Studies on the Dynamics of D–T Fusion Reaction Based on the Relativistic Equilibrium Velocity Distribution

The Coulomb barrier is in general much higher than thermal energy. Nuclear fusion reactions occur only among few protons and nuclei (i.e., deuterium and tritium) with higher relative energies than Coulomb barrier. It is the equilibrium velocity distribution of these high-energy protons and nuclei that participates in determining the rate of nuclear fusion reactions. In the circumstance it is inappropriate to use the Maxwellian velocity distribution for calculating the nuclear fusion reaction rate. We use the relativistic equilibrium has a reduction factor with respect to that based on the Maxwellian distribution, which factor depends on the temperature, reduced mass and atomic numbers of the studied nuclear fusion reactions. In this paper, we concluded at energy range 10⁵ (keV) ≤ E ≤ 10⁶ (keV), that is smaller than reduced mass energy of deuterium–tritium, m _r c ², the numerical values of R and R _M are not different from each other very much, but by increasing energy near the region of m _r c ² the difference between them are visible, also by increasing energy for example 9 × 10⁶ (keV) ≤ E ≤ 10 × 10⁶ (keV) the difference is obviously more visible. Therefore, we have to use relativistic equilibrium velocity distribution instead of Maxwellian velocity distribution.     

Studies on the 30–450°C thermoluminescence of synthetic mullite

The 30–450°C thermoluminescence (TL) characteristics of synthetic mullite samples are presented. Thermal peaks at 115°C, 190°C, 250°C and 280°C have been observed in variously treated samples. The relationship between the intensities of the four TL peaks, the irradiation dose and the thermal activation characteristics of the 115°C peak have been examined. The activation energy of the 115°C peak is ∼0.61 eV. An exponential relation between the intensity of the 190°C peak and the dose is established by a curve fitting. Emission processes of the peaks are discussed.     

Studies on the Separation of Cesium From Fission Products

~(135)Cs is a long-life fission product. When measuring its thermal cross section, we must separateradiochemical purity cesium from fission products. Except for decontaminating radio-nuclides, otherswhich can be activated must be avoided to come into solution. So ion exchanger is used. Inorganic ionexchangers have received increased attention because of their high resistance to radiation and their veryefficient separation of alkali metal ions.     

Studies on Reaction Kinetics of Nitrous Acid With Acetohydroxamic Acid in HClO4 Medium

The existence of HNO2 in the Pruex process will oxidate Pu（Ⅲ） to Pu（Ⅵ） quickly, so HNO2 must be eliminated in the U/Pu cycle in order to stabilize Pu（Ⅲ）. There are many papers report the reaction of hydroxylamine, aldehyde, hydroxyurea and their derivatives. But the reaction of AHA with nitrous acid has not been studied.     

Studies on Reaction Kinetics of Nitrous Acid With Acetohydroxamic Acid in HClO_4 Medium

The existence of HNO2 in the Pruex process will oxidate Pu(Ⅲ) to Pu(Ⅳ) quickly,so HNO2 must be eliminated in the U/Pu cycle in order to stabilize Pu(Ⅲ). There are many papers report the reaction of hydroxylamine, aldehyde, hydroxyurea and their derivat…     

Studies of Ash Removal Efficiency Improvement and Tritium Inventory Reduction for FEB

Experiments show that helium ash can be removed by pump limiter or divertor. However a fraction of α particles has not been pumped out after they get neutralized on the limiter or divertor target plate, but re-ionized by edge plasma; as a result, they flow back to the SOL region and even diffuse into main plasma. A new method has been explored to suppress this back stream,     

Neutronic Comparison of Tritium－Breeding Performance of Candidate Tritium－Breeding Materials

Tritium self-sustainment, which will meet the fuel requirement of fusion reactor, is one of the key issues of fusion power development. The tritium breeding performances of various tritium-breeding materials are compared based on a series of neutronics calculations using three-dimensional Monte Carlo neutron-photon transport code MCNP/4C with the IAEA FENDL-2 data library. The effects of the dimensions of the tritium-breeding zone and the enrichment of 6Li on Tritium Breeding Ratio (TBR) are analyzed. The effects of Be as a neutron multiplier on TBR are also calculated.     

Studies on the coating of fuel particles for the ‘dragon’ reactor experiment

The requirements of fission product retaining coatings on coated fuel particles are reviewed and the scope of development necessary to meet these requirements for the initial charges of the Dragon Reactor Experiment is described. These studies on the coating of fuel particles were carried out using a laboratory scale fluidized bed type of coating furnace.Within the range of deposition temperatures investigated, laminar or metallographically structureless pyrolytic carbon was deposited with methane concentrations greater than 15 per cent, while the structure deposited at low methane concentrations was columnar. Appreciable temperature gradients were found in these small fluidized beds of fuel particles, particularly under the relatively static conditions of fluidization which favoured deposition of the columnar structure.The rate of deposition of pyrolytic carbon was found to increase linearly with methane concentration at a given temperature, and within specified limits of methane concentration such that the relationship was linear within each of two separate ranges of concentration corresponding to the different metallographic structures. The room temperature density of the deposited pyrocarbons showed minimum values for deposition temperatures of 1600–1700°C. Under the experimental conditions described, the carbon efficiency of deposition increased to the order of 100 per cent at deposition temperatures of 1600°C and above.The deposition of silicon carbide interlayers from methyltrichlorosilane is described. The surface contamination of coated particle fuel was shown to be sensitive to the temperature of deposition of the pyrocarbon, to the rate of deposition at a fixed temperature, and to the presence of silicon carbide interlayers. The latter reduced surface contamination to near background values.     

Effect of Nuclear Data Libraries on Tritium Breeding in a (D–T) Fusion Driven Reactor

In design a Deuterium–Tritium (D–T) fusion driven hybrid reactor, neutronics and nuclear data libraries have an essential role for reliable neutronics calculations. Therefore, nuclear data libraries are very important to calculate of the neutronic parameters and selection of tritium breeder materials to be used in the blanket. In this study tritium breeding performances of candidate tritium breeding materials, namely, Li₂O, LiH, Li₂TiO₃, Li₂ZrO₃ and Li₄SiO₄ in a (D–T) driven fusion–fission (hybrid) reactor is investigated based on three dimensional (3-D) and one dimensional (1-D) neutronic calculations. 3-D and 1-D neutron transport calculations are performed with Monte Carlo transport code (MCNP 4C), SCALE 5 and ANISN nuclear data codes to determine the tritium breeding ratio (TBR) of the blanket. The effects of different nuclear data libraries on TBR are examined and TBR calculation results are comparatively investigated.     

Studies on unfolding energy spectra of neutrons using maximumlikelihood expectation–maximization method

Energy spectra of neutrons are important for identification of unknown neutron sources and for determination of the equivalent dose. Although standard energy spectra of neutrons are available in some situations, e.g.,for some radiotherapy treatment machines, they are unknown in other cases, e.g., for photoneutrons created in radiotherapy rooms and neutrons generated in nuclear reactors. In situations where neutron energy spectra need to be determined, unfolding the required neutron energy spectra using the Bonner sphere spectrometer(BSS) and nested neutron spectrometer(NNS) has been found promising. However, without any prior knowledge on the spectra, the unfolding process has remained a tedious task.In this work, a standalone numerical tool named‘‘NRUunfold' was developed which could satisfactorily unfold neutron spectra for BSS or NNS, or any other systems using similar detection methodology. A generic and versatile algorithm based on maximum-likelihood expectation–maximization method was developed and benchmarked against the widely used STAY'SL algorithm which was based on the least squares method. The present method could output decent results in the absence of precisely calculated initial guess, although it was also remarked that employment of exceptionally bizarre initial spectra could lead to some unreasonable output spectra. The neutron count rates computed using the manufacturer's response functions were used for sensitivity studies. The present NRUunfold code could be useful for neutron energy spectrum unfolding for BSS or NNS applications in the absence of a precisely calculated initial guess.     

Studies on physics parameters of metal (U–Pu–Zr) fuelled FBR cores

For faster growth of nuclear power in India, it is essential to shift to the use of metal-fuels in fast breeder reactors (FBR), which gives a higher breeding ratio (BR) and lower doubling time (DT). Also, future commercialization of the FBR fuel cycle necessitates the use of metallic fuel along with the pyro-process recycling, which can be less costly than oxide fuel reprocessing. Two-dimensional diffusion calculations have been performed to investigate the various physics parameters of metal (U–Pu–Zr) fuelled FBR cores as a function of reactor parameters like reactor power, smear density, zirconium content in the fuel and the number of rows in radial blankets. A 1000 MWe fast reactor with U–Pu fuel (i.e. metal-fuel with no zirconium – which is a theoretical possibility now, due to the lack of irradiation experience) can attain a breeding ratio of 1.61 and a reactor fuel doubling time of 6.6 yrs. Two methods to reduce the sodium void reactivity, which is high and positive in metal-fuelled FBR cores, are suggested.     

Testing of the Tritium Production for the ~6Li and ~7Li

The tritium production cross section of the lithium, P_T~(Li) is a very important factor of the fusion system. Several experiments have been made to measure it. In 1954, tile tritium production of ~(Nat)LiD was measured by M. E. Wyman for the first time in Los Alamos The P_T~6, the tritium production of ~6Li, was measured with a ~6LiD sphere by Hemmendinger ct al in 1978, the radius of the sphere is 30 cm. A similar experiment was also done to measure the P_T~6 in China, the 14 MeV neutron source was used in the experiments.     

Computer Simulation of FEB-E Tritium System

Based on Fusion Experimental Breeder (FEB) engineering outline design, a dynamic subsystem model is constructed for tritium fuel cycle system. A computer simulation code-SWITRIM has been developed to     

Studies on structural features of human tumor necrosis factor

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Fusion in the Era of Burning Plasma Studies: Workforce Planning for 2004–2014

This is the final report of a panel set up by the U.S. Department of Energy (DOE) Fusion Energy Sciences Advisory Committee (FESAC) in response to a charge letter from Dr. Raymond Orbach (Appendix A), asking FESAC to addressed the issue of workforce development in the U.S. fusion program. This report, submitted to FESAC March 29, 2004 and subsequently approved by them (Appendix B), presents FESAC's response to that charge.     

Assortativity Characteristic Transition on Harmonious Unifying Hybrid Networks

Many systems take the form of networks—sets of vertices joined together by edges. There exist a lot of networks around us, including social networks, information networks, technical networks and biological networks. In past few years, many properties such as small-world phenomenon and scale-free behavior were discovered from networked complex systems.     

Entropy Characteristic on Harmonious Unifying Hybrid Preferential Networks

The discovery of the ubiquity of small world (SW) and scale-free (SF) networks has led to many exciting insights into fundamental underlying principles that govern complex systems. It has been realized that, despite functional diversity, most real web like systems share important structural features, e.g.: