Nuclear Electric Ltd

Gloucester, United Kingdom

Nuclear Electric Ltd

Gloucester, United Kingdom
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He M.,State Key Laboratory for Geomechanics and Deep Underground Engineering | He M.,China University of Mining and Technology | Li C.,Nuclear Electric Ltd | Gong W.,State Key Laboratory for Geomechanics and Deep Underground Engineering | And 4 more authors.
Tunnelling and Underground Space Technology | Year: 2017

Rockbursts frequently occur in deep underground excavations in a sudden or violent ejection of blocks of rocks from excavation walls. In addition to understanding rockburst mechanisms, rockburst control is an important issue for the safety of mining operations. Bolts and anchors are efficient measures to control rockbursts and permit the efficient exploration of underground excavations in mines. As mining depths increase, anchor and bolts with larger extension and higher loading capacity are needed. This paper introduces a Constant Resistant Large Deformation (CRLD) bolt which has been developed at the State Key Laboratory for Geomechanics and Deep Underground Engineering (GDUE), in Beijing, China. Static and dynamic tests were developed for this type of bolt. Advancements in Hopkinson tests were recently developed for CRLD bolts and Split-Hopkinson Tension Bar (SHTB) experiments for these bolts were performed. This paper presents the SHTB equipment and the results obtained with one and two CRLD bolts, as well a deep analysis of the obtained results. To better understand the complex nature of the problem, numerical simulations using several softwares were done for the case of one bolt, which had the dual goal of verifying the experimental and numerical results. In addition, the numerical predictions permit one conducting analysis the behavior of the bolt while targeting the development of large deformations. Finally some relevant conclusions are drawn. © 2016 Elsevier Ltd

Peng H.,Chongqing Electric Power Company | Zhang J.,Chongqing University | Wu Y.,Shaanxi Electrical Power Research Institute | Sun M.,Nuclear Electric Ltd | Wang Z.,Chongqing University
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2017

A "minimum segment quantity" model based on the reliability index is proposed together with the corresponding algorithms for the overhead lines of single-feeder and multi-feeder systems. A concept of "maximum effective segment quantity" is proposed together with its calculation method to improve the reliability index of overhead lines. A simplified reliability estimation model for single-feeder and multi-feeder systems is obtained, based on which, the maximum effective segment quantity and the minimum segment quantity of single feeder are calculated for different lengths. Research shows that, the maximum effective segment quantity for 1~15 km radial line is 3~5, obviously lower than 5~15 for tie-line;for the multi-feeder system, the minimum segment quantity of each line is related not only to its length, but also to its user quantity, as well as to the lengths and user quantities of other lines;the segment quantity recommended by existing relevant guidelines is 3 or less than 5, which limits the further improvement of distribution network reliability to a certain extent. © 2017, Electric Power Automation Equipment Press. All right reserved.

Tachikawa H.,Hokkaido University | Haga K.,Nuclear Electric Ltd | Yamada K.,Japan National Institute of Environmental Studies
Computational and Theoretical Chemistry | Year: 2017

Since the accident at the Fukushima nuclear power plant, the removal of radioactive cesium ions (137Cs+) from wastewater has become an important topic. Nickel ferrocyanide (Ni-FeCN) is known to adsorb 137Cs+ preferentially from radioactive waste solutions. However, the mechanism underlying the selectivity of Ni-FeCN is not clearly understood. In the present study, the ion selectivity of Ni-FeCN was investigated by means of density functional theory (DFT) calculations to determine why Ni-FeCN selectively adsorbs Cs+. Models of the interactions of Cs+ and K+ with Ni-FeCN were examined via DFT calculations, which revealed that the hydration energy of Cs+ plays an important role in its selective adsorption by Ni-FeCN. The electronic states of Cs+/K+ in Ni-FeCN are discussed based on the theoretical results. © 2017 Elsevier B.V.

Li G.,Shanghai JiaoTong University | Zhang M.,Nuclear Electric Ltd | Huang J.,Shanghai JiaoTong University | Sun Z.,Nuclear Electric Ltd | Wu Y.,Shanghai JiaoTong University
International Journal of Advanced Manufacturing Technology | Year: 2015

The current study investigates the overlays deposited by laser beam (LB) and gas tungsten arc (GTA) cladding with Inconel 52M filler wire in nuclear power plants. The effects of the deposition methods on the cross section profile, microstructures, and mechanical properties of both overlays are studied using optical microscope, scanning electron microscope (SEM), tensile and impact test and microhardness measurements. Experimental results show that LB cladding with higher wire feed rate improves the deposition efficiency as compared with GTA cladding. The microstructure of the LB clads consists of cellular and columnar dendrites, and Nb-rich spherical particles are precipitated in the interdendritic regions, while the equiaxed dendrites are dominant in the GTA clads. The microhardness of the GTA clads is 20–30 HV higher than that of the LB clads. Furthermore, the tensile strength, toughness, and elongation of the LB clads decrease in comparison to the GTA clads. The deep penetration of the LB clads resulting in a wave shape of each pass and high dilution does not benefit the mechanical properties as compared with the GTA clads. © 2015 Springer-Verlag London

Long Y.,Shanghai JiaoTong University | Yin J.L.,Shanghai JiaoTong University | Wang D.Z.,Shanghai JiaoTong University | Li T.B.,Nuclear Electric Ltd
IOP Conference Series: Materials Science and Engineering | Year: 2016

In this paper, CFD approach was employed to study how the blade number of impeller and diffuser influences reactor coolant pump performances. The three-dimensional pump internal flow channel was modelled by pro/E software, Reynolds-averaged Naiver-Stokes equations with the k-ϵ turbulence model were solved by the computational fluid dynamics software CFX. By post-processing on the numerical results, the performance curves of reactor coolant pump were obtained. The results are as follows, with the blade number of the impeller increasing, the head of the pump with different diffuser universally increases in the 8Qn∼1.2Qn conditions, and at different blade number of the diffuser, the head increases with the blade number of the impeller increasing. In 1.0Qn condition, when the blades number combination of impeller and diffuser chooses 4+16, 7+14 and 6+18, the head curves exist singular points. In 1.2Qn condition, the head curve still exists singular point in 6+18. With the blade number of the impeller increasing, the efficiency of the pump with different diffuser universally decreases in the 0.8Qn and 1.0Qn conditions, but in 1.2Qn condition, the efficiency of the pump with different diffuser universally increases. In 1.0Qn condition, the impellers of 4 and 5 blades are better. When the blade number combination of impeller and diffuser choose 4+11, 4+17, 4+18, 5+12, 5+17 and 5+18, the efficiencies relatively have higher values. With the blade number of the impeller increasing, the hydraulic shaft power of the pump with different diffuser universally increases in the 0.8Qn∼1.2Qn conditions, and with the blade number of the diffuser increasing, the power of different impeller overall has small fluctuation, but tends to be uniform. This means the increase of the diffuser blade number has less influence on shaft power.The influence on the head and flow by the matching relationship of the blades number between impeller and diffuser is very complicated, which still need further research.This paper provides a reference for exploring the match relationship between the impeller and diffuser blade number of reactor coolant pump.

Li G.,Shanghai JiaoTong University | Zhang M.L.,Nuclear Electric Ltd | Huang J.,Shanghai JiaoTong University | Sun Z.Y.,Nuclear Electric Ltd | Wu Y.X.,Shanghai JiaoTong University
Surface Engineering | Year: 2015

The current study investigates Inconel 52M multilayer by electroslag cladding. The four-layer multilayer with good formation is obtained. The experimental results indicate that the microstructure of the multilayer consists of numerous coarse columnar dendrites in the same growth direction. Nb rich carbides, the mixture of Al rich oxides and Nb rich carbides and long chains of eutectic phases are precipitated in the interdendritic regions. The significant composition changes merely occur in the limited interface regions between the substrate and the first layer, while the smooth composition changes occur in the 1st layer. Moreover, the microhardness in single layer decreases from the root to the top. The microhardness decrease in the first layer is more significant than that in the other single layer as a result of the composition transitions by the effect of dilution. © 2015 Institute of Materials, Minerals and Mining.

Ogawa H.,Nuclear Electric Ltd | Nawa T.,Hokkaido University
Journal of Advanced Concrete Technology | Year: 2012

Crushed recycled aggregate contains particles with brittle defects such as cracks, pores, and voids. This study presents a method for improving the quality of recycled fine aggregate by selectively removing these defects. Fourteen recycled fine aggregates were manufactured by three types of processors including a jaw crusher, ball mill, and granulator. The influence of the recycled fine aggregate on the flowability and strength of the mortar was evaluated by multivariate analysis. The results showed that flowability was mainly affected by the filling fraction of the recycled fine aggregate and the content of components passing through a 0.075-mm sieve. Both the compressive and flexural strengths of the recycled mortars were unaffected by the filling fraction, but they were affected by the fraction of defects in the aggregate and its surface smoothness. In addition, the results clearly showed that polishing involved in ball mill or granulator processing is effective both for increasing the filling fraction of recycled fine aggregate and reducing the fraction of defects in the aggregate. Moreover, it was determined that the grain surface of grains was more irregular with the granulator than that with the ball mill, resulting in higher strength of the mortar subjected to the granulator. The fracture configuration resulting from flexural stress on the recycled fine aggregate in the mortar differed according to the type of aggregate. Furthermore, the calculated amounts of emitted CO2 and the compressive strength of the recycled mortar showed that the recycled fine aggregate should not be polished excessively. Copyright © 2012 Japan Concrete Institute.

Ishimoto S.,Nuclear Electric Ltd | Fumon H.,Nuclear Electric Ltd | Yokoyama M.,Nuclear Electric Ltd
International Conference on Nuclear Engineering, Proceedings, ICONE | Year: 2010

Mitsubishi digital safety Instrumentation and Control (I&C) system has been developed and approved in Japan. The digital I&C system has been applied to many safety and non-safety system applications including full digital I&C system for new plants and digital upgrading for operating plants in Japanese Pressurizer Water Reactor (PWR) plants. The digital I&C system ensures defense-in-depth and diversity for plant safety and control, and this feature also provides countermeasures against software common cause failures. Based on this proven technology, the digital I&C system will also be applied for the US-APWR in the U.S. plant. The US-APWR is one of the candidate reactor of future nuclear power plants in U.S., which has been developed by Mitsubishi Heavy Industries, Ltd. (MHI) modifying Japanese Advanced Pressurizer Water Reactor (APWR) design to comply with U.S codes and standards. The I&C system of the US-APWR also conforms to the U.S. regulatory requirements and industry guidelines. The safety I&C system design and digital platform for the US-APWR are summarized into topical reports and are currently reviewing by U.S. Nuclear Regulatory Commission (NRC). The I&C system includes Human System Interface System (HSIS), Protection and Safety Monitoring System (PSMS), Plant Control and Monitoring System (PCMS) and Diverse Actuation System (DAS). The paper describes our digital I&C design features and application of the digital I&C system to new plants and digital upgrading for operating PWR plants. Copyright © 2010 by ASME.

Li G.,Shanghai Key Laboratory for Engineering Materials Evaluation | Fang K.,Shanghai Key Laboratory for Engineering Materials Evaluation | Yang W.,Shanghai Key Laboratory for Engineering Materials Evaluation | Zhang M.,Nuclear Electric Ltd | Sun Z.,Nuclear Electric Ltd
Key Engineering Materials | Year: 2011

The microstructures and mechanical properties of a dissimilar metal weld A508/52M/316L used in the primary water system of pressurized water reactor (PWR) nuclear power plants were investigated. The weld exhibits complicated microstructures, with significant change around the interfaces A508/52M and 52M/316L. The variations of main elements in 52M weld metal are greater than those in the A508 and 316L, with significant changes in the zones closed to the interfaces. The bulk 52M weld metal has higher and more uneven hardness than both of the base metals A508 and 316L. The HAZ of A508 exhibits the highest hardness value in the weld. The area around the A508/52M interface is the most weak part for stress corrosion cracking (SCC) resistance of the weld in simulated PWR primary water at 290°C. SCC was only found in the specimens tested at +200mV(SHE) but not in those tested at both -780mV and E corr (about -500mV).

Li G.F.,Shanghai Key Laboratory for Engineering Materials Evaluation | Li G.J.,Shanghai Key Laboratory for Engineering Materials Evaluation | Peng J.,Shanghai Key Laboratory for Engineering Materials Evaluation | Zhang M.L.,Nuclear Electric Ltd | Sun Z.Y.,Nuclear Electric Ltd
Applied Mechanics and Materials | Year: 2014

The mechanical behaviors of dissimilar metal weld SA508-52M-316L in several environments were investigated by using tensile tests with smooth specimens, focusing on the behavior of SA508-52M weld part during slow strain rates testing (SSRT) at 290°C in nitrogen gas and in simulated primary water at different electrode potentials. The mechanical properties at room temperature of main materials were obtained first. When tested at 290°C, the weld exhibited characteristics of dynamic strain ageing (DSA), which was more significant when strain rate was decreased from 1x10-6 (1/s) to 3.1 x10-7 (1/s). When tested in the water at the potentials from -720 to +200mV(SHE), SA508-52M specimens showed the mechanical behaviors almost the same as that in nitrogen gas, with ductile failure happened in the 52M bulk weld metal. When the potential was raised to +300 and +400mV(SHE), brittle failure of stress corrosion cracking (SCC) took place around the interface, causing the significant drop of elongation and reduction in area. © (2014) Trans Tech Publications, Switzerland. All Rights Reserved.

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