bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seismic Analysis and Design Upgrade of Condensate Storage Tanks
Authors: Moreno Daniel , O’Sullivan John , Tseng Tsiming 
Published: October 2016

Following the accident at the Fukushima Daiichi Nuclear Power Plant resulting from the March 11, 2011 Great Tohoku Earthquake and subsequent tsunami, there was a general concern regarding the beyond design basis capability of existing nuclear power plants. The Condensate Storage Tanks (CST) in the nuclear power plant were originally designed to withstand an earthquake with a peak ground acceleration (PGA) of 0.3g.
The government regulatory commission increased the required PGA to 0.4g, therefore, an upgrade of the design basis for the CSTs was required. Due to the vintage of the existing nuclear power plant, the United States Nuclear Regulatory Commission (USNRC) Unresolved Safety Issue (USI) A-46 methodology may be used for seismic upgrade work of the mechanical and electrical equipment. The Condensate Storage Tanks (CST) belong to the mechanical and electric equipment and therefore were required to have seismic upgrade work because of significant deficiencies that were found in the anchorage of the tanks to the concrete foundation.
A seismic analysis and design upgrade of the Condensate Storage Tanks (CST) was performed to resolve exceedances for base shear, overturning moment and sloshing due to recently updated seismic loads. A detailed analysis of the CST showed that the as-built anchor chair detail did not provide sufficient margin for the Beyond Design Basis Earthquake Event (BDBEE). The as-built anchor chair detail did not provide the required strength to transfer the shear and pull-out loads from the tank shell to the concrete foundation, i.e. no clear load path was provided for the updated seismic loads. Therefore, as a result of the inadequate anchorage, the main issues to resolve in the CST were tank sliding, shell buckling and sloshing due to earthquake loading. The principal challenges encountered during the analysis, design and construction stages were (1) not allowing to loosen the double nut configuration attaching the anchor bolt to the existing anchor chair, and therefore allowing to (2) remove or replace only a few components of the as-built anchor chair, and (3) the retrofit design had to be implemented while tanks were operable, i.e. filled with fluid. An additional challenge faced during the design of the new anchor chair components was the limit in anchor chair height imposed by the numerous interferences in the CST such as nozzles, reinforcing plates and existing welds. A mitigation strategy is analyzed, designed and successfully implemented for retrofitting the ninety-six anchor chairs and allowing for full development of the anchor bolt shear and pull-out strength.
Effect of Cooling Rates on Mechanical Behavior of U-10Mo Monolithic Mini-Plate
Authors: Roh Hee Seok , Mohamed Walid 
Published: October 2016

To investigate the effect of cooling on the thermo-mechanical behavior of U-10Mo fuel plate during shutdown step, Finite Element (FE) analysis was performed on the plate L1P756 from RERTR-12 experiments [1]. Changes in cooling rates were simulated by varying the coolant velocity on the two sides of the plate. Since coolant velocity was directly related to heat transfer coefficient (hc), different cooling velocities have been implemented by changing heat transfer coefficient corresponding to coolant velocity ranging from 10% to 200% of the baseline coolant velocity. Also, this study investigated the effect of strain rate on residual stresses of the mini-plates, which may be caused by the cooling rate.
From numerical analysis results, it was found that cooling time increases as the coolant velocity decreases. It was observed that the cooling time is seven times longer if the coolant velocity is reduced 90%. A plate with two times faster coolant than the baseline reduced the cooling time by half of the original cooling time. As the cooling proceeded, von Mises stress was being increased in the plate and the highest stress at a certain time during the shutdown period was observed in the plate with the fastest coolant flow. However, no difference in residual stress was found at all different cooling rates at the end of the shutdown step. For strain rate effect analysis, the maximum strain rate was calculated to be 3 s−1 as soon as the cooling was started and the strain rate drastically decreased close to zero. The change of strain rate in time was found the same in all cases with different cooling rates. Therefore, it turned out that the cooling rate did not affect the residual stress of the cladding considered in this study.
Thermal Mixing Behavior in the Annulus of Co-Axial Double-Walled Piping in HTGR
Authors: Tochio Daisuke , Fujiwara Yusuke , Ono Masato , Shinohara Masanori , Hamamoto Shimpei , Iigaki Kazuhiko , Takada Shoji 
Published: October 2016

The future HTGR has been designed in JAEA. The HTGR uses the helium gas as the coolant in primary cooling system. The reactor has many merging points of the higher-temperature helium gas and the lower-temperature helium gas in the cooling system.
Previously, the reactor inlet coolant temperature was controlled lower than the specific one in the HTTR constructed in JAEA. It was confirmed that this event was caused by the lack of mixing of helium gas thermally at the measurement point of the reactor inlet coolant temperature. From this operational experience, it is needed to clear the thermal mixing characteristics of the helium gas at the annulus of the co-axial double-walled piping in HTGR from the viewpoint of the appropriate temperature control in future HTGR.
In this paper, thermal-hydraulic analysis on the helium gas at the annular flow path of the co-axial double pipe with T-junction was conducted to clarify the thermal mixing behavior of the helium gas.
It is shown that the thermal mixing behavior is not so much affected by the flow rate helium gases. Moreover it is difficult to mix the helium gas with the smaller height of the annular flow path. This is caused by smaller contact area of higher- and lower-temperature helium gas and the lack of helium gas flow in radial direction.
It is confirmed that it is difficult to mix the higher- and the lower-temperature helium gas in the annular flow path of the co-axial double-walled piping by using the hydraulic behavior, and it is necessary to arrange the mixing promotor in the annular flow path in order to mix the higher- and the lower-temperature helium gas.
The Application of an Integrated Head Assembly for Advanced Power Reactor 1400
Authors: Kang Tae Kyo , Jo Won Ho , Cho Yeon Ho , Chang Sang Gyoon , Lee Dae Hee 
Published: October 2016

The reactor vessel head region consists of a number of components and systems including reactor vessel head, CEDMs with their cables, cooling air system with ducts and fans, missile shield, seismic supports, head lift rig and cable supports. Prior to refueling operation, those components must be dismantled separately, and moved to the designated storage area. It was a very complicated and time consuming process. As a result, the integrated head assembly (IHA) was introduced to simplify those disassembling procedures, reduce refueling outage period, and improve safety in the containment building as those components are combined into a single system.
To reduce refueling outage duration and radiation exposures to the workers by integrating the complicated reactor head region structures, KEPCO E&C has developed the IHA concept in the Korean Next Generation Reactor (KNGR) project [1]. The first application was implemented for the Optimized Power Reactor 1000 (OPR1000) at Shin-Kori units 1&2 and Shin-Wolsong units 1&2. With the past experience, the IHA was upgraded to be applied to the Advanced Power Reactor 1400 (APR1400). The design was patented in Korea [2], China, EU and the USA as modular reactor head area assembly. The IHA was applied for APR1400 nuclear power plants at Shin-Kori and Shin-Hanul, Korea. The design was also supplied to Barakah Nuclear Power Plants in the United Arab Emirates. This paper presents the design features and a variety of analysis which have been used for the APR1400 IHA.
New IAEA Coordinated Research Project on Thermal-Hydraulics of Supercritical Water Cooled Reactors
Authors: Yamada Katsumi , Leung Laurence , Ambrosini Walter 
Published: October 2016

In view of the high interest among a number of Member States in the Supercritical Water Cooled Reactor (SCWR) concept, the IAEA launched the second Coordinated Research Project (CRP) on thermal-hydraulics of SCWRs, entitled “Understanding and Prediction of Thermal-Hydraulics Phenomena Relevant to SCWRs” in 2014 to foster international collaboration. The key objectives of this new CRP are to (i) improve the understanding and prediction accuracy of thermal-hydraulics phenomena relevant to SCWRs and (ii) benchmark numerical toolsets for their analyses. At present, 12 institutes participate in the CRP from 10 IAEA Member States, and the OECD/NEA is in cooperation, based on a special agreement with the IAEA, to host a database housing experimental and analytical results contributed from the CRP participants. The expected outcomes from this CRP include (i) enhancement of the understanding of thermal-hydraulics phenomena, (ii) sharing of experimental and analytical results, and the prediction methods for key thermal-hydraulics parameters, and (iii) cross-training of personnel between participating institutes through their close interactions and collaboration.
This paper describes the plan of the new CRP: overall and specific research objectives; tasks and sub-tasks; schedule; and expected outcomes and outputs. It also introduces briefly other IAEA activities to facilitate and support R&D for SCWR technology in Member States, which include technical meetings and training courses.
Fuel Assembly Flow Measurement and Calculation in an Oversized Test Flow Housing
Authors: Wood Carrie A. , Wang Jiwei , Lu Roger Y. , Conner Michael E. , Evans Paul M. 
Published: October 2016

To determine fuel assembly mechanical damping under PWR conditions during a postulated seismic event or LOCA, fuel assembly flowing water damping tests were needed. Since flowing water damping values are high, pluck tests were used in which the fuel assembly was deflected, pluck mechanism retracted, and fuel assembly vibration decay observed and measured. To allow for the pluck vibration to occur, an oversized flow housing was utilized, which allowed additional flow to bypass the fuel assembly in the gaps between the assembly and the flow housing walls that would otherwise flow through the bundle rodded region. Since a direct measurement of the average bundle flow velocity could not be made, a method was developed for determining the flowrate through the bundle using fuel assembly lift force measurements.
This paper will present the method for determining the actual flowrate that was used in recent testing. The use of custom load cells that were designed for this testing to measure the fuel assembly lift force will be described in this paper. Additionally, the paper will show how the correlation between total test flow and bundle flow was developed from a series of flow calibration tests at different hydraulic conditions. This correlation was then used to prescribe the loop flow setpoints necessary to achieve targeted bundle flow velocities during the pluck test series.
Outline of Specification for Composite SC Walls in Nuclear Facilities
Authors: Bhardwaj Saahastaranshu R. , Varma Amit H. , Al-Shawaf Taha 
Published: October 2016

Appendix N9 to AISC N690s1 presents the design provisions for steel-plate composite (SC) walls in safety related nuclear facilities. AISC N690s1 is Supplement No. 1 to AISC N690-12 specification for safety related steel structures in nuclear facilities and was published in October 2015. This paper discusses the outline of Appendix N9 as well as how the appendix can be used for the design of SC wall structures.
Appendix N9 establishes the minimum requirements that SC walls need to meet in order for the specification to be applicable. The requirements include minimum and maximum wall thickness and steel reinforcement ratio. Detailing requirements for SC wall panel sections are also discussed. The faceplate slenderness requirement to prevent the limit state of buckling before yielding is provided. Steel anchor requirements are based on developing adequate composite action, and preventing interfacial shear failure. Requirements for tie bars connecting the steel plates (faceplates) are provided to prevent splitting failure and out-of-plane shear failure. The detailing and design provisions for regions around openings in SC walls are also included. Appendix N9 provides a method of checking the design of SC walls for impactive and impulsive loads.
A discussion of the analysis requirements for SC walls is presented. The provisions include effective stiffnesses, accident thermal loading and model parameters for analysis.
The design strength equations for axial tension, axial compression, out-of-plane shear, out-of-plane flexure, in-plane shear, and for combined in-plane forces and out-of-plane moment demands are parts of the provisions of the appendix. The provisions also include interaction equations for evaluating tie bars resisting demands due to combination of out-of-plane and interfacial shear forces. Performance requirements for the anchorage of SC walls to concrete basemat, SC wall-to-wall connections and SC walls to floor slab connections are given in the appendix.
The provisions also include requirements for fabrication, inspection, and quality control of SC walls constructed for safety-related nuclear facilities.
Design of SC Walls and Connections in Nuclear Facilities
Authors: Varma Amit H. , Bhardwaj Saahastaranshu R. , Malushte Sanjeev R. 
Published: October 2016

Steel-plate composite (SC) walls and associated connections can be designed based on the provisions of Appendix N9 to AISC N690s1. AISC N690s1 is Supplement No. 1 to AISC N690-12 specification for safety related steel structures in nuclear facilities and was published in October 2015. AISC is currently in the process of developing a design guide to further enable the use of this specification. This design guide will explore the provisions of this specification in detail and discuss different possible design methodologies.
SC wall details at the beginning of the design process are based on typical plant layouts, shielding requirements and prevalent practices. The spacing of tie bars and steel anchors in SC wall needs to ensure the faceplate does not undergo buckling before steel yielding. The steel anchor additionally need to be spaced to ensure that (i) interfacial shear failure does not occur before out-of-plane shear failure, and (ii) the yield strength of the faceplates is developed over the development length. The tie bars need to have sufficient tensile strength to prevent splitting failure of SC walls. The elastic analysis of the SC walls is performed using a finite element analysis. The analysis needs to consider cracked transformed stiffnesses and equivalent material properties. The analysis will be conducted for operating thermal and accident thermal load combinations. The individual demands and the combination of demands need to be compared with the available strengths. The SC walls need to be adequately detailed for openings, meet construction and fabrication tolerances, and satisfy the Quality Assurance and Quality Control requirements. The designed SC walls needs to be safe for impactive and impulsive loads.
SC wall panel may need to be (i) anchored to basemat, (ii) connected to another SC wall panel, or (iii) connected to RC slab. The SC connections can be designed as full strength connection or over strength connections. The connection needs to have a well-defined force transfer mechanism. The connection required strength is determined from the design demands of SC walls and the connection design philosophy. The available strength is determined from the individual strengths of connectors participating in the force transfer mechanism.
A Hybrid Probabilistic Physics of Failure Pattern Recognition Based Approach for Assessment of Multi-Unit Causal Dependencies
Authors: Zhou Taotao , Droguett Enrique López , Modarres Mohammad 
Published: October 2016

The recent dependencies studies have mainly been done in context of single unit, which means the failures involving components in different units are not explicitly treated. The major scopes are also limited to the simultaneous failures as the direct results of shared causes, namely the Common Cause Failures (CCFs). The causal relations among components or units are rarely addressed. Thus it’s the prime topic of this investigation that the dependencies among multiple units co-located at a site which is called multi-unit dependencies.
This paper seeks to propose a hybrid approach by combining physics-based models and supervised learning techniques. The essential idea is to account for the multi-unit dependencies by explicitly modeling the interactions of the underlying physical failure mechanisms. Ultimately a hybrid Dynamic Bayesian Belief Network is developed to model the possible dependencies, and supervised learning techniques are adopted to quantify the likelihood of failures due to dependency effects. Furthermore, an experiment has been designed and presented involving redundant pumping system, the performance of which are monitored by an advanced sensing system. The experiment is now operating and the gathered multi-sensor data will be used to illustrate the proposed approach as the next stage of this research. These sensor data should be of good quality to allow revealing the underlying failure behavior and dependent failures. This study provides an understanding of the inherent risk significance of dependencies among multiple units, and can also work as the basis for the reliability of multi-unit systems where causal dependencies play a relevant role.
Population Pharmacokinetics and Dosing Considerations for Gentamicin in Newborns with Suspected or Proven Sepsis Caused by Gram-Negative Bacteria
Authors: Bijleveld Yuma A. , van den Heuvel Maria E. , Hodiamont Caspar J. , Mathôt Ron A. A. , de Haan Timo R. 
Published: October 2016

ABSTRACT
The aim of this study was to describe the population pharmacokinetics (PK) of gentamicin in neonates with suspected or proven Gram-negative sepsis and determine the optimal dosage regimen in relation to the bacterial MICs found in this population. Data were prospectively collected between October 2012 and January 2013 in the Neonatal Intensive Care Unit (NICU) at the Academic Medical Center (AMC), Amsterdam, The Netherlands. A single nonlinear mixed-effects regression analysis (NONMEM) was performed to describe the population PK of gentamicin. Dosage regimens based upon gestational age (GA) were generated using Monte Carlo simulations with the final model. Target values were based on the MIC distribution in our patient population. In total, 136 gentamicin concentrations from 65 (pre)term neonates were included. The PK was best described by an allometric 2-compartment model with postmenstrual age (PMA) as a covariate on clearance (Cl). The MIC distribution (median, 0.75 [range, 0.5 to 1.5] mg/liter) justified a gentamicin target peak concentration of 8 to 12 mg/liter. This study describes the PK of gentamicin in (pre)term neonates. Dosage regimens of 5 mg/kg of body weight every 48 h, 5 mg/kg every 36 h, and 5 mg/kg every 24 h for patients with GAs of <37 weeks, 37 to 40 weeks, and ≥40 weeks, respectively, are recommended.
Comparative Evaluation of Etest, EUCAST, and CLSI Methods for Amphotericin B, Voriconazole, and Posaconazole against Clinically Relevant Fusarium Species
Authors: Al-Hatmi Abdullah M. S. , Normand Anne-Cécile , Ranque Stephane , Piarroux Renaud , de Hoog G. Sybren , Meletiadis Joseph , Meis Jacques F. 
Published: October 2016

ABSTRACT

We compared EUCAST and CLSI methods versus Etest for antifungal susceptibility testing of 20 clinically relevant
Fusarium
species against amphotericin B, posaconazole, and voriconazole. The median Etest amphotericin B and posaconazole MICs were 1 dilution higher than the median EUCAST and the CLSI MICs. The essential agreement (within ±1/±2 dilutions) was 60/90%, 80/95%, and 70/85% between the Etest and EUCAST methods and 80/95%, 75/95%, and 45/100% between the Etest and CLSI methods for amphotericin B, voriconazole, and posaconazole, respectively. The categorical agreement was >85%. Etest can be used for antifungal susceptibility testing of
Fusarium
species.
Multimerization of the Virulence-Enhancing Group A Streptococcus Transcription Factor RivR Is Required for Regulatory Activity
Authors: Ramalinga Anupama , Danger Jessica L. , Makthal Nishanth , Kumaraswami Muthiah , Sumby Paul 
Published: October 2016

ABSTRACT

Group A
Streptococcus
(GAS) (
Streptococcus pyogenes
) causes more than 700 million human infections each year. The significant morbidity and mortality rates associated with GAS infections are in part a consequence of the ability of this pathogen to coordinately regulate virulence factor expression during infection. RofA-like protein IV (RivR) is a member of the Mga-like family of transcriptional regulators, and previously we reported that RivR negatively regulates transcription of the
hasA
and
grab
virulence factor-encoding genes. Here, we determined that RivR inhibits the ability of GAS to survive and to replicate in human blood. To begin to assess the biochemical basis of RivR activity, we investigated its ability to form multimers, which is a characteristic of Mga-like proteins. We found that RivR forms both dimers and a higher-molecular-mass multimer, which we hypothesize is a tetramer. As cysteine residues are known to contribute to the ability of proteins to dimerize, we created a library of expression plasmids in which each of the four cysteines in RivR was converted to serine. While the C68S RivR protein was essentially unaffected in its ability to dimerize, the C32S and C377S proteins were attenuated, while the C470S protein completely lacked the ability to dimerize. Consistent with dimerization being required for regulatory activity, the C470S RivR protein was unable to repress
hasA
and
grab
gene expression in a
rivR
mutant. Thus, multimer formation is a prerequisite for RivR activity, which supports recent data obtained for other Mga-like family members, suggesting a common regulatory mechanism.

IMPORTANCE
The modulation of gene transcription is key to the ability of bacterial pathogens to infect hosts to cause disease. Here, we discovered that the group A
Streptococcus
transcription factor RivR negatively regulates the ability of this pathogen to survive in human blood, and we also began biochemical characterization of this protein. We determined that, in order for RivR to function, it must self-associate, forming both dimers (consisting of two RivR proteins) and higher-order complexes (consisting of more than two RivR proteins). This functional requirement for RivR is shared by other regulators in the same family of proteins, suggesting a common regulatory mechanism. Insight into how these transcription factors function may facilitate the development of novel therapeutic agents targeting their activity.