Showing papers in "World Journal of Nuclear Science and Technology in 2014"

On a New Elementary Particle from the Disintegration of the Symplectic &#39t Hooft-Veltman-Wilson Fractal Spacetime

Abstract: 't Hooft-Veltman Wilson dimensional regularization depends crucially upon Borel summability which entails strong links to the modern mathematical theory of transfinite sets and consequently to the fractal-Cantorian spacetime proposal of Ord-Nottale-El Naschie. Starting from the above, we interpret the main step of the mathematical analysis in terms of elementary particles interaction. Thus 't Hooft-Veltman “perturbation” parameter which measures the deviation of the regulated space from the four dimensionality of spacetime is interpreted as an elementary particle with a topological mass charge equal to 0.18033989, i.e. double the magnitude of Hardy’s quantum entanglement. In turn, Hardy’s quantum entanglement which may be interpreted geometrically as a consequence of the zero set embedded in an empty set could also be interpreted as an exchange of pseudo elementary particles with a topological mass charge equal to Hardy’s entanglement where is the Hausdorff dimension of the zero set of the corresponding 't Hooft-Veltman spacetime.

Radioactivity Levels and Soil-to-Plant Transfer Factor of Natural Radionuclides from Protectorate Area in Aswan, Egypt

Abstract: The aim of this study is to determine the transfer factor soil-to-plant and to assess the concentration level of natural and artificial radionuclide (238U, 226Ra, 228Ra, 232Th, 40K and 137Cs) in samples from Saluga and Ghazal Protectorate area in Aswan, Egypt, by using High Pure Germanium detector (HPGe) Environmental Radioactivity Measurements Labrotary in faculty of science Qena. Reported values for natural radionuclides ranged from 8.81 ± 0.64 to 28.88 ± 2.10, from 6.98 ± 0.51 to 26.01 ± 1.89, from 12.29 ± 0.89 to 33.32 ± 2.43, from 12.53 ± 0.91 to 32.81 ± 2.39 and from 383.90 ± 27.95 to 711.98 ± 51.83 Bq.kg-1 for 238U, 226Ra, 228Ra, 232Th and 40K, respectively. 137Cs activity concentration was found to be in the range from 0.36 ± 0.03 to 9.73 ± 0.71 Bq.kg-1 and was calculated through transfer factor TF reported in this article.

Steady-State Thermal-Hydraulic Analysis of TRIGA Research Reactor

Abstract: The COOLOD-N2 and PARET computer codes were used for a steady-state thermal hydraulic and safety analysis of the 3 MW TRIGA Mark-II research reactor located at Atomic Energy Research Establishment (AERE), Savar, Dhaka, Bangladesh. The objective of the present study is to ensure that all important safety related thermal hydraulic parameters uphold margins far below the safety limits by steady-state calculations at full power. We, therefore, have calculated the hot channel fuel centreline temperature, fuel surface temperature, cladding surface temperature, the departure from nucleate boiling (DNB) heat flux and DNB ratio, axial fuel centreline temperature and compared. The comparison indicates that the calculated values are in satisfactory agreement between the codes. The data obtained in this investigation are largely far to compromise safety of the reactor. The results can also be used to upgrade the current core configuration of the TRIGA reactor.

Radioactive Contamination Factor (RCF) Obtained by Comparing Contaminant Radioactivity ( 137 Cs) with Natural Radioactivity ( 40 K) in Marine Sediments Taken up from Mexican Sea Waters

Abstract: Radioactive contamination at planet scale started in 1945 when the first nuclear taste was performed in Alamo Gordo, New Mexico, followed by two war actions in Japan, a second test in Bikini, and more than 2000 tests were performed all over the world by different countries since then on In this context, 10 main accidents in power and research nuclear reactors seem to be negligible in the general radioactive contamination at planet scale, which can be measured by comparing radioactivity of fission product 137Cs with that of natural 40K, both detected from marine sediments taken up at different places and depth This paper shows 9 results obtained from Gulf of Mexico samples and one from Pacific North ocean, confirming the fact that this simple method works well enough to keep watching the process of radioactive contamination on earth, whatever may be the cause, to prove if it remains constant for a time, by equilibrium between contamination and decaying of 137Cs, it is decreasing at same rate than 137Cs radioactive decaying, or by the contrary, it is growing up and approaching at some extent the natural radioactivity from 40K

Study of Criticality Safety and Neutronic Performance for a 348-Fuel-Pin Ghana Research Reactor-1 LEU Core Using MCNP Code

Abstract: The National Nuclear Research Institute of the Ghana Atomic Energy Commission is undertaking steps to convert the Ghana Research Reactor-1 from HEU Core to LEU. The proposed LEU core consists of 12.5% enriched UO2 fuel elements clad in Zircaloy-4 alloy. This is done in collaboration with Reduced Enrichment for Research and Test Reactor. The versatile MCNP code was used to analyse the neutronics parameters given in the SAR of HEU core, thereby characterizing the core. Subsequently, the LEU core was indentified with necessary changes to the HEU MCNP model. It was ascertained that the reactivity for the LEU core with the same number of fuel pins as the HEU was inadequate, hence the fuel pins were increased from 344 to 348. The neutron flux at the irradiation sites was found to be below the nominal value at full power for the LEU and hence the nominal power was increased to 34 kW for a nominal flux value of 1 × 1012 n/cm2.s. The parameters investigated for the HEU and LEU are shown in this paper.

Dynamic Interaction Confinement

Abstract: The importance of developing new technologies to obtain energy by means of nuclear fusion procedures is beyond question. There are several different and technically possible models for doing this, though to date none of these has been able to attain an industrial reactor with an end performance greater than unity. We still find ourselves at the initial phase, after many years, as a result of having failed as yet to come up with a commercially productive machine. Nuclear fusion research has defined a prototype reactor based on a fluid conductor, isolated materially in a physical container and confined by means of magnetic fields. In this fluid-plasma which interacts with magnetic fields, fusion reactions are caused that release energy, while at the same time a quantity of movement and angular momentum is moved or “rotated” and transported. However, turbulence is caused in these magnetic confinement fusion processes that reduces system efficiency and prevents the obtaining of sufficient net energy from the nuclear reactions. This paper aims to propose new dynamic hypotheses to enhance our understanding of the behaviour of the plasma in the reactor. In doing so, we put forward a profound revision of classical dynamics. After over thirty years studying rotational dynamics, we propose a new theory of dynamic interactions to better interpret nature in rotation. This new theory has been tested experimentally returning positive results, even by third parties. We suggest that these new dynamic hypotheses, which we hold applicable to particle systems accelerated by rotation, be used in the interpretation and design of fusion reactors. We believe that this proposal could, in addition to magnetic confinement, achieve confinement by simultaneous and compatible dynamic interaction. Accordingly, we are of the opinion that it would be possible to get better performance and results in the design of fusion reactors by way of simultaneous magnetic and dynamic interaction confinement.

Tandem Mirror Experiment for Basic Fusion Science

Abstract: Research on controlled nuclear fusion has been largely concentrated on plasma confinement using toroidal magnetic fields. Toroidal systems are complex. A simpler magnetic confinement system may provide a valuable platform for understanding fusion plasmas. The linear mirror machine has delivered good performance with the potential of giving a direct conversion of nuclear energy into electric power. The GAMMA-10 (G-10) linear mirror confinement system at Tsukuba University demonstrated the principle of the direct conversion of plasma energy into electric power on a small scale from the exhaust plasma in the exterior divertor chamber. The tokamak fusion system has to prove that the 10 to 15 MA of plasma current can be sustained continuously with acceptable efficiency. Plasma confinement is due to the magnetic field from the plasma current in tokamaks. There is room for creative new solutions in the magnetic confinement of fusion plasmas, and consideration is given for the alternative approach of using a linear machine with high magnetic mirror fields and the direct conversion of the high temperature escaping plasma to electric power.

A Study on the Cause Analysis for the Wall Thinning and Leakage in Small Bore Piping Downstream of Orifice

Abstract: A number of components installed in the secondary system of nuclear power plants are exposed to aging mechanisms such as FAC (Flow-Accelerated Corrosion), Cavitation, Flashing, and LDIE (Liquid Droplet Impingement Erosion). Those aging mechanisms can lead to thinning of the components. In April 2013, one inch small bore piping branched from the main steam line experienced leakage resulting from wall thinning in a 1000 MWe Korean PWR nuclear power plant. During the normal operation, extracted steam from the main steam line goes to condenser through the small bore piping. The leak occurred in the downstream of an orifice. A control valve with vertical flow path was placed in front of the orifice. This paper deals with UT thickness data, SEM images, and numerical simulation results in order to analyze the extent of damage and the cause of leakage in the small bore piping. As a result, it is concluded that the main cause of the small bore pipe wall thinning is liquid droplet impingement erosion. Moreover, it is observed that the leak occurred at the reattachment point of the vortex flow in the downstream side of the orifice.

Zppr fuel element thermal stress-strain analysis

Abstract: The design temperature of high plutonium concentration ZPPR fuel plates is 600°C. Cladding integrity of the 304 L stainless steel cladding is a significant concern with this fuel since even small holes can lead to substantial fuel degradation. Since the fuel has a higher coefficient of thermal expansion than the cladding, an investigation of the stress induced in the cladding due to the differential thermal expansion of fuel and cladding up to the design temperature was conducted. Small holes in the cladding envelope would be expected to lead to the fuel hydriding and oxidizing into a powder over a long period of time. This is the same type of chemical reaction chain that exists in the degradation of the high uranium concentration ZPPR fuel. Unfortunately, the uranium fuel was designed with vents which allowed this degradation to occur. The Pu cladding is sealed so only fuel with damaged cladding would be subject to this damage. The thermal stresses that can be developed in the fuel cladding have been calculated in this paper and compared to the ultimate tensile stress of the cladding. The conclusion is drawn that thermal stresses cannot induce holes in the cladding even for the highest storage temperatures predicted in calculations (292°C). In fact, thermal stress cannot cause cladding failure as long as the fuel temperatures are below the design limit of 600°C (1112°F).

Gamma Dose Rate Measurements in Kuwait Using a Car-Borne GPS Integrated Dosimetric System

Abstract: A mobile system comprising of a Geiger-Muller (GM) dosimeter connected with a smart phone was used for ambient gamma dose rate survey within the districts and on the roads within the state of Kuwait. While the dosimeter provides data on gamma dose rates, the smart phone provides the GPS navigation information and saves the data for subsequent analysis and mapping. The survey covered a total distance of about 2300 km within the country and 3117 data points were recorded to show the dose rate distribution on the map of Kuwait. The results show that the ambient dose rates in Kuwait range from 40 to 180 nSv.h-1 with a mean value of 103 nSv.h-1. The dosimetric system described has good potential as a tool for determining baseline background radiation dose rates in an area.

Positron Annihilation in Perfect and Defective TiO 2 Rutile Crystal with Single Particle Wave Function: Slater Type Orbital and Modified Jastrow Functions

Abstract: Positron annihilation in TiO2 rutile crystal is studied by an assumption that a positron binds with valance electrons of a titanium dioxide to form a pseudo TiO2-positron molecule before it annihilates with these electrons. The orbital modification consisting of explicit electron-positron and electron-electron correlation in each electronic orbital is used for the electrons and positron wave functions. By these wave functions, the calculation results of the positron lifetimes in unmitigated and defective TiO2 crystals are about 170 ps, 266 ps and 243 ps, respectively. These results are in good agreement with experimental data of the positron lifetimes in vacancies of TiO2 from 180 ps to 300 ps.

An Integrated Approach for Process Control Valves Diagnosis Using Fuzzy Logic

Abstract: Control valves are widely used in industry to control fluid flow in several applications. In nuclear power systems they are crucial for the safe operation of plants. Therefore, the necessity of improvements in monitoring and diagnosis methods started to be of extreme relevance, establishing as main goal of the reliability and readiness of the system components. The main focus of this work is to study the development of a model of non-intrusive monitoring and diagnosis applied to process control valves using artificial intelligence by fuzzy logic technique, contributing to the development of predictive methodologies identifying faults in incipient state. Specially in nuclear power plants, the predictive maintenance contributes to the security factor in order to diagnose in advance the occurrence of a possible failure, preventing severs situations. The control valve analyzed belongs to a steam plant which simulates the secondary circuit of a PWR—Pressurized Water Reactor. The maintenance programs are being implemented based on the ability to diagnose modes of degradation and to take measures to prevent incipient failures, improving plant reliability and reducing maintenance costs. The approach described in this paper represents an alternative departure from the conventional qualitative techniques of system analysis. The methodology used in this project is based on signatures analysis, considering the pressure (psi) in the actuator and the stem displacement (mm) of the valve. Once the measurements baseline of the control valve is taken, it is possible to detect long-term deviations during valve lifetime, detecting in advance valve failures. This study makes use of MATLAB language through the “fuzzy logic toolbox” which uses the method of inference “Mamdani”, acting by fuzzy conjunction, through Triangular Norms (t-norm) and Triangular Conorms (t-conorm). The main goal is to obtain more detailed information contained in the measured data, correlating them to failure situations in the incipient stage.

Determination of Tritium Concentration in Heavy Water

Abstract: In this work, tritium concentration was determined in different D2O enrichment in heavy water samples. Samples were prepared from Arak Heavy Water Production Plant. Tritium concentration was determined utilizing liquid scintillation detector (LSC) system based on β-decay of tritium isotope. In this work instead of simple distillation, the azeotropic distillation method was used. Absorbed spectra and fluorescence spectra were registered by Shimadz spectrometer UV-2100 model and fluorescence spectrometer LS50B model respectively. Tritium concentration was obtained from 1.75 ± 0.80 up 6.16 ± 1.01 Bq/L for 0.35% to 77.50% enrichment of D2O concentration in heavy water samples. Coefficient correlation between tritium concentration and D2O concentration in heavy water R2 = 0.853 was derived. For 99.8% enriched D2O in heavy water, deviation was observed from direct line that caused decreasing of R2.

Characteristics of Filtered Neutron Beam Energy Spectra at Dalat Reactor

Abstract: Filtered neutron technique was applied for producing quasi-monoenergetic neutron beams of 24 keV, 54 keV, 133 keV and 148 keV at the horizontal neutron channel No. 4 of the Dalat Nuclear Research Reactor. The study on physical characteristics of these beam lines has been carried out for efficient applications in neutron capture experiments. The filtered neutron spectrum of each beam has been simulated by Monte-Carlo method and experimentally measured by a gas-filled protonrecoil spectrometer. The neutron fluxes of these filtered beams were measured by the activation technique with standard foils of 197Au, using a high efficient HPGe digital gamma-ray spectrometer.

Conversion of U-238 and Th-232 Using a Fusion Neutron Source

Abstract: This article proposes a general framework for the conversion of U-238 and Th-232 utilizing fusion-produced neutrons. This recognizes that emerging fusion technologies may not produce sufficient net energy output to justify stand-alone applications, yet may be commercially viable for breeder transmutation or hybrid fusion-fission reactor concepts proposed herein to dispose of nuclear wastes and long life high radioactive fission products remaining in shutdown nuclear power plants. Results show that this could be achievable within a decade, given an appropriate fusion source. However, if 20% beryllium of nuclei density is added to the convertor blanket, the efficiency of the conversion process can be significantly increased. Also, the neutron energy spectrum resulting from dense D-D plasma core fusion is much softer than D-T fusion neutron source, hence the probability of (n, p) (n, α) backward decay reaction paths will be smaller and the conversion efficiency will be elevated.

A Study on the Structural Response of a PSC Inner Containment Dome with Large Openings Due to Prestress Transfer

Abstract: A linear three dimensional finite element (FE) study has been carried out to examine the structural response of a prestressed concrete (PSC) inner containment (IC) dome of reactor building (double containment system) of a typical Indian Nuclear Power Plant, having large steam generator (SG) openings with due emphasis on the local behaviour of the steel-concrete interfaces at the SG openings, due to initial prestress transfer. The predominant thrust of the study has been placed on the objective of predicting the possibilities of separation at the steel-concrete interface zones adjacent to the embedded plates (EPs) of the SG openings. Two types of modeling and analysis have been made to study the overall and local behaviour of the structure. Prestressing ducts, passive reinforcements and EPs have been included in the models in certain ways. For the FE analysis, the interface zone has been modeled using interface elements, the properties of which were derived from the results of past experiments conducted on steel plate-concrete inter-face specimens. The FE analysis results have been compared with the results of the past two FE analytical studies on the linear behaviour of the same PSC IC dome. Important observations have been made regarding dome deformation and stresses throughout the structure with special emphasis on the local behaviour of steel-concrete interfaces at and around the SG openings.

Development of 24 and 59 keV Filtered Neutron Beams for Neutron Capture Experiments at Dalat Research Reactor

Abstract: External filtered neutron beams have been developed at the horizontal radial channels No. 4 of Dalat research reactor. In the material composition of the neutron filters, the primary material components of Iron, Aluminum, Nickel and Vanadium are used to obtain the mono-energetic neutron beams of 24 and 59 keV, with low level of Gamma and slow neutron background. A computer code and Monte-Carlo simulation technique were applied to optimize the filter configurations and to deduce the neutron energy distributions in the filtered beams. A hydrogen-filled proton recoil detector and the activation method with Gold foils were used to measure the neutron energy spectrum and flux of each beam at sample position. The results of experimental neutron fluxes are 6.1 × 105 and 5.3 × 105 n/cm2/s for 24 and 59 keV beams, respectively.

Gamma Cascade Transition of 51 V(n th , g ) 52 V Reaction

Abstract: The thermal neutron capture gamma radiations for 51V(n, g)52V reaction have been studied at Dalat Nuclear Research Reactor (DNRR). The gamma two-step cascade transition was measured by event-event coincidence spectrometer. The added-neutron binding energy in 52V was measured as 7.31 MeV. Energy and the intensity transition of cascades were consistent with prediction of single particle model. Furthermore, the spin and the parity of levels were confined.

An Investigation of the Impact of Installation of Cd-Lined Irradiation Channel in NIRR-1 on Core Physics Data for ENAA

Abstract: Prior to the installation of the Cd-liner in one of the large outer irradiation channels of NIRR-1, a Monte Carlo simulation was performed using MCNP5 version 1.4 code. This was done to investigate the effect of installation of Cd-liner in either an inner or outer irradiation channel on reactor physics parameters. Data obtained indicate that the core excess reactivity in both inner and outer irradiations channels is reduced by 3.60 ± 0.07 mk and 0.64 ± 0.06 mk, respectively. Considering the fact that NIRR-1 has a cold core excess reactivity of 3.77 mk, results obtained show that installation of the 1 mm thick Cd-sheet in one of the large outer irradiation channels would have no significant impact on the core physics data. After installation of a 1 mm Cd sheath in a large outer irradiation channel, the neutron flux distribution and the stability in the irradiation channels were monitored by foil activation method. Results indicate that the uniformity of neutron flux distribution in the irradiation channel is preserved and the neutron flux data were found to be comparable with the data obtained before the installation.

Determination of Major, Minor and Trace Element Compositions of the Gd 2 O 2 S:Pr,Ce Scintillation Ceramics with Neutron Activation Analysis

Abstract: Neutron activation analysis technique of the Gd2O2S:М scintillation ceramics was developed. The concentrations of 15 trace, minor and major elements (As, Ce, Co, Cr, Cs, Eu, Fe, La, Sc, Tb, Zn, Zr, Pr, Gd, Na) have been measured with the instrumental neutron activation analysis of the Gd2O2S:Pr sample. The concentrations range of the determined elements is from 3 × 10-8 to 2.0% in mass. The determination limit of the elements was calculated to be (0.6 - 1.3 × 10-8% in mass).

Simulation of Lower Hybrid Current Drive for DEMO

Abstract: Lower hybrid (LH) wave is not only convenient to generate a flat or reversed magnetic shear profiles, but also helps one to explore scenarios for steady-state tokamak operation with improved confinement. Here with LSC code (lower hybrid simulation code), we calculate density and temperature profiles, relative power of injected wave and current wave lunch for two options of DEMO at the launched LH wave frequency 5 GHz. Two plasma scenarios pertaining to two different DEMO options, known as pulsed (option 1) and steady-state (option 2) models, have been analyzed. We perceive that power deposition by using lower hybrid wave injection mainly takes place near the edge of plasma and approximately in more peripheral region for both of options but has approximately higher efficiency for option 1 compared to option 2. About current wave lunch, a major part of that is close to the plasma edge for both of options. We have some considerable parts that reach to internal layers for option 1 and then current drive mainly takes place in a wider, more peripheral region for option 1.

Superficial Layer MHD Effect and Full-Cover Free Surface Flow Characterizing

Abstract: Up to now, no a real full-cover liquid metal (LM) free surface flow have been successfully used in magnetic fusion devices as MHD instability and unavoidable rivulet flow. Recently, after we carried out a guidable free curve-surface flow on theoretically and experimentally, seeking for other way to get a full-cover free surface flow is also in implementing. The superficial layer MHD effect in free surface flow is experimentally observed. After compared and analyzed the characteristic parameters of the free surface flow, the conditions of full-cover free surface flow are found. Meanwhile, the new two parameters of surface cover ratio and rivulet flow index are introduced to characterize the flowing characteristic of the full-cover free surface flow under magnetic field. According to the analysis rule, for different liquid metal, there are the different unique conditions to meet full-cover free surface flow under magnetic field. This may be a way to solve free surface flow major MHD key issue for LM PFCs.

Assessment and Development of Two Phase Turbulent Mixing Models for Subchannel Analysis Relevant to BWR

Abstract: Determination of turbulent mixing rate of two phase flow between neighboring subchannels is an important aspect of sub channel analysis in reactor rod bundles. Various models have been developed for two phase turbulent mixing rate between subchannels. These models show that turbulent mixing rate is strongly dependent on flow regimes; their validity was examined against specific or limited experiments. It is vital to evaluate these models by comparing the predicted two phase turbulent mixing rate with available experimental data conducted for various subchannel geometries and operating conditions. This paper describes evaluation of different models for two phase turbulent mixing rate for both gas and liquid phase against large range of experimental data which are obtained from various subchannel geometries. The results indicate that there is large discrepancy between the predicted and experimental data for turbulent mixing rate. This paper provides important shortcoming of the previous work and need for the development of a new model. In the view of this, a two phase flow model is presented, which predicts both liquid and gas phase turbulent mixing rate between adjacent sub channels of reactor rod bundles. The model presented here is for slug churn flow regime, which is dominant as compared to the other regimes like bubbly flow and annular flow regimes, since turbulent mixing rate is the highest in slug churn flow regime. The present model has been tested against low pressure and temperature air-water and high pressure and temperature steam-water experimental data found that it shows good agreement with available experimental data.

Relation between Gamma Decomposition and Powder Formation of γ -U8Mo Nuclear Fuel Alloys via Hydrogen Embrittlement and Thermal Shock

Abstract: Gamma uranium-molybdenum alloys have been considered as the fuel phase in plate type fuel elements for material and test reactors (MTR), due to their acceptable performance under irradiation. Regarding their usage as a dispersion phase in aluminum matrix, it is necessary to convert the as cast structure into powder, and one of the techniques considered for this purpose is the hydration-dehydration (HDH). This paper shows that, under specific conditions of heating and cooling, γ-UMo fragmentation occurs in a non-reactive predominant mechanism, as shown by the curves of hydrogen absorption/desorption as a function of time and temperature. Our focus was on the experimental results presented by the addition of 8% weight molybdenum. Following the production by induction melting, samples of the alloys were thermally treated under a constant flow of hydrogen for temperatures varying from 500°C to 600°C and for times of 0.5 to 4 h. It was observed that, even without a massive hydration-dehydration process, the alloys fragmented under specific conditions of thermal treatment during the thermal shock phase of the experiments. Also, it was observed that there was a relation between absorption and the rate of gamma decomposition or the gamma phase stability of the alloy.

Measurement of the Nucleon Nucleon Scattering Length with the ESC04 Interaction

Abstract: We have determined a value for the 1S0 neutron-neutron scattering length (ann). The scattering length result is presented for the extended-soft-core (ESC04) interaction. The value obtained in the present work is ann = -18.6249 fm. The method of solution of the radial Schr?dinger equation with nonlocal potential for nucleonnucleon pairs is described and the result is consistent with previous determinations of ann = -18.63 ± 0.10 (statistical) ± 0.44 (systematic) ± 0.30 (theoretical) fm. The nonlocal potentials are of the central, spin-spin, spin-or-bital, and tensor type. The analysis from the ESC04 interaction is done at energies 0 ￡ Tlab ￡ 350 MeV. We compare the present result with experimental S-wave phase shifts analysis and agreement is found.

Electromagnetic Schr&oumldinger Equation of the Deuteron 2 H (Heavy Hydrogen)

Abstract: The binding energy of the deuteron is calculated electromagnetically with the Schrödinger equation. In mainstream nuclear physics, the only known Coulomb force is the repulsion between protons, inexistent in the deuteron. It is ignored that a proton attracts a neutron containing electric charges with no net charge and that the magnetic moments of the nucleons interact together significantly. A static equilibrium exists in the deuteron between the electrostatic attraction and the magnetic repulsion. The Heitler equation of the hydrogen atom has been adapted to its nucleus where the centrifugal force is replaced by the magnetic repulsive force, solved graphically, by trial and error, without fit to experiment. As by chance, one obtains, at the lowest horizontal inflection point, with a few percent precision, the experimental value of the deuteron binding energy. This success, never obtained elsewhere, proves the purely static and electromagnetic nature of the nuclear energy.

Numerical Case Study on the LDIE Degradation Occurred in the Vent Header of a High Pressure Feedwater Heater

Abstract: Piping installed in nuclear power plants is affected by various types of degradation mechanisms and may be ruptured due to gradual thinning. The degradation mechanisms such as flow-accelerated corrosion (FAC), cavitation, liquid droplet impingement erosion (LDIE), etc., can lead to costly outages and repairs and possibly affect plant reliability. In August 2008, the header pipe in the high pressure feedwater heater vent system leaked at a Korean nuclear power plant. After cutting the pipe during refueling outage, it was identified that the leak was due to LDIE. This paper presents the numerical analysis results, using various multi-phase models of ANSYS FLUENT for the purpose of identifying the cause of the LDIE. The numerical analysis methods which are most similar to the damage of the pipe are proposed for the comparison of analysis results with each multi-phase model.

How Do the Nucleons Pack in an Atomic Nucleus

Abstract: A nuclear structure model of “ring plus extra nucleon” is proposed. For nuclei larger than 4He, protons (P) and neutrons (N) are basically bound alternatively to form a ZP + ZN ring. The ring folds with a “bond angle” of 90° for every 3 continuous nucleons to make the nucleons packed densely. Extra N(‘s) can bind to ring-P with the same “bond angle” and “bond distance”. When 2 or more P’s are geometrically available, the extra N tends to be stable. Extra P can bind with ring N in a similar way when the ratio of N/P < 1 although the binding is weaker than that of extra N. Even-Z rings, as well as normal even-even nuclei, always have superimposed gravity centers of P and N; while for odd-Z rings, as well as all odd-A (A: number of nucleon) nuclei, the centers of P and N must be eccentric. The eccentricity results in a depression of binding energy (EB) and therefore odd and even Z dependent zigzag features of EB/A. This can be well explained by the shift of eccentricity by extra nucleons. Symmetrical center may present in even-Z rings and normal even-even nuclei. While for odd-Z ring, only antisymmetric center (every P can find an N through the center and vice versa) is possible. Based on this model, a pair of mirror nuclei, PX+nNX and PXNX+n, should be equivalent in packing structure just like black-white photo and the negative film. Therefore, an identical spin and parity was confirmed for any pair. In addition, the EB/A difference of mirror nuclei pair is nearly a constant of 0.184n MeV. Many other facts can also be easily understood from this model, such as the neutron halo, the unusual stability sequence of 9Be, 7Be and 8Be and so on.

Theoretical Determination and Experimental Verification of Transport Index of Rectangular Shaped Radioactive Containers

Abstract: Ionizing radiations are widely used to sustain and enhance our quality of life in the areas such as medical diagnosis, therapy, scientific research and industry etc. Ionizing radiations are available from radioactive sources which are made of radioactive materials. The radioactive materials are produced in either nuclear power or research reactors or nuclear accelerators or extracted from the naturally found radioactive ores. These radioactive sources and radioactive materials need to be transported from their places of production to the places of applications and finally to waste repositories. The radioactive materials are transported in well designed packages having various shapes and sizes. In the field of radioactive transport, it is a mandatory to find the Transport Index (TI) to be mentioned on each package for transportation. This research is focused on the determination of the maximum γ-ray radiation dose at one meter from the surface of cubic and rectangular shaped package or containers. A computer code “Solid Angle for Transport Index” (SAFTI) has been developed using MATLAB to determine the location of maximum value of the radiation dose rate from the surface of a rectangular or square container. This maximum dose rate is used to determine the transport index. Some of the results of the code have been compared with the experimental results. The results of this research are useful not only to determine TI for individual packages but also to find the TI of the vehicles carrying the transport packages.

The Precise Methods for the Measurement of Collimator Hole Angulation and Center of Rotation of SPECT by Adaptive Quality Control Phantom

Abstract: The Adaptive Quality Control Phantom (AQCP) is a computer-controlled phantom which positions and moves a radioactive source in the Field of View (FOV) of an imaging nuclear medicine device on a definite path to produce a spatial distribution of gamma rays to perform QC Tests such as the Collimator Hole Angulation (CHA) and the Center of Rotation (COR) of Single Photon Emission Computer Tomography (SPECT). The collimator hole angulation for six collimators was measured using a point source and a computer-controlled cylindrical positioning system. In this method, the displacement of the image of a point source was examined as the AQCP was moving point source vertically away from the collimator face. The results of the high-accuracy measurement method of CHA show that the measurement accuracy for absolute angulation errors is better than ±0.024°. The Root Mean Square (RMS) of CHA for LEHR, LEHS and LEUHR collimators of SMV dual heads camera and LEGP, MEGP and HEGP of GE Millennium MG were evaluated to be 0.290°, 0.292°, 0.208°, 0.154°, 0.220° and 0.202°, respectively. It is to be added in this connection that the evaluated RMS of CHA for LEHR collimator with the distance variation from the collimator’s surface ±1 mm has been varied ±0.04 degree. A new method for the center of rotation assessment by AQCP is introduced and the results of this proposed method as compared with the routine QC test and their differences are discussed in detail. We defined and measured a new parameter called Dynamic Mechanical Error (DME) for applying the gantry motion correction.