Vol.12,

By using the microscopic sdIBM-2 formalism, procedures of canonical ensemble average and saddle point method, the finite-temperature internal energy, specific heat and level density of nucleus were calculated. The temperature of the phase transition of thermal excitation mode was determined in reference to the single boson energy. As there is a peak in the specific heat, it is established that the symmetric phase transition takes place in the nucleus. For ^56,58Fe isotopes, numerical results were calculated and compared with the experimental data and the values obtained by quantum Monte Carlo calculations. The present results indicate that this approach can be successfully used in describing light nuclei and their finite-temperature behavior.

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The excitation functions were measured in the reaction of ²⁷Al+²⁷Al at incident energies from 114MeV to 127MeV in steps of 200 keV. The detection angles were continuously covered from 10° to 57° in the laboratory system. The energy autocorrelation functions of the dissipative fragments were analyzed by using different approaches. The nonself-averaging oscillations in the excitation functions were considered due to the angular momentum coherence and damping of the coherent nuclear rotation. The damping results from a quantum chaotic motion.

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Metal vapor vacuum are (MEVVA) source ion implantation is a new technology used for achieving long range ion impantation. It is very important for research and application of the ion beam modification of materials. The results show that the implanted atom diffusion coefficient increases in Mo implanted Al with high ion flux and high dose. The implanted depth is 3~11.6 times greater than that of the corresponding ion range. The ion species, doses and ion fluxes play an important part in the long-range implantation. Especially, thermal atom chemistry have specific effect on the long-range implantation during high ion flux implantation at transient high target temperature.

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Neodymium silicides were synthesized by Nd ion implanted into Si substrates with the aid of a metal vapor vacuum arc (MEVVA) ion source. The blender of Nd₅Si₄ and NdSi₂ was formed in a neodymium-implanted silicon thin film during the as-implanted state, but there was only single neodymium silicide compound in the post-annealed state, and the phase changed from NdSi₂ to Nd₅Si₄ with increasing annealing temperature. The blue-violet luminescence excited by ultra-violet was observed at the room temperature (RT), and the intensity of photoluminescence (PL) increased with increasing the neodymium ion fluence. Moreover, the photoluminescence was closely dependent on the temperature of rapid thermal annealing (RTA). A mechanism of photoluminescence was discussed.

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The penetration depth and concentration distribution of implanted ions have been studied for low energy heavy ions implanted in the dry seeds of plant, such as peanut, mung bean, sunflower, wheat and radish seeds, etc. by SEM+EDS. The results show that the maximum penetration depth is about 12µm for V⁺ with an energy 200 keV implanted in cotyledon of the peanut, 18µm, 5µm, 20µm for V²⁺ with 90keV implanted in sunflower, wheat, radish seeds, respectively. The penetration depth of implanted Cu²⁺ with 80 keV is about 90µm in the remainder funicle derivative of the mung bean seeds. The experimental result of the maximum penetration depth of implanted V⁺ in the peanut seeds was compared with the calculated value of the TRIM95.

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Flow patterns in upstream and downstream straight tubes of sudden-changed areas in a horizontal straight pipe were experimentally examined. Both sudden-expansion cross-section (SECS) and sudden-contraction cross-section (SCCS) were investigated. The flow pattern maps upstream and downstream were delineated and compared with those in straight tubes with uniform cross-sections. The effects of the SECS and SCCS on flow patterns were discussed and analyzed. Furthermore, flow pattern transition mechanisms resulting in occurrences of different flow patterns were simply discussed and some transition criteria for the flow pattern transitions were deduced by using the non-dimensionlized analysis method.

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A computer model has been developed for prediction of the pressure in the pressurizer under transient conditions. In the model three separate thermodynamic regions which are not required to be in thermal equilibrium have been considered. The mathematical model derived from the general conservation equations includes all of the important thermal-hydraulics phenomena occurring in the pressurizer, i.e.. stratification of the hot water and incoming cold water, bulk flashing and condensation, wall condensation, and interfacial heat and mass transfer, etc. The bubble rising and rain-out models are developed to describe bulk flashing and condensation, respectively. To obtain the wall condensation rate, a one-dimensional heat conduction equation is solved by the pivoting method. The presented model will predict the pressure-time behavior of a PWR pressurizer during a variety of transients. The results obtained from the proposed mathematical model are in good agreement with available data on the CHASHMA nuclear power plant's pressurizer performance.

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The static bifurcation of the two-phase natural circulation (TPNC) system was studied theoretically and numerically. By the DERPAR algorithm the solution diagram was calculated, which shows that the static bifurcation occurs under some conditions in the TPNC systems Also, it shows that, in a region of multiple solutions, the static instability may occur. It is defined as a region of thermal-siphon instability induced flow rate jumping. By means of the solution diagram, the stability margin can be determined in this region. Furthermore, the heat input at the peak of the solution diagram is defined as the maximum capacity of heating load that can be used to judge the capacity of the TPNC of a given geometry topological structure. Meanwhile, it is interesting that the TPNC systems have the hysteresis phenomenon defined as thermal-siphon hysteresis. Some parametric effects related were also studied.

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Stabilization and volume reduction of spent radioactive ion-exchange resins (IERs) were studied. Stabilization technology includes volume reduction with wet chemical oxidation process and immobilization of the residue into cement. Under suitable conditions, the exhausted radioactive ion-exchange resins were dissolved successfully in a H₂O₂-Fe²⁺/Cu²⁺ catalytic oxidation system (Fenton reagent). The analytical results indicated that the radioactive nuclides loaded in the resins were concentrated in decomposed solution and solid residues. The process parameters of wet chemical oxidation and solidification were also obtained. The decomposition ratios were 100% and more than 90% for cation and anion IERs respectively. The waste volume was decreased by 40% compared with that of original spent resins.

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The average air γ-ray dose rates measured from the field, road, bone coal, bone coal cinder and bone coal cinder bricks in the three bone coal mines in west Zhejiang Province, are 3.8×10², 4.1x10², 7.1x10², 4.0×10² and 7.1×10² nGy/h, respectively. The mean contents of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K in the bone coal of the three bone coal mines are 2.0×10³, 2.1×10³, 3.9×10¹ and 6.1×10² Bq/kg, respectively, in the bone coal cinder(BCC) are 1.6×10³, 1.6×10³, 2.3×10¹ and 4.5×10² Bq/kg, respectively, and in the bone coal cinder brick(BCCB) are 1.2×10³, 1.2x10³, 2.4x10¹ and 4.0×10² Bq/kg, respectively, and those in the reference soil are 3.4×10², 1.0×10², 4.9×10¹ and 4.9×10² Bq/kg, respectively. The annual mean of effective dose equivalent for public living in house buildings made with BCCB near the three mines is 6.8 mSv.

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