bluuebunny/crossref_metadata_2025 huggingface dataset:
Critical Heat Fluxes of Subcooled Water Flow Boiling Against Outlet Subcooling in Short Vertical Tube
Authors: Hata Koichi , Sato Toshiyuki , Tanimoto Takeya , Shiotsu Masahiro , Noda Nobuaki
Published: March 2009

The critical heat fluxes (CHFs) of subcooled water flow boiling are systematically measured for the flow velocities (u = 4.0 to 13.3 m/s), the outlet subcoolings (ΔTsub,out = 3 to 129 K) and the outlet pressure (Pout = 800 kPa). The SUS304 test tubes of 3, 6, 9 and 12 mm in inner-diameter, d, and 33, 66, 99 and 133 mm in length, L, respectively for L/d = 11 are used. The CHFs first become lower and then become higher with the increase in subcooling. The CHFs for four different inner-diameters with L/d = 11 measured here become higher with the decrease in the diameter. CHF correlation for the latter increasing regime was given in non-dimensional form against average outlet subcoolings based on the experimental data. The correlation can describe not only the CHFs obtained in this work at the outlet pressure of 800 kPa but also the authors’ published CHFs (1284 points) for the wide range of Pout = 159 kPa to 1 MPa, d = 6, 9 and 12 mm, L = 49, 99 and 149 mm, ΔTsub,out = −4 to 130 K and u = 4.0 to 13.3 m/s within 15% difference for 50 K≤ΔTsub,out≤130 K and within +30 to −10% for 30 K<ΔTsub,out<50 K.
Corrosion Resistant Cladding by YAG Laser Welding in Underwater Environment
Authors: Kochi Tsutomu , Kojima Toshio , Hirata Suemi , Morita Ichiro , Ohwaki Katsura
Published: March 2009

It is known that stress-corrosion cracking (SCC) will occur in nickel-base alloys used in Reactor Pressure Vessel (RPV) and Internals of nuclear power plants. A SCC sensitivity has been evaluated by IHI in each part of RPV and Internals. There are several water level instrumentation nozzles installed in domestic BWR RPV. In water level instrumentation nozzles, 182 type nickel-base alloys were used for the welding joint to RPV. It is estimated the SCC potential is high in this joint because of a higher residual stress than the yield strength (about 400MPa). This report will describe a preventive maintenance method to these nozzles Heat Affected Zone (HAZ) and welds by a corrosion resistant cladding (CRC) by YAG Laser in underwater environment (without draining a reactor water). There are many kinds of countermeasures for SCC, for example, Induction Heating Stress Improvement (IHSI), Mechanical Stress Improvement Process (MSIP) and so on. A YAG laser CRC is one of them. In this technology a laser beam is used for heat source and irradiated through an optical fiber to a base metal and SCC resistant material is used for welding wires. After cladding the HAZ and welds are coated by the corrosion resistant materials so their surfaces are improved. A CRC by gas tungsten arc welding (GTAW) in an airenvironment had been developed and already applied to a couple of operating plants (16 Nozzles). This method was of course good but it spent much time to perform because of an installation of some water-proof working boxes to make a TIG-weldability environment. CRC by YAG laser welding in underwater environment has superior features comparing to this conventional TIG method as follows. At the viewpoint of underwater environment, (1) an outage term reduction (no drainage water). (2) a radioactive exposure dose reduction for personnel. At that of YAG laser welding, (1) A narrower HAZ. (2) A smaller distortion. (3) A few cladding layers. A YAG laser CRC test in underwater environment was carried out in the different welding position, horizontal, vertical upward and downward. The soundness of cladding layers (about 3 mm) is confirmed in visual and penetration test, and cross section observation. In the application to the actual plants, it is preferable to reduce the start and end point numbers of beads with which a defect is easy to cause. Therefore a special welding equipment for a YAG laser CRC that could weld continuously was developed.
Integrated Analysis of Mechanical and Thermal Hydraulic Behavior of Graphite Stack in Channel-Type Reactors in Case of a Fuel Channel Rupture Accident
Authors: Soloviev Sergei L. , Gabaraev Boris A. , Parafilo Leonid M. , Kruchkov Dmitry V. , Novoselsky Oleg Yu. , Filinov Vladimir N. , Melikhov Oleg I.
Published: March 2009

The paper discusses the methodology and a computational exercise analyzing the processes taking place in the graphite stack of an RBMK reactor in case of a pressure tube rupture caused by overheating. The methodology of the computational analysis is implemented in integrated code U_STACK which models thermal-hydraulic and mechanical processes in the stack with a varying geometry, coupled with the processes going on in the circulation loop and accident localization (confinement) system. Coolant parameters, cladding and pressure tube temperatures, pressure tube ballooning and rupture, coolant outflow are calculated for a given accident scenario. Fluid parameters, movement of graphite blocks and adjacent pressure tubes bending after the tube rupture are calculated for the whole volume of the core. Calculations also cover additional loads on adjacent fuel channels in the rupture zone, reactor shell, upper and lower plates. Impossibility of an induced pressure tube rupture is confirmed.
Leap Frog and Time Step Sub-Cycle Scheme for Coupled Neutronics and Thermal-Hydraulic Codes
Authors: Lu S.
Published: March 2009

As the result of the advancing TCP/IP based inter-process communication technology, more and more legacy thermal-hydraulic codes have been coupled with neutronics codes to provide best-estimate capabilities for reactivity related reactor transient analysis. Most of the coupling schemes are based on closely coupled serial or parallel approaches. Therefore, the execution of the coupled codes usually requires significant CPU time, when a complicated system is analyzed. Leap Frog scheme has been used to reduce the run time. The extent of the decoupling is usually determined based on a trial and error process for a specific analysis. It is the intent of this paper to develop a set of general criteria, which can be used to invoke the automatic Leap Frog algorithm. The algorithm will not only provide the run time reduction but also preserve the accuracy. The criteria will also serve as the base of an automatic time step sub-cycle scheme when a sudden reactivity change is introduced and the thermal-hydraulic code is marching with a relatively large time step.
Study on Ultra-Long Life, Small U-ZR Metallic Fuelled Core With Burnable Poison
Authors: Tsuji Kenji , Inagaki Hiromitsu , Nishikawa Akira , Matsumiya Hisato , Sakashita Yoshiaki , Moriki Yasuyuki , Yamaoka Mitsuaki , Handa Norihiko
Published: March 2009

A conceptual design for a 50MWe sodium cooled, U-Pu-Zr metallic fuelled, fast reactor core, which aims at a core lifetime of 30 years, has been performed [1]. As for the compensation for a large burn-up reactivity through 30 years, an axially movable reflector, which is located around the core, carries the major part of it and a burnable poison does the rest. This concept has achieved not only a long core lifetime but also a high discharged burn-up. On this study, a conceptual design for a small fast reactor loading U-Zr metallic fuelled core instead of U-Pu-Zr fuelled core has been conducted, based on the original core arrangement of 4S reactor [2]. Within the range of this study including safety requirements, adopting the burnable poison would be effective to construct a core concept that achieves both a long lifetime and a high discharged burn-up.
Molten Pool Coolability: COMECO Experiments
Authors: Konovalikhin M. J. , Karbojian A. , Sehgal B. R.
Published: March 2009

A series of experiments, named COMECO (COrium MElt COolability) were conducted at RIT (Royal Institute of Technology) in which molten core pools were quenched by establishing a water layer onto the top of the molten pool and by injection of water from the bottom delivered through a downcomer from the water overlayer. For this experimental program the following approach was adopted. We reasoned that since water addition from the bottom has been shown to be a more efficient mode of cooling in the DECOBI (Paladino, 1999) and in the COMET (Alsmeyer, 1998) experiments for melt coolability, water should be channeled to the bottom of the debris bed, with a downcomer, to accelerate the coolability process. The primary objective was to obtain data, which will provide a phenomenological basis for assessing the improvement in the coolability of a core melt pool by provision of downcomers as well as steam generation rate from the interactions between core debris and water. This paper summarizes the experimental results along with related analysis.
The Influence of Seasonal Characteristics on the Accident Consequence Analysis
Authors: Jeong Jongtae , Jung Wondea
Published: March 2009

In order to examine the influence of seasonal characteristics on accident consequences, we defined a limited number of basic spectra based on the relative importance of source term release parameters and meteorological conditions on offsite health effects and economic impacts. We then investigated the variation in numbers and frequency of early health effects and economic impacts resulting from the severe accidents of the YGN 3&4 nuclear power plants from spectrum to spectrum by using MACCS code. These investigations were for meteorological conditions defined as typical on an annual basis. Also, we investigated the variation in numbers and frequency of early health effects and economic impacts for the same standard spectra for meteorological conditions defined as typical on a seasonal basis recognizing that there are four seasons with distinct meteorological characteristics. Results show that there are large differences in consequences from spectrum to spectrum, although an equal amount and mix of radioactive material is released to the atmosphere in each case. Therefore, release parameters and meteorological data have to be well characterized in order to estimate accident consequences resulting from an accident accurately. Also, there are large differences in the estimated number of health effects and economic impacts from season to season due to distinct seasonal variations in meteorological conditions in Korea. In fall, the early fatalities and early fatality risk show minimum values due to enhanced dispersion arising from increased atmospheric instability, and the early fatalities show maximum value in summer due to a large rainfall rate. On the contrast, the economic cost shows maximum value in fall and minimum in summer due to different atmospheric dispersion and rainfall rate. Therefore, it is necessary to consider seasonal characteristics in developing emergency response strategies for reducing offsite early health risks in the event of a severe accident.
Multi-Dimensional Thermal-Hydraulic Analysis for Horizontal Tube Type PCCS
Authors: Arai Kenji , Kurita Tomohisa , Nakamaru Mikihide , Fujiki Yasunobu , Nakamura Hideo , Kondo Masaya , Obata Hiroyuki , Shimada Rumi , Yamaguchi Ken
Published: March 2009

A passive containment cooling system (PCCS) using a shell-and-tube type heat exchanger has been developed as a decay heat removal system following a severe accident. A horizontal heat exchanger has been studied for the PCCS heat exchanger since it has several advantages over a vertical large diameter tube heat exchanger that was originally proposed for the SBWR. Based on the fundamental thermal-hydraulic test using a single horizontal U-tube, the feasibility of the horizontal tube type PCCS has been confirmed, and the analysis models for the steam condensation heat transfer with a non-condensable and the pressure loss with steam condensation have been established. In addition, the criterion for the film dryout type heat transfer deterioration in the boiling side has been clarified in the test. The heat exchanger performance is affected by the multi-dimensional thermal-hydraulic behavior in the cooling water pool and the interactions among the multiple heat transfer tubes. In order to clarify the multi-dimensional behavior, numerical analyses have been conducted employing a two-fluid model. From the analyses results, it has been confirmed that the horizontal PCCS heat exchanger meets the design requirements for both the heat removal and the pressure loss and there would be no film dryout type heat transfer deterioration occurred in the cooling pool.
RELAP5-3D Code Application for RBMK-1500 Reactor Core Analysis
Authors: Bubelis Evaldas , Kaliatka Algirdas , Uspuras Eugenijus
Published: March 2009

The paper presents an evaluation of RELAP5-3D code suitability to model specific transients that take place during RBMK-1500 reactor operation, where the neutronic response of the core is important. A successful best estimate RELAP5-3D model of the Ignalina NPP RBMK-1500 reactor has been developed and validated against real plant data. Certain RELAP5-3D transient calculation results were benchmarked against calculation results obtained using the Russian code STEPAN, specially designed for RBMK reactor analysis. Comparison of the results obtained, using the RELAP5-3D and STEPAN codes, showed quite good mutual coincidence of the calculation results and good agreement with real plant data.
The Integral PWR SIR Transients: Comparisons Between CATHARE and RELAP Codes
Authors: Pignatel Jean-Franc¸ois
Published: March 2009

Within the framework of the research program on innovative light water reactors, the SERI (Service of Studies on Innovative Reactors) of the French Atomic Energy Commission (CEA), is presenting a predictive study on the modeling of a low-power integral Pressurized Water Reactor, using the CATHARE thermalhydraulic code. The concept selected for this study is that of the SIR reactor project, developed by AEA-T and ABB consortium. This very interesting concept is no doubt that which is the most complete to this date, and on which most information in the literature can be obtained. Many safety calculations made with the RELAP code are also available and represent a highly interesting base for comparison purposes, in order to improve the approach on the results obtained with CATHARE. A comparison of the behavior of the two codes is thus presented in this article. This study therefore shows that CATHARE finely models this type of new PWR concept. The transients studied cover a large area, ranging from natural circulation to loss of primary coolant accidents. The ATWS and a power transient have also been calculated. The comparison made between the CATHARE and RELAP results shows a very good agreement between the two codes, and leads to a very positive conclusion on the pertinence of simulating an integral PWR. Moreover, even though this study is a thorough investigation on the subject, it confirms the potentially safe nature of the SIR reactor.
An Overview of the Direct Energy Conversion Power Production Program
Authors: Rochau G. , Cash J. , King D. , Morrow C. , Seidel D. , Slutz S. , Anghaie S. , Smith B. M. , Brown L. , Tsvetkov P. , Hart R. , Parish T. , Williams R. , Jordan K.
Published: March 2009

The United States Department of Energy, Nuclear Energy Research Initiative (NERI) Direct Energy Conversion (DEC) project has as its goal the development of a direct energy conversion process suitable for commercial development. We define direct energy conversion as any fission process that returns usable energy without an intermediate thermal process. Enough of the project has been completed, roughly two thirds, to indicate that a viable direct energy device is possible. This paper reports on the progress of the DEC project. Three concepts are under development: Fission Electric Cell using magnetic insulation, Magnetic Collimator using magnetic fields to direct fission fragments to collectors, and Gas Vapor Core Reactor using magnetohydrodynamics to generate electrical current. Included in this paper area a short project description, an abbreviated summary of the work completed to date, a description of ongoing and future project activities, and a discussion of the potential for future research and development.
CFD Simulation of the CANDU-6 Moderator Circulation Under Normal Operating Conditions
Authors: Rhee Bo Wook , Yoon Churl , Min Byung-Joo
Published: March 2009

A steady-state 3D simulation for predicting the local subcooling of the moderator in the vicinity of the calandria tubes in a CANDU-6 reactor is performed. For the current simulation, a set of grid structures with the same geometry as the CANDU-6 moderator tank, called ‘calandria vessel’, is generated and the momentum, heat and continuity equations are solved by CFX-4.3, a CFD code developed by AEA technology. The standard k-ε turbulence model associated with logarithmic wall treatment is used to model turbulence generation and dissipation within the vessel. The moderator fluid is heavy water. Buoyancy forces are modeled using the Boussinesq approximation in which density is assumed to be a linear function of temperature. The matrix of the calandria tubes in the center region of the calandria vessel is simplified by the porous media approach. The anisotropic hydraulic impedance of the calandria tubes is modeled using the frictional pressure drop correlations suggested by Idelchik and Szymanski. The heat load in this steady-state simulation is conservatively set as 103 MW of 103% full power, consisting of 96.7 MW to the core region and 6.3 MW to the reflector region. The total volumetric flow rate through eight inlet nozzles is 940 L/s and the outlet temperature is constantly 71.0 °C. The thermal boundary condition of the circumferential vessel wall is assumed a little heat flux out. As a result, the velocity field and temperature distribution of a CANDU-6 moderator in the operating condition are presented. The flow pattern identified in this simulation is the weak jet momentum-dominated flow, which is generated by the interaction between the buoyancy force by heating and the dominant momentum forces by inlet jets. The calculated maximum temperature of the moderator is 83.0 °C at the lower center region of the core, which corresponds to the minimum subcooling of 33.0 °C considering the boiling point increase due to the hydrostatic pressure change.
Life Cycle Management: Managing the Aging of Critical Nuclear Plant Components
Authors: Meyer Theodore A. , Elder G. Gary , Llovet Ricardo
Published: March 2009

Life Cycle Management is a structured process to manage equipment aging and long-term equipment reliability for nuclear plant Systems, Structures and Components (SSCs). The process enables the identification of effective repair, replace, inspect, test and maintenance activities and the optimal timing of the activities to maximize the economic value to the nuclear plant. This paper will provide an overview of the process and some of the tools that can be used to implement the process for the SSCs deemed critical to plant safety and performance objectives. As nuclear plants strive to reduce costs, extend life and maximize revenue, the LCM process and the supporting tools summarized in this paper can enable development of a long term, cost efficient plan to manage the aging of the plant SSCs.
Effect of Non-Condensible Gas on the Subcooled Water Critical Flow in a Safety Valve
Authors: Kim Se Won , Lee Sang Kyoon , No Hee Cheon
Published: March 2009

The effect of non-condensable gas on the subcooled water critical flow in a safety valve is investigated experimentally at various subcoolings with 3 different disk lifts. To evaluate its effect on the critical pressure ratio and critical flow rate, three parameters are considered: the ratios of outlet pressure to inlet pressure, the subcooling to inlet temperature, and the gas volumetric flow to water volumetric flow are 0.15–0.23, 0.07–0.12, and 0–0.8, respectively. It turns out that the critical pressure ratio is mainly dependent on the subcooling, and its dependency on the gas fraction and the pressure drop is relatively small. When the ratio of nitrogen gas volumetric flow to water volumetric flow becomes lower than 20%, the subcooled water critical flow rate is decreased about 10% compare to the water flow rate of without non-condensable gas. However, it maintains a constant value after the ratio of gas volumetric flow to water volumetric flow becomes higher than 20%. The subcooled water critical flow correlation, which considers subcooling, disc lift, backpressure, and non-condensable gas, shows good agreement with the total present experimental data with the root mean square error 8.17%.
Multipurpose Small Size Fast Reactor: Its Basic Concept and Application to Nuclear Hydrogen Production
Authors: Endo H. , Sawada T. , Ninokata H.
Published: March 2009

Here we propose a basic concept of a multipurpose small-sized fast reactor and its applicability to produce nuclear hydrogen for near future mass use of hydrogen industrial and public use. The modular-type fast reactor of 150 MW thermal output does not require fuel exchange nor decommissioning on the site, and can be transported from the factory in a fabricated form. For the hydrogen production, we propose to use the sorption enhanced reforming process (SERP), in which the steam-methane reforming can take place around 450–550 °C. Since this temperature range is rather low compared to the ongoing steam reforming method (> 800°C), the SERP system combined with an adequate nuclear reactor system should be a promising one to cope with the coming age of hydrogen civilization.
Boron Concentration Model and Effects of Boron Holdup on Axial Offset Anomaly (AOA) in PWRs
Authors: Zhou Dawei , Jones Barclay G.
Published: March 2009

A significant number of current PWRs are experiencing axial offset anomaly (AOA), a condition that continues to elude prediction and thus creates an operational difficulty of being unable to accurately estimate safety margin. The cause of AOA is complex, involving both thermal-hydraulics and chemistry of core operation and design. This paper considers the structure of crud layers, which lead to AOA, and presents a thermal performance and neutron absorber concentration model for the crud layer that satisfactorily predicts the amount of boron accumulated to match that required to cause the observed power shifts.
Next Generation CANDU Technology: Competitive Design for the Nuclear Renaissance
Authors: Hopwood J. M. , Hedges K. R. , Pakan M.
Published: March 2009

AECL has developed the design for a next generation of CANDU® plants by marrying a set of enabling technologies to well-established successful CANDU features. The basis for the design is to replicate or adapt existing CANDU components for a new core design. By adopting slightly enriched uranium fuel, a core design with light water coolant, heavy water moderator and reflector has been defined, based on the existing CANDU fuel channel module. This paper summarizes the main features and characteristics of the reference next-generation CANDU design. The progress of the next generation of CANDU design program in meeting challenging cost, schedule and performance targets is described. AECL’s cost reduction methodology is summarized as an integral part of the design optimization process. Examples are given of cost reduction features together with enhancement of design margins.
Evaluation and Repair of Primary Water Stress Corrosion Cracking in Alloy 600/182 Control Rod Drive Mechanism Nozzles
Authors: Frye Charles R. , Arey Melvin L. , Robinson Michael R. , Whitaker David E.
Published: March 2009

In February 2001, a routine visual inspection of the reactor vessel head of Oconee Nuclear Station Unit 3 identified boric acid crystals at nine of sixty-nine locations where control rod drive mechanism housings (CRDM nozzles) penetrate the head. The boric acid deposits resulted from primary coolant leaking from cracks in the nozzle attachment weld and from through-thickness cracks in the nozzle wall. A general overview of the inspection and repair process is presented and results of the metallurgical analysis are discussed in more detail. The analysis confirmed that primary water stress corrosion cracking (PWSCC) is the mechanism of failure of both the Alloy 182 weld filler material and the alloy 600 wrought base material.
Incorporation of Risk Insights in the Regulatory Treatment of Nuclear Power Plant Structures, Systems, and Components
Authors: Imbro Eugene , Scarbrough Thomas G.
Published: March 2009

The U.S. Nuclear Regulatory Commission (NRC) has established an initiative to risk-inform the requirements in Title 10 of the Code of Federal Regulations (10 CFR) for the regulatory treatment of structures, systems, and components (SSCs) used in commercial nuclear power plants. As discussed in several Commission papers (e.g., SECY-99-256 and SECY-00-0194), Option 2 of this initiative involves categorizing plant SSCs based on their safety significance, and specifying treatment that would provide an appropriate level of confidence in the capability of those SSCs to perform their design functions in accordance with their risk categorization. The NRC has initiated a rulemaking effort to allow licensees of nuclear power plants in the United States to implement the Option 2 approach in lieu of the “special treatment requirements” of the NRC regulations. In a proof-of-concept effort, the NRC recently granted exemptions from the special treatment requirements for safety-related SSCs categorized as having low risk significance by the licensee of the South Texas Project (STP) Units 1 and 2 nuclear power plant, based on a review of the licensee’s high-level objectives of the planned treatment for safety-related and high-risk nonsafety-related SSCs. This paper discusses the NRC staff’s views regarding the treatment of SSCs at STP described by the licensee in its updated Final Safety Analysis Report (FSAR) in support of the exemption request, and provides the status of rulemaking that would incorporate risk insights into the treatment of SSCs at nuclear power plants.
3-D Simulation of Rotary Atomized Nozzle Flow Characteristics at Low Pressure
Authors: Ran Jingyu , Zhang Li , Xin Mingdao , Yang Lin
Published: March 2009

In order to realize liquid (oil etc.) atomized and to improve the combustion efficiency, the atomization or adding moisture is required by atomized nozzle in the oil burner and some power driven thrusters. Based on physics model and some suitable hypothesizes, the 3-D mathematical models for rotary atomized nozzle with micro-expanded tangent channel at low pressure are presented, and the same time, the various simulation tests are taken with the k-ε/RNG models and SIMPLE method, the tests results shown: The angle (θ) of the micro-expanded tangent channel plays an important role for the fluid characteristics, if θ<0, the circumfluence at the exit of the nozzle is obviously, and θ>0, the solid cone in nozzle are formed easily, but its energy loss is bigger. While the initial pressure p0 = 0.3Mpa, Ux,0 = 0, Uy,0 = 0, Uz,0 = −0.2m/s, the circumfluence at the exit of the nozzle isn’t exactly formed with θ = 5.8°, and the energy loss is reduced and the atomized angle can get 80°. The nozzle can be widely adequate to the medium atomized instrument about the oil burner and some power driven thrusters.
Visualization of Heat Transfer and Core Damage With RGUI 1.5
Authors: Mesina George L.
Published: March 2009

Graphical User Interfaces (GUI) have become an integral and essential part of computer software. In the ever-changing world of computing, they provide the user with a valuable means to learn, understand, and use the application software while also helping applications adapt to and span different computing paradigms, such as different operating systems. For these reasons, GUI development for nuclear plant analysis programs has been ongoing for a decade and a half and much progress has been made. With the development of codes such as RELAP5-3D [1] and SCDAP/RELAP5 that have multi-dimensional modeling capability, it has become necessary to represent three-dimensional, calculated data. The RELAP5-3D Graphical User Interface (RGUI) [4] was designed specifically for this purpose. It reduces the difficulty of analyzing complex three-dimensional models and enhances the analysts’ ability to recognize plant behavior visually. Previous versions of RGUI [5] focused on visualizing reactor coolant behavior during a simulated transient or accident. Recent work has extended RGUI to display two other phenomena, heat transfer and core damage. Heat transfer is depicted through the visualization of RELAP5-3D heat structures. Core damage is visualized by displaying fuel rods and other core structures in a reactor vessel screen. Conditions within the core are displayed via numerical results and color maps. These new features of RGUI 1.5 are described and illustrated.
A Life-Cycle Risk-Informed Systems Structured Nuclear Code
Authors: Hill Ralph S.
Published: March 2009

Current American Society of Mechanical Engineers (ASME) nuclear codes and standards rely primarily on deterministic and mechanistic approaches to design. The design code is a separate volume from the code for inservice inspections and both are separate from the standards for operations and maintenance. The ASME code for inservice inspections and code for nuclear plant operations and maintenance have adopted risk-informed methodologies for inservice inspection, preventive maintenance, and repair and replacement decisions. The American Institute of Steel Construction and the American Concrete Institute have incorporated risk-informed probabilistic methodologies into their design codes. It is proposed that the ASME nuclear code should undergo a planned evolution that integrates the various nuclear codes and standards and adopts a risk-informed approach across a facility life-cycle — encompassing design, construction, operation, maintenance and closure.
Stress Corrosion Cracking and Non-Destructive Examination of Dissimilar Metal Welds and Alloy 600
Authors: Jackson Deborah A.
Published: March 2009

The United States Nuclear Regulatory Commission (USNRC) has conducted research since 1977 in the areas of environmentally assisted cracking and assessment and reliability of non-destructive examination (NDE). Recent occurrences of cracking in Alloy 82/182 welds and Alloy 600 base metal at several domestic and overseas plants have raised several issues relating to both of these areas of NRC research. The occurrences of cracking were identified by the discovery of boric acid deposits resulting from through-wall cracking in the primary system pressure boundary. Analyses indicate that the cracking has occurred due to primary water stress corrosion cracking (PWSCC) in Alloy 82/182 welds. This cracking has occurred in two different locations: in hot leg nozzle-to-safe end welds and in control rod drive mechanism (CRDM) nozzle welds. The cracking associated with safe-end welds is important due to the potential for a large loss of reactor coolant inventory, and the cracking of CRDM nozzle base metal and welds, particularly circumferential cracking of CRDM nozzle base metal, is important due to the potential for a control rod to eject resulting in a loss of coolant accident. The industry response in the U.S. to this cracking is being coordinated through the Electric Power Research Institute’s Materials Reliability Project (EPRI-MRP) in a comprehensive, multifaceted effort. Although the industry program is addressing many of the issues raised by these cracking occurrences, confirmatory research is necessary for the staff to evaluate the work conducted by industry groups. Several issues requiring additional consideration regarding the generic implications of these isolated events have been identified. This paper will discuss the recent events of significant cracking in domestic and foreign plants, discuss the limitations of NDE in detecting SCC, identify deficiencies in information available in this area, discuss the USNRC approach to address these issues, and discuss the development of an international cooperative effort.
Application of Image Analysis With Noise Removal for Supercritical CO2
Authors: Ota J. , Sakurai K. , Okamoto K. , Madarame H.
Published: March 2009

It is very important to understand the thermo-fluid characteristics of supercritical fluid, for the development of advanced supercritical water cooled nuclear reactor. In this study, visualization experiment for forced convection of the supercritical fluid was carried. Using the measured images with cross-correlation technique, the velocity distribution was obtained. To reduce the error of the reconstructed data, novel approach for the image analysis and advanced visualization technique was applied. For the visualization technique, the frame straddling was applied with infrared pulse laser. The temporal and spatial noise removal procedure was developed for the image analysis.
Film Boiling of Saturated Nitrogen in Horizontal Tubes of Double Pipe Heat Exchangers
Authors: Chen X. L. , Sutton W. H. , Sanchez M. A.
Published: March 2009

The data of a nitrogen film boiling experiment in horizontal tubes are presented in the paper. The experiment condition was the same as the actual application, which is neither a uniform heat flux nor a uniform wall temperature condition. The purpose is trying to find a good method to calculate the heat transfer coefficient for actual film boiling applications. The experiment data are carefully analyzed and compared with some current available correlations. A combined method is recommended in this paper for average heat transfer coefficient of film boiling in horizontal tubes based on the understanding of flow regimes.
Preliminary Investigation of an Optimally Scramming Control Rod for Gas-Cooled Reactors
Authors: Ougouag Abderrafi M. , Schultz Richard R. , Terry William K. , Stephens Alan G.
Published: March 2009

A passively safe control rod for gas-cooled reactors is proposed. This Optimally Scramming Control Rod (OSCR) is lifted out of the core region by the core coolant and descends back into the core when the coolant flow is not sufficient for core cooling purposes or in the event of depressurization. It is shown that for the current design of the OSCR, the reactor can be operated under normal lower power conditions down to about 80% of total power. It is also shown that cold shutdown can be achieved with rods of sufficiently low mass to allow naturally passive operation of the concept.
Functional Proteomics Identify Cornichon Proteins as Auxiliary Subunits of AMPA Receptors
Authors: Schwenk Jochen , Harmel Nadine , Zolles Gerd , Bildl Wolfgang , Kulik Akos , Heimrich Bernd , Chisaka Osamu , Jonas Peter , Schulte Uwe , Fakler Bernd , Klöcker Nikolaj
Published: March 2009

Glutamate receptors of the AMPA-subtype (AMPARs), together with the transmembrane AMPAR regulatory proteins (TARPs), mediate fast excitatory synaptic transmission in the mammalian brain. Here, we show by proteomic analysis that the majority of AMPARs in the rat brain are coassembled with two members of the cornichon family of transmembrane proteins, rather than with the TARPs. Coassembly with cornichon homologs 2 and 3 affects AMPARs in two ways: Cornichons increase surface expression of AMPARs, and they alter channel gating by markedly slowing deactivation and desensitization kinetics. These results demonstrate that cornichons are intrinsic auxiliary subunits of native AMPARs and provide previously unknown molecular determinants for glutamatergic neurotransmission in the central nervous system.
The Earliest Horse Harnessing and Milking
Authors: Outram Alan K. , Stear Natalie A. , Bendrey Robin , Olsen Sandra , Kasparov Alexei , Zaibert Victor , Thorpe Nick , Evershed Richard P.
Published: March 2009

Horse domestication revolutionized transport, communications, and warfare in prehistory, yet the identification of early domestication processes has been problematic. Here, we present three independent lines of evidence demonstrating domestication in the Eneolithic Botai Culture of Kazakhstan, dating to about 3500 B.C.E. Metrical analysis of horse metacarpals shows that Botai horses resemble Bronze Age domestic horses rather than Paleolithic wild horses from the same region. Pathological characteristics indicate that some Botai horses were bridled, perhaps ridden. Organic residue analysis, using δ
13
C and δD values of fatty acids, reveals processing of mare's milk and carcass products in ceramics, indicating a developed domestic economy encompassing secondary products.
Concurrent Titration and Determination of Antibiotic Resistance in
Ureaplasma
Species with Identification of Novel Point Mutations in Genes Associated with Resistance
Authors: Beeton Michael L. , Chalker Victoria J. , Maxwell Nicola C. , Kotecha Sailesh , Spiller O. Brad
Published: March 2009

Antibiotic resistance determination of
Ureaplasma
spp. (
Ureaplasma parvum
and
Ureaplasma urealyticum
) usually requires predetermination of bacterial titer, followed by antibiotic interrogation using a set bacterial input. This 96-well method allows simultaneous quantification of bacteria in the presence and absence of antibiotics. A method for determining precise MICs and a method for screening against multiple antibiotics using breakpoint thresholds are detailed. Of the 61
Ureaplasma
-positive clinical isolates screened, one (1.6%) was resistant to erythromycin (MIC, >64 mg/liter) and clarithromycin (MIC, 4 mg/liter), one to ciprofloxacin (1.6%), and one to tetracycline/doxycycline (1.6%). Five isolates were also consistently found to have an elevated MIC of 8 mg/liter for erythromycin, but this may not represent true antibiotic resistance, as no mutations were found in the 23S rRNA operons or ribosome-associated L4 and L22 proteins for these strains. However, two amino acids (R66Q67) were deleted from the L4 protein of the erythromycin-/clarithromycin-resistant strain. The
tetM
genetic element was detected in the tetracycline-resistant clinical isolate as well as in the positive control Vancouver strain serotype 9. The
tetM
gene was also found in a fully tetracycline-susceptible
Ureaplasma
clinical isolate, and no mutations were found in the coding region that would explain its failure to mediate tetracycline resistance. An amino acid substitution (D82N) was found in the ParC subunit of the ciprofloxacin-resistant isolate, adjacent to the S83L mutation reported by other investigators in many ciprofloxacin-resistant
Ureaplasma
isolates. It is now possible to detect antibiotic resistance in
Ureaplasma
within 48 h of positive culture without prior knowledge of bacterial load, identifying them for further molecular analysis.
Molecular Mechanisms of Macrolide Resistance in Clinical Isolates of
Mycoplasma pneumoniae
from China
Authors: Xin Deli , Mi Zuhuang , Han Xu , Qin Ling , Li Jing , Wei Tianli , Chen Xiaogeng , Ma Shaojie , Hou Ancun , Li Gui , Shi Dawei
Published: March 2009

Fifty clinical
Mycoplasma pneumoniae
strains were isolated from 370 children with respiratory tract infections. Four strains were susceptible to macrolides, while the other 46 (92%) were macrolide resistant. The molecular mechanism of resistance was shown to be associated with point mutations in 23S rRNA at positions 2063 and 2064.
Inactivation of the Glycoside Hydrolase NagZ Attenuates Antipseudomonal β-Lactam Resistance in
Pseudomonas aeruginosa
Authors: Asgarali Azizah , Stubbs Keith A. , Oliver Antonio , Vocadlo David J. , Mark Brian L.
Published: March 2009

The overproduction of chromosomal AmpC β-lactamase poses a serious challenge to the successful treatment of
Pseudomonas aeruginosa
infections with β-lactam antibiotics. The induction of
ampC
expression by β-lactams is mediated by the disruption of peptidoglycan (PG) recycling and the accumulation of cytosolic 1,6-anhydro-
N
-acetylmuramyl peptides, catabolites of PG recycling that are generated by an
N
-acetyl-β-
d
-glucosaminidase encoded by
nagZ
(PA3005). In the absence of β-lactams,
ampC
expression is repressed by three AmpD amidases encoded by
ampD
,
ampDh2
, and
ampDh3
, which act to degrade these 1,6-anhydro-
N
-acetylmuramyl peptide inducer molecules. The inactivation of
ampD
genes results in the stepwise upregulation of
ampC
expression and clinical resistance to antipseudomonal β-lactams due to the accumulation of the
ampC
inducer anhydromuropeptides. To examine the role of NagZ on AmpC-mediated β-lactam resistance in
P. aeruginosa
, we inactivated
nagZ
in
P. aeruginosa
PAO1 and in an isogenic triple
ampD
null mutant. We show that the inactivation of
nagZ
represses both the intrinsic β-lactam resistance (up to 4-fold) and the high antipseudomonal β-lactam resistance (up to 16-fold) that is associated with the loss of AmpD activity. We also demonstrate that AmpC-mediated resistance to antipseudomonal β-lactams can be attenuated in PAO1 and in a series of
ampD
null mutants using a selective small-molecule inhibitor of NagZ. Our results suggest that the blockage of NagZ activity could provide a strategy to enhance the efficacies of β-lactams against
P. aeruginosa
and other gram-negative organisms that encode inducible chromosomal
ampC
and to counteract the hyperinduction of
ampC
that occurs from the selection of
ampD
null mutations during β-lactam therapy.
The effect of retail cigarette pack displays on unplanned purchases: results from immediate postpurchase interviews: Table 1
Authors: Carter O B J , Mills B W , Donovan R J
Published: March 2009

Objective:

To assess the influence of point-of-sale (POS) cigarette displays on unplanned purchases.

Methods:

Intercept interviews were conducted with customers observed purchasing cigarettes from retail outlets featuring POS cigarette displays. Measures included intention to purchase cigarettes prior to entering the store, unprompted and prompted salience of POS tobacco displays, urge to buy cigarettes as a result of seeing the POS display, brand switching and support for a ban on POS cigarette displays.

Results:

In total, 206 daily smokers aged 18–76 years (90 male, 116 female) were interviewed. Unplanned cigarette purchases were made by 22% of participants. POS displays influenced nearly four times as many unplanned purchases as planned purchases (47% vs 12%, p<0.01). Brand switching was reported among 5% of participants, half of whom were influenced by POS displays. Four times as many smokers were supportive of a ban on POS tobacco displays than unsupportive (49% vs 12%), and 28% agreed that such a ban would make it easier to quit.

Conclusions:

POS tobacco displays act as a form of advertising even in the absence of advertising materials. They stimulate unplanned cigarette purchases, play an important role in brand selection and tempt smokers trying to quit. This justifies removing POS tobacco displays from line of sight—something that very few smokers in our sample would object to.
A REVIEW APPROACH TO DETECTING VIOLATIONS OF CONSISTENCY BETWEEN SPECIFICATION AND PROGRAM STRUCTURES
Authors: CHEN YUTING , LIU SHAOYING , WONG W. ERIC
Published: March 2009

The application of specification-based program verification techniques (e.g., black-box testing, formal proof) faces strong challenges in practice when the gap between the structure of a specification and that of its program is large. This paper describes a view-based program review approach to addressing these challenges. The essential idea of the approach is first to derive comparable views from the specification and program, and then detect and eliminate the violations of structural consistency in the program views on the basis of a set of criteria. We also developed a prototype tool to support the review approach, and conducted a case study to assess the effectiveness of the approach.
THE APPLICATION-BASED DOMAIN ANALYSIS APPROACH AND ITS OBJECT-PROCESS METHODOLOGY IMPLEMENTATION
Authors: STURM ARNON , DORI DOV , SHEHORY ONN
Published: March 2009

Domain engineering can simplify the development of software systems in specific domains. During domain analysis, the first step of domain engineering, the domain is modeled at an abstract level, providing guidelines for modeling applications within that domain. Drawbacks of existing domain analysis approaches include poor guidelines for domain-specific application modeling, insufficient validations capability, and limited usability. In this paper we apply the Application-based Domain Modeling (ADOM) to the Object-Process Methodology (OPM). This application requires the extension of OPM with a classification mechanism. Showing that the ADOM-OPM approach overcomes limitations of existing approaches, we further verify experimentally that the level of correctness of an ADOM extended OPM model is higher than that achieved without the extension. Finally, we ensure that the proposed extension does not degrade the generic vanilla form of OPM.
OPTICALLY INDUCED ELECTROSTRICTION MODES IN A NANOPARTICLE OF A UNIFORMLY CHARGED ELECTRET
Authors: BASTRUKOV S. I. , MOLODTSOVA I. V. , LAI PIK-YIN
Published: March 2009

The electromagnetic response of a nanoparticle of an ion-doped polymeric elastic insulator, commonly called an electret, is considered in the continuum model of a uniformly charged elastic sphere. The spectral formulae for the frequency of optically induced spheroidal and torsional shear oscillations driven by bulk force of elastic and dielectric stresses are obtained in analytic form. Particular attention is given to the relaxation dielectric mode of the electrostriction response and its stability in the lowest quadrupole mode. The practical usefulness of ultrafine particles of electrets as biolabels capable of accumulating like-charged inclusions uniformly dispersed over the spherical volume of an elastic matrix is briefly discussed.
QUANTUM STATE DEPRESSION IN A SEMICONDUCTOR QUANTUM WELL
Authors: TAVKHELIDZE AVTO , SVANIDZE VASIKO
Published: March 2009

In this study, the quantum state depression (QSD) in a semiconductor quantum well (QW) is investigated. The QSD emerges from the ridged geometry of the QW boundary. Ridges impose additional boundary conditions on the electron wave function, and some quantum states become forbidden. State density is reduced in all energy bands, including the conduction band (CB). Hence, electrons, rejected from the filled bands, must occupy quantum states in the empty bands due to the Pauli exclusion principle. Both the electron concentration in the CB and the Fermi energy increased, as in the case of donor doping. Since quantum state density is reduced, the ridged quantum well (RQW) exhibits quantum properties at widths approaching 200 nm. A wide RQW can be used to improve photon confinement in QW-based optoelectronic devices. Reduction in the state density increases the carrier mobility and makes the ballistic transport regime more pronounced in the semiconductor QW devices. Furthermore, the QSD doping does not introduce scattering centers and can be used for power electronics.
Spectral fingerprinting of porphyrins for distributed chemical sensing
Authors: Filippini Daniel , Gatto Emanuela , Alimelli Adriano , Ali Malik Muhamad , Di Natale Corrado , Paolesse Roberto , D'Amico Arnaldo , Lundström Ingemar
Published: March 2009

Recent progress in spectral fingerprinting of fluorescent indicators using distributed instrumentation based on consumer electronic devices is reviewed. In particular, the evaluation of disposable assays using a computer screen photo-assisted technique (CSPT) is discussed. Sample identification and optimization strategies are analyzed as well as the underlying theoretical background for polychromatic spectral fingerprinting.