bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Evaluation Method for Cold Trap in Fast Breeder Reactor: Part 2 — Analytical Evaluation of Impurity Capturing Capacity in Cold Trap
Authors: Takahashi Shiro , Tamura Akinori , Nakata Hiroyuki , Takota Akio
Published: October 2017

Because of the reactor core characteristics of fast breeder reactors (FBRs), liquid sodium must be used for the reactor core cooling. Small amounts of oxygen and hydrogen are dissolved in the FBR sodium coolant. To decrease those impurity concentrations, cold traps (CTs) are installed in the primary and secondary systems. CTs are a purification apparatus universally used in FBR sodium systems to maintain the oxygen and hydrogen concentration levels in sodium within acceptable limits. CTs can capture oxygen and hydrogen as sodium compounds by packing materials with stainless steel wires using precipitation phenomenon (crystallization) by decreasing the inlet sodium temperature below the saturation temperature. Oxygen and hydrogen are precipitated as Na2O and NaH.

We have been developing an evaluation method of the impurity capturing capacity in CTs. In this study, we investigated the impurity capturing capacity of CTs through three-dimensional computational fluid dynamics (CFD) analysis. We also used CFD analysis to evaluate the time variation of the pressure loss of packing material. The amount of precipitation was decided from the temperature, concentration and velocity distributions through the CFD analysis.

First, a uniform wire mesh was used for the capturing capacity analysis in the CTs. Precipitation speed was higher for the hydrogen sodium compound than for the oxygen sodium compound. As sodium flowed from the outer to the inner side of the packing material, the hydrogen sodium compound was precipitated near the outer surface of the CTs and that blocked the sodium flow at the outer surface. As a result, if a lot of the hydrogen flowed into the CTs, the inner side of the wire mesh could not be used effectively. Second, we also proposed non-uniform wire meshed shapes and analyzed their capturing capacity in the CTs. The shape of the wire mesh was changed in the radial direction. A coarse meshed wire was placed on the outer side of the packing material and a closely packed meshed wire was placed on the inner side. Our CFD results showed that the most effective impurity capturing capacity of hydrogen sodium compound could be obtained by changing the precipitation speed and wire shape in the radial direction.
Development of Evaluation Method for Cold Trap in Fast Breeder Reactor: Part 1 — Numerical Analysis of Impurity Precipitation on Mesh Wire
Authors: Tamura Akinori , Takahashi Shiro , Nakata Hiroyuki , Takota Akio
Published: October 2017

A cold trap is one of the important components in the Fast Breeder Reactor (FBR) to control oxygen and hydrogen concentration of liquid sodium. For more accurate evaluation of the cold trap performance, we have started a research program to develop the evaluation method based on the 3D numerical analysis. Our evaluation method consists of two steps: one is a numerical analysis of sodium compound deposition on the mesh wires; the other is a numerical analysis of the sodium flow in the cold trap where the effect of the sodium compound deposition is considered as local pressure loss increment. In this study, we have focused on the development of the numerical analysis method of the sodium compound deposition on the mesh wires of the cold trap. As a numerical method, we have adopted the lattice Boltzmann method which is known to be useful for the flow simulation around the complex geometry like the mesh wires. In order to apply the lattice Boltzmann method to the sodium compound deposition simulation around the mesh wire, we proposed a low Reynolds number model and an impurity precipitation model for the conventional lattice Boltzmann method. The low Reynolds number model was validated by a comparison with a theoretical solution of the two-dimensional channel flow. To validate the impurity precipitation model, we conducted a precipitation experiment by using the supersaturated sucrose in the water instead of the liquid sodium with the oxygen and the hydrogen. The comparison between the experiment and the simulation showed good agreement regarding the pressure loss increment. From these results, we confirmed the accuracy of the low Reynolds number model and the impurity precipitation model. The accuracy of our models in the sodium condition will be confirmed in the future study.
Analyses of Off-Design Point Performances of Simple and Intercooled Brayton Helium Recuperated Gas Turbine Cycles for Generation IV Nuclear Power Plants
Authors: Gad-Briggs Arnold , Pilidis Pericles
Published: October 2017

The Design Point (DP) performance of a Nuclear Power Plant (NPP) is fairly straightforward to establish for a given mass flow rate, turbomachinery compressor Pressure Ratio (PR) and reactor Core Outlet Temperature (COT). The plant components are optimum for that point but this is no longer the case if the plant’s operating conditions are changed for part-load performance. Data from tests or previous operating experiences are useful in determining typical part load performance of components based on characteristic maps. However, when individual components are linked in a plant, the range of operating points for part load performances are severely reduced. The main objective of this study is to derive Off-Design Points (ODPs) for the Simple Cycle Recuperated (SCR) and Intercooled Cycle Recuperated (ICR) when considering a temperature range of −35 to 50°C and COTs between 750 to 1000°C, using a modelling & performance simulation tool designed specifically for this study, which calculates the best operational equilibrium ODPs that are critical to the economics of the NPP. Results show that the recuperator High-Pressure (HP) side and reactor pressure losses alter the actual operating parameters (mass flow rate and compressor PR). The SCR yielded a drop in plant cycle efficiency of 1% for a 4% pressure loss in comparison to the ICR (5%) for the same amount of recuperator HP losses. Other parameters such as the precooler and recuperator Low-Pressure (LP) losses still retain the same operating inlet PRs and mass flow rates regardless of the magnitude of the losses. In the absence of characteristic maps in the public domain, the ODPs have been used to produce characteristic trend maps for first order ODP calculations. The analyses intend to aid the development of cycles for Generation IV NPPs specifically Gas Cooled Fast Reactors (GFRs) and Very High Temperature Reactors (VHTRs), where helium is the coolant.
Numerical and Experimental Investigation on Influence Factors of the Leakage Rate for a Large-Size Pressure Gate With Rubber O-Ring Sealing Structure
Authors: Hao Huang , Xiaoming Huang , Guoliang Xu , Lin Fang , Chunyu Shi , Jiawei Sun , Xiangkui Lv
Published: October 2017

Leakage of these hatches with large sizes must be strictly controlled in any operating conditions for the safety of a nuclear power plant. In this work, an effective numerical approach to construct a leakage prediction model to analysis the tightness performance of the rubber O-ring sealing structure of a large-size pressure gate was proposed. The model is built based on the transport theory of the porous media, and combined the micro roughness effect and the macro mechanical behavior on the leak rate, which were obtained by using Finite Element Method (FEM) simulation. A series of experiments are designed to validate the results predicted by this model. Experimental results are in good agreement with that predicted by the proposed model, which verifies the rationality and preciseness of the model. Based on the model, a further research to understand the effect of various factors on the leak characteristics was made. The results show that the tightness performance of the O-ring with an elliptical trapezoid cross-section is better than that with a round cross-section. And the rubber with lower hardness can provide a better sealing capability during accidents (corresponding to the inside pressure increasing conditions).The new model is very helpful in the optimum design of a rubber sealing structure.
Minimum Dose Path Planning in Complex Radioactive Environments With Sampling-Based Algorithms
Authors: Chao Nan , Liu Yong-kuo , Xia Hong , Bai Lu
Published: October 2017

The objective of this paper is to provide a minimum dose path navigation method for occupational workers to avoid additional radiation exposure and quantitatively analyze the cost of paths in radioactive environments. A sampling-based algorithm named Bias-based T-RRT* (BT-RRT*) was proposed, which is an extension of nearly the latest sampling-based algorithm T-RRT*. It combines the exploration strength of T-RRT* that favors the exploration of low-cost regions and connects sampling points selectively with the strategy of biased sampling around the suboptimal paths to increase the convergence rate. To improve planning efficiency, a branch-and-bound strategy is also integrated to improve the efficiency of maintaining the node tree. A walking path-planning system was also developed using virtual reality. Simulation results presented in several radioactive environments show that the walking path planning method was effective in providing the minimum dose path navigation for occupational workers to avoid additional radiation exposure and to increase personnel safety.
Ant Colony Optimization of Multilayer Shielding for Mixed Neutron and Gamma Radiations: A Preliminary Study
Authors: Bin Sazali Muhammad Arif , Alang Md Rashid Nahrul Khair , Hamzah Khaidzir
Published: October 2017

Mixed neutron and gamma radiations require different shielding materials as their interaction with materials is different. Composites were developed in order to combine the shielding capabilities of different materials. However, their homogeneity is difficult to be assured which can lead to pinholes where radiation can penetrate. To avoid this problem, several materials arranged in layers can be used to shield against mixed radiations. Since the multilayer shielding can be made from any material in many configurations, the ant colony optimization (ACO) is a promising method because it deals with combinatorial optimization problems. The candidate materials are HDPE, boron, cadmium, gadolinium, tungsten, bismuth, and iron. Preliminary MCNP simulations were done to observe the effect of arrangements, thicknesses, and types of materials on the radiation spectrum. It was found that: (1) the final layer should be made of high density material, (2) an increase beyond certain thicknesses did not result in a significant increase in attenuation, and (3) there should be an optimum combination of material that can effectively shield against both neutrons and gamma rays.
The Effect of MA Transmutation in the PWR on Fuel Cycle
Authors: Yu Haoyang , Liu Bin , Zhang Wenxin , Cai Jin
Published: October 2017

The minor actinides (MA) is important nuclides in the spent fuel which is bad for human ecological environment. Pressurized water reactor (PWR) is the main reactor type at commercial operation around world. It is important to find the appropriate loading patterns when introducing minor actinides to the PWR core.

In this paper, we study the effect of MA transmutation in the PWR on fuel cycle. First, we use the MCNP program to simulate the model of PWR and the effective multiplication factor.Then,the MA is introduced into core in different ways and mass to simulate the effective multiplication factor.

In conclusion,without considering chemical skim control and control rods, we change the thickness of the MA, until the keff closes to 1, We find that loading minor actinides to burnable poison rods for transmutation is an optimal minor actinide loading pattern.
Development of Uncertainty Quantification Capability for NESTLE
Authors: Huang Dongli , Abdel-Khalik Hany S.
Published: October 2017

This work aims to develop an uncertainty analysis methodology for the propagation and quantification of the effects of nuclear cross-section uncertainties on important core-wide attributes, such as power distribution and core critical eigenvalue. Given the computationally taxing nature of this endeavor, our goal is to develop a methodology capable of preserving the accuracy of brute force sampling techniques for uncertainty quantification while realizing the efficiency of deterministic techniques. To achieve that, a reduced order modeling (ROM) approach is proposed to deal with the enormous size of the uncertainty space, comprising all the cross-section few-group parameters required in core-wide simulation. The idea is to generate a compressed representation of the uncertainty space, as represented by a covariance matrix, that renders sampling techniques computationally a feasible option for quantifying and prioritizing the various sources of uncertainties.

While the proposed developments are general to any reactor physics computational sequence, we customize our approach to the NESTLE [1]-TRITON [2] computational sequence, which will serve as a demonstrative tool for the implementation of our approach. NESTLE is a software used for core wide simulation, which relies on the few-group cross-sections to calculate core wide attributes over multiple cycles of depletion. Its input cross-sections are generated using a matrix of conditions evaluated using a lattice physics code, which in our implementation is done using the TRITON software of the ORNL’ SCALE suit. This manuscript presents one of the early steps towards this goal. Specifically, we focus here on the development of the algorithms for determining the reduced dimension of covariance matrix. Numerical experiment using the TRITON software is employed to demonstrate how the reduction is achieved.
Study on Hydrogen Risk of Spent Fuel Compartment Induced by Containment Venting
Authors: Li Yabing , Cao Xuewu
Published: October 2017

Hydrogen risk in the spent fuel compartment becomes a matter of concern after the Fukushima accident. However, researches are mainly focused on the hydrogen generated by spent fuels due to lack of cooling. As a severe accident management strategy, one of the containment venting paths is to vent the containment through the normal residual heat removal system (RNS) to the spent fuel compartment, which will cause hydrogen build up in it. Therefore, the hydrogen risk induced by containment venting for the spent fuel compartment is studied for advanced passive PWR in this paper. The spent fuel pool compartment model is built and analyzed with integral accident analysis code couple with the containment analysis. Hydrogen risk in the spent fuel pool compartment is evaluated combining with containment venting. Since the containment venting is mainly implemented in two different strategies, containment depressurization and control hydrogen flammability, these two strategies are analyzed in this paper to evaluated the hydrogen risk in the spent fuel compartment. Result shows that there will not be significate hydrogen built up with the hydrogen control system available in the containment. However, if the hydrogen control system is not available, venting into the spent fuel pool compartment will cause a certain level of hydrogen risk there. Besides, suggestions are made for containment venting strategy considering hydrogen risk in spent fuel pool compartment.
Severe Accident Steady-State Modeling of Advanced Nuclear Power Plant Based on ASTEC Code
Authors: Song Wei , Zuo Jiaxu , Chen Yan , Li Chaojun , Zheng Peng
Published: October 2017

Severe accident is an attractive topic today for the nuclear power plant (NPP) safety. In the nuclear safety regulatory work, it is planned to build a full scale severe accident model for the advanced nuclear power plant of China to study the new designs of severe accident prevention and mitigation systems and strategies, and to further deploy the application on the level 2 PSA and severe accident management guidance. This paper firstly introduces the modeling tool, ASTEC, and then presents the progress of modeling work, which is mainly on the steady state modeling and regulation including reactor block, primary and secondary cooling systems, regulation systems etc. Last but not least, the work plan for the future is given.
Research on Special Analysis of Verification and Validation in Nuclear Power Instrument and Control System
Authors: Liu Jingbin , Feng Yan , Qiao Ning , Zhang Yunbo , Wang Zhongqiu
Published: October 2017

At present, there is still lack of detailed software V&V guidance standards in China, while a number of US nuclear power units and I&C platform are introduced and applied. So the software verification and validation work in our country usually cited the methods in IEEE 1012. With reference to the requirements of IEEE 1012, the V&V process of the software can be mainly divided into three forms: audit evaluation, special analysis and testing. This paper focuses on these parts and gives a detailed description and annotations of the technical methods and their life cycle stages in IEEE 1012, which cover multiple V&V phases. At the same time, the author puts forward his own understanding of the special analysis approach and procedure, such as criticality analysis, interface analysis, traceability analysis, hazard analysis, risk analysis and security analysis, and gives his own experience and related recommendations.
Basic Experimental Study on Effectiveness of Nuclear Waste Long-Term Storage Containers With PAR for Reducing Concentration of Hydrogen Gas: Part 1 — Research Plan and Preliminary Simulation Results
Authors: Tanaka Y. , Suzuki Y. , Takase K.
Published: October 2017

In the decommissioning of nuclear power plants, the long-term management of radioactive waste of fuel debris, etc. are necessary. In the process, hydrogen which is the flammable gas is generated by the decomposition of water by radiation. Therefore, it is important to ensure the safety of the waste storage container to reduce the concentration of hydrogen gas, and to keep below the explosion limit (4%). Consequently, a basic experiment to investigate the effectiveness of the waste storage container with the flammable gas concentration reduction mechanism using the passive autocatalytic recombiner (PAR) has been planned. The present study describes the research plan to use a small modeled experimental apparatus.

In addition, in order to clarify quantitatively natural convection behavior of hydrogen gas due to the decay heat of radioactive materials in the long-term waste storage container, preliminary analyses were performed on the system of a small-scale experimental apparatus in which specification of the long-term radioactive waste storage container is simply simulated. From the present results, the perspective which can predict natural convection phenomena in the long-term waste storage container numerically was obtained.
Measurement of Two-Dimensional Void Fraction Distributions of Rising Bubbles in a Simulated Sub-Channel by Wire-Mesh Sensors at Conditions of Forced Convective and Stagnant Flows
Authors: Suzuki Yota , Tanaka Yusei , Sakka Taku , Sato Akinori , Takase Kazuyuki , Uesawa Shinichiro , Yoshida Hiroyuki
Published: October 2017

Clarifying thermal-hydraulic characteristics in a nuclear reactor core is important in particular to enhance the thermo-fluid safety of nuclear reactors. Spacers installed in subchannels of fuel assemblies have the role of keeping the interval between adjacent fuel rods constantly. Similarly, in case of PWR the spacer has also the role as the turbulence promoter. When the transient event occurs, two-phase flow is generated by boiling of water due to heating of fuel rods. Therefore, it is important to confirm the two-phase flow behavior around the spacer. So, the effect of the spacer affecting the two-phase flow was investigated experimentally at forced convective flow condition. Furthermore, in order to improve the thermal safety of current light water reactors, it is necessary to clarify the two-phase flow behavior in the subchannels at the stagnant flow condition. So, the bubbly flow data around a simulated fuel rod were obtained experimentally at the stagnant flow condition. A wire-mesh sensor was used to obtain a detailed two-dimensional void fraction distribution around the simulated spacer and fuel rod. As a result of this research, the bubbly behavior around the simulated spacer and fuel rod was qualitatively revealed and also bubble dynamics in the sub-channels at the conditions of forced convective and stagnant flows were evaluated. The present experimental data are very useful for verifying the detailed three-dimensional two-phase flow analysis codes.
Study on Active Magnesium Oxide Adsorption Properties of Sr (II) in Aqueous Solution
Authors: Qifeng Qin , Xiaoyan Li
Published: October 2017

The active magnesium oxide (AMO) was synthesized by homogeneous precipitation method with microwave and characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and infrared spectroscopy (FTIR). Adsorption of Sr(II) by AMO was investigated under the effect of AMO dosages, pH of solution, temperature and contact time and analyzed the kinetics and thermodynamics characteristics. The results showed that AMO has very good adsorption capacity on Sr(II) in aqueous solution,When pH of solution is 8.0, the solid-liquid ratio is 0.25 g·L−1, initial Sr(II) concentration is 50mg·L−1, the contact time is 80 min at 298K, the removal rate and adsorption capacity reached 98.29% and 187.5 mg·g−1, respectively. Kinetic and thermodynamic results indicate that adsorption behavior of Sr(II) by AMO fitted well with pseudo-second-order model and the Freundlich isothermal model. Adsorption thermodynamic parameters showed that the process of adsorption is spontaneous and endothermic.
Study on Adsorption of U(VI) From Aqueous Solution by Activated MgO
Authors: Liu Qingqing , Li Xiaoyan
Published: October 2017

The activated MgO was synthesized by microwave homo-precipitator method and characterized by SEM, EDS and FT-IR methods. It was used to adsorption of U(VI) from aqueous solution with batch system. The paper discussed the effect of pH, temperature, contact time, adsorbent dose and initial U(VI) concentration on the adsorption. The results showed that activated MgO has good adsorption capacity for U(VI), the removal rate and equilibrium adsorption capacity reached 83.5% and 84.04mg·g−1 at pH 5.0, 15mg dose and 313K,respectively. The adsorption kinetics of U(VI) onto activated MgO were better fitted with pseudo-second-order kinetic.The adsorption isotherm data were fitted well to Freundlich isotherm model.The thermodynamic parameters showed that the adsorption process is endothermic and spontaneous.
Improvement of Structure in a Honeycomb Porous Plate for Pool Boiling CHF Enhancement
Authors: Maruoka Naru , Mori Shoji , Okuyama Kunito
Published: October 2017

The critical heat flux (CHF) during saturated pool boiling of water was investigated experimentally using a honeycomb porous plate attached to a heated surface. In a previous study, we demonstrated that the CHF by a honeycomb porous plate was enhanced to more than twice compared with that of a plain surface. According to the proposed capillary limit model, the CHF can be increased by decreasing the thickness of the honeycomb porous plate. However, the CHF could not be greatly enhanced when the thickness of the honeycomb porous plate was comparable to the thickness of the thin liquid film (the macro-layer thickness) formed beneath coalescent vapor bubbles. The results of this study showed that honeycomb porous plates for CHF enhancement in saturated pool boiling should be constructed by the superposition of two kinds of porous materials and that each of the honeycomb porous plates must fulfill two conditions. First, a honeycomb porous plate simply attached to a heated surface should have very fine pores to supply water to the heated surface due to strong capillary action, and the honeycomb porous plates should be as thin as possible to decrease the pressure drop caused by internal water flow. Second, the other honeycomb porous plate, stacked on top of the thin honeycomb porous plate, needs to be structured to hold a sufficient amount of water in order to prevent the inside of the honeycomb porous plate from drying out during the bubble hovering period on the plate.
Development of Manufacturing Technologies for the ITER Toroidal Field Coil: Insertion Processes of Conductors
Authors: Yamamoto K. , Matsumoto T. , Baba T. , Yamamoto A. , Kanbayashi S. , Kagawa T. , Okamoto T. , Fujii S. , Ando S. , Matsui K. , Nakahira M. , Koizumi N.
Published: October 2017

Series productions of the toroidal field (TF) coils for the ITER have been launched since Oct. 2013. Prior to manufacturing of the TF coils, preliminary tests and mock-up tests were conducted in order to clarify and confirm the conditions of the welding and machining processes. The ITER TF coil has dimensions of 16.5m height and 9.0m width, and the TF coil weight is more than 300 ton. The tolerance requirements for the manufacture of the TF coils are very strict from a view point of stable plasma confinement. The double pancakes, which are layered up to seven and then contained into the TF Coil case, are formed by inserting winding conductor into a radial plate (RP), grooves of which are machined from the special forging. The RP consists of 10 small segments, and each segment is machined and welded to each other to form sectors, and finally, a D-shaped RP is formed. Therefore, the minimization of deformation during welding and machining processes is a key issue to manufacture the D-shaped RP. As for the preliminary tests for the RP, the requirement of flatness within 1mm was achieved by turning segment several times for balancing machining deformation. As for the RP welding, a laser beam welding (LBW) using a 30kW fiber laser was applied to about a half of the plate thickness of 120mm from both sides to minimize the welding deformation and remained portions are welded by TIG welding from both sides. In the process of winding conductor insertion, length of RP grooves is adjusted by final machining since winding conductors are elongated due to heat treatment before insertion. To minimize the error of length between RP grooves and winding conductors, length of winding conductor after heat treatment is measured and length of RP grooves has to be designed according to results of measurement so that winding conductor can be inserted smoothly and Cover plates (CP), which are used for cover of the winding conductor after insertion, do not interfere with winding conductor. From the above, the manufacturing of TF coils has been realized coping with the challenges by the high technique and kinds of tests.
Determination of Convective Heat Transfer Coefficients in the Core of the Pebble-Bed Fluoride-Salt-Cooled High Temperature Reactor Using Frequency Response Techniques
Authors: Huddar Lakshana , Kuhnert Brandon , Albaaj Ali James , Lee Connie , Peterson Per F.
Published: October 2017

Frequency response techniques have been historically used to characterize various reactor parameters. In this paper, we apply these techniques to the Pebble-Bed Fluoride-Salt-Cooled High Temperature Reactor (PB-FHR) in order to extract experimental values for the interfacial convective heat transfer coefficient in the pebble-bed reactor core. A test section is filled with randomly packed copper spheres and a simulant fluid is passed through it. The temperature of the fluid is made to vary at a given frequency, thereby affecting the temperature of the spheres in the test section as well. Using this data the heat transfer coefficient between the surface of the spheres and the fluid can be extracted. The preliminary results from these tests are shown in this paper along with the predicted heat transfer coefficients using the Wakao correlation for heat transfer in packed beds. The experiments were carried out for a range of Reynolds numbers from 250–500 and Prandtl numbers from 20 to 50. The Wakao correlation predicts the experiment fairly well. Generally, the experimental Nusselt numbers were found to exceed the predictions by up to 32%. An analytical solution for the solid and fluid temperatures in the test section is presented, and used to show the optimal frequency of oscillation for this experimental setup. This methodology can be used in the future to better characterize the dynamic response of coolant-boundary structures in the PB-FHR.
Uncertainty Analysis of the TRU-Burning Thorium-Fueled RBWR Using Generalized Perturbation Theory
Authors: Bogetic Sandra , Gorman Phillip , Aufiero Manuele , Fratoni Massimiliano , Greenspan Ehud , Vujic Jasmina
Published: October 2017

The RBWR-TR is a thorium-based reduced moderation BWR (RBWR) with a high transuranic (TRU) consumption rate. It is charged with LWR TRU and thorium, and it recycles all actinides an unlimited number of times while discharging only fission products and trace amounts of actinides through reprocessing losses. This design is a variant of the Hitachi RBWR-TB2, which arranges its fuel in a hexagonal lattice, axially segregates seed and blanket regions, and fits within an existing ABWR pressure vessel. The RBWR-TR eliminates the internal axial blanket, eliminates absorbers from the upper reflector, and uses thorium rather than depleted uranium as the fertile makeup fuel. This design has been previously shown to perform comparably to the RBWR-TB2 in terms of TRU consumption rate and burnup, while providing significantly larger margin against critical heat flux.

This study examines the uncertainty in key neutronics parameters due to nuclear data uncertainty. As most of the fissions are induced by epithermal neutrons and since the reactor uses higher actinides as well as thorium and 233U, the cross sections have significantly more uncertainty than in typical LWRs. The sensitivity of the multiplication factor (keff) to the cross sections of many actinides is quantified using a modified version of Serpent 2.1.19 [1]. Serpent [2] is a Monte Carlo code which uses delta tracking to speed up the simulation of reactors; in this modified version, cross sections are artificially inflated to sample more collision, and collisions are rejected to preserve a “fair game.” The impact of these rejected collisions is then propagated to the multiplication factor using generalized perturbation theory [3]. Covariance matrices are retrieved for the ENDF/B-VII.1 library [4], and used to collapse the sensitivity vectors to an uncertainty on the multiplication factor. The simulation is repeated for several reactor configurations (for example, with a reduced flow rate, and with control rods inserted), and the difference in keff sensitivity is used to assess the uncertainty associated with the change (the uncertainty in the void feedback and the control rod worth). The uncertainty in the RBWR-TR is found to be dominated by the epithermal fission cross section for 233U in reference conditions, although when the spectrum hardens, the uncertainty in fast capture cross sections of 232Th becomes dominant.
Lessons Learned From the Operation of Large-Scale Reprocessing-Recycling Facilities in France: What Is in It for China?
Authors: Gros Jean-Pierre
Published: October 2017

AREVA has been running since decades nuclear reprocessing and recycling installations in France. Several industrial facilities have been built and used to this aim across the time.

Following those decades and with the more and more precise monitoring of the impact of those installations, precise data and lessons-learned have been collected that can be used for the stakeholders of potential new facilities.

China has expressed strong interest in building such facilities. As a matter of fact, the issue of accumulation of spent fuel is becoming serious in China and jeopardizes the operation of several nuclear power plants, through the running out of space of storage pools. Tomorrow, with the extremely high pace of nuclear development of China, accumulation of spent fuel will be unbearable.

Building reprocessing and recycling installations takes time. A decision has to be taken so as to enable the responsible development of nuclear in China. Without a solution for the back end of its nuclear fuel cycle, the development of nuclear energy will face a wall.

This is what the Chinese central government, through the action of its industrial CNNC, has well understood. Several years of negotiations have been held with AREVA. Everybody in the sector seems now convinced.

However, now that the negotiation is coming to an end, an effort should be done towards all the stakeholders, sharing actual information from France’s reference facilities on: safety, security, mitigation measures for health protection (of the workers, of the public), mitigation measures for the protection of the environment.

Most of this information is public, as France has since years promulgated a law on Nuclear transparency. China is also in need for more transparency, yet lacks means to access this public information, often in French language, so let’s open our books!
Fundamental Study of Telemetry System With Phased Array Ultrasonic Velocity Profiler Method for Flow Measurement
Authors: Nishiwaki Ryo , Tsukada Keisuke , Zhou Jiaju , Kawachi Takuya , Kikura Hiroshige
Published: October 2017

Measurement accuracy of flow velocity by phased array UVP method was confirmed in order to develop a basic telemetry system for detections of leakage points. The basic telemetry system which consists of a robot arm for moving ultrasonic sensor and a phased array sensor for wide range area measurement of flow velocity was developed. Additionally, flow mapping of water flow around imitated leakage was conducted by the developed system and PIV method. As a result, the velocities by both methods were in agreement with 20 %. The possibility of measuring two-dimensional velocity of flow near the leakage point by the developed telemetry system was verified. Consequently, the basic telemetry system for the detection of the leakage was established.
Recognising the Influence of Landslide Transition Zones in the Assessment of Pipeline Integrity
Authors: Laing Matthew , Young Andy
Published: October 2017

Pipelines crossing mountainous areas are susceptible to ground movement loading from landslides. Structural analysis of pipeline performance from landslide loads is critical for making decisions on the requirement and timing of intervention activities. Current analytical assessment methodologies for pipelines affected by ground movement tend to assume the landslide as an abrupt boundary from the stable region to moving ground, causing an over conservative estimation of the condition of the pipeline. In-line inspection using inertial mapping tools provides invaluable information to assist in the determination of the current pipeline integrity but does not provide a complete picture because axial loads are not defined. Interpretation of in-line inspection data allows the estimation of a transition zone width between stable and unstable ground, where there is a progressive increase in ground movement. Due allowance for the transition zone can remove conservatisms in the assessment methodology and allow a pipeline integrity plan to be created.

This paper investigates the influence of landslide transition zone dimensions on the pipeline response and a methodology is developed for the prediction of the transition zone width. The interaction between the ground and the pipe movement is modelled using finite element analysis techniques.

The definition of the transition zone properties provides a more reliable prediction of the pipeline performance and enables the current and future pipe integrity to be established with greater confidence.
Trump team raises price tag for 2020 census
Authors: Mervis Jeffrey
Published: October 2017

Funding squeeze has hampered development of cost-saving technologies.
Storms await weather executive at climate agency
Authors: Voosen Paul
Published: October 2017

If confirmed as NOAA head, Barry Myers would face a wary staff and the fraught politics of climate change.
Original sin
Authors: Wade Lizzie
Published: October 2017

Some artifacts have questionable origins, and its initial mission was religious. Can the Museum of the Bible win scholarly respect?
Defibrillation of soft porous metal-organic frameworks with electric fields
Authors: Knebel A. , Geppert B. , Volgmann K. , Kolokolov D. I. , Stepanov A. G. , Twiefel J. , Heitjans P. , Volkmer D. , Caro J.
Published: October 2017

Tuning porosity with electric fields

Many metal-organic framework (MOF) compounds exhibit soft porosity—i.e., their lattices can undergo considerable deformation. Knebel
et al.
formed membrane layers of the MOF ZIF-8 and found that it was converted into a polar polymorph with a stiffer lattice in response to an applied electric field (see the Perspective by Gascon). This change reduced gas transport but, for certain gas mixtures such as propane and propene, also improved their separation factor.

Science
, this issue p.
347
; see also p.
303
Ectopic colonization of oral bacteria in the intestine drives T
H
1 cell induction and inflammation
Authors: Atarashi Koji , Suda Wataru , Luo Chengwei , Kawaguchi Takaaki , Motoo Iori , Narushima Seiko , Kiguchi Yuya , Yasuma Keiko , Watanabe Eiichiro , Tanoue Takeshi , Thaiss Christoph A. , Sato Mayuko , Toyooka Kiminori , Said Heba S. , Yamagami Hirokazu , Rice Scott A. , Gevers Dirk , Johnson Ryan C. , Segre Julia A. , Chen Kong , Kolls Jay K. , Elinav Eran , Morita Hidetoshi , Xavier Ramnik J. , Hattori Masahira , Honda Kenya
Published: October 2017

Gut reasons to brush your teeth

Some gut conditions, such as inflammatory bowel disease (IBD), ulcerative colitis, and Crohn's disease (CD), are associated with imbalances in the gut microbe community. The causes of these intractable diseases have been difficult to discern. Atarashi
et al.
took samples from the mouths of IBD and CD patients and inoculated the extracted bacteria into germ-free mice (see the Perspective by Cao). Some of the inoculated mice showed strong proliferation of T helper 1 cells associated with the establishment of oral
Klebsiella
species in the colon.
Klebsiella
can be resistant to multiple antibiotics and are able to replace normal colon microbes after antibiotic therapy. Now we know that they probably originate from the mouth and could potentially contribute to bowel disease.

Science
, this issue p.
359
; see also p.
308
Converting MOFs into amination catalysts
Authors: Chen Li-Feng , Xu Qiang
Published: October 2017

Pyrolysis of metal-organic frameworks creates graphitic carbon–coated cobalt nanoparticles
Rapid Detection and Differentiation of Clinically Relevant Candida Species Simultaneously from Blood Culture by Use of a Novel Signal Amplification Approach
Authors: Ao Wanyuan , Klonoski Joshua , Berlinghoff Eric , Jensen Jordan , Afroz Taliman , Munns Denton , Lindsey Wes , Denys Gerald , Jenison Robert
Published: October 2017

Fungal bloodstream infections are a significant problem in the United States, with an attributable mortality rate of up to 40%. An early diagnosis to direct appropriate therapy has been shown to be critical to reduce mortality rates. Conventional phenotypic methods for fungal detection take several days, which is often too late to impact outcomes. Herein, we describe a cost-effective multiplex assay platform for the rapid detection and differentiation of major clinically relevant
Candida
species directly from blood culture. This approach utilizes a novel biotin-labeled polymer-mediated signal amplification process combined with targeting rRNA to exploit phylogenetic differences for sensitive and unambiguous species identification; this assay detects seven pathogenic
Candida
species (
C. albicans
,
C. glabrata
,
C. parapsilosis
,
C. tropicalis
,
C. krusei
,
C. lusitaniae
, and
C. guilliermondii
) simultaneously with very high specificity to the species level in less than 80 min with the limits of detection at 1 × 10
3
to 10 × 10
3
CFU/ml or as few as 50 CFU per assay. The performance of the described assay was verified with 67 clinical samples (including mixed multiple-species infections as well), with an overall 100% agreement with matrix-assisted laser desorption ionization (MALDI) mass spectrometry-based reference results. By providing a species identity rapidly, the clinician is aided with information that may direct appropriate therapy sooner and more accurately than current approaches, including PCR-based tests.
An Improved Extended-Spectrum-β-Lactamase Detection Test Utilizing Aztreonam plus Clavulanate
Authors: Thomson Gina K. , Ayaz Maaz , Lutes Kelli , Thomson Kenneth S.
Published: October 2017

Clinical laboratories test for extended-spectrum β-lactamases (ESBLs) for epidemiological and infection control purposes and also for the potential of cephalosporins to cause therapeutic failures. Testing can be problematic, because the CLSI does not recommend the testing of all producers of ESBLs and also falsely negative results may occur with isolates that coproduce AmpC. Boronic acid-supplemented tests can enhance ESBL detection in AmpC producers. Because aztreonam inhibits AmpCs, a study was designed to compare ESBL detection by the CLSI disk test (CLSI), a boronic acid-supplemented CLSI disk test (CLSI plus BA), and an aztreonam plus clavulanate disk test (ATM plus CA). The study tested 100 well-characterized
Enterobacteriaceae
,
Acinetobacter baumannii
, and
Pseudomonas aeruginosa
isolates. Seventy produced TEM, SHV, or CTX-M ESBLs, with 15 coproducing an AmpC and 11 coproducing a metallo-β-lactamase. Thirty ESBL-negative isolates were also tested. Tests were inoculated by CLSI methodology and interpreted as positive if an inhibitor caused a zone diameter increase of ≥5 mm. The percentages of ESBL producers detected were as follows: ATM plus CA, 95.7%; CLSI plus BA, 88.6%; and CLSI, 78.6%. When AmpC was coproduced, the sensitivities of the tests were as follows: ATM plus CA, 100%; CLSI plus BA, 93.3%; and CLSI, 60%. ATM plus CA also detected an ESBL in 90.1% of isolates that coproduced a metallo-β-lactamase. Falsely positive tests occurred only with the CLSI and CLSI plus BA tests. Overall, the ATM plus CA test detected ESBLs more accurately than the CLSI and CLSI plus BA tests, especially with isolates coproducing an AmpC or metallo-β-lactamase.
Mutations in the Influenza A Virus M1 Protein Enhance Virus Budding To Complement Lethal Mutations in the M2 Cytoplasmic Tail
Authors: Liu Hsuan , Grantham Michael L. , Pekosz Andrew
Published: October 2017

The influenza A virus M1 and M2 proteins play important roles in virus assembly and in the morphology of virus particles. Mutations in the distal cytoplasmic tail region of M2, and in particular a tyrosine-to-alanine mutation at residue 76 (Y76A), were essential for infectious virus production and filament formation while having limited effects on total virus particle budding. Using a novel selection method, mutations at seven different M1 amino acids (residue 73, 94, 135, 136, or 138 or a double mutation, 93/244) that are not found in circulating influenza virus strains or have not been previously identified to play a role in influenza A virus assembly were found to complement the lethal M2Y76A mutation. These M1 suppressor mutations restored infectious virus production in the presence of M2Y76A and mediated increased budding and filament formation even in the absence of M2. However, the efficiency of infectious virus replication was still dependent on the presence of the distal region of the M2 cytoplasmic tail. The data suggest that influenza A virus budding and genome incorporation can occur independently and provide further support for complementary roles of the M1 and M2 proteins in virus assembly.

IMPORTANCE
Influenza virus particle assembly involves the careful coordination of various viral and host factors to optimally produce infectious virus particles. We have previously identified a mutation at position 76 of the influenza A virus M2 protein that drastically reduces infectious virus production and filament formation with minimal effects on virus budding. In this work, we identified suppressor mutations in the M1 protein which complement this lethal M2 mutation by increasing the efficiency with which virus particles bud from infected cells and restoring filament formation at the infected-cell surface. M2 distal cytoplasmic domain sequences were still required for optimal infectivity. This indicates that M1 and M2 can functionally replace each other in some, but not all, aspects of virus particle assembly.
Deep Sequencing of Foot-and-Mouth Disease Virus Reveals RNA Sequences Involved in Genome Packaging
Authors: Logan Grace , Newman Joseph , Wright Caroline F. , Lasecka-Dykes Lidia , Haydon Daniel T. , Cottam Eleanor M. , Tuthill Tobias J.
Published: October 2017

Nonenveloped viruses protect their genomes by packaging them into an outer shell or capsid of virus-encoded proteins. Packaging and capsid assembly in RNA viruses can involve interactions between capsid proteins and secondary structures in the viral genome, as exemplified by the RNA bacteriophage MS2 and as proposed for other RNA viruses of plants, animals, and human. In the picornavirus family of nonenveloped RNA viruses, the requirements for genome packaging remain poorly understood. Here, we show a novel and simple approach to identify predicted RNA secondary structures involved in genome packaging in the picornavirus foot-and-mouth disease virus (FMDV). By interrogating deep sequencing data generated from both packaged and unpackaged populations of RNA, we have determined multiple regions of the genome with constrained variation in the packaged population. Predicted secondary structures of these regions revealed stem-loops with conservation of structure and a common motif at the loop. Disruption of these features resulted in attenuation of virus growth in cell culture due to a reduction in assembly of mature virions. This study provides evidence for the involvement of predicted RNA structures in picornavirus packaging and offers a readily transferable methodology for identifying packaging requirements in many other viruses.

IMPORTANCE
In order to transmit their genetic material to a new host, nonenveloped viruses must protect their genomes by packaging them into an outer shell or capsid of virus-encoded proteins. For many nonenveloped RNA viruses the requirements for this critical part of the viral life cycle remains poorly understood. We have identified RNA sequences involved in genome packaging of the picornavirus foot-and-mouth disease virus. This virus causes an economically devastating disease of livestock affecting both the developed and developing world. The experimental methods developed to carry out this work are novel, simple, and transferable to the study of packaging signals in other RNA viruses. Improved understanding of RNA packaging may lead to novel vaccine approaches or targets for antiviral drugs with broad-spectrum activity.