Design Of Safety Systems Research Articles

Investigation of vibrations caused by the steam condensation at sub-atmospheric condition in VVPSS

Fusion technology deployment passes through the design of safety systems aimed to protect the Vacuum Vessel (VV) from pressurizing accidents event such as LOVA (Loss Of Vacuum Accident) or the failure of the Tokamak Water Cooling System (TWCS) causing the LOCA (Loss Of Coolant Accident). One of important safety systems of the ITER plant is the Vacuum Vessel Pressure Suppression System (VVPSS), which is designed to protect the VV by the steam condensation at sub-atmospheric pressure conditions in Suppression Tanks.The aim of this study is to investigate vibrations phenomenon, originated during the steam-water direct contact condensation (DCC) at sub-atmospheric conditions, and determine any correlations between the steam jet dynamic and water temperature (TW), steam mass flux (GS) and downstream pressure (PW).According to the thermal hydraulic conditions characterising the DCC, vibrations may evolve because of the latent heat of the phase change (large amount of heat transmitted quickly to the water).In the paper also presents the numerical investigations performed by means of proper FEM code, the set-up procedure and the experimental activity carried out at Lab. B. Guerrini of DICI- University of Pisa. This latter allowed correlating the different steam condensation regimes (chugging, condensation oscillation, etc.) to the acceleration and force, to be in turn used to determine the strength capacity of the VVPSS.

Investigating the effect of urgency and modality of pedestrian alert warnings on driver acceptance and performance

Active safety systems have the potential to reduce the risk to pedestrians by warning the driver and/or taking evasive action to reduce the effects of or avoid a collision. However, current systems are limited in the range of scenarios they can address using primary control interventions, and this arguably places more emphasis in some situations on warning the driver so that they can take appropriate action in response to pedestrian hazards. In a counterbalanced experimental design, we varied urgency (‘when’) based on the time-to-collision (TTC) at which the warning was presented (with associated false-positive alarms, but no false negatives, or ‘misses’), and modality (‘how’) by presenting warnings using audio-only and audio combined with visual alerts presented on a HUD. Results from 24 experienced drivers, who negotiated an urban scenario during twelve 6.0-min drives in a medium-fidelity driving simulator, showed that all warnings were generally rated ‘positively’ (using recognised subjective ‘acceptance’ scales), although acceptance was lower when warnings were delivered at the shortest (2.0 s) TTC. In addition, drivers indicated higher confidence in combined audio and visual warnings in all situations. Performance (based on safety margins associated with critical events) varied significantly between warning onset times, with drivers first fixating their gaze on the hazard, taking their foot off the accelerator, applying their foot on the brake, and ultimately bringing the car to a stop further from the pedestrian when warnings were presented at the longest (5.0 s) TTC. In addition, drivers applied the brake further from the pedestrian when combined audio and HUD warnings were provided (compared to audio-only), but only at 5.0 s TTC. Overall, the study indicates a greater margin of safety associated with the provision of earlier warnings, with no apparent detriment to acceptance, despite relatively high false alarm rates at longer TTCs. Also, that drivers feel more confident with a warning system present, especially when it incorporates auditory and visual elements, even though the visual cue does not necessarily improve hazard localisation or driving performance beyond the advantages offered by auditory alerts alone. Findings are discussed in the context of the design, evaluation and acceptance of active safety systems.

Numerical investigation on heat transfer of the supercritical fluid upward in vertical tube with constant wall temperature

The supercritical fluid has been extensively applied in many industry applications and heat transfer characteristics of the supercritical fluid play an important role in system safety and economic design. In this paper, heat transfer characteristics and mechanism of the supercritical fluid upward in vertical tube with constant wall temperature are numerically investigated. Heat transfer fluctuation phenomenon is found at the trans-critical section where fluid experiences the pseudo-critical point. Heat transfer fluctuation takes place only when the wall temperature is higher than the pseudo-critical temperature and the bulk temperature is lower than the pseudo-critical temperature. The traditional prediction correlation can’t predict heat transfer fluctuation at the trans-critical section correctly. Heatflux fluctuation is caused by the buoyancy effect. The buoyancy effect induces the periodic flow variation and the periodic convective heat transfer variation on the radial direction, which determine heatflux fluctuation on the wall. The fluctuation amplitude of heatflux on the wall decreases along the axial direction due to the weakened buoyancy effect. Influence of operating conditions on heat transfer of the supercritical fluid is investigated. R134a is chosen as the working fluid. Operating condition includes mass flow ranging from 500 to 800 kg/(m2 s), inlet temperature ranging from 313.15 to 343.15 K, wall temperature ranging from 403.15 to 433.15 K and operating pressure ranging from 4.35 to 5.04 MPa. It is observed that heat transfer coefficient rises with mass flow, wall temperature and operating pressure increasing, but it doesn’t vary obviously with inlet temperature. Fluctuation amplitude of heat transfer coefficient decreases with mass flow, wall temperature, inlet temperature and operating pressure increasing.

What Does the Sustainability-Risk Interaction Look Like? Exploring Nuanced Relationships in Emerging Economy Sustainability Initiatives

To be viable long-term, sustainability programs must be profitable. Unfortunately, current sustainability practices increase risk, increasing costs and threatening revenues. Higher costs and lower revenues negatively impact profitability and, thus, the viability of sustainability. To understand how sustainability-induced risks affect food production systems, sustainability-induced risks in food production systems are identified and classified. It is also explored how sustainability risks interact, making it especially costly and difficult to eradicate them. An inductive, interview-based method was employed, which relies on 41 semi-structured interviews, with managers at 32 companies. The study documents the interaction between sustainability and risk in five risk categories—behavioral, opportunism, organizational routines, safety and traceability routines and systems design. The negative impact of intensive interactions among these risk categories threatens food production systems’ sustainability initiatives. Behavioral risks are particularly pervasive and harmful as they either induce or exacerbate other risk clusters. Elaborating the interaction between sustainability and risk, as well as documenting risk types and interactions, provides a more holistic view of sustainability implementation. This nuanced view will lead to a more accurate and insightful costing of sustainability programs. Lamentably, the most pervasive risk category—i.e., behavioral risks—are often overlooked in the supply chain management literature. However, this research shows a clear need to delve more deeply into the behavioral dimension to improve risk management and to increase the viability of sustainability. This study identifies and categorizes sustainability-induced risk factors in food production systems, and shows how they interrelate, providing the foundation for better planning and execution of viable sustainability programs.

Assessing the effects of auditory-vocal distraction on driving performance and physiological measures using a driving simulator

In this research, a driving simulator experiment with physiological sensors is conducted to quantify the effect of an increase in workload on driving performance and physiological state in the presence of particular road situations. A secondary cognitive task with multiple levels of difficulty designed to simulate auditory-vocal distraction is added to the primary driving task. Driving performance and physiological indices such as heart rate and skin conductance level are monitored throughout the experiment. Nonparametric statistical tests are used to test the effect of the secondary task at three different road situations frequently encountered in an urban context. It is hypothesized that an increase in workload leads to variations in the driver’s physiology as well as decrement in his/her driving performance. Results of the study showed that the driver adopts a regulatory behavior at the operational level (e.g., reduces the speed) in order to allow the performance of the additional task and driving at the same time. The effect of the regulatory behavior is minor on the longitudinal and lateral control measures (e.g., the speed, the pedal depression, the lane position). However, the impact on the reaction time can have important implications for road safety. An increase in the heart rate and skin conductance level reflects the increase in the cognitive workload when performing the secondary task. No major differences are found in terms of the driving performance and the physiological measures across the difficulty levels of the secondary task at the three considered road situations. In order to maintain control of driving, particularly at the high levels of difficulty, some subjects are found to pay less attention to the secondary task and shift their focus towards the primary driving task. The study highlights the advantage of implementing the driver’s cognitive workload measures in the development, design, and assessment of effective in-vehicle safety systems.

Conceptional design of Airbag-based seismic safety system in structures of nuclear power plants (NPPs)

ABSTRACTNuclear safety system is investigated by the airbag in which the earthquake-resistance performance is manifested. Most degrees’ earthquake could be compromised, which is different from the conventional earthquake regulation where the fixed regulation as 6.5 or 7.0 in Richter magnitude scale is used. Assuming some variable in the simulations, the volume is obtained. In the simulations, at 307th day (at this time, 2,601.94 10,000 pascals), the volume is 9.58647 m3. So, one side of the airbag is proposed as the size of 2.124318 meters. The perfect safety system for the earthquake is constructed in the nuclear power plants (NPPs). This skill could be applicable to the other kinds of industry for the earthquake protections.

DSS application on single-phase natural circulation in a simple rectangular loop

Scaling analysis is widely used in the design of nuclear reactor passive safety systems to ensure those scaled-down test facilities can accurately capture important phenomena in a full-scale prototype. In this study, the transient scaling distortion of a single-phase natural circulation system was evaluated using the new Dynamical System Scaling (DSS) method. For convenience of comparison, the conventional Hierarchical Two-Tiered Scaling (H2TS) method, based on the initial static characteristic values, was applied first to determine the system scaling ratios. The different scaled-down cases based on the two methods were calculated with the Relap5 computational code. The results show that two different scaling number groups can be obtained based on the traditional H2TS method and the new DSS identity method, and both of the methods can effectively model the single phase natural circulation in a simple loop. The relative scaling distortion of the transient mass flow rate fluctuated sharply at the initial stage, when the power input increased step-wise, but gradually grew afterwards. In addition, with a smaller power ratio, the DSS identity method was more helpful for the scaled-down facility design.

Designing and Developing an Effective Safety Program for a Student Project Team

In the workplace, safety must be the first priority of all employers and employees alike. In order to maintain the safety and well-being of their employees, employers must demonstrate due diligence and provide the appropriate safety training to familiarize employees with the hazards within the workplace. Although, a student “project team” is not a business, the work done by students for their respective teams is synonymous with the work done in a place of business and thus requires that similar safety precautions and training be administered to students by their team leads and faculty advisors. They take on the role of supervisors within the team dynamic. Student teams often utilize the guidelines and policies that their universities or colleges have developed in order to build a set of standard operating procedures and safety training modules. These guidelines aid in providing a base for training for the team, however, they are no substitute for training specific to the safety risks associated with the work the team is doing. In order to comply with these requirements, a full analysis of the workplace is required to be completed. A variety of safety analysis techniques need to be applied to define the hazards within the workplace and institute appropriate measures to mitigate them. In this work, a process is developed for establishing a safety training program for a student project team, utilizing systems safety management techniques and the aspect of gamification to produce incentives for students to continue developing their skills. Although, systems safety management is typically applied to the design of active safety components or systems, the techniques for identifying and mitigating hazards can be applied in the same fashion to the workplace. They allow one to analyze their workplace and determine the hazards their employees might encounter, assign appropriate hazard ratings and segregate each respective hazard by their risks. In so doing, safety level assignment can be completed to ensure team members are trained to be able to work on the systems associated with a given risk level.

Drivers’ effective decelerating zone in an urban Vehicle-Pedestrian conflict situation: Observational studies and analyses

To analyse the drivers’ decelerating behavior in conflict avoidance process under Vehicle-Pedestrian conflict situation is accordingly a surrogate method for the guidance of driver evasive manoeuvre and improving the active driving safety. Field observation data has been collected by video recording and image processing at urban unsignalized midblock crosswalks in Beijng, China and Munich, Germany. The relationship between deceleration rate and vehicle speed has been statistically described. By analyzing how the time-related measures (Vehicle Time to Conflict Point and Pedestrian Time to Conflict Point) and the distance-related measures (Vehicle longitudinal distance to Conflict Point and Pedestrian Lateral distance to Conflict Point) affect the deceleration rate choice, the drivers‘ effective decelerating zone with sight angle has been proposed with the consideration of longitudinal & lateral conflict behavior. Minimum Vehicle-Pedestrian conflict distance is calculated and a 2 m minimum distance is suggested as the threshold for collision discrimination. Comparisons which address the needs to make the intercultural adaptation when introducing Driver Assistance Systems to developing countries have also been made to show the significant differences between China and Germany. The whole work could hopefully be the groundwork in the target of conflict pre-scanning by decelerating zones under various conflict situations and the design of vehicle active safety systems.

Target Safety System design for the ESS target station

The European Spallation Source (ESS) will be a 5 MW neutron spallation research facility where an energetic proton beam incident upon a helium-cooled tungsten target is converted to neutron beams. The liquid hydrogen moderator, water moderator, and reflector systems within the target monolith slow the high-energy spallation neutrons down to cold and thermal neutrons suitable for use by experiments. Several layers of control, protection, and safety systems will be implemented in order to ensure safe operation of this advanced facility. The Target Safety System (TSS) is part of the overall radiation safety plan for the Target Station. As such, in case of an abnormal event, the TSS will protect the public from exposure to unsafe levels of radiation, prevent the release of radioactive material beyond permissible limits, and bring the neutron spallation function into a safe state. This safe state is defined as no beam incident upon the target. Since the target is the source of the release of radiation in the presence of the beam, putting the target station into the safe state (no beam), brings the spallation process to the safe state.The TSS safety functions are based on the results from hazard and accident analyses done to evaluate radiation hazards within the target station. The most critical hazards are related to increased temperature of the target wheel tungsten, which can be the result of cooling system malfunctions or stopping of the rotating target. Therefore, the TSS will monitor parameters related to the cooling conditions and rotation of the target.As a safety system, the TSS is subject to requirements from the Swedish Nuclear Safety Authority (SSM), including single failure and common cause failure criteria. These requirements impact the system architecture in terms of redundancy, separation and diversity. Dedicated redundant and diverse TSS sensors are connected to two diverse and separated trains performing the same safety functions. Each train acts on diverse and separated mechanisms to stop the beam from reaching the target.This paper will describe the design and architecture of the TSS, which implements the safety functions identified in the radiation safety analyses and fulfils the SSM conditions.

Neonatal Nurses Experience Unintended Consequences and Risks to Patient Safety With Electronic Health Records.

In this article, we examine the unintended consequences of nurses' use of electronic health records. We define these as unforeseen events, change in workflow, or an unanticipated result of implementation and use of electronic health records. Unintended consequences experienced by nurses while using electronic health records have been well researched. However, few studies have focused on neonatal nurses, and it is unclear to what extent unintended consequences threaten patient safety. A new instrument called the Carrington-Gephart Unintended Consequences of Electronic Health Record Questionnaire has been validated, and secondary analysis using the tool explored the phenomena among neonatal nurses (N = 40). The purposes of this study were to describe unintended consequences of use of electronic health records for neonatal nurses and to explore relationships between the phenomena and characteristics of the nurse and the electronic health record. The most frequent unintended consequences of electronic health record use were due to interruptions, followed by a heavier workload due to the electronic health record, changes to the workflow, and altered communication patterns. Neonatal nurses used workarounds most often with motivation to better assist patients. Teamwork was moderately related to higher unintended consequences including patient safety risks (r = 0.427, P = .007), system design (r = 0.419, P = .009), and technology barriers (r = 0.431, P = .007). Communication about patients was reduced when patient safety risks were high (r = -0.437, P = .003). By determining the frequency with which neonatal nurses experience unintended consequences of electronic health record use, future research can be targeted to improve electronic health record design through customization, integration, and refinement to support patient safety and better outcomes.

From factor to vector, a quantum transition in assessing safety in ATM systems

Recently, several major events in various high tech industries have revealed deficiencies in assessing safety at a systems level. Conventional analytic approaches in the operational phase suffer from paradigmatic limitations. In non-plus, ultra-safe and complex, dynamic systems, such as Air Traffic Management systems, safety requires a new approach in which:-Safety is a strategic value in decision making and business modeling.-Safety is a system property, represented by state/space vectors.-Safety assessment focuses on quantifiable dissimilarities between various system states and operating conditions throughout their life cycle phases.In order to cope with non-linear interactions and interventions, firstly, safety has to be integrally designed into the system and assessed as an inherent property before it can manifest itself in practice as an emergent property. Secondly, engineering design methods have to be mobilized, such as forensic engineering, value and knowledge based engineering and resilience engineering. The design of safer systems should apply a non-linear design methodology, with an integral assessment of all values and performance requirements, including safety. Such a predictive, quantifiable assessment includes simulation, prototyping and dissimilarity measurements. Finally, system adaptation should focus on the functional level, inherent system properties and synchronization of event vectors and system state vectors.

Estimation of natural circulation flow based on temperature in the FASSIP-02 large-scale test loop facility

In the future, the use of passive cooling system without electrical power input become highly considered to be implemented in the design of nuclear reactor safety system. Moreover, the lessons learned from the Fukushima-Daiichi accident encourage the incorporation of such passive cooling system. The passive safety cooling system is aimed to cope with both design bases as well as severe accidents. The natural circulation is one example parameter of the passive cooling system features being widely considered. However, some of the parameters involving in natural circulation are still being investigated, in particular the problem of flow instability. BATAN is designing a large-scale test loop facility, named FASSIP-02 loop, with a height of 11 meters between a heat source and a cooling source. The FASSIP-02 loop is designed to simulate the residual heat in the reference reactor. To ensure the validity of the design prior to the construction, it is necessary to make an analytical calculation using some correlations to estimate the natural circulation flow rate. The calculation method is performed by using the derived two principle correlations of the buoyancy force in the heating section and the gravitational force on the cooling section. The water temperatures in the heating section are varied at 50°C, 60°C, 70°C, 80°C and 90°C with the water temperature in the cooling tank pool are varied at 10°C, 20°C, 30°C, 40°C and 50°C. The calculation results can estimate the water temperature and volume are required. In addition, it could be used to determine the experimental matrix that is based on the FASSIP-02 loop design.

Food Safety System Design Using Hazard Analysis Critical Control Point (HACCP) on Beverage Product X at a Milk Tea Producer

Food safety is a primary concern in food industry. Hazard Analysis Critical Control Point (HACCP) is a systematic preventive approach that aims to ensure food safety in a comprehensive manner, starting from raw material retrieval from supplier, production phase, up to the distribution to end consumers. Furthermore, the approach is capable of reducing risks associated with food hazard to their acceptable level. Our research took place in a company that produces a wide array of milk tea with a variety of flavours, i.e. product X. Recent increase in overall demand and competitors in Indonesian milk tea market subsequently forces the company to pay more attention to the quality of their product X. Thus, the company aspires to certify its food safety system and management. This research proposes a design and implementation plan of HACCP for quality assurance and food safety of product X. The main outcomes of this research are the HACCP plan for raw material, packaging material, and production process. Further potential improvements are suggested with regard to production process, production equipment, production layout, human resource, sanitation, and documentation system. The HACCP plan consists of ten Critical Control Points (CCPs), a series of documentation forms, and additional documents specifically attributed to support the implementation phase of HACCP plan.

Development of safety analysis code for SCWR and its LOCA analysis of CSR1000

In this study, Transient Analysis Code Of SCWR (TACOS), with the ability of simulating transients or accidents under both supercritical water conditions and subcritical water conditions, has been developed. A 3-equation model for supercritical water flow and single phase flow, and a 4-equation drift-flux model for two-phase mixture are adopted. Coupling of the 3-equation model and 4-equation model is utilized to perform simulation of transition between supercritical and subcritical conditions. Furthermore, an illustration of heat transfer models suitable for potential boiling crisis under near-critical pressure condition is introduced and presented. The code TACOS is then applied to simulate SWAMUP trans-critical test to validate its feasibility of simulating trans-critical transients. Furthermore, validations with the Edward-O’Brian blow-down experiment data and other codes’ results are illustrated to evaluate its capacity in simulating the fast blow-down progress under both sub-critical condition and supercritical condition.At last, the Loss of Coolant Accidents (LOCAs) with a small break size and a large break size occurring at the main coolant line of Chinese Super-Critical Water-cooled Reactor (CSR1000) are simulated. The results show that CSR1000 with its official safety system design can be cooled down during the considered accidents and code TACOS has good feasibility for safety analysis of supercritical water systems.

Uncertainty modeling for vibration and buckling behaviors of functionally graded nanobeams in thermal environment

High accuracy modeling of nanostructure is a crucial issue in nano electromechanical systems. This study investigates the effect of nanomaterial uncertainties on vibration and buckling behaviors of functionally graded (FG) nanobeams in thermal environment. The size-dependent governing differential equation is derived based on the nonlocal Euler–Bernoulli beam theory with the thermal effect and the analytical formulations of the natural frequencies are deduced. To avoid the shortcoming of probabilistic method in the case of inadequate data, a non-probabilistic uncertainty modeling for the FG nanobeams is developed by quantifying nanomaterial uncertainties as interval parameters. Meanwhile, a hull iterative algorithm (HIA) for solving this model is presented to evaluate the bounds of the natural frequencies. After validation of HIA by comparing with Monte Carlo simulation and sensitivity based interval analysis method, the detailed parametric study is performed to understand the combined influences of nanomaterial uncertainties and size-dependent parameter, power-law index as well as temperature change on the natural frequencies. Additionally, the lower bound of the critical buckling temperature is discussed under different size-dependent parameters and power-law indices. The bounds of the natural frequencies and the critical buckling temperature obtained here are helpful for the safety and optimal design of nano electromechanical systems.

Design of a passive safety system for a nuclear thermal rocket

Long-term high payload missions necessitate the need for nuclear space propulsion. Several nuclear reactor types were investigated by the Nuclear Engine for Rocket Vehicle Application (NERVA) program of National Aeronautics and Space Administration (NASA). Study of planned/unplanned transients and their impact on nuclear thermal rockets is important due to the need for long-term missions. It has been determined that a loss-of-flow-accident (LOFA) is the most serious design basis accident that will affect nuclear thermal rockets. A safety system is needed to respond to a LOFA and to prevent the core from melting. In this paper, a special secondary loop has been designed that utilizes the existing components of the Pewee I reactor. In particular, the tie rod tubes are connected to a secondary loop with radiator tubes. A check valve is also present in the circuit to help facilitate natural circulation in one direction in the absence of gravity. The radiator tube heat transfer surface area was increased to the following specifications: (i) 2 times the heat transfer surface area (HTSA) of the tie rod tubes, (ii) 4 times the HTSA of the tie rod tubes, (iii) 6 times the HTSA of the tie rod tubes, (iv) 8 times the HTSA of the tie rod tubes, and (v) 10 times the HTSA of the tie rod tubes. The following expected results were achieved: (i) during both steady-state operation and post-LOFA decay heat removal, temperature of the tie rod can be kept below the material melting point; (ii) during both steady-state operation and post-LOFA decay heat removal, natural circulation can be facilitated with a decent flow rate; (iii) during post-LOFA decay heat removal, the coolant temperatures in the tie rod tubes decreases and the mass flow rate increases; and (iv) in the secondary system, the heat sinks are able to remove the heat generated by the heat sources, during both steady-state and transient operation. As far as minimum radiator HTSA is concerned, the radiator tubes need to have a HTSA of approximately twice of that of the tie rod tubes. This ensures the tie rod tubes won’t melt and there is a decent natural circulation flow rate.

Experimental investigation of functional performance of a vacuum vessel pressure suppression system of ITER

Important challenges for fusion technology deal with the design of safety systems aimed to protect the Vacuum Vessel (VV) from pressurizing accidents like the Loss Of Coolant Accident (LOCA). To prevent or mitigate structural damages, the solution proposed is a safety system able to quickly condense released steam in cold water at sub-atmospheric conditions. This water suppression tank (VVPSS) is so aiming at limiting the maximum pressure in the VV to 0.2MPa during in-vessel coolant leak events and at maintaining the VV long-term pressure below atmospheric pressure during air or incondensable gases ingress, through the Direct Contact Condensation (DCC).The novelty of this study resides especially in the working condition of VVPSS, which operates precisely to sub-atmospheric pressure: up to date no explicit experimental data or investigation of DCC are in fact available in literature. To overcome this lack an extensive experimental work has been done at DICI – University of Pisa, where numerous condensation tests (more than 300) were performed. The operation condition investigated took into account downstream pressure between 30 and 117kPa and water pool temperature from 30 up to 85°C.The experimental measurements allow to study the influence of steam mass flux, water temperature and pool pressure on the steam condensation phenomenon (and in turn, based on the stable condensation regime, correctly analyze the design parameter of VVPSS). The results obtained are presented and discussed. Innovative condensation regime maps are in addition provided.

The Energy Multiplier Module (EM2): Status of Conceptual Design

The Energy Multiplier Module (EM2) is a helium-cooled fast reactor with a core outlet temperature of 850°C. It is designed as a modular, grid-capable power source with a net unit output of 265 MWe. The reactor employs a convert-and-burn core design that converts fertile isotopes to fissile and burns them in situ over a 30-year core life. The reactor is sited in a below-grade sealed containment. It uses passive safety methods for heat removal and reactivity control to protect the integrity of the fuel, reactor vessel, and containment. The plant also incorporates a below-grade, passively cooled spent fuel storage facility with capacity for 60 years of full-power operation. EM2 employs a direct closed-cycle gas turbine power conversion unit (PCU) with an organic Rankine bottoming cycle for 53% net power conversion efficiency assuming evaporative cooling. The high-power conversion efficiency and long-burn fuel cycle reduce the electricity cost by 35% when compared with the conventional light water reactor.The conceptual design has been conducted for the EM2 plant with focus on the reactor, fuel, and safety system designs. A detailed model of the passive direct reactor auxiliary cooling system was created to demonstrate functionality for selected design-basis accidents. The bench-scale fuel development campaign demonstrated high-quality uranium carbide pellet fabrication as well as β-SiC composite cladding and SiC-joining technologies. Irradiation tests of reactor materials are also being conducted. The PCU variable-speed generator mechanical design was validated with operational testing of its novel rotor at speeds >13 000 rpm. The design of the turbo-compressor with active magnetic bearings continues. A large cost database and financial model have been constructed for use as a key driver for the design to be economically competitive with competing generating technologies after 2030.

Model of Computer Network Topology Optimization Based on Pattern Recognition Technology

The topological structure of the computer network has an important influence on the efficiency of the whole network system, the exertion of the technical performance, the reliability and the cost. The concept of computer network topology classification, introduces the characteristics, based on the analysis of the complex network structure, explore the effective construction of computer network topology model, for its practical application in the design of redundancy is studied, to improve the network system reliability and system safety design.