Highest Safety Research Articles

Design and Analysis of “Filling-Evacuating” High-Pressure Helium-Cooled Loop

The breeder blanket and divertor are crucial plasma facing components in a fusion reactor. The helium cooled blanket and divertor concepts have exhibited the best potential to come up to the highest safety requirements and therefore been chosen for the development object. As a result of high heat flux radiated from the plasma in the fusion reactor and high power density nuclear heat deposited by high-energy neutrons, the cooling of the first wall (FW) and the discharge of nuclear heat have become one of the major technical challenges. To demonstrate and verify the helium-cooled technology and tools of China test blanket module, and explore the feasibility and key technology of thermal hydraulics process of helium-cooled divertor, we have creatively adopted the “filling-evacuating” approach to design and fabricate the high-pressure helium-cooled loop (HPHCL), in which a mock-up of reduced-scale helium-cooled blanket module is designed and manufactured as a test section. Based on different experimental cases, the operating pressures of helium at mock-up range from 3 to 10 MPa and the maximum mass flow rate can reach up to 0.21 kg/s. In this paper, the design scheme of the HPHCL is presented, and the key issues of engineering manufacture and the test cases are calculated and analyzed. The helium gas flow and the heat transfer are calculated according to the test working conditions of the referenced International Thermonuclear Experimental Reactor TBM’s FW surface heat flux, using ANSYS fluid dynamics software FLUENT. The results will provide support for the follow-up fabrication of test system and implementation of the tests.

Multi-physics models for design basis accident analysis of sodium fast reactors. Part I: Validation of three-dimensional TRACE thermal-hydraulics model using Phenix end-of-life experiments

The demonstrated technological feasibility of Sodium-cooled Fast Reactors (SFRs) makes them stand out among the other reactor concepts proposed by Generation IV International Forum (GIF) for short-term deployment. The availability of reliable computational tools in support of safety analyses and plant simulations under complex transient scenarios is essential to assure SFR’s compliance with the highest safety goals.Answering this need, a multi-physics three-dimensional core and system model is being developed to enable a more detailed representation of the physics of the plant and to anticipate more accurately plant behaviour, even under wider three-dimensional scenarios, such as asymmetric transients. The coupling will be performed using the U.S.NRC system codes TRACE-PARCS, modified to simulate more accurately when using sodium as coolant.The publicly available end-of-life tests conducted in the French SFR Phenix were chosen as baseline to perform a first validation of the computational model. The development of the tool started with a three-dimensional thermal-hydraulic nodal system of Phenix using the TRACE system code.The system simulates the Phenix end-of-life natural circulation test and the result have been compared with published experimental and benchmark results. The main physical phenomena of the 3 phases of the transient (rise in temperature in the low part of the reactor vessel, establishment of natural convection and subsequent cooling of the lower and upper part of the vessel) are predicted by the developed nodal system. More specifically, the analysis of parameters such as Intermediate Heat Exchangers (IHX), primary pumps and core temperatures, shows that the developed system is able to predict and study natural convection phenomena in Phenix-type reactors.The three-dimensional nodal system is able to clearly illustrate the existing thermal stratification in the hot pool, which is neglected by one-dimensional systems and enables the modelling of thermal hydraulic asymmetric behaviour, as it is shown by the uneven flow distribution in Phenix’s primary IHXs as they are asymmetrically located in the reactor vessel.

Percutaneous Treatment of Mitral Regurgitation: Present and Future

ABSTRACT Mitral valve regurgitation poses a significant public health burden, with more than 3 million people in the US alone suffering from moderate or severe mitral valve regurgitation. Surgical correction with mitral valve repair or replacement is the mainstay of therapy. However, a significant proportion of elderly patients are not eligible for mitral valve repair or replacement due to prohibitive surgical risk from increased age, poor ventricular function, or associated comorbidities. Percutaneous mitral valve repair/replacement techniques have been developed to fill this void. The most advanced percutaneous technique with the highest safety and efficacy to date is the edge-to-edge MitraClip repair system. The majority of other catheter-based mitral valve repair/replacement devices are at early developmental stages, but have shown encouraging initial results in feasibility trials. Transcatheter mitral valve replacement holds promise to emerge as the leading transcatheter treatment of choice in the fu...

Comparison of the tolerability of newly introduced childhood vaccines in the Netherlands

Addition of antigens to a vaccine resulted in a higher reactogenicity, but the AEs were in general mild and transient. What is Known: • Assessment of adverse events is crucial for achieving the highest safety in immunization programs, in order to inform public health actions and maintain public confidence in immunization programs. What is New: • Newly introduced vaccines DTaP-IPV-Hib-HepB and PCV10 are generally safe and well tolerated in infants. • These results are useful for information purposes and for monitoring variations in rates of AEs in the general population or in the target group over time.

5. Adaptive radiotherapy: methods and tools

Anatomical and/or biological changes occurring during radiotherapy course modify delivered dose to the patient requiring an adaptation of the treatment especially in case of intensity modulated Radiotherapy (IMRT). Adaptive radiotherapy (ART) has been introduced when several plans are used to treat a patient during radiotherapy. Adaptation may be performed online, offline or in a hybrid way. The implementation of RTA in routine use requires the automating of the entire process: decision criteria, segmentation, planning, validation and quality control. An automated process should allow a fast and fluid implementation to limit the increase of workload but especially to ensure the quality and safety of treatments. New images of the patient are needed for ART to perform many process: image registration, segmentation and evaluation of cumulative dose. Deformable image registration methods are generally used to image registration and contours propagation. Fraction and cumulative dose evaluations use deformable image registration methods or more complex methods based on Monte Carlo calculation. These methods have uncertainties and have to be evaluated. However evaluation and validation tools are still being developed. The physicist mission is to ensure that every new technology, as RTA, is deployed with highest safety by technical validation and by implementing a specific quality assurance program. RTA implementation still raises many questions, so its potential clinical application requires great caution and should be carefully explored in prospective clinical trials. It requires close collaboration between oncologists, medical physicists, expert engineers in image processing and equipment manufacturers.

Evaluation of survival stow position and stability analysis for heliostat under strong wind

Heliostats are sensitive to the wind load, thus as a key indicator, the study on the static and dynamic stability bearing capacity for heliostats is very important. In this work, a numerical wind tunnel was established to calculate the wind load coefficients in various survival stow positions. In order to explore the best survival stow position for the heliostat under the strong wind, eigenvalue buckling analysis method was introduced to predict the critical wind load theoretically. Considering the impact of the nonlinearity and initial geometrical imperfection, the nonlinear post-buckling behaviors of the heliostat were investigated by load-displacement curves in the full equilibrium process. Eventually, combining B-R criterion with equivalent displacement principle the dynamic critical wind speed and load amplitude coefficient were evaluated. The results show that the determination for the best survival stow position is too hasty just by the wind load coefficients. The geometric nonlinearity has a great effect on the stability bearing capacity of the heliostat, while the effects of the material nonlinearity and initial geometrical imperfection are relatively small. And the heliostat is insensitive to the initial geometrical imperfection. In addition, the heliostat has the highest safety factor for wind-resistant performance in the stow position of 90-90 which can be taken as the best survival stow position. In this case, the extreme survival wind speeds for the static and dynamic stability are 150 m/s and 36 m/s, respectively.

Percutaneous mitral valve repair: The MitraClip device.

Chronic mitral regurgitation (MR) is the most common cardiac valvular disease with more than 4 million people in the United States alone suffering from moderate or severe MR. Left untreated, chronic MR results in serious consequences. Surgical correction with mitral valve repair or replacement remains the mainstay of therapy for MR. Nevertheless, a large proportion of patients may not be offered treatment due to concerns over surgical risk. This unmet therapeutic need for a less invasive approach led to a marked explosion in the development of a variety of transcatheter approaches to treat mitral regurgitation in the past decade. The majority of these devices are based on principles learned from surgical mitral valve repair techniques. Inspired by the Alfieri surgical technique, the MitraClip edge-to-edge repair system is the most advanced technique with the highest safety and efficacy to date. In this review, we discuss the current status of the MitraClip repair system in the treatment of mitral regurgitation.

Load capacity simulation of an agricultural gear reducer by surface heat treatment

Gear reducers are widely used for various agricultural machinery applications such as greenhouses, tractors, and agricultural vehicles. However, thermal deformation and surface pitting at gear tooth flank frequently occur in gear reducers due to high torque. Thus, surface heat treatment of gears is required to improve wear and fatigue resistance. The objective of this study was to simulate the load capacity of the agricultural gear reducer. The simulation was performed for the following three surface heat treatment methods: untreated gears, nitriding heat treatment, and induction hardening method, those mostly used for agricultural gear reducers. The load capacity of the gear reducer was simulated using the safety factor, limit bending stress, and limit contact stress of the gear. The simulation of the load capacity was conducted using KISSsoft commercial software for gear analysis. The main results of simulation test were as follows: first, the nitriding heat treatment resulted in the highest safety factor for bending stress, which was increased about 77% from those of the untreated gears. Second, the induction hardening was the highest safety factor for contact stress, which was increased about 150% from those of the untreated gears. The safety factor for contact stress of the induction hardening was increased about 64% from those of the nitriding heat treatment. The study result suggested that the surface heat treatments could enhance load capacity and that the method of surface heat treatment should be determined based on simulation results for appropriate use scenarios.

An Update on Ebola Virus Epidemiology and Experimental Modalities

Ebola virus disease (EVD), formerly known as Ebola hemorrhagic fever, is a re-emerging zoonotic disease that has caused periodic outbreaks since the first reported outbreak in 1976. In 2014, in West Africa, the largest outbreak of Ebola virus in history emerged, affecting close to 30,000 people; more than 10,000 of these individuals died. This virus, which causes fatal hemorrhagic fever in humans and non-human primates, has the highest mortality rate (25-90%) among the viral hemorrhagic fever diseases. Ebola virus is transmitted through the blood and body fluids of infected animals and humans, as well as through contaminated materials. The virus is often spread in the hospital setting, and it is classified as a biosafety level 4 agent. Accordingly, diagnostic procedures and infected patient care should be performed at the highest safety levels. The potential therapies and vaccines against EVD have continued developing or been used in emergency situations during last outbreak. Some of these include the chimpanzee adenovirus type-3 and recombinant vesicular stomatitis virus-Ebola vaccines and new treatment modalities, such as passive immunization, brincidofovir, and ZMapp. Although these trials have shown different levels of success, there are no standardized treatments or vaccines that have been approved for humans. Such prevention is the only way to reduce human infection and the spread of outbreaks and is primarily based on personal protection measures and raising awareness of the risk factors.

Application of a Network Safety Management Tool in Urban Areas: Zurich, Switzerland, Case Study

Because of the economic and social cost of traffic accidents, it is essential for road administrators to evaluate where infrastructure investments are necessary to improve the system. Network safety management (NSM) is an analysis tool typically used on freeways and other interurban roads to identify the locations with the highest potential for infrastructure improvements from a safety perspective. A study was done on how this tool could also be used to identify such locations within an urban environment. The area of study was the city of Zurich, Switzerland, and the accident data were for the period 2009 to 2013. The aim was to investigate the application of NSM in urban environments, illustrate it with a real case study, evaluate the results obtained, and test robustness of the results for different input parameters. To do this, georeferenced data were required to have explicit distinctions between the three road network elements used: primary road segments, intersections, and residential zones. On the basis of different accident cost rates, a prioritization of the individual network elements was made. Results show that mostly network elements with numerous conflict points have the highest safety potential. Further tests reveal that traffic volume is the most influential parameter within the model. Additionally, more differentiated cost rates are presented, and a comparison with the road safety tool Black Spot Management is employed to verify the detected accident clusters. The findings are used to make pragmatic recommendations on the use of NSM in an urban context.

Dissipation pattern and accumulation of bifenthrin in tomato

The dissipation pattern of initial deposit of bifenthrin on tomato was 0.24 mg kg-1 which dissipated to below detectable level (BDL) by 10th day after first spray in harvested tomato fruits. The half life of bifenthrin was worked as 8.82 days. The highest safety periods of 4.1 to 4.8 days are required for consumption, if the tomato fruits are sprayed with bifenthrin against fruit borer. Accumulation pattern of bifenthrin revealed that after third spraying, maximum initial deposit was 0.86 mg kg−1. The safety interval of bifenthrin were recorded as 4.10 days at first spray and 14.5 days at third spray.

Case Study of an Alternative Merging Sign Design for Temporary Traffic Control in Work Zones

Signage plays an important role in work zones to provide guidance to drivers under changed conditions. This study investigated the safety effect of an alternative merge sign configuration in a freeway work zone. In this alternative configuration, the graphical-only lane closed sign from the Manual on Uniform Traffic Control Devices (MUTCD) was compared against a MERGE/arrow sign on one side and a Right Lane Closed sign on the other side. Although the graphical-only MUTCD signage for work zones has been in use for several years, it is not known if the signage recommended by the MUTCD offers the highest safety for all jurisdictions. The study measured driver behavior characteristics including speeds and open lane occupancies. The measurements were taken at a work zone on Interstate 70 in Missouri. The study found that the open lane occupancy upstream of the merge sign was higher for the test sign in comparison to the MUTCD sign. The occupancy values at different distances between the merge sign and the taper were similar for both signs. The test sign had 11% more traffic in the open lane upstream of the merge sign. In terms of safety, it is desirable for vehicles to occupy the open lane as far upstream from the taper as possible to avoid conflicts due to the lane drop. The analysis of speed characteristics did not reveal substantial differences between the two sign configurations. The 85th percentile speeds with the MUTCD sign were only 1.6 and 3.2 kph (1 and 2 mph) lower than the test sign at the merge sign and taper locations, respectively. In considering all the aforementioned performance measures, the alternative sign configuration was not superior, but performed equal to the MUTCD sign configuration. Language: en

Radiothérapie adaptative en routine ? État de l’art : point de vue du physicien médical

The development of both image-guided and intensity-modulated radiotherapy has underlined the question of treatment adaptation to anatomical and/or biological changes occurring during radiotherapy course and modifying delivered dose to the patient. Adaptive radiotherapy has been introduced when several plans are used to treat a patient during radiotherapy. Adaptation may be performed online, offline or in a hybrid way. New images of the patient are needed for adaptive radiotherapy to perform many processes: image registration, segmentation and evaluation of cumulative dose. Deformable image registration methods are generally used to image registration and contours propagation. Fraction and cumulative dose evaluations use deformable image registration methods or more complex methods based on Monte-Carlo calculation. These methods have uncertainties and have to be evaluated. However, evaluation and validation tools are still being developed. The physicist's mission is to ensure that every new technology, such as adaptive radiotherapy, is deployed with highest safety, by technical validation and by implementing a specific quality assurance program. Adaptive radiotherapy implementation still raises many questions, so its potential clinical application requires great caution and should be carefully explored in prospective clinical trials.

Stances in mountaineering and climbing activities: an analysis and a proposal for an improved equalized anchoring

In climbing on a long rock or ice route, mountaineers are tied by means of a rope. The climb is subdivided into “pitches” by “stances”, i.e. places where anchoring points are available for security and for the mutual belay of the partners. In this paper, the problem of setting up a stance by connecting two or more anchor points is addressed. The methods for achieving the highest safety in this connection are discussed. In past work, this type of analysis is generally performed for cases where the free fall line is aligned to the stance midpoint; this paper shows that the best understanding of the phenomena is achieved by investigating falls with an “offset” from the stance midpoint. The two most important cases of the current best practice are compared: the mobile and the fixed connection of the anchor points. The analysis was conducted by means of experimental and analytical investigations, to a detail that was never achieved before. The assessments are based on the dynamics of the events, not on static tests as reported in the majority of the literature. The comparison of the two practices of connection is the major task of the paper. It was conducted to such a detail as to allow the readers to form their judgement on the issue. An improved stance arrangement, which increases the stance reliability of 20 % still keeping an easy arrangement, is proposed.

Alternative Vaccine Strategies for Cervical Cancer

Cervical cancer, caused by Human Papillomavirus (HPV) is the third largest cause of female mortality over the world with an estimated 500,000 cases and 270,000 deaths annually [1]. Nevertheless there are only two vaccines are available in the world market to protect cervical cancer. Gardasil® (Merck, USA)) and Cervarix® (GlaxoSmithKline, UK) are both Virus Like Particle (VLP) based vaccines and administered intravenously in liquid form along with other adjuvants such as aluminum hydroxyphosphatesulfate, sodium chloride, polysorbate 80 etc [2]. When launched onto the market in 2007 and 2010, the vaccines Cervarix and Gardsil were considered as highly effective and complete safe vaccines. However, the cost of the vaccine itself, the expensive storage system, need for an expert to administer the vaccines tremendously inhibits the mass use of the vaccines globally. Also the antigens in the vaccines are Virus-Like Particles (VLPs), which are grown in the insect (Gardasil) or yeast cells (Cervarix) from the DNA obtained from Human Papillomavirus [2,3]. Growing VLPs is a complicated process and requires special research facilities where virus can be handled with highest safety. Unfortunately most of the resource poor countries where cervical cancer mostly prevails are unable to afford the huge burden of cutting edge technology and conduct sophisticated research. Therefore finding an alternative option to VLP based vaccine is becoming an important research challenge. More importantly, recent controversy over the side effects of both vaccines also calls for a demand to develop an alternative vaccine formulation which will be able to address all the above mentioned issues.

Maximum Gauge Pressure in Dangerous Goods Packagings Under Normal Conditions of Carriage - Comparison of Direct Measurement and Calculation

The objective of this work was to determine the maximum gauge pressure in the vapour phase above the liquid in different design types of dangerous goods packagings under normal conditions of carriage. The design types investigated were steel and plastic packagings with a volume of approximately 6 l. Two different methods were applied. In method 1, the pressure inside the packaging filled with a certain filling substance (dichloromethane) was directly measured under simulated conditions of carriage (degree of filling: 90%; filling temperature: 15°C; temperature during storage: 31°C). The maximum measured gauge pressures were between 89 mbar for a light plastic jerrican and 336 mbar for a steel drum. In method 2, the gauge pressure was calculated. The consideration of a rigid packaging combined with the assumption of a vapour pressure of zero during filling and sealing can serve as a worst case scenario. The calculated gauge pressure is approximately 1061 mbar. This procedure leads to the highest safety factor and does not require any experimental investigations. For a more realistic approximation of the gauge pressure of a non-rigid packaging, a packaging-specific function of relative expansion can be used, which is determined by a hydraulic pressure test. The calculated values ranged from 105 to 347 mbar. Method 2 provides conservative results. No hazardous filling substance is needed, and it allows a prediction of gauge pressure for other temperatures, substances and filling degrees. Therefore, this method could serve as alternative to UN Model Regulations 6.1.5.5.4 (a). Copyright © 2014 John Wiley & Sons, Ltd.

Comparison of Performance and Emission Parameters in Two Developmental Stages of Boilers

To meet the high demands of customers for low temperature boilers, a semi-automatic boiler MAGA PU 25 was developed. One of the main customer requirements is to get the best price-quality ratio. Another very important requirement is to meet emission standards. At the time of development of the boiler PU 25, the European standard STN EN 303-5 was valid in Slovakia. Because this boiler did not satisfy the strictest performance criteria, a new type of the boiler, i.e. boiler MAGA P 20, was designed; as a result of design modifications, this boiler fulfils these criteria. The article compares the designs and the results of testing both the boilers using a test fuel in an accredited laboratory. The article deals with testing a new biomass boiler developed to satisfy the highest safety and emission criteria. It presents the comparison of two boilers, namely the standard biomass boiler PU 20 and the latest P 20 version with specific design modifications. Laboratory tests have shown an increase in combustion efficiency to the desired level.

Schutzzielorientiertes Design der Sicherheitsleittechnik

Safety instrumentation and control in nuclear power plants has to be systematically designed and revisable in order to meet the highest safety requirements. A safety objective oriented design process is presented in combination with the defence in depth philosophy. The approach is applicable for the construction of new plants like the European Pressurized Reactor (EPR) and for the comprehensive refurbishment of existing plants. Its success has been demonstrated in several domestic and international I&C projects.

Sedation and analgesia for gastrointestinal endoscopy in children

Different sedation or anesthesia protocols are available to enable gastrointestinal endoscopic examinations in children. None is optimal. Sedation is organized according to the medical system, resources and the availability of personnel and medication (sedatives, anesthetics, analgesics). If anesthesiologist’s sedation teams for children are not available, strong evidence supports sedation safety and efficiency when it is performed by specially educated non-anesthesiologists and registered nurses. This review is a brief synthesis of main guidelines and position papers of procedural sedation in children and, when unavailable, in adults, who are eligible for pediatric gastrointestinal endoscopy sedation by non-anesthesiologist. Published data are supplemented by clinical experience and the findings of author’s research on ketamine sedation. Other established sedative combinations are benzodiazepine and opioid or propofol as a sole agent or in combination with analgesics. Special stress is given on a proper choice of the sedation protocol for specific examination or procedure in accordance with institution’s policy. Whole endoscopic team has to be engaged in the implementation of new evidence and continuous education to achieve the highest possible safety and quality standards.

Heat development at nasal endoscopes' tips: Danger of tissue damage? A laboratory study

The aim of this study was to measure the temperature generated by light sources in conjunction with angulated endoscopes and to analyze whether the heat generated at the endoscopes' tips harbors potential damage to mucosa or highly sensitive structures like the optic nerve or brain when in direct contact, considering a beginning necrosis of human protein starting at 40°C. Laboratory setting, prospective. Brand new 4-mm, 0° and 30° rigid nasal endoscopes were measured each with halogen, xenon, and light-emitting diode (LED) light sources, respectively, at different power levels for tip contact temperature. The highest temperatures were reached with a xenon light source at a maximum of 44.3°C, 65.8°C, and 91.4°C at 33%, 66%, and 100% power levels, respectively, for 4-mm, 0° endoscopes. For 30° endoscopes, temperatures of 47.0°C, 75.1°C, and 95.5°C were measured at 33%, 66%, and 100% power levels (P < .001; 0° vs. 30°), respectively. At 5-mm distance from the tip, temperatures were below body temperature for all light sources (<36°C) at all power settings. Within 2 minutes after switching off light sources, temperatures dropped to room temperature (22°C). Xenon light sources have the greatest illumination potential; however, at only 33% power level, potentially harmful temperatures can be reached at the tips of the endoscopes. Power LED and halogen have the highest safety; however, only LED has very good illumination. In narrow corridors, direct contact to tissues or vital structures should be avoided, or endoscopes should be cooled during surgical procedures.