Characterization of crud deposited on fuel rods under HWC environment in Kuosheng Nuclear Power Plant

Under normal water chemistry conditions, the oxygen and hydrogen peroxide produced by water radiolysis in the coolant of boiling water reactors(BWRs) can lead to intergranular stress corrosion cracking in the constituent materials of plant components. This fact has led to the wide-scale adoption of hydrogen water chemistry(HWC) in the nuclear industry to counteract these effects.This study seeks to characterize the metallic composition and the surface properties of the constituent materials of plant components in order to determine their effects on the accumulation of chalk river unidentified deposits(crud) on fuel rods in the BWR Unit-1 of the Kuosheng Nuclear Power Plant in Taiwan. Inductively coupled plasma-atomic emission spectroscopy was used to calculate the concentrations of surface crud and gamma spectrometry was used to determine the radioactivity of the corrosion products, as well as their axial distribution across the surface of the fuel rods. X-ray diffraction analysis and scanning electron microscopy/energy-dispersive X-ray spectroscopy were used to identify the crystalline phase and morphology of the crud as irregular shapes and flakes. The amount of crud deposited during the fourth fuel cycle exceeded that of the third fuel cycle due to extended burn-up time. Our analytical results indicate that the implementation of HWC had no significant effect on the characteristics of subsequent crud.

APPLICATION OF NUCLEAR ANALYSIS TECHNIQUES IN STUDY OF ENVIRONMENTAL POLLUTION IN THE VICINITY OF SHANGHAI

Aerosol samples were collected from three typical areas during three years: 1) north suburb of Shanghai city (NSSC); 2) north part of Shanghai city; 3) a lead-zinc smeltery and its surrounding areas. The hair samples were collected from lead-exposed workers and control people. Aerosol samples have been analyzed by PIXE, and hair samples by EDXRF (energy-dispersive X-ray fluorescence) method. S, Cl, K, Ca, Mn, Fe, Cu, Zn, Pb etc were detected in most of the aerosol and hair samples. According to the analytical results, the compositions of NSSC aerosol samples were quite similar to those from north part of Shanghai city, both the lead concentrations of these samples were less than the limit of the National Standard (70 μ g/m3); There was serious air pollution in smeltery and its surrounding areas. Especially, the lead concentration in the aerosol exceeded 200 μg/m3; The average lead concentration of hair samples for half-year exposed group was about 3-fold higher than that of unexposed group.

ORIGIN OF THE REPULSIVE CORE OF NUCLEAR FORCE

A soliton model for a baryon is extended to study nucleon-nucleon interaction by virtue of the relativistic two-quark-cluster theory・A repulsive core is obtained mainly due to the one ghtoji exchange interaction and quark exchange between two nucleons.In this connexion the relativistic effect of quark motion must be considered for producing the repulsive core.

NUCLEAR POLARIZATION OF 8Li PRODUCED BY BEAM-FOIL INTERACTION

The njLclear polarization of ^(8)Li produced by beam-foil interaction with a single carbon foil was measured.The sign of the polarization was also deter-mined,and it tuned out to be opposite to that of the atomic polarization predicted by electric density gradient model.

CONTRIBUTIONS OF NUCLEAR CORE POLARIZATION TO Ovββ DECAY OF ^(48)Ca MEDIATED BY HEAVY NEUTRINO

Nuclear core polarization processes in the Ovββ decay of ^(48)Ca are discussed in a diagrammatic effective operator approach.The main effect of these processes is to increase the limit on heavy neutrino mass of about 8%.

Energy and Target Dependence of Azimuthal Distributions at Mid-Rapidity in Mediate-Energy Nuclear Reactions

The azimuthal distributions at mid-rapidity for ^(40)Ar-induced reactions are investigated by nuclear transport theory.The rotation-like behavior which is one of collective motions becomes stronger with the increasing of the imp&ct parameter and weaker with the increasing of the projectile energy.At about 85 MeV/nucleon the rot&tion-like behvior aim os t vanishes for ^(40)Ar+^(27)Al system.While the rotation-like behavior becomes weaker and the out-of-plane enhancement of particle emisBion is revealed with the increasing of target mass.Some quantitative agreements with the experiment data are also obtained.

Measurements of Total Reaction Cross Section for Light Nuclei and Evidence for the Anomalous Nuclear Structure in ^(15)C

Measurements of the total reaction cross section for^(12-16)C,^(14-17)N and^(16-18)O on carbon target at intermediate energies were performed on RIBLL of HIRFL.A larger enhancement ofσR for^(15)C was observed than that for its neighbors.The analysis of these data indicates possible existence of an anomalous nuclear structure in^(15)C.A new quantity was suggested as the criterion to distinguish anomalous structure nuclei from normal nuclei.

Variation of Effective Mass and Level Density Parameter with Nuclear Temperature in Semi-infinite Nuclear Matter

The temperature dependence of the self-energy of a particle is studied in semi-infinite nuclear matter.Based on the finite temperature Green’s function Mat-subara formalism and applying it to the single particle-states in ^(208)Pb,the calculated results show that the characteristic enhancement of the effective mass at near the Fermi energy disappears at temperature T=3 MeV,and correspondingly,as a consequence the level-density parameter should decrease in agreement with recent empirical data.

Effect of Calcium Leaching on the Properties of Cement-based Composites

Leaching is one of the major factors that alter the mechanical properties of cement-based composites.This study is aimed to investigate the effect of leaching on the properties of cement-based composites.Specimens with two water/cementitious ratios and two mineral admixtures were tested.An electrical potential was applied to accelerate the leaching process.Compressive strength test,scanning electronic microscopy,thermogravimetric analysis and X-ray diffraction analysis were conducted.Test results demonstrated that the calcium leaching reduced compressive strengths of concrete specimens,and such effect was prominent on the specimens without mineral admixtures.The leaching resistance increased with a decrease in water/cementitious ratio and an increase in amount of mineral admixtures.The mineral admixtures would reduce the amount of calcium hydroxide and refine the pore structure through pozzolanic reactions.A fair relationship was found between the calcium leaching and the compressive strength.

Neutron Halos in the Excited States of Spherical Nuclei Near the β-Stable Line

The newly discovered neutron halos in the excited states of nuclei 12B, 13C, and 209pb are studied by therelativistic mean-field theory. The calculated binding energies are very close to the experimental ones. The experimentally extracted root-mean-square radii of the last neutron with different occupations in nuclei are well reproduced bycalculations. New candidates for the neutron halos in excited states are predicted and are useful for further search ofneutron halos in the excited states of stable nuclei.

Sputtering Angular Distributions of Individual Elements for Low-Energy Ar Ion Irradiation of PtCu Alloy

The dynamic Monte Carlo program including a bombardment-induced Gibb-sian segregation process was used to^calculate angular distributions of individual elements from 3putlcrcd Cuq^PIq^alloy in the Ar ion energy range between 0.2 and 1.5ke V.Calculated results show that for each investigated incident energy,the angular distribution of the Pt element is more forward-pointed than that of the Cu one;the reason may be that different percentage of sputtered atoms(37-45% of Pt and 12-19% of Cu)come from beneath the topmost layer.

Diffusion characteristics of HTO and 99TcO_4^- in compacted Gaomiaozi(GMZ) bentonite

The characteristics of diffusion are essential to the transport of radionuclides through buffer/backfill materials, such as bentonite, which are commonly found in waste repositories. This study used through-diffusion techniques to investigate the diffusion behavior of HTO and ^(99)TcO_4^- on GMZ bentonite of various densities. Diffusion rates were calculated by measuring the diffusion coefficients(De, Da), plotting breakthrough curves and interpreting experiment data. The apparent and effective diffusion coefficients of HTO ranged from(1.68 ± 0.40) 9 × 10^(-11) to(2.80 ± 0.62) 9 × 10^(-11) m^2/s and from(4.61 ±1.28) 9 × 10^(-12) to (16.2 ± 2.50) 9 × 10^(-12) m^2/s, respectively.The apparent and effective diffusion coefficients of^(99)TcO_4^-ranged from(5.26 ± 0.16) 9 × 10^-12to(7.78 ± 0.43) 9× 10^-12m^2/s and from(1.49 ± 0.002) 9 × 10^(-12) to(4.16 ±0.07) 9 × 10^(-12) m^2/s, respectively. The distribution coefficients of HTO and^(99)TcO_4^-ranged from(0.70 ± 0.12) 9× 10^(-2) to(1.36 ± 0.53) 9 × 10^(-2) mL/g and from(1.12 ±0.06) 9 × 10^(-2) to(5.79 ± 2.22) 9 × 10^(-2) mL/g, respectively.The Deand Kdvalues were shown to decrease with an increase in the bulk dry density of compacted bentonite. Our results show that HTO and ^(99)Tc could be considered nonsorbent radionuclides. The data obtained in this studyprovide a valuable reference for the safety assessment of waste repositories.

EXPERIMENTAL EVIDENCE OF DINEUTRON EXISTENCE

The average binding energy of the dineutron virtual state was derived from the correlative spectrum of two protons in ^(2)H(d,^(2)p)^(2)n reaction,and from the p-p coincidence measurement the value is estimated to be about 210keV.

Measurements of Total Reaction Cross Sections for Exotic Nuclei Close to the Proton Drip-line at Intermediate Energies and Observation of a Proton Halo in ^(27)P

Measurements of total reaction cross sections(σR)for some proton-rich nuclei(N=11-15 isotones)on carbon target at intermediate energies have been performed on the Radioactive Ion Beam Line of the Heavy Ion Research Facility in Lanzhou.A large enhancement ofσR for ^(27)P has been observed than for its neighbors.Evidence for a proton halo in ^(27)P has been revealed in the Glauber analysis of the total reaction cross sections in terms of the difference factor d.

Quantum Signature of Classical Chaos in a Lipkin Model:Sensitivity of Eigenfunctions to Parameter Perturbations

In this paper,xve have studied the properties of eigenfunctions in a three-level Lipkin model whose classical counterpart can exhibit classical chaos.In the regime of classical chaotic motions,sensitivity of eigenfunctions to parameter perturbation is exposed,which may be taken as a quantum signature of classical chaos.

Numerical Simulation of the Blood Flow through a Brain Vascular Aneurysm with an Artificial Stent Using the SPH Method

We present numerical simulations of blood flow through a brain vascular aneurysm with an artificial stent using Smoothed Particle Hydrodynamics (SPH). The aim of this work is to analyze how the flow into an aneurysm changes using different stent configurations. The initial conditions for the simulations were constructed from angiographic images of a real patient with an aneurysm. The wall shear stresses, pressure and highest velocity within the artery, and other particular quantities are calculated which are of medical specific interest. The numerical simulations of the cerebral circulation help doctors to determine if the patient’s own vascular anatomy has the conditions to allow arterial stenting by endovascular method before the surgery or even evaluate the effect of different stent structure and materials. The results show that the flow downstream the aneurysm is highly modified by the stent configuration and that the best choice for reducing the flow in the aneurysm is to use a completely extended Endeavor stent.

~3H—LABELLING OF BELLADONNA ALKALOIDS BY CATALYSED EXCHANGE WITH MICROWAVE EXCITATION

The ~3H-labelled belladonna alkaloids obtained by catalysed exchange method with microwave excitation was investigated. The specific activities of the labelled products Were 16—32 TBq/mol. More than 90% labelled positions of these ~3H-tracers were on phenyl rings. The radiochemical purity and chemical purity of crude products were both in 75—80%.

SYNTHESES OF N- METHYL-^(14)C BENZYL AMINE AND N- METHYL-^(14)C BENZYL NITROSAMINE

The syntheses of N-Methyl-14C benzyl amine and N-Methyl-14C benzyl nitrosamine are reported. Specific activities were approximately 920 MBq/mmol. Chemical and radiochemical purity checked by HPLC were more than 95%.

THE DAMAGE MEASUREMENT OF ION- IMPLANTED COMPOUND SEMICONDUCTOR GaAs BY PIXE-CHANNELING TECHNIQUE

A combined PIXE-RBS channeling measurement system to examine Ⅲ-Ⅴ compound semiconductors has been established. Preliminary results on studying Si+ and Te+ implanted GaAs have been presented and discussed.

THE SYNTHESES OF 1,1,1-TRIFLUORO-2-SUBSTITUTED-PHENYL-2-PROPYL-3-^(14)C P- TOLUENESULFONATES

1,1,1,-Trifluoro-2- substituted- phenyl- 2- propanols- 3- 14C were prepared from addition of methyl- 14C magnesium iodide to appropriate trifluoroacetophenone. These alcohols were converted into tosylatcs by reaction with n-butyllithium and then with p-toluenesulfonyl chloride. The yield, boiling point or melting point and pertinent spectral data of these compounds are reported.