  
Energy Applications ◽  
Ultrafine Grained ◽  
Nanoscale Interactions

The understanding of nanoscale interactions of nuclear materials will help to mastering the complex behavior of actinides and of fission products, and the interfacial behavior of fuel-cladding under extreme conditions. Ultrafine grained and nanostructured engineering materials are also suggested as protective armors on the plasma-facing first wall of D-T fusion power plants. We review the constitution and preparation by arc-melting and ball milling of ultrafine grained materials for the advanced nuclear reactor fuels UC, UC-W, UN, UN- Mo , and UN-W. We report also the preparation of the first wall armour materials nano-W, nano W-Y alloys, nano-graphite, and nano- B 4 C by high energy ball milling and their characterization by metallography, XRD, DSC and HRTEM.

Ultrafine-grained boron carbide ceramics fabricated via ultrafast sintering assisted by high-energy ball milling

2018 ◽  
Vol 44 (6) ◽  
pp. 7291-7295 ◽  
Author(s):  
Xiaorong Zhang ◽  
Zhixiao Zhang ◽  
Bin Nie ◽  
Huanyu Chen ◽  
Guangshuo Wang ◽  
...  
Keyword(s):  
Boron Carbide ◽  
Ball Milling ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Ultrafine Grained ◽  
Energy Ball ◽  
Carbide Ceramics

Thermodynamic Analysis of Power Generation Cycles With High-Temperature Gas-Cooled Nuclear Reactor and Additional Coolant Heating Up to 1600 °C

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Michał Dudek ◽  
Zygmunt Kolenda ◽  
Marek Jaszczur ◽  
Wojciech Stanek
Keyword(s):  
Energy Efficiency ◽  
High Temperature ◽  
Thermodynamic Analysis ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Electric Energy ◽  
High Energy ◽  
Medium Size ◽  
Outlet Temperature ◽  
High Temperature Gas

Nuclear energy is one of the possibilities ensuring energy security, environmental protection, and high energy efficiency. Among many newest solutions, special attention is paid to the medium size high-temperature gas-cooled reactors (HTGR) with wide possible applications in electric energy production and district heating systems. Actual progress can be observed in the literature and especially in new projects. The maximum outlet temperature of helium as the reactor cooling gas is about 1000 °C which results in the relatively low energy efficiency of the cycle not greater than 40–45% in comparison to 55–60% of modern conventional power plants fueled by natural gas or coal. A significant increase of energy efficiency of HTGR cycles can be achieved with the increase of helium temperature from the nuclear reactor using additional coolant heating even up to 1600 °C in heat exchanger/gas burner located before gas turbine. In this paper, new solution with additional coolant heating is presented. Thermodynamic analysis of the proposed solution with a comparison to the classical HTGR cycle will be presented showing a significant increase of energy efficiency up to about 66%.

Properties of Ultrafine-Grained Tungsten Prepared by Ball Milling and Spark Plasma Sintering

2016 ◽  
Vol 821 ◽  
pp. 399-404 ◽  
Author(s):  
Monika Vilémová ◽  
Barbara Nevrlá ◽  
Zdenek Pala ◽  
Lenka Kocmanová ◽  
Marek Janata ◽  
...  
Keyword(s):  
Ball Milling ◽  
Spark Plasma Sintering ◽  
Ball Mill ◽  
Planetary Ball Mill ◽  
Coarse Grained ◽  
First Wall ◽  
Fine Grained ◽  
Plasma Sintering ◽  
Ultrafine Grained ◽  
Spark Plasma

Tungsten is currently considered as the most suitable plasma facing material for the first wall of a nuclear fusion reactor. First wall will be subjected to harsh conditions that will gradually deteriorate properties of the wall material. Some studies point out that fine-grained tungsten could be more resistant to the structure and property changes than coarse-grained tungsten. However, tailoring of tungsten microstructure is very laborious. Due to its high melting point, tungsten is very often processed mechanically and subsequently sintered into a compact body. In this study, preparation of ultrafine-grained tungsten by mechanical processing in a planetary ball mill was examined. Three types of tungsten samples were compared. One was made from coarse grained tungsten powder consolidated by SPS (spark plasma sintering). Other two samples were prepared from the powder processed in a planetary ball mill with and without addition of Y2O3. After ball milling, the powders were consolidated by SPS, i.e. fast sintering process that allows preserving fine-grained structure of the powder material. Properties of the samples such as hardness and thermal conductivity were examined and correlated with the processing history and microstructure.

The Autoignition of Nuclear Reactor Power Plant Explosions

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Robert A. Leishear
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Nuclear Reactions ◽  
High Energy ◽  
Reactor Power ◽  
Common Cause ◽  
Fluid Transients ◽  
Accident Conditions

Abstract Explosive research proves that there is a common cause for most explosions in nuclear reactor power plants during normal operations and accident conditions. The autoignition of flammable hydrogen is a common cause for nuclear power plant explosions, where complex corrosion processes, nuclear reactions, and thermal-fluid transients autoignite explosions. Research evaluated increasingly complicated accidents. First, piping explosions occurred at Hamaoka and Brunsbuttel. Fluid transients compressed oxygen and flammable hydrogen to heat these gases to autoignition, where resultant explosions shredded steel pipes. This identical mechanism was responsible for pipe and pump damages to U.S. reactor systems since the 1950s, where water hammer alone has been assumed to cause damages. Small explosions inside the piping actually cause damages during nuclear reactor startups and flow rate changes. Second, explosions are caused by thermal-fluid transients during nuclear reactor restarts, following accidental nuclear reactor meltdowns. Disastrous explosions destroyed nuclear reactor buildings (RBs) at Fukushima Daiichi. Previously considered to be a fire, a 319 kilogram hydrogen explosion occurred at Three Mile Island (TMI). The explosion cause following each of these loss-of-coolant accidents was identical, i.e., after meltdowns, pump operations heated gases, which in turn acted as the heat source to autoignite sequential hydrogen explosions in reactor systems to ignite RBs. Third, the Chernobyl explosion followed a reactor meltdown that was complicated by a high energy nuclear criticality. The hydrogen ignition and explosion causes are more complicated as well, where two sequential hydrogen explosions were ignited by high-temperature reactor fuel.

Influence of high-energy ball milling on the solid-phase sintering kinetics of ultrafine-grained heavy tungsten alloy

2017 ◽  
Vol 62 (9) ◽  
pp. 420-424 ◽  
Author(s):  
V. N. Chuvil’deev ◽  
A. V. Nokhrin ◽  
M. S. Boldin ◽  
N. V. Sakharov ◽  
G. V. Baranov ◽  
...  
Keyword(s):  
Ball Milling ◽  
Solid Phase ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Tungsten Alloy ◽  
Sintering Kinetics ◽  
Ultrafine Grained ◽  
Energy Ball ◽  
Heavy Tungsten Alloy ◽  
Kinetics Of

CFD Simulation of Debris Transport in a PWR Reactor Sump Following a Loss of Coolant Event

2005 ◽  
Author(s):  
Stuart A. Cain ◽  
Fariba Gartland ◽  
Andrew E. Johansson
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Cfd Simulation ◽  
Energy Levels ◽  
High Energy ◽  
Material Transport ◽  
Pressurized Water ◽  
Laboratory Flume ◽  
Debris Transport

High Energy Line Breaks (HELBs) inside nuclear reactor containment are recognized as challenges to Pressurized Water Reactor (PWR) nuclear power plants arising from the collateral damage due to insulation, fireproofing, coatings, and other miscellaneous materials (such as tags, stickers, signs, etc) which are shredded and transported during the event. These materials, as well as latent debris (dirt and dust) will be washed towards the containment floor and the recirculation sump screens by flow from both the HELB and the containment spray headers. This debris, if washed towards the recirculation pumps, could potentially impede the performance of the ECCS system. To evaluate transport of material towards the sump and the potential for degradation in performance of the ECCS system, Computational Fluid Dynamics (CFD) has been used to predict the flow patterns and energy levels in the containment pool during the recirculation phase of the event. Further, a unique methodology has been applied to correlate the CFD results with material-specific laboratory flume data and predict the volume of material transported to the sump screens. The predicted volume of debris transported to the sump screens is then used to determine if there is sufficient suction head for the pumps to operate without the potential for cavitation. In this paper, the CFD-based methodology used to predict material transport to the sump screens is discussed and the results of a prototype containment analysis are presented. Of particular interest is the analytical method for introducing the HELB flow into the containment pool and the quasi-steady treatment of the water surface to simulate the gradual filling of the pool. Coupling of the velocity and kinetic energy fields from the CFD simulations with material-specific incipient tumbling velocities (as predicted during a series of laboratory flume tests) are presented and used to demonstrate overall material transport to the sump screens.

MECHANOCHEMICAL SYNTHESIS OF TIAL3/AL2O3 ULTRAFINE GRAINED COMPOSITE

2008 ◽  
Vol 22 (18n19) ◽  
pp. 2914-2923 ◽  
Author(s):  
M. M. VERDIAN ◽  
S. HESHMATI-MANESH
Keyword(s):  
Ball Milling ◽  
Titanium Oxide ◽  
Milled Powder ◽  
Xrd Analysis ◽  
High Energy ◽  
Reduction Reaction ◽  
High Energy Ball Milling ◽  
X Ray Diffraction ◽  
Ultrafine Grained ◽  
Energy Ball

The TiAl 3/ Al 2 O 3 metal-ceramic composite was synthesized using high energy ball milling, powder compaction and thermal treatment. Micron sized powders of titanium oxide ( TiO 2) and aluminum were subjected to high energy ball milling under an argon protected atmosphere. Milling of this powder mixture although reduced crystallites sizes to a nano scale, did not result in a reaction between the reactants. Further compaction of the milled powder and annealing, paved the way to a reduction reaction and led to the formation of an ultrafine grained composite structure. The reaction appeared to proceed through two-steps. Titanium oxide was first reduced to TiO and later on, TiO was reduced to Ti . The resulting Ti was alloyed with extra Al to produce TiAl 3 intermetallic in which alumina particles were dispersed. Also, mechanical activation was found to reduce the reaction temperature between Al and TiO 2. The morphology and phase composition of the milling products were evaluated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis.

Sign in / Sign up

Export Citation Format

Share Document