bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Tightening Procedure on the Sealing Performance of Bolted Gasketed Pipe Flange Connections
Authors: Zheng Xing , Sato Koji , Fujihara Takahiro , Akamatsu Yoshiko , Sawa Toshiyuki
Published: November 2019

The objective of the present paper is to examine the effect of tightening procedure on scatter in axial bolt forces and the bolt forces distribution in bolted gasketed pipe flange connections where spiral-wound gaskets and PTFE blended gaskets are used. The scatter in the axial bolt forces was examined by several tightening procedures which are JIS B 2251, ASME PCC-1 legacy, ASME alternative #1, #2, #3 and 3 rounds method procedures in ASME 24“ bolted gasketed pipe flanged connection. The leak rate of the tightened bolted flanged connections was also measured. Furthermore, the assembly efficiency based on both axial bolt forces and the tightness parameters of the bolted pipe flange connections was calculated and compared. The obtained results are as following. First, the leak rate of the connection tightened by JIS procedure is the lowest of all the tightening procedures. Second, the assembly efficiency based on axial bolt forces tightened by JIS procedure is the highest, and the assembly efficiency based on tightness parameters according to JIS procedure is also the highest. Third, the assembly efficiency based on tightness parameters is smaller than that based on the axial bolt forces. As a conclusion, the JIS B 2251 procedure is the most efficient tightening procedure of all the tightening procedures tested in the present study and the assembly efficiency based on the tightness parameters is suggested to design bolted connections for more safety.
Evaluation of Flange Calculations Using Strain-Based Acceptance Criteria
Authors: Mutz Alexander , Schaaf Manfred
Published: November 2019

The Nuclear Power Plant KKG in Gösgen, Switzerland was designed according to the ASME Boiler and Pressure Vessel Code. The ASME BPVC, Section III, Appendix 11 regulates the flange calculation for class 2 and 3 components, it is also used for class 1 flanges. A standard for the determination of the required gasket characteristics is not well established which leads to a lack of clarity. As a hint different y and m values for different kinds of gasket are invented in ASME BPVC Section III [1].

The KTA 3201.2[2] and KTA 3211.2[3] regulate the calculation of bolted flanged joints in German nuclear power plants. The gasket characteristics required for these calculation methods are based on DIN 28090-1[4], they can be determined experimentally. In Europe, the calculation code EN 1591-1 [5] and the gasket characteristics according to EN 13555[6] are used for flange calculations. Because these calculation algorithms provide not only a stress analysis but also a tightness proof, it would be preferable to use them also in the NPP’s in Switzerland. Additionally, for regulatory approval also the requirements of the ASME BPVC must be fullfilled.

For determining the bolting up torque moment of flanges several tables for different nominal diameters of flanges using different gaskets and different combinations of bolt and flange material were established. As leading criteria for an allowable state, the gasket surface pressure, the allowable elastic stress of the bolts and the strain in the flange should be a good and conservative basis for determining allowable torque moments. The herein established tables show only a small part according to a previous paper [7] where different calculation methods for determining bolting up moments were compared to each other.

In this paper the bolting-up torque moments determined with the European standard EN 1591-1 for the flange, are assessed on the strain-based acceptance criteria in ASME BPVC, Section III, Appendices EE and FF. The assessment of the torque moment of the bolts remains elastically which should lead to a more conservative insight of the behavior of the flanges.
An Efficient Modelling Approach for Predicting Residual Stress in Power-Beam Welds
Authors: Horne Graeme , Thomas Danny , Collett Andrew , Clay Andrew , Cott Martin , Moffat Andrew
Published: November 2019

The prediction of welding residual stress in components is often an important input to structural integrity assessments. An efficient modelling approach was developed for predicting residual stress in power-beam welds, including validation against residual stress measurements. Specifically, sequentially coupled thermo-mechanical finite element analysis was conducted using a simplified heat source that was tuned to the observed fusion zone from a weld macrograph and thermocouple data for a series of electron beam welds in 316L austenitic stainless steel with a variety of geometries. The predicted residual stresses were compared with contour method and neutron diffraction residual stress measurements.
Development of GTN Model Parameters for Simulating Ductile Fracture Behavior of X 70 Carbon Steel SENT Specimens
Authors: Yoon Sung Ho , Ryu Tae-Young , Kim Moon Ki , Choi Jae-Boong , Kim Ik-Joong
Published: November 2019

Single-Edge-Notched-Bending (SENB) specimen is mainly used for fracture characteristics test of pipe material. However, there is also a disadvantage in that it does not sufficiently simulate the fracture characteristics of thin pipes due to the difference in boundary effect between the SENB specimen and the actual pipe. The Single-Edge-Notched-Tensile (SENT) specimen can be used as complementary test method due to its less boundary effect compared to the SENB specimen. In this study, the SENT specimen which are fabricated with API X 70 carbon steel was simulated ductile fracture behavior by using finite-element-analysis (FEA). To simulate ductile fracture behavior, Gurson-Tvergaard-Needleman (GTN) model was applied. GTN model is a kind of damage model that describes the behavior of ductile fracture through three steps of void changes : nucleation, growth, and coalescence. And GTN model is composed of three constitutive equations and nine parameters. In order to develop the GTN ductile fracture model for API X 70 carbon steel, five kinds of tensile specimen tests were simulated by FEA. In addition, we analyzed the influence of parameters of GTN model through analysis and developed optimal material parameters for API X 70 carbon steel. Finally, the ductile fracture behavior of the SENT specimen was simulated and the FEA results of SENT specimen was compared with actual SENT specimen test.
Comparison of Allowable Bending Moments for Circumferentially Flawed Pipes in ASME Boiler and Pressure Vessel Code Section XI Nonmandatory Appendices C and H
Authors: Kim Hune-Tae , Kim Ji-Su , Seo Jun-Min , Kim Yun-Jae , Lee Kuk-Hee , Huh Nam-Su
Published: November 2019

In this paper, allowable bending moments for circumferential inner surface cracked pipes are evaluated. ASME Boiler and Pressure Vessel code Section XI, “Rules for Inspection of Nuclear Power Plant Components” provides analytical evaluation procedures. Analytical evaluation methods based on the failure mechanism are provided in nonmandatory Appendix C and those based on failure assessment diagram are given in nonmandatory Appendix H. Allowable bending moments are evaluated using both appendices and compared with experiments. Conservativeness is compared quantitatively between both methods by normalizing allowable bending moments with experimental maximum moments.
Advanced Structural Integrity Assessment Tools for Safe Long Term Operation: ATLAS+ Project — Status of the Activities of the WP3 on Modelling
Authors: Marie Stéphane , Blouin Arnaud , Nicak Tomas , Moinereau Dominique , Dahl Anna , Le Delliou Patrick , Bourgeois Myriam
Published: November 2019

The main objective and mission of the ATLAS+ project is to develop advanced structural assessment tools to address the remaining technology gaps for the safe and long term operation of nuclear reactor pressure coolant boundary systems.

ATLAS+ WP3 focuses mainly on ductile tearing prediction for large defect in components: Several approaches have been developed to accurately model the ductile tearing process and to take into account phenomena such as the triaxiality effect, or the ability to predict large tearing in industrial components. These advanced models include local approach coupled models or advanced energetic approaches. Unfortunately, the application of these tools is today rather limited to R&D expertise. However, because of the continuous progress in the performance of the calculation tools and accumulated knowledge, in particular by members of ATLAS+, these models can now be considered as relevant for application in the context of engineering assessments.

WP3 will therefore:

• Illustrate the implementation of these models for industrial applications through the interpretation of large scale mock-ups (with cracks in weld joints for some of them),

• Make recommendations for the implementation of the advanced models in engineering assessments,

• Correct data from the conventional engineering approach by developing a methodology to produce J-Δa curve suitable case by case, based on local approach models,

• Improve the tools, guidance and procedures for undertaking leak-before-break (LBB) assessments of piping components, particularly in relation to representing structural representative fracture toughness J-Resistance curves and the influence of weld residual stresses.

To achieve these goals, WP3 is divided into 4 sub-WPs and this paper presents the progress of the work performed in each sub-WP after 24 months of activities.
Study on Seismic Designs Controlling Locations of Failure Inside Steel Frame Structures Under Severe Ground Motions
Authors: Shiomi Kensuke
Published: November 2019

For steel frame infrastructure facilities like thermal power plants, storage facilities or port facilities, the more advanced seismic performance is needed which not only prevent major damages against assumed design ground motions but also result in the “desirable failure mode” that concerns the recovery works or prevent from resulting in catastrophic failure mode, even under severe ground motions beyond design assumptions in which occurrence of some damages in structures are inevitable.

“Seismic structures which can control the locations of failure of structural members inside structures” is one of the examples of this seismic performance. By adding this performance to steel frame structures at the stage of seismic design, the high resilience structures which concern recovery works after earthquakes can be realized.

In this research, a basic study on the seismic performance which controls the locations of fractures of steel frame members by adjusting the cross sections of each structural member was carried out. The analytical studies about the design procedure to realize this seismic performance were conducted. Then, by conducting the shaking table tests for simple steel frame structures and confirming the location of fractures under dynamic loads, the possibility of this seismic performance was discussed experimentally.
Addressing NRC Concerns Regarding Proposed CC N-830: Direct Use of Fracture Toughness for Flaw Evaluations of Pressure Boundary Materials in Class 1 Ferritic Steel Components
Authors: Erickson Marjorie , Kirk Mark
Published: November 2019

Section XI of the ASME Boiler and Pressure Vessel Code provides KIc and KIa fracture toughness models for ferritic steels. These models are based on linear elastic fracture mechanics methods and were initially developed in the 1970s; they remain largely unchanged since that time. Recently, a modification to Code Case (CC) N-830 has been proposed to provide alternative fracture toughness models for use in the flaw evaluation methodologies of ASME Section XI Nonmandatory Appendices A and K. The integrated models contained in proposed Code Case revision predict the mean trends and scatter of the fracture toughness behavior of ferritic steels throughout the temperature range from the lower shelf to the upper shelf. These models include the transition fracture toughness Master Curve and crack arrest master curve approaches that describe the temperature dependence and scatter in KJc and KIa, respectively in the lower transition temperature region. Also included is a model describing the temperature dependence and scatter of JIc on the upper shelf. Finally, linkage models quantify the inter-relationships between these toughness metrics and how they change due to the irradiation-induced hardening. Together, these models describe the temperature dependence and scatter of fracture toughness initiation and arrest behavior for all ferritic reactor pressure vessel (RPV) steels from lower shelf through transition to the upper shelf, all indexed to a single parameter: T0.

In late 2017 the Electric Power Research Institute (EPRI) published a report, MRP-418, providing the technical basis for these revisions to CC N-830. Nuclear Regulatory Commission (NRC) staff review of the revised Code Case and MRP-418 resulted in substantive questions regarding validation and range of applicability of the various toughness models. An on-going effort addresses these concerns, and a revision to MRP-418 scheduled for publication later in 2019 will summarize that work. This paper describes the efforts of the WGFE CC-N-830 group to respond to the NRC’s comments, and summarizes responses to some of the comments.
Material Properties of Non-Irradiated Zircaloy 4 in Support of ASME Code Acceptance for Pressure Vessel Design
Authors: Nanstad R. K. , Server W. L. , Kombaiah B. , Geringer J. W.
Published: November 2019

A program underway at Oak Ridge National Laboratory (ORNL) to support private industry design of a system for production of 99Mo includes review of Zircaloy-4 (Zry-4) properties as a potential material for a primary vessel in the system. Because Zry-4 is not a material specified in the ASME Boiler and Pressure Vessel Code, a review has been performed to obtain the necessary data in the non-irradiated condition from the literature and from additional testing of Zry-4 to enable creation of tables of material properties required for ASME Code Section III Article ND-3000 design. A strategy for an in-vessel surveillance program is also recommended for early detection of potential corrosion and irradiation degradation issues during operational life of the vessel. Additionally, the ASME Code Section II, Part D was reviewed to ascertain the requirements for proposing a new material for Code approval. A plate of Zry-4 procured by ORNL was used to obtain tensile properties that were used as the basis for determining the maximum allowable stresses applicable to the vessel design. The materials properties of primary interest for ASME Code application are tensile properties, fracture toughness, fatigue, and five specific physical properties required by the Code for approval of a new material. The literature review revealed that all reported experimental data showed tensile strengths to substantially exceed the minimum specifications in ASTM B352. Sufficient fracture toughness and fatigue data are available to conclude that Zry-4 has sufficient fracture and fatigue resistance in the unirradiated condition for vessel design and operation. Of the physical properties reviewed, only thermal conductivity revealed a discrepancy that is recommended for further review. A surveillance program plan has been developed that is probably the maximum that would need to be implemented for the specific vessel design considered. Once adequate non-irradiated and irradiated data are available from preproduction testing of the Zry-4 and weld metal and HAZ materials, the program could be reduced to reflect that either initial properties are very good and/or the effects of embrittlement appear to be minimal. However, the overall design of a surveillance program is, of course, also dependent on the ASME Code design class for the pressure vessel.
Importance of Accurate and Detailed Data Processing of Laser Mapping in Coke Drum
Authors: Rutt Daryl , Park Stephen , Love Darren , Araque Egler , Clark Rick
Published: November 2019

Laser mapping is a well-accepted technique for obtaining surface profiles of coke drum walls to identify bulges. The resulting data is used to track and trend vessel distortions and mapped to illustrate the shape of the vessel from a base radius and or previous inspection. Monitoring the development and evolution of these distortions over time in an accurate and consistent manner has been demonstrated to be an effective tool for predicting bulging induced crack in a coke drum. In this paper, the authors discuss several aspects of the laser mapping technique such as scanner positioning, data noise, laser range accuracy, missing data and the repercussions in the assessment of bulging. The effects on second derivative-based analysis are covered in detail and the use of techniques to reduce the effects of data noise and sensor motion are discussed.
Development of the Containment and Confinement System for Hazardous Material Shock Physics Experiments at Los Alamos National Laboratory
Authors: Spernjak Dusan , Valdiviez Robert , Fehlmann Kevin , Hill Dallas , Gibson Joshem , Bustos Gerald , Tafoya Jose , Yost Nathan , Cardon Devin , Bernardin John , Llobet Megias Anna , McNeil Wendy V.
Published: November 2019

A unique containment and confinement system is under development to conduct small explosively driven physics experiments containing hazardous materials at the Proton Radiography facility at Los Alamos National Laboratory (LANL). In these experiments, the detonation of high explosives (HE) is used to drive materials to extreme loading conditions, where some of the materials tested can be extremely hazardous (e.g. nuclear materials). The main components of the system are the Inner Pressure Confinement Vessel (IPCV, which hosts the physics experiment), the Outer Pressure Containment Vessel (OPCV) and Beam Pipes and Auxiliary Hardware (BPAH).

This paper describes the design and preliminary analyses of the IPCV. The body of the IPCV, also referred to as the Inner Vessel, is being designed to the criteria of the ASME Boiler and Pressure Vessel Code, Section VIII, Division 3, Code Case 2564, with the exception of the materials of construction. The closure covers have different devices mounted on them, such as feedthrough devices for sending or receiving electrical and optical signals across the pressure boundary, and valves for venting the vessel interior. The unique feature in the vessel design are the radiographic windows, tentatively made of Beryllium, which need to be strong enough to maintain the pressure boundary during dynamic events, while being radiographically low-attenuating for the purpose of proton imaging.
Effect of Hydrogen Isotopes on the Fracture Toughness Properties of Types 316L and 304L Stainless Steel Forgings
Authors: Morgan Michael J.
Published: November 2019

Forged stainless steels are commonly used for the containment of hydrogen isotopes and fracture toughness properties are needed for structural integrity assessments. In this study, the effects of hydrogen and tritium precharging on the fracture-toughness properties of Types 316L and 304L stainless steel forgings were measured. The purpose of the study was to evaluate hydrogen and tritium effects on fracture toughness properties of: (1) Type 316 stainless steel stem-shaped and cup shaped forgings; and (2) Type 304L cylindrical block forgings with two different yield strengths. Arc-shaped fracture toughness specimens were cut from the forgings and precharged by exposing the specimens to hydrogen or tritium gas at 623K and 34.5 MPa. Tritium precharged specimens were aged at 193 K for 45 months prior to testing to build-in helium-3 from tritium decay. In the as-received condition, the J-Integral fracture toughness of the stem, cup, and block forgings were very high and exceeded 1200 kJ/m2 on average. The fracture toughness of specimens cut from the low yield strength Type 304L stainless steel block forging had the highest fracture toughness values and Type 316L stainless steel cup forging had the lowest. The reduced fracture toughness values were attributed to the large strain required to produce the cup forging and its high yield strength. Hydrogen precharging reduced the fracture toughness of the stem, cup, and block forgings to values between 34%–51% of a baseline value which was taken to be the fracture toughness value of the low yield strength block forging. Tritium precharging reduced the fracture-toughness values more than hydrogen precharging because of the effects of helium from radioactive decay of tritium. The fracture-toughness properties of tritium-precharged forgings ranged from 12% to 23% of the baseline values. In general, Type 316L stainless steel was more resistant to toughness reductions by hydrogen or tritium (and decay helium) than Type 304L stainless steel. Yield strength had only minor effects on fracture toughness for the precharged steels.
Use of Stainless Steel Tubing in Boiling Applications for Shell and Tube Heat Exchangers
Authors: Radovcich Sarah , Shargay Cathleen , Daru Kuntak
Published: November 2019

The use of stainless steel (SS) tubes in boiling applications must consider the potential risk of chloride stress corrosion cracking (SCC). Most steam generating tube bundles are carbon steel or low alloy steels, but occasionally, higher alloys are needed for the process side corrosion resistance. The use of SS tubes for these cases has had both successes and failures. SS has performed very well in other water and steam services, such as condensing, steam superheating, and boiler feed water (BFW) preheating applications, but for steam generating (i.e. boiling services) the experience has been mixed. Similar failures have also occurred in various process services which are being heated and contain water. The boiling of the water can lead to SCC. Some of the variables that can affect the risk of SCC for SS tube bundles in boiling services include: chloride concentration, tube wall temperature, exchanger design (i.e. kettle, thermosiphons, etc.), vertical vs. horizontal tubes, full vaporization vs. partial vaporization, recirculation rate, and BFW blow down rate. If SS materials are being considered, the risk of SCC can be determined by analyzing these variables as described in this paper. Where the risk of SCC cannot be avoided, an alternate, resistant tube material should be selected. The material options for various services are presented herein.
Computation of Boiling Water Reactor Annulus Flow Loads Using 2D Potential Flow Methodology and 3D Finite Element Analysis: A Comparative Study
Authors: Day Shari , Fong Minji , Walter Matthew
Published: November 2019

During a Loss of Coolant Accident (LOCA) in a Boiling Water Reactor (BWR), subcooled water flows past jet pump assemblies located in the annular region between the Reactor Pressure Vessel (RPV) and the shroud as it moves toward the break location and is subsequently discharged from the RPV. Flow loads caused by such an event are required design basis loads that must be considered for BWR internal components. A comparison is presented between BWR annulus flow loads calculated by the 2D potential flow methodology using complex variables and the 3D finite element method using the heat transfer analogy described in PVP2016-63091 [1]. The comparison demonstrates that greater solution fidelity is available using the FEA method. The results also demonstrate the importance of applying the appropriate velocity correction factor when flow loads are computed using complex variable techniques.
Effect of Bending Load on Burst Pressure of Nuclear Power Plant Steam Generator Tubes With Uniform Wall Thinning
Authors: Liu Michael C. , Gialdini Robert J. , Cipolla Russell C. , Ha Chang-Hoon , Cho Min-Ki , Park Tae-Jung
Published: November 2019

Tube integrity is an important aspect for safe and reliable operation of nuclear power plant steam generators. As a U.S. industry and licensing requirement, all in-service steam generator tubes shall retain structural integrity over the full range of normal operating conditions and design basis accidents by meeting the structural integrity performance criterion (SIPC) as given in NEI 97-06. The SIPC margin shall be maintained during plant operation between tube examinations.

The burst strength of tubes subjected to wall thinning will depend on the extent and mode of degradation, and the magnitude of design loads to include pressure differential across the tube wall during normal operation and postulated accident conditions. In addition, non-pressure loads that can occur during postulated accident events shall be evaluated and included in the assessment of tube integrity if determined to significantly reduce the tube burst strength. The EPRI Flaw Handbook provides burst pressure relationships for flaws which include a reduction factor that accounts for the effect of applied bending stress on circumferential degradation. However, this previous industry work was only for planar crack-like flaws and did not directly address uniform volumetric wall loss which can have both axial and circumferential extent.

This paper describes a test program to determine the effect of bending loads on the burst pressure of a tube with uniform thinning over a given axial length. The uniform thinning geometry was selected since it represented a bounding case of general wall loss and is conservative for calculating a tube repair limit for volumetric degradation for a given steam generator design. Tube repair limits are required for defining an upper limit on in-service degradation for which a tube is to be removed from service. Tube repair limits are cited in the Plant Technical Specifications, which is an important part of the licensing basis.
Effect of Outer Surface Defects on Large Capacity Composite Cylinders for Tube Trailers
Authors: Deng Guide , Wang Hao , Jia Guodong , Gao Zhaojiang , Sun Liang
Published: November 2019

Tube trailers with large capacity glass fiber wrapped composite cylinders with steel liners have entered the Chinese market to deliver compressed gases since 2011. The tube trailers with the composite cylinders can carry more gases than those with full steel cylinders, and are welcomed by the market. However, the outer surfaces of the composite layers of the cylinders are susceptible to abrasion damages as resin-based glass fiber composites have low surface hardness. Effect of outer surface defects on the large capacity composite cylinders for tube trailers was investigated in this paper using finite element analysis. First, a mesh model of the large capacity composite cylinder without any defects was built according to its actual geometrical dimensions, in which each layer of the composite overwrap was modeled using a layer of solid elements. Second, the meshes corresponding to surface defects with different surface sizes and different depths were killed using element birth and death method to generate surface defects. Then, the models under internal pressure were solved to obtain stress distribution and predict burst pressure. Numerical results show that the surface defects decrease the burst pressure of the cylinders, and the defect depth has a more important effect on the burst pressure than the surface sizes of the defects. Based on the numerical results, three suggestions to deal with the surface defects were proposed: 1) the cylinders having surface defects with depths less than 1 mm can be acceptable, 2) those having surface defects with depths greater than 3 mm should be condemned, and 3) those having surface defects with depths between 1 mm and 3 mm may be repaired but the inspection interval of the cylinders must be shortened.
A Hybrid Model to Analyze the Fluid-Structure Interaction Phenomenon of a Relief System and Experimental Validation
Authors: Zheng Feng Jie , Qu Fu Zheng , Song Xue Guan
Published: November 2019

As one essential component of a pressurized system, a relief valve is used to guarantee the pressure within a prescribed range. But in practical engineering, pressure fluctuation caused by the operation of a relief valve will travel along the pipeline and couple with the motion of the valve, which might result in malfunction of the valve and the system. In order to investigate the fluid-structure interaction (FSI) phenomenon, a hybrid model combining the method of characteristics (MOC) and computational fluid dynamics (CFD) method is proposed. In the hybrid FSI model, the characteristics of pressure resource is modeled using the performance curves, the compressible gas transmitting in the pipe is calculated by one-dimensional MOC, and the air flow in the valve as well as the valve motion is simulated by a two-dimensional CFD model. To validate the hybrid model, 1:1 scaled test rig is conducted. The compared results show that the hybrid model not only can accurately capture the pressure fluctuation in straight pipeline induced by the closure of the valve but also can accurately predict the forms of the valve motion.
Understanding Lift Force Discontinuity of Pressure Safety Valve
Authors: Zong Chao Yong , Zheng Feng Jie , Song Xue Guan
Published: November 2019

A pressure safety valve (PSV) is a safety valve designed to protect a vessel or a system during an overpressure event. For pressure safety valve to perform its function, the lift force as one of the key factors influencing the overall performance must be predicted. However, the lift force shows discontinuity with the increase of the valve opening under certain situations. This discontinuity could cause a series of problems, such as dynamic instability. In order to deeply explore the mechanism of the discontinuities numerical and experimental investigation were performed on a direct operated PSV in this paper. A test rig was constructed to measure the steady state lift forces at different valve openings. The working fluid was air and the valve body was removed. To obtain the details of the flow inside the valve, a series of computational fluid dynamics (CFD) simulations were conducted. The simulation indicated that the changing flow pattern is the main cause of the lift force discontinuity and the flow pattern is very sensitive to the valve nozzle thickness and the position of the adjustment ring. Thus, the lift force discontinuity could be weakened or even eliminated by proper valve design.
Safe and Reliable Temperature and Pressure Measurement for High Pressure Applications
Authors: Maupin Tony , Breunig Jennifer
Published: November 2019

For high pressure polyethylene applications, reliable temperature and pressure measurement with extremely fast response time, is crucial in order to avoid decomposition. Furthermore instrumentation must withstand not only the high pressures and temperatures, but also the vibration present in such a challenging environment. The requirements of temperature and pressure instrumentation include high quality mineral insulated cable, production techniques such as vacuum brazing and thin film sputtering as well as testing facilities. With this information, operators will be able to select high pressure thermocouples and pressure transmitters which are specifically designed for their application.
UK Programme on Codes, Standards and Procedure Needs for SMR and Gen IV Reactors: Phase 1 Output
Authors: James P. M. , Underwood N. J. , Sharples J. K.
Published: November 2019

The UK government has committed to a clean growth strategy, whereby it is legally bound to reduce the UK’s greenhouse gas emissions by at least 80% by 2050 compared to levels in 1990. In order to achieve this the UK needs to develop low carbon energy sources for electricity, transportation, domestic and industrial heat, light and power. This, combined with the fact that the UK demand for electricity is likely to double by 2050, poses a significant challenge for the UK. In light of these finding the UK government has invested £250 million into nuclear research and development (R&D), thus recognising the key role that nuclear plays in producing low carbon, clean, safe and reliable energy for the UK both now and into the future.

This paper provides an overview of the ongoing activities in the UK within this R&D programme focused on developing a UK forward plan for defining the long term requirements for the design codes and standards for small modular reactors (SMRs) and generation (Gen) IV reactors (also including advanced modular reactors). The project is being undertaken by Wood Nuclear and National Nuclear Laboratory (NNL). In order to ensure a complete UK perspective is captured, an advisory board has been established with experts in this field, from academia, industry and also national laboratories. Discussions with all parties produced a series of items to be addressed in order for current Design Codes and Standards to be applicable for SMR and Gen IV reactors.

This paper summarises these activities and key findings.
Optimal Design of Tuned Mass Dampers With Variable Inerter and Damping
Authors: Chang Chang-Ching , Wang Jer-Fu , Lin Chi-Chang , Lin Tzu-Ting , Lin Chih-Shiuan
Published: November 2019

Conventional tuned mass damper (TMD) is a popular and generally accepted vibration control device in the field of passive structural control. However, it was found that the control efficacy of a conventional TMD may significantly degrade when the TMD’s frequency does not tune to its desired value. In addition, the vibration energy of controlled structure transferred into the TMD is dissipated by viscous or friction damper and becomes waste heat. In this paper, a new type of TMD, called electromagnetic TMD inerter (EM-TMDI) is developed by replacing the viscous dampers with electromagnetic rotary transducers so that a more flexible viscous damping can be achieved and part of the energy originally dissipated by the dampers could be harvested. A flywheel with variable mass moment of inertia will be introduced into the transmission system of the TMD to adjust TMD’s frequency to mitigate the frequency detuning effect and to enhance the control efficacy of TMD system. The theoretical derivation is performed to generate the relationship between the DC motor and the transmission system of the EM-TMDI. Optimal design method considering the inerter of rotary transducers will be developed. This study first designed and manufactured a scale-down, double-deck EM-TMDI. A series of shaking table tests were conducted at NCREE Tainan laboratory to verify the capability of inerter to change TMD’s frequency.
Environmental Fatigue Management for Long Time Operation: Finnish Point of View
Authors: Solin Jussi , Seppänen Tommi , Lemettinen Petri , Isometsä Juha , Pulkkinen Erkki
Published: November 2019

Accounting for environmental effects in fatigue has long been a necessity in Finland. This requirement was placed into the national regulatory guides in 2002 and the regulatory body, Radiation and Nuclear Safety Authority (STUK) required the license holders of operating reactors to respond by 2004.

At that time, the international state-of-the-art was reviewed and found not mature. However, reasonable approaches for accounting environmental effects were developed and adopted by both utilities, Fortum and TVO. Adoption of the proposed new design curves was considered impractical and calculation of Fen factors was preferred. This placed the Finnish utilities among the first industries, who brought environment assisted fatigue (EAF) into practice. At the same time, fatigue design of the new EPR design (OL3) was also subject of the requirement. The experimental work and approaches developed by Areva have been widely discussed in previous PVP Conferences.

A high number of PVP papers in these ‘ENVIRONMENTAL FATIGUE ISSUES’ sessions reveals that work remains to be done before the state-of-the-art in EAF is mature and an international consensus can be reached. Follow-up of evolving state-of-the-art is a part of the safety culture for Finnish utilities and regulator. Therefore, we encourage the researchers and engineers together to find solutions, which can be justified by sound arguments and brought into practice to reduce confusion and bias in fatigue management.
Economic Impact of Current SIF, Flexibility, Inspection and Manufacturing Changes As They Relate to the B31 Piping Codes
Authors: Paulin Anthony W. , Woods Glynn E.
Published: November 2019

Research shows how the impact of inaccurate fatigue calculations (SIFs), poor quality materials and manufacturing shortcuts will eventually result in pipe content leaks that will cause significant business interruption costs and potentially casualties in a very small population of operating piping systems. B31J-2017 corrects many of these inaccurate SIFs but has been slow to be implemented by the piping user community because failures due to thermal overstresses occur much closer to the end of the piping system life than the beginning. Fortunately for the owner this leaves time to correct for any errors once they have been recognized. Relatively simple screening is described that allows the owner and designer to identify the relatively small population of piping systems that should be addressed.
Using spatial release from masking to estimate the magnitude of the familiar-voice intelligibility benefit
Authors: Domingo Ysabel , Holmes Emma , Macpherson Ewan , Johnsrude Ingrid S.
Published: November 2019

The ability to segregate simultaneous speech streams is crucial for successful communication. Recent studies have demonstrated that participants can report 10%–20% more words spoken by naturally familiar (e.g., friends or spouses) than unfamiliar talkers in two-voice mixtures. This benefit is commensurate with one of the largest benefits to speech intelligibility currently known—that which is gained by spatially separating two talkers. However, because of differences in the methods of these previous studies, the relative benefits of spatial separation and voice familiarity are unclear. Here, the familiar-voice benefit and spatial release from masking are directly compared, and it is examined if and how these two cues interact with one another. Talkers were recorded while speaking sentences from a published closed-set “matrix” task, and then listeners were presented with three different sentences played simultaneously. Each target sentence was played at 0° azimuth, and two masker sentences were symmetrically separated about the target. On average, participants reported 10%–30% more words correctly when the target sentence was spoken in a familiar than unfamiliar voice (collapsed over spatial separation conditions); it was found that participants gain a similar benefit from a familiar target as when an unfamiliar voice is separated from two symmetrical maskers by approximately 15° azimuth.
Transmembrane Prolines Mediate Signal Sensing and Decoding in Bacillus subtilis DesK Histidine Kinase
Authors: Fernández Pilar , Porrini Lucía , Albanesi Daniela , Abriata Luciano A. , Dal Peraro Matteo , de Mendoza Diego , Mansilla María C.
Published: November 2019

Signal sensing and transduction is an essential biological process for cell adaptation and survival. Histidine kinases (HK) are the sensory proteins of two-component systems that control many bacterial responses to different stimuli, like environmental changes. Here, we focused on the HK DesK from
Bacillus subtilis
, a paradigmatic example of a transmembrane thermosensor suited to remodel membrane fluidity when the temperature drops below 30°C. DesK provides a tractable system for investigating the mechanism of transmembrane signaling, one of the majors interrogates in biology to date. Our studies demonstrate that transmembrane proline residues modulate the conformational switch of a 2-helix coiled-coil (2-HCC) structural motif that controls input-output in a variety of HK. Our results highlight the relevance of proline residues within sensor domains and could inspire investigations of their role in different signaling proteins.
A rare case of adult colocolonic intussusception of the descending colon
Authors: Taher Randa , Kopelman Yael , Younis Aurwa , Sheffer Daniel
Published: November 2019

A 28-year-old woman approached the emergency department because of recent diffuse abdominal pain and diarrhoea. Peritoneal signs on physical exam led to abdominal CT scan which demonstrated colonic obstruction, resulting from colocolonic intussusception of the descending colon. An exploratory laparotomy confirmed the diagnosis as well as the aetiology of a 4 cm intraluminal polyp. Left hemicolectomy with primary anastomosis was performed. The final pathology revealed a tubulovillous adenoma with multiple foci of high-grade dysplasia. Intussusception is a rare cause for colonic obstruction, and ~90% of cases in adults are secondary to an anatomical or pathological condition. Therefore, we recommend oncological resection of the affected part.
Four-year trajectory of Korean youth mental health and impacts of school environment and school counselling: a observational study using national schools database
Authors: Park Seongjun , Lee Dayoung , Jung Song , Hong Hyun Ju
Published: November 2019

Objectives

This study aimed to investigate changes in the mental health status of South Korean adolescents at a school level and identify school-related factors affecting these changes.

Design

A retrospective data analysis, population study.

Setting

South Korean high schools from 2013 to 2016.

Participants

Randomly sampled 827 schools (316 834 boys and 299 304 girls)

Primary outcome measures

Mean scores of the Adolescent Mental Health and Problem Behavior Questionnaire-II (AMPQ-II), a school-based mental health screening test, were used to explore changes in youth mental health. Data regarding the school environment and school counselling were gathered from the ‘School info’ website. A multilevel growth model was used to determine relationships between students’ mental health and school-related factors.

Results

Students’ mental health statuses in South Korea gradually improved over time (coefficient=−1.46 to −1.70, p<0.001). School mobility rates (coefficient=0.93 to 1.00, p<0.05), school dropout rates (coefficient=0.38 to 0.40, p<0.001), school budgets per student (coefficient=−0.05 to −0.06, p<0.01) and number of school counselling sessions (coefficient=0.14, p<0.01) were significantly associated with baseline AMPQ-II scores. The rate of change in AMPQ-II score increased when the number of school counselling sessions was higher (coefficient=−0.03, p<0.05) or the school budget was lower (coefficient=0.02, p<0.001). School environment explained 21.6% of the AMPQ-II baseline score variance and 9.3% of the rate of change variance. School counselling further explained 2.0% of the variance in baseline AMPQ-II scores and 2.3% of the rate of change variance.

Conclusions

This study suggests that school environment stability and active provision of school-based mental health services have a positive impact on youth mental health.
Study protocol for the COMET study: a cluster-randomised, prospective, parallel-group, superiority trial to compare the effectiveness of a collaborative and stepped care model versus treatment as usual in patients with mental disorders in primary care
Authors: Heddaeus Daniela , Dirmaier Jörg , Brettschneider Christian , Daubmann Anne , Grochtdreis Thomas , von dem Knesebeck Olaf , König Hans-Helmut , Löwe Bernd , Maehder Kerstin , Porzelt Sarah , Rosenkranz Moritz , Schäfer Ingo , Scherer Martin , Schulte Bernd , Wegscheider Karl , Weigel Angelika , Werner Silke , Zimmermann Thomas , Härter Martin
Published: November 2019

Introduction

Mental healthcare is one of the biggest challenges for healthcare systems. Comorbidities between different mental disorders are common, and patients suffer from a high burden of disease. While the effectiveness of collaborative and stepped care models has been shown for single disorders, comorbid mental disorders have rarely been addressed in such care models. The aim of the present study is to evaluate the effectiveness of a collaborative and stepped care model for depressive, anxiety, somatoform and alcohol use disorders within a multiprofessional network compared with treatment as usual.

Methods and analysis

In a cluster-randomised, prospective, parallel-group superiority trial, n=570 patients will be recruited from primary care practices (n=19 practices per group). The intervention is a newly developed collaborative and stepped care model in which patients will be treated using treatment options of various intensities within an integrated network of outpatient general practitioners, psychiatrists, psychotherapists and inpatient institutions. It will be compared with treatment as usual with regard to effectiveness, cost-effectiveness and feasibility, with the primary outcome being a change in mental health-related quality of life from baseline to 6 months. Patients in both groups will undergo an assessment at baseline, 3, 6 and 12 months after study inclusion.

Ethics and dissemination

The study has been approved by the ethics committee of the Hamburg Medical Association (No. PV5595) and will be carried out in accordance with the principles of the Declaration of Helsinki. For dissemination, the results will be published in peer-reviewed journals and presented at conferences. Within the superordinate research project Hamburg Network for Health Services Research, the results will be communicated to relevant stakeholders in mental healthcare.

Trial registration number

NCT03226743.
Improving access to health care for people with severe chronic obstructive pulmonary disease (COPD) in Southern New Zealand: qualitative study of the views of health professional stakeholders and patients
Authors: Stokes Tim , Tumilty Emma , Latu Anna Tiatia Fa'atoese , Doolan-Noble Fiona , Baxter Jo , McAuley Kathryn , Hannah Debbie , Donlevy Simon , Dummer Jack
Published: November 2019

Objectives

Chronic obstructive pulmonary disease (COPD) is a common chronic disease with significant morbidity and mortality, particularly for Māori, which places a large burden on the New Zealand (NZ) health system. We undertook a qualitative study as part of a mixed-methods implementation research project which aimed to determine the barriers and enablers to the provision of accessible high-quality COPD care.

Setting

Southern Health Region of NZ (Otago and Southland).

Participants

Thirteen health professional stakeholders and 23 patients with severe COPD (including one Māori and one Pasifika participant).

Methods

Semistructured interviews were undertaken. A thematic analysis using the Levesque conceptual framework for access to healthcare was conducted.

Results

Health professional stakeholders identified barriers to providing access to health services, in particular: availability (inadequate staffing and resourcing of specialist services and limited geographical availability of pulmonary rehabilitation), affordability (both of regular medication, medication needed for an exacerbation of COPD and the copayment charge for seeing a general practitioner) and appropriateness (a shared model of care across primary and secondary care was needed to facilitate better delivery of key interventions such as pulmonary rehabilitation and advance care planning (ACP). Māori stakeholders highlighted the importance of communication and relationships and the role of whānau (extended family) for support. Patients’ accounts showed variable ability to access services through having a limited understanding of what COPD is, a limited knowledge of services they could access, being unable to attend pulmonary rehabilitation (due to comorbidities) and direct (medication and copayment charges) and indirect (transport) costs.

Conclusions

People with severe COPD experience multilevel barriers to accessing healthcare in the NZ health system along the pathway of care from diagnosis to ACP. These need to be addressed by local health services if this group of patients are to receive high-quality care.