Comparison of Two Models for a Pebble Bed Modular Reactor Core Coupled to a Brayton Cycle
2nd International Topical Meeting on HIGH TEMPERATURE REACTOR TECHNOLOGY
Beijing, CHINA, September 22-24, 2004 #Paper D08 Comparison of Two Models for a Pebble Bed Modular Reactor Core
Coupled to a Brayton Cycle
Ayelet Walter, Alexander Schulz, Günter Lohnert
Institute of Nuclear Technology and Energy Systems (IKE),
University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart, Germany Tel: +49-(0)711-6852145 ; Fax: +49-(0)711-6852010; e-mail: walter@ike.uni-stuttgart.de
Abstract
The Pebble Bed Modular Reactor (PBMR) plant is a promising concept for inherently safe nuclear power generation. This paper presents two dynamic models for the core of a High Temperature Reactor (HTR) power plant with a helium gas turbine. Both the PBMR and its power conversion unit (PCU) based on a three-shaft, closed cycle, recuperative, inter-cooled Brayton cycle have been modeled with the network simulation code Flownex.
One model utilizes a core simulation already incorporated in the Flownex software package, and the other a core simulation based on multi-dimensional neutronics and thermal-hydraulics. The reactor core modeled in Flownex is a simplified model, based on a zero-dimensional point-kinetics approach, whereas the other model represents a state-of-the-art approach for the solution of the neutron diffusion equations coupled to a thermal-hydraulic part describing realistic fuel temperatures during fast transients. Both reactor models were integrated into a complete cycle, which includes a PCU modeled in Flownex.
Flownex is a thermal-hydraulic network analysis code that can calculate both steady-state and transient flows. An interesting feature of the code is its ability to allow the integration of an external program into Flownex by means of a memory map file.
The total plant models are compared with each other by calculating representative transient cases demonstrating that the coupling with external models works sufficiently. To demonstrate the features of the external program a hypothetical fast increase of reactivity was simulated.
1 Introduction
Substantial interest has emerged in advanced reactors over the last few years. This interest has been motivated by the view of new nuclear power reactors that will be needed to provide low carbon generation electricity and possibly hydrogen to support the future growth in demand of both of these commodities [1]. Some governments feel that substantially different designs will be needed to satisfy the desires for public perception, improved safety, proliferation resistance, reduced waste and competitive economics. This has motivated the creation of the Generation IV Nuclear Energy Systems program in which ten countries have agreed on a framework for international cooperation in research for advanced reactors. Six designs have been selected for continued evaluation with the objective of deployment by 2030. One of these designs is the Very High Temperature Reactor (VHTR), which is a thermal neutron spectrum system with a helium-cooled graphite moderated core.
The pebble bed modular reactor (PBMR), being currently developed in South Africa as a world wide international association between Eskom the national utility, and other industrial partners, will represent a key milestone on the way to achievement of a new generation of High Temperature Reactor design objectives.
1
COMPARISON OF TWO MODELS FOR A PEBBLE BED MODULAR REACTOR CORE COUPLED TO A BRAYTON CYCLE #D08 This high temperature gas cooled reactor is based on the recuperative inter-cooled closed loop Brayton cycle using helium as coolant (see in figure 1) [2]. Starting at 1, helium at a relatively low pressure and temperature (1) is compressed by a low-pressure compressor (LPC) to an intermediate pressure (2) after which it is cooled in an inter-cooler to state 3. A high pressure compressor (HPC) then compresses the helium to state 4. From 4 to 5 the helium is preheated in the recuperator before entering the reactor, which heats the helium to state 6. After the reactor the hot high pressure helium is expanded in a high pressure turbine (HPT) to state 7 after which it is further expanded in a low pressure turbine (LPT) to state 8. The high pressure turbine drives the high pressure compressor while the low pressure turbine drives the low pressure compressor. After the low pressure turbine the heated helium is further expanded in the power turbine, which drives the generator, to the pressure 9, which is approximately the same pressure at 10 and 1. From 9 to 10 the still hot helium is cooled in the recuperator after which it is further cooled in the pre-cooler to state 1. This completes the cycle. The heat rejected from 9 to 10 is equal to the heat transferred to the helium from 4 to 5.
Figure 1. Schematic diagram of the PBMR high temperature gas cooled reactor Brayton cycle [2]. The complexity associated with the thermal-flow design of the cycle requires the use of a variety of analysis techniques and simulation tools. These range from simple one-dimensional models that do not capture all the significant physical phenomena to large-scale three-dimensional CFD codes that, for practical reasons, can not simulate the entire plant as a single integrated model [3]. Furthermore, the treatment of the coupled neutronics and thermal-hydraulics in the reactor core coupled to the PCU network is a complex part which requires a realistic connection of a detailed core model with the network model.
One of the most prominent codes that provide a suitable compromise, is the thermal-flow network simulation code Flownex.
2Description of Flownex
Flownex is a network simulation code, which encompasses the ability to perform detailed analysis and design of complex thermal-fluid systems such as power plants. Flownex solver, described elsewhere [4], is based on the implicit pressure correction method (IPCM) that solves the momentum equation at each element and the continuity and energy equations at each node in large arbitrary structured networks for both steady state and dynamic flow. The solver can deal with both fast and slow transients. Fast simulation speeds, on standard desktop computers, allow for real time simulations to be performed. The code has been validated against other codes as well as with experimental data. With the network approach, a complex thermal-fluid system is represented as a network of one-dimensional elements connected at common nodes (see figure 2). In this figure, elements are denoted by cycles and nodes are denoted by squares. Elements represent components such as pipes, compressors, turbines, heat exchangers, control valves or the pebble bed reactor core.
Figure 2. Example of Flownex network representation [5]
The code features the ability to simultaneously solve multiple gas and liquid networks that are connected through heat exchangers. It also enables the user to construct re-usable models of complex components or sub-systems such as gas-cooled nuclear reactors and heat exchangers. The reactor and the heat exchangers are not treated as lumped systems but as distributed systems. The code can also deal with conductive heat transfer through solid structures.
Advanced rotating model allows for stage-by-stage modeling of compressors and turbines. Other features of the code are its ability to design PID controllers and control systems.
The software can be directly linked with other external computational codes, which can be externally coupled to it.
3 Characterization of the Flownex core model
The pebble bed reactor core is made up of fuel spheres and passive graphite spheres [6], such as the one shown schematically in figure 3. Each of the fuel spheres that make up the core consists of an inner fuel region with a 50 mm outer diameter made up of coated Uranium dioxide (UO2) particles imbedded in a graphite matrix. A fuel-free graphite protective layer with an outer diameter of 60 mm covers the fuel region.
Figure 3. Schematic representation of a fuel sphere [2].
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Figure 4. Schematic two-dimensional representation of the core of the pebble bed reactor [2].A schematic two-dimensional representation of the geometry of the reactor core is shown in figure 4.The inner core region contains passive graphite spheres while the outer active core region is filled with fuel spheres. Helium gas enters the top of the reactor core at approximately 500°C. The gas is heated primarily through the active core region where heat is generated inside the fuel spheres. Upon leaving the core at the bottom the hot gas is mixed with gas from the passive region to obtain a fully mixed exit temperature of approximately 900°C.
Figure 5. Graphical representation of the thermal-hydraulic network for the reactor core [2].The existing model consists of three main parts [7]:
? Heat transfer and fluid flow of the gas within the core . The model is based on a discretised two
dimensional axi-symetric network, which consists of any number of control volumes in the axial and/or radial directions as demonstrated in figure 5. The model includes the convective heat transfer between the gas and the surface of a representative sphere in each of the control volumes.However, it only allows for the simulation of the core itself, excluding all core structures, and is based on a core layout with a homogeneous graphite pebble region at the center and a homogeneous fuel pebble region in the annulus without a solid central reflector column. Also, it does not allow for the addition or extraction of leak flows from the inner or outer perimeter of the core and the gas inlet and outlet is assumed to be from voids at the very top and the very bottom of
the core.
COMPARISON OF TWO MODELS FOR A PEBBLE BED MODULAR REACTOR CORE COUPLED TO A BRAYTON CYCLE #D08
HTR 2004 Beijing, CHINA, 2004.9 ?Heat conduction within the pebbles. Each of the core control volumes contains a representative pebble for which the heat conduction is modeled in a one-dimensional spherical frame of reference together with the convection heat transfer between the gas and the surface of the sphere. The sphere consists of an outer graphite layer and the inner fuel matrix region, both of which can be discretised into any number of spherical `onion ring shaped′ control volumes. This allows for the calculation of the temperature distribution within the pebbles in any region of the core. The nuclear power generated in the core is distributed with the fuel matrix region only in the form of a source term in the heat conduction equation.
?Nuclear power and decay heat generation. The model is based on a zero-dimensional point-kinetics approach and calculates a single normalized power level for the core as a whole based on reactivity feedback equations taking into account the average fuel and moderator temperatures, xenon concentration and the control rod settings. The total reactor power is distributed among the axial layers of the core based on a fixed normalized power distribution profile. However, it does not account for any radial power distribution profile on each of the different axial levels. Figure 6 shows a schematic representation of the interaction between the three models mentioned.
Figure 6. Schematic illustration of the interaction between the three models [2].
The purpose of this model was not to do detailed reactor design, but rather to allow for the integrated simulation of the reactor together with the PCU within acceptable computer simulation times. Hence, the requirement for this existing model was to provide quick results of the main flow and heat transfer phenomena in the core only, in order to obtain boundary values for the simulation of the rest of the PCU [7].
The phenomena that cannot be simulated in the existing model include the following:
?The presence of a central reflector column that implies that the core itself has an annular rather than a cylindrical shape.
?The addition and extraction of gas via purpose provided channels and/or leak paths along the inner or outer perimeters of the core.
?The simulation of heat transfer and fluid flow through porous and solid core structures surrounding the core.
?The simulation of fluid flow and heat transfer, including radiation and natural convection, in purpose provided cavities between core structures with a two-dimensional rather than one-dimensional nature.
?The ability to take into account variations in porosity throughout the core.
?The ability to specify normalized radial power distribution profiles within the different axial layers in the core.
? The ability to account for heat generation that may occur in any of the core structures.
Therefore, a need exists for the development of a more comprehensive pebble bed reactor model that can still provide with integrated plant simulations, but includes the phenomena listed above.
COMPARISON OF TWO MODELS FOR A PEBBLE BED MODULAR REACTOR CORE COUPLED TO A BRAYTON CYCLE #D08 4Description of an alternative (WKIND) core model
The core model built in into Flownex describes the reactor mainly like a point without detailed consideration of changes in power distribution during reactivity transients (e. g. by control rod movement, strong temperature changes or spatial changes in xenon distribution). These effects can only be regarded by solving the space dependent neutron diffusion equation together with an adequate model for calculating the temperatures of active core and reflector zones. Furthermore, it is very important to model the detailed heat transfer from fuel zone in the coated particle to the graphite matrix and finally to the coolant gas since the fuel temperature is mainly responsible for the negative reactivity feedback and a homogeneous model under-estimates the fuel temperature and correspondingly over-estimates the power increase for fast reactivity transients.
As several verified core models for coupled neutronics and thermal-hydraulics exist, it is obviously needed to couple such stand alone core models with a corresponding network for the PCU to get the realistic boundary conditions and core-PCU interaction for the simulation of operational and accidental transients. Presently at IKE two programs for core models are available: WKIND and RZKIND [8].
WKIND is a one-dimensional neutronics thermal-hydraulics code which solves the one group neutron diffusion equation in axial direction based on a set of prepared cross sections which regard spectrum effects from fuel, moderator, reflector (via bucklings), control rods, small absorber spheres (SAS) and xenon. The thermal-hydraulics part regards the average axial fuel, moderator and gas temperature distribution in the core as well as the reflector temperature distribution. An important feature is the detailed model for the heat transport from fuel in the coated particle to the moderator. For fast transient this is very important since the relaxation time for heat transport from the graphite is dominant for the fuel temperature and is therefore responsible for a fast negative feedback via the Doppler effect. The cross section sets used in WKIND will be prepared by the stationary HTR neutronics and thermal-hydraulics system WKIND [9] developed by Framatome ANP GmbH. RZKIND is the two-dimensional (R,Z) version of WKIND, but with a different solver for the neutronics and the thermal-hydraulics equations. The thermal-hydraulics equations can be solved alternatively to the original version of RZKIND also by the 2D THERMIX/KNOVEK code . At the moment the detailed fuel temperature model of WKIND is not yet implemented into RZKIND but it will be done in future. With the core models available several transients can be treated with sufficient accuracy by the 1D-method WKIND. For a more detailed transient analysis with significant changes in radial and axial power distributions the 2D version RZKIND and if necessary in future also a 3D version will be available.
The coupling with the PCU network will be done via an interface with Flownex in order to simulate the realistic boundary conditions for the core mass flow and the temperature and pressure at the inlet node. The results of the neutronics thermal-hydraulics model serve as the transferred energy from core to the coolant and the pressure drop.
Both codes were validated against theoretical and experimental results especially for the German AVR Reactor and reviewed by German licensing authorities for the HTR-Modul concept.
The codes WKIND and RZKIND allow for the following quasi stationary and transient simulations:?Slow transients due to load changes, start up, shut down;
?Analysis of slow xenon transients after load changes;
?Slow transients after restart from a hot stand-by;
?Slow transients due to recriticality after core heat-up accidents;
?Fast transients due to changes of control rod position, SAS position or loss of absorbing substances;
HTR 2004 Beijing, CHINA, 2004.9 ?Fast transients due to changes of coolant mass flow;
?Fast transients due to changes of coolant inlet temperature;
?Fast transients due to ingress of moderating substances (e. g. water);
?Fast transients due to reactivity increase because of compression of the pebble bed.
Once these codes are coupled with a network model, the parameters: coolant inlet temperature and coolant mass flow through the core are not specified in the WKIND or RZKIND input, but are given from Flownex. The time dependant control rod or SAS absorber position (or any other external reactivity event) will be specified in the core model input description. The outlet temperature and power of the core will be transmitted to the Flownex model. If there are actions initiated by the reactor protection system, they can be formulated by the core model input description (e. g. scram by too high reactor power or exceeding of maximum outlet temperature) or by the interface core model – Flownex or by the input data tables of diverse Flownex elements (e. g. predefined set of time points for opening valves etc.). With these features a realistic simulation of diverse operational and accidental transients can be formulated and executed by the coupled Flownex-WKIND (RZKIND) model. Pre-condition for a successful coupled calculation is a consistency of the core parameters and the network parameters for the initial conditions of the transient and a synchronous solving of the core model and network equations.
5Coupling of Flownex Power Conversion Unit model with an alternative core model
A system code consisting of the dynamic systems code Flownex and the neutron kinetic/dynamic code WKIND has been created through the use of an independent software component. The main goal of the design of this coupling component was to develop a software solution, which enables a coupling between the two before mentioned applications as well as having the opportunity to couple arbitrary components with Flownex.
The basic coupling technique is a time step based data exchange. After the initialization sequence the two applications alternately calculate the results for a distinct time step. Each application is interrupted after one time step, so that the data can be read from the coupling component. Hereafter the data is processed and transferred to the second application, which is now able to calculate the next time step. As long as the calculation proceeds, the data is transferred back to the first application.
In order to enable such a time step based data exchange, the participating applications have to provide suitable interfaces, that can be used within a software component. Flownex and WKIND provide different interfaces, which are described more in details as following:
?Flownex: Flownex and an external component interact by means of a memory map file. Methods for the usage and handling of such a memory map file are provided by the so called Windows?API (application programming interface). The Windows? API is an inherent part of the Windows? operating system. In order to enable the interaction of two applications by means of a memory map file, the Windows? API provides a global access point for the file. The input and output variables stored in that file are defined within Flownex.
?WKIND: The interface for data exchange provided by WKIND is a file based mechanism. When WKIND is initialized a file is created. This file contains the time step size, the inlet temperature, the relative coolant mass flow, the control rod position and the power. A character at the beginning of the file indicates whether WKIND or Flownex is the active application.
As Flownex provides only with the access to the variables of a model, it was still necessary to find a proper substitute for the reactor core. In this case a pipe was used, to replace the reactor core within the Flownex model. The pressure drop of the pipe was adapted according to the reactor model. The inlet temperature and the mass flow at the pipe entry are used for generating the input for WKIND.
It simulates the heat up of the coolant as in the core model for the actual time step. The transient simulation of the coupled system begins with starting the Flownex transient until the initial stationary conditions are reached. In parallel the WKIND program which calculates also the stationary initial conditions is started. Afterwards both programs solve their equations for the next time step alternately.The time step size is determined by the WKIND time step specification.6 Results
The following section will present results generated with the Flownex PCU network coupled with the Flownex integrated pebble bed core, compared to corresponding results generated using the same Flownex PCU network but coupled with the WKIND core model. Furthermore coupled Flownex-WKIND simulations will be presented for a fast reactivity transient by rapid withdrawing all control rods without shutdown and a reactivity transient due to withdrawing of control rods and shutdown (control rod insertion and load rejection after scram signal).
The cases are presented as following: first, a short description of the problem that was modeled is given. Second, the main interesting results are presented and compared to results obtained with the alternative core model for the first example and discussed for all examples.6.1 Load rejection
Description
In the first transient a load rejection case is simulated. Full load rejection due to the loss of grid power is one of the most severe load control scenarios for a power plant [1]. Initially the plant operates at maximum power and in less than one second the generator load is instantaneously reduced to zero.The shaft directly goes into over speed, and thus it is necessary to quickly reduce the power output of the power turbine to prevent the generator from over speeding. The generator speed is therefore controlled by opening the Gas Cycle Bypass Valve (GCBV). This valve connects the points of the highest and lowest pressure within the system and reduces the overall system pressure ratio and thus also the power output. The GCBV is a quick acting, open-close valve. After the power output has been reduced, the GCBV is closed again to maintain stable operation.
In the load rejection of the design configuration simulated here, the grid power is reduced from full load (=111.578 MW) to 10 MW.
Results
Figure 7 shows the increase in power turbine speed up to 51.5 Hz.
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COMPARISON OF TWO MODELS FOR A PEBBLE BED MODULAR REACTOR CORE COUPLED TO A BRAYTON CYCLE #D08
From figure 7 it can be seen that the controller managed successfully to reduce the power turbine over speed to 1.5 Hz in both models. Both models reach the same degree of over speed. In the system utilizing a Flownex pebble bed reactor model, the shaft reaches the nominal value of the rotational velocity (50 Hz) after 7.5 seconds, whereas in the alternative model, the speed returns to operate at its nominal value after 12.9 seconds after load rejection.
Figure 8 and figure 9 show the variation in the recuperator inlet and outlet temperature after the event.
Figure 8. Temperatures at recuperator inlet after load rejection.
Figure 9. Temperatures at recuperator outlet after load rejection.
The recuperator low pressure inlet temperature increases with approximately 300°C during the event,while no significant change in temperature is visible at the High Pressure (HP) recuperator outlet. It can be seen that short circuiting the power turbine results in hotter helium gas entering the Low pressure (LP) side of the recuperator. Both models here agree very well in trends and in maximal values.
Figure 10 shows the variation that occur in HP side and in the LP side of the circuit during the event.The pressure of HP side is taken at the manifold and the pressure of the LP side is taken at Low Pressure compressor (LPC) inlet.
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Figure 10. System pressure after load rejection at LPC Inlet and Manifold.
The pressure at the low pressure side of the system increases to a value of approximately 5500 kPa,whereas the pressure at the high pressure side of the system decreases to a value just above.The models show a good agreement for this transient.
The figures 11-13 show the effect of load rejection on the reactor core. The change in reactor power,reactor mass flow and reactor temperature is demonstrated.
Figure 11. Reactor power after load rejection.
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Figure 12. Reactor mass flow after load rejection.
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Figure 13. Reactor temperatures after load rejection.
The reactor power decreases in approximately 30% in both models, or if assumed a control rods insertion. The large heat capacity of the pebbles prevent a very fast decrease in reactor power. The reduction in mass flow does not correspond to that and latter decreases considerably, and shows a decrease of approximately 70% of its initial value.
Figure 13 shows that a sharp change occurs in the reactor inlet temperature. This change occurs due to the high level of interdependence between the recuperator and the reactor. The reactor inlet temperature rises in approximately 300°C in both models. However, the reactor outlet temperature remains almost constant. The reactor outlet temperature does not significantly deviate from its original value because of the rapid feedback from the fuel temperature to reactivity by which the output power is adjusted to match the cooling capacity of the reduced helium flow.
The reactor power starts to decrease due to the higher reactor inlet temperature and the lower mass flow levels.
It can be seen that the models agree reasonably well with each other, and show a similar behavior in all demonstrations described above.
6.2 Withdrawal of all control rod after 30 s
In the following transient simulation it is assumed that due to an unknown malfunction of the power plant all control rod are withdrawn with a hypothetical speed of 100 cm/s. This causes to an instantaneous increase in reactor power. However, the reactor inlet temperature as well as the reactor outlet temperature remain nearby constant due to large heat capacity of the core.
As mentioned previously in this paper, the action of withdrawal is simulated with the WKIND core model only, since the Flownex core model lacks this feature.
Figure 14 shows the change in reactor heat transfer and the change of control rods position that was initiated after 30 s simulation run time.
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Figure 14. Reactor control rods position and heat transfer.
It can be clearly seen, that simultaneously during the withdrawal a very strong increase in WKIND reactor heat transfer occurs. This increase is almost seven folds greater than the initial power. The rapid decrease of power after the strong increase is due to the prompt increase in fuel temperature on the control rods position, which was calculated by heterogeneous fuel temperature module (see figure 15).
Figure 15. Reactor fuel temperature after withdrawal of all control rods without scram.
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COMPARISON OF TWO MODELS FOR A PEBBLE BED MODULAR REACTOR CORE COUPLED TO A BRAYTON CYCLE #D08
For a short time the temperature of the coated particles differs very much compared to the moderator temperature.
Figure 16 shows this difference during the event.
Figure 16. Temperature difference between moderator and fuel temperature.
For a short relaxation time this difference reduces the power of the core remarkably. Therefore this
model is much more realistic than a homogeneous model which shows power increase by a factor of about 80 since the fuel temperature is strongly coupled to the slowly increasing moderator temperature.
Figure 17 shows a linear plot of fuel temperature, coating temperatures, average moderator temperature and surface temperature of the spheres in the axial center of the core.
Figure 17. Fuel temperature, coating temperatures, average moderator temperature and surface
temperature in the axial center of the core.Even if the assumed control rod withdrawal is not a realistic accident scenario, the results show that the reactor temperatures exceed no deign limits even for fast reactivity transients.
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Figure 18 shows the reactor inlet and the reactor outlet temperature.
Figure 18. Reactor temperatures.
The current simulation case is shown in order to demonstrate the additional features of the WKIND core modeled that means the capability of changing the position of the control rods and of calculating the fuel and the moderator temperature, which exist in the WKIND model but has not yet been applied in the Flownex model.
6.3 Withdrawal of all control rods and load rejection
The withdrawal of all control rods at the speed of 1 cm/s is initiated and simulated by the WKIND model at a predefined time (5s). It was specified that a complete shut down by control rods would be initiated as soon as a power level of 120% has been reached. This causes an immediate decrease in reactor power at about 22 seconds. Simultaneously a load rejection is initiated in Flownex, in order to maintain a stable operation of the power turbine.
Figure 19 shows the variations in reactor power and in heat transfer to the PCU.
Figure 19. Reactor power after a control rods withdrawal and load rejection.
Regarding the PCU state variables he results are consistent to the ones obtained in the first transient,but due to the shut down the reactor power decreases until a level of approximately 10% of its nominal values at about 50 s.
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Figure 20 shows the variation in reactor mass flow.
Figure 20. Reactor mass flow after a control rods withdrawal and load rejection.
A reduction in reactor mass flow is due to the load rejection initiated by the opening of the bypass valve (BPV).
Figure 21. Reactor temperatures after a control rods withdrawal and load rejection.
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The reactor outlet temperature maintains an almost constant value, whereas the reactor inlet temperature shows an increase of approximately 200°C.The models show a satisfactory level of consistency.
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COMPARISON OF TWO MODELS FOR A PEBBLE BED MODULAR REACTOR CORE COUPLED TO A BRAYTON CYCLE #D08 7Conclusions and Discussion
In this paper two different models for the reactor core were incorporated within a Flownex PCU, thereby creating a plant wide model. The first model is the Flownex core model and the second one is the WKIND core model. The integrated core models have been compared for three transient cases. The control system implemented in the PCU has been kept straightforward throughout the transients, and focused on keeping the shaft speed within bounds.
In the first transient a load rejection (a generator trip) is simulated. In this case both models have shown a rather good agreement. Based on this case it can be concluded that coupling Flownex to an external component via a mutual interface is feasible.
In the second case the withdrawal of all control rods at a speed of 100 cm/s is simulated. The results obtained by the WKIND model are more important in this case, as the action of changing the rods position has so far only been featured in this model. From the results attributed in this case inherent differences between the two core models and their features could be derived. In the Flownex model it is assumed that the fuel temperature is approximately similar to the moderator temperature in the core. However, in the WKIND model the calculation of the fuel temperature is done explicitly. Thus, a major difference between the capabilities and limitations of models exist. The WKIND model by accounting for the in control rods position demonstrates a more realistic behavior of the core. Accordingly, it is recommended to modify the Flownex model and feature an option to insert and to withdraw the control rods for the extension of further control and emergency actions which play a key role in plant operation simulations.
In the third transient the control rods are withdrawn at the speed of 1 cm/s. In this case there was a need to simultaneously initiate a load rejection in Flownex to maintain a stable operation. Also here both models have shown similar results and agree well. The realization of an external transient and is demonstrated here, yet the coupling methodology should be further improved. Instead of the Flownex element assimilating a heat source which utilized in the current coupling, a more sophisticated coupling model should be implemented in order to improve this. Furthermore, since the control system of the PCU plays an important role in the whole plant behavior and is extremely important for the simulation of transient and accidental cases, and as it is necessary to model the process behavior in a larger operating region, and to include the establishment of start-up and shut-down simulations in the investigations, the control strategies have to be further improved.
For the total PBMR plant it can be concluded that the models agree well. However, some differences still exist. Thus, it is recommended to extend and improve the models. This is currently done as a part of an ongoing work which at IKE, which is aiming towards the application of a multidimensional core neutronics in the reactor models, and thus allows for more possibilities to simulate the thermo-hydraulics and analyze the natural convection in the core. Additionally, the synchronization of the time step and the control interaction that characterize the present coupling should be improved. Nevertheless, the results can be considered acceptable for a conceptual study of the system. The various transients demonstrated have shown satisfactory results to prove that a successful realization of the coupling has been accomplished.
HTR 2004 Beijing, CHINA, 2004.9 References
1.Ion, S, Nicholls, D, Matzie, R, Matzner, D, “Pebble bed modular reactor the first generation 4
reactors to be constructed”, World Nuclear Association Annual Symposium, London, 3-5
September, 2003.
2.Greyvenstein, GP, Rousseau, PG, “Basic principles of HTR thermal-hydraulics”, HTR/ECS 2002
High Temperature Reactor School, Cadarache, France, November 4-8, 2002.
3.Botha, BW, Rousseau, PG, “Simulation investigation of control options for full load rejection in
the PBMR closed cycle gas turbine power plant”, Proceedings of IGTI Turbo Expo, Amsterdam, June 3-6, 2002.
4.Greyvenstein, GP, “An implicit method for analysis of transient flows in pipe networks“, Int. J.
Numer. Meth Eng., 53, 2002, 1127-1143.
5.Coetzee, RV, der Merwe, V, Rousseau, PG, FLOWNEX Version 6 USER MANUAL, M-Tech
Industrial, Potchsfstroom, South Africa, 2003.
6.Rousseau, PG, Greyvenstein, GP, “One-dimensional reactor model for the integrated simulation of
the PBMR power plant”, Proc of 1st International Conference on Heat Transfer, Fluid Mechanics and thermodynamics, Kruger Park, South Africa, 8-10 April, 2002.
7.Du Toit, CG, Greyvenstein, GP, Rousseau, PG, “A comprehensive reactor model for the
integrated network simulation of the PBMR power plant”, 2003 International Congress on Advanced Nuclear Power Plants, Cordoba, Spain, May 4-7, 2003.
8.Kindt, T, Hauque, H, “Recriticality of the HTR-Module Power Reactor after hypothetical
accidents”, Nuc. Eng. Des. 137, 1992, 107-114.
9.Bernnat, W, Feltes, W, “Models for reactor physics calculations for HTR pebble bed modular
reactors”, Nuc. Eng. Des. 220, 2003, 331-347.
10.Verkerk, EC, Kikstra, JF, “Comparison of two models for a high temperature reactor coupled to a
gas turbine”, Nuc. Eng. Des. 220, 2003, 51-65.
常用介词的用法
分考点1 表示时间的介词 Point 1 at, in, on 的用法 （1）at 的用法 At 表示时间点，用于具体的时刻（几点，正午，午夜，黎明，拂晓，日出，日落等），或把某一时间看作某一时刻的词之前以及某些节假日的词之前。 at 6：00 在6点钟 At noon 在中午 At daybreak 在拂晓 At down 在黎明 At Christmas 在圣诞节 【特别注意】在以下的时间短语中，at 表示时间段。 At dinner time 在（吃）晚饭时 At weekends/ the weekend 在周末 （2）in 的用法 ①表示时间段，与表示较长一段时间的词搭配，如年份，月份，季节，世纪，朝代，还可以用于泛指的上午、下午、傍晚等时间段的词前。 In 2009 在2009年 In April 在四月 In the 1990s 在20世纪90年代 In Tang Dynasty 在唐朝 In the morning在上午 ②后接时间段，用于将来时，表示“在一段时间之后”。 The film will begin in an hour. 电影将于一个小时之后开始。 【特别注意】当时间名词前有this，that，last，next，every，each，some等词修饰时，通常不用任何介词。 This morning 今天上午last year 去年 （3）on 的用法 ①表示在特定的日子、具体的日期、星期几、具体的某一天或某些日子。 On September the first 在9月1号 On National Day 在国庆节 We left the dock on a beautiful afternoon. 我们在一个明媚的下午离开了码头。 ②表示在具体的某一天的上午、下午或晚上（常有前置定语或后置定语修饰）。 On Sunday morning 在星期日的早上 On the night of October 1 在10月1号的晚上 【特别注意】“on +名词或动名词”表示“一...就...”. On my arrival home/ arriving home, I discovered they had gone. 我一到家就发现他们已经离开了。 Point 2 in，after 的用法 In 和after都可以接时间段，表示“在...之后”，但in 常与将来时连用，after 常与过去时连用。 We will meet again in two weeks.
英语介词用法大全
英语介词用法大全 TTA standardization office【TTA 5AB- TTAK 08- TTA 2C】
介词（The Preposition）又叫做前置词，通常置于名词之前。它是一种虚词，不需要重读，在句中不单独作任何句子成分，只表示其后的名词或相当于名词的词语与其他句子成分的关系。中国学生在使用英语进行书面或口头表达时，往往会出现遗漏介词或误用介词的错误，因此各类考试语法的结构部分均有这方面的测试内容。 1. 介词的种类 英语中最常用的介词，按照不同的分类标准可分为以下几类： (1). 简单介词、复合介词和短语介词 ①.简单介词是指单一介词。如： at , in ,of ,by , about , for, from , except , since, near, with 等。②. 复合介词是指由两个简单介词组成的介词。如： Inside, outside , onto, into , throughout, without , as to as for , unpon, except for 等。 ③. 短语介词是指由短语构成的介词。如： In front of , by means o f, on behalf of, in spite of , by way of , in favor of , in regard to 等。 (2). 按词义分类 {1} 表地点（包括动向）的介词。如： About ,above, across, after, along , among, around , at, before, behind, below, beneath, beside, between , beyond ,by, down, from, in, into , near, off, on, over, through, throught, to, towards,, under, up, unpon, with, within , without 等。 {2} 表时间的介词。如： About, after, around , as , at, before , behind , between , by, during, for, from, in, into, of, on, over, past, since, through, throughout, till(until) , to, towards , within 等。 {3} 表除去的介词。如： beside , but, except等。 {4} 表比较的介词。如： As, like, above, over等。 {5} 表反对的介词。如： againt ,with 等。 {6} 表原因、目的的介词。如： for, with, from 等。 {7} 表结果的介词。如： to, with , without 等。 {8} 表手段、方式的介词。如： by, in ,with 等。 {9} 表所属的介词。如： of , with 等。 {10} 表条件的介词。如：
of与for的用法以及区别
of与for的用法以及区别 for 表原因、目的 of 表从属关系 介词of的用法 （1）所有关系 this is a picture of a classroom （2）部分关系 a piece of paper a cup of tea a glass of water a bottle of milk what kind of football，American of soccer？ （3）描写关系 a man of thirty 三十岁的人 a man of shanghai 上海人 （4）承受动作 the exploitation of man by man．人对人的剥削。 （5）同位关系 It was a cold spring morning in the city of London in England． （6）关于，对于 What do you think of Chinese food？ 你觉得中国食品怎么样？ 介词 for 的用法小结 1. 表示“当作、作为”。如: I like some bread and milk for breakfast. 我喜欢把面包和牛奶作为早餐。What will we have for supper? 我们晚餐吃什么?
2. 表示理由或原因,意为“因为、由于”。如: Thank you for helping me with my English. 谢谢你帮我学习英语。 Thank you for your last letter. 谢谢你上次的来信。 Thank you for teaching us so well. 感谢你如此尽心地教我们。 3. 表示动作的对象或接受者,意为“给……”、“对…… (而言)”。如: Let me pick it up for you. 让我为你捡起来。 Watching TV too much is bad for your health. 看电视太多有害于你的健康。 4. 表示时间、距离,意为“计、达”。如: I usually do the running for an hour in the morning. 我早晨通常跑步一小时。We will stay there for two days. 我们将在那里逗留两天。 5. 表示去向、目的,意为“向、往、取、买”等。如: let’s go for a walk. 我们出去散步吧。 I came here for my schoolbag.我来这儿取书包。 I paid twenty yuan for the dictionary. 我花了20元买这本词典。 6. 表示所属关系或用途,意为“为、适于……的”。如: It’s time for school. 到上学的时间了。 Here is a letter for you. 这儿有你的一封信。 7. 表示“支持、赞成”。如: Are you for this plan or against it? 你是支持还是反对这个计划? 8. 用于一些固定搭配中。如: Who are you waiting for? 你在等谁? For example, Mr Green is a kind teacher. 比如,格林先生是一位心地善良的老师。
to与for的用法和区别
to与for的用法和区别 一般情况下, to后面常接对象; for后面表示原因与目的为多。 Thank you for helping me. Thanks to all of you. to sb.表示对某人有直接影响比如，食物对某人好或者不好就用to; for表示从意义、价值等间接角度来说，例如对某人而言是重要的，就用for. for和to这两个介词，意义丰富，用法复杂。这里仅就它们主要用法进行比较。 1. 表示各种“目的” 1. What do you study English for? 你为什么要学英语？ 2. She went to france for holiday. 她到法国度假去了。 3. These books are written for pupils. 这些书是为学生些的。 4. hope for the best, prepare for the worst. 作最好的打算，作最坏的准备。 2．对于 1．She has a liking for painting. 她爱好绘画。 2．She had a natural gift for teaching. 她对教学有天赋/ 3．表示赞成同情，用for不用to. 1. Are you for the idea or against it? 你是支持还是反对这个想法？ 2. He expresses sympathy for the common people.. 他表现了对普通老百姓的同情。 3. I felt deeply sorry for my friend who was very ill. 4 for表示因为，由于（常有较活译法） 1 Thank you for coming. 谢谢你来。 2. France is famous for its wines. 法国因酒而出名。 5．当事人对某事的主观看法，对于（某人），对…来说（多和形容词连用）用介词to，不用for.. He said that money was not important to him. 他说钱对他并不重要。 To her it was rather unusual. 对她来说这是相当不寻常的。 They are cruel to animals. 他们对动物很残忍。 6．for和fit, good, bad, useful, suitable 等形容词连用，表示适宜，适合。 Some training will make them fit for the job. 经过一段训练，他们会胜任这项工作的。 Exercises are good for health. 锻炼有益于健康。 Smoking and drinking are bad for health. 抽烟喝酒对健康有害。 You are not suited for the kind of work you are doing. 7. for表示不定式逻辑上的主语，可以用在主语、表语、状语、定语中。 1．It would be best for you to write to him. 2．The simple thing is for him to resign at once. 3．There was nowhere else for me to go. 4．He opened a door and stood aside for her to pass.
英语介词用法详解
英语常用介词用法与辨析 ■表示方位的介词：in, to, on 1. in 表示在某地范围之内。如： Shanghai is/lies in the east of China. 上海在中国的东部。 2. to 表示在某地范围之外。如： Japan is/lies to the east of China. 日本位于中国的东面。 3. on 表示与某地相邻或接壤。如： Mongolia is/lies on the north of China. 蒙古国位于中国北边。 ■表示计量的介词：at, for, by 1. at表示“以……速度”“以……价格”。如： It flies at about 900 kilometers a hour. 它以每小时900公里的速度飞行。 I sold my car at a high price. 我以高价出售了我的汽车。 2. for表示“用……交换，以……为代价”。如： He sold his car for 500 dollars. 他以五百元把车卖了。 注意：at表示单价(price) ，for表示总钱数。 3. by表示“以……计”，后跟度量单位。如： They paid him by the month. 他们按月给他计酬。 Here eggs are sold by weight. 在这里鸡蛋是按重量卖的。 ■表示材料的介词：of, from, in 1. of成品仍可看出原料。如： This box is made of paper. 这个盒子是纸做的。 2. from成品已看不出原料。如： Wine is made from grapes. 葡萄酒是葡萄酿成的。 3. in表示用某种材料或语言。如： Please fill in the form in pencil first. 请先用铅笔填写这个表格。 They talk in English. 他们用英语交谈(from 。 注意：in指用材料，不用冠词；而with指用工具，要用冠词。请比较：draw in penc il/draw with a pencil。 ■表示工具或手段的介词：by, with, on 1. by用某种方式，多用于交通。如by bus乘公共汽车，by e-mail. 通过电子邮件。
with的用法大全
with的用法大全----四级专项训练with结构是许多英语复合结构中最常用的一种。学好它对学好复合宾语结构、不定式复合结构、动名词复合结构和独立主格结构均能起很重要的作用。本文就此的构成、特点及用法等作一较全面阐述，以帮助同学们掌握这一重要的语法知识。 一、 with结构的构成 它是由介词with或without+复合结构构成，复合结构作介词with或without的复合宾语，复合宾语中第一部分宾语由名词或代词充当，第二部分补足语由形容词、副词、介词短语、动词不定式或分词充当，分词可以是现在分词，也可以是过去分词。With结构构成方式如下： 1. with或without-名词/代词+形容词; 2. with或without-名词/代词+副词; 3. with或without-名词/代词+介词短语; 4. with或without-名词/代词+动词不定式; 5. with或without-名词/代词+分词。 下面分别举例：
1、 She came into the room，with her nose red because of cold.(with+名词+形容词，作伴随状语) 2、 With the meal over ， we all went home.(with+名词+副词，作时间状语) 3、The master was walking up and down with the ruler under his arm。(with+名词+介词短语，作伴随状语。) The teacher entered the classroom with a book in his hand. 4、He lay in the dark empty house，with not a man ，woman or child to say he was kind to me.(with+名词+不定式，作伴随状语) He could not finish it without me to help him.(without+代词 +不定式，作条件状语) 5、She fell asleep with the light burning.(with+名词+现在分词，作伴随状语) 6、Without anything left in the cupboard， she went out to get something to eat.(without+代词+过去分词，作为原因状语) 二、with结构的用法 在句子中with结构多数充当状语，表示行为方式，伴随情况、时间、原因或条件(详见上述例句)。
常用介词用法(for to with of)
For的用法 1. 表示“当作、作为”。如: I like some bread and milk for breakfast. 我喜欢把面包和牛奶作为早餐。 What will we have for supper? 我们晚餐吃什么? 2. 表示理由或原因,意为“因为、由于”。如: Thank you for helping me with my English. 谢谢你帮我学习英语。 3. 表示动作的对象或接受者,意为“给……”、“对…… (而言)”。如: Let me pick it up for you. 让我为你捡起来。 Watching TV too much is bad for your health. 看电视太多有害于你的健康。 4. 表示时间、距离,意为“计、达”。如: I usually do the running for an hour in the morning. 我早晨通常跑步一小时。 We will stay there for two days. 我们将在那里逗留两天。 5. 表示去向、目的,意为“向、往、取、买”等。如: Let’s go for a walk. 我们出去散步吧。 I came here for my schoolbag.我来这儿取书包。 I paid twenty yuan for the dictionary. 我花了20元买这本词典。 6. 表示所属关系或用途,意为“为、适于……的”。如: It’s time for school. 到上学的时间了。 Here is a letter for you. 这儿有你的一封信。 7. 表示“支持、赞成”。如: Are you for this plan or against it? 你是支持还是反对这个计划? 8. 用于一些固定搭配中。如: Who are you waiting for? 你在等谁? For example, Mr Green is a kind teacher. 比如,格林先生是一位心地善良的老师。 尽管for 的用法较多，但记住常用的几个就可以了。 to的用法: 一：表示相对，针对 be strange (common, new, familiar, peculiar) to This injection will make you immune to infection. 二：表示对比，比较 1：以-ior结尾的形容词，后接介词to表示比较，如：superior ,inferior,prior,senior,junior 2: 一些本身就含有比较或比拟意思的形容词，如equal，similar，equivalent，analogous A is similar to B in many ways.
高中英语45个介词的基本用法
——45个基本介词的用法 1、about 【原始含义】 a-b-out “A在B外面” 【引申含义】 [prep] （1）在…到处，在…各处here and there eg: We wandered about the town for an hour or so. He looked about the room. （2）在…附近next to a place eg. She lives about the office. （3）关于in connection with eg: a book about English study I don’t know what you are talking about. [adv] （1）大约close to eg: We left there about 10 o’clock. It costs about 500 dollars. （2）到处，各处 eg: The children were rushing about in the garden. （3）在附近 eg : There is no food about. 【常见搭配】 作介词时的搭配: 一.动词+(about+名词) （1）arrange (about sth) 安排关于某事（2）argue (about sth) 讨论某事 （3）ask (about sth) 询问关于某事（4）boast (about sb/sth) 吹嘘... （5）care (about sb/sth)关心…,对…感兴趣（6）chat(about sth) 谈论某事（7）complain(about sb/sth) 抱怨… （8）dream (about sb/sth) 梦见某人/某物（9）go (about sth) 着手做...；从事...
with用法归纳
with用法归纳 （1）“用……”表示使用工具，手段等。例如： ①We can walk with our legs and feet. 我们用腿脚行走。 ②He writes with a pencil. 他用铅笔写。 （2）“和……在一起”，表示伴随。例如： ①Can you go to a movie with me? 你能和我一起去看电影'>电影吗？ ②He often goes to the library with Jenny. 他常和詹妮一起去图书馆。 （3）“与……”。例如： I’d like to have a talk with you. 我很想和你说句话。 （4）“关于，对于”，表示一种关系或适应范围。例如： What’s wrong with your watch? 你的手表怎么了？ （5）“带有，具有”。例如： ①He’s a tall kid with short hair. 他是个长着一头短发的高个子小孩。 ②They have no money with them. 他们没带钱。 （6）“在……方面”。例如： Kate helps me with my English. 凯特帮我学英语。 （7）“随着，与……同时”。例如： With these words, he left the room. 说完这些话，他离开了房间。 [解题过程] with结构也称为with复合结构。是由with+复合宾语组成。常在句中做状语，表示谓语动作发生的伴随情况、时间、原因、方式等。其构成有下列几种情形： 1.with+名词(或代词)+现在分词 此时，现在分词和前面的名词或代词是逻辑上的主谓关系。 例如:1)With prices going up so fast, we can't afford luxuries. 由于物价上涨很快，我们买不起高档商品。（原因状语） 2)With the crowds cheering, they drove to the palace. 在人群的欢呼声中，他们驱车来到皇宫。（伴随情况） 2.with+名词(或代词)+过去分词 此时，过去分词和前面的名词或代词是逻辑上的动宾关系。
of和for的用法
of 1....的,属于 One of the legs of the table is broken. 桌子的一条腿坏了。 Mr.Brown is a friend of mine. 布朗先生是我的朋友。 2.用...做成的;由...制成 The house is of stone. 这房子是石建的。 3.含有...的;装有...的 4....之中的;...的成员 Of all the students in this class,Tom is the best. 在这个班级中,汤姆是最优秀的。 5.(表示同位) He came to New York at the age of ten. 他在十岁时来到纽约。 6.(表示宾格关系) He gave a lecture on the use of solar energy. 他就太阳能的利用作了一场讲演。 7.(表示主格关系) We waited for the arrival of the next bus. 我们等待下一班汽车的到来。
I have the complete works of Shakespeare. 我有莎士比亚全集。 8.来自...的;出自 He was a graduate of the University of Hawaii. 他是夏威夷大学的毕业生。 9.因为 Her son died of hepatitis. 她儿子因患肝炎而死。 10.在...方面 My aunt is hard of hearing. 我姑妈耳朵有点聋。 11.【美】(时间)在...之前 12.(表示具有某种性质) It is a matter of importance. 这是一件重要的事。 For 1.为,为了 They fought for national independence. 他们为民族独立而战。 This letter is for you. 这是你的信。
介词with的用法大全
介词with的用法大全 With是个介词，基本的意思是“用”，但它也可以协助构成一个极为多采多姿的句型，在句子中起两种作用；副词与形容词。 with在下列结构中起副词作用： 1.“with+宾语+现在分词或短语”，如： (1) This article deals with common social ills, with particular attention being paid to vandalism. 2.“with+宾语+过去分词或短语”，如： (2) With different techniques used, different results can be obtained. (3) The TV mechanic entered the factory with tools carried in both hands. 3.“with+宾语+形容词或短语”，如： (4) With so much water vapour present in the room, some iron-made utensils have become rusty easily. (5) Every night, Helen sleeps with all the windows open. 4.“with+宾语＋介词短语”，如： (6) With the school badge on his shirt, he looks all the more serious. (7) With the security guard near the gate no bad character could do any thing illegal. 5.“with+宾语＋副词虚词”，如： (8) You cannot leave the machine there with electric power on. (9) How can you lock the door with your guests in? 上面五种“with”结构的副词功能，相当普遍，尤其是在科技英语中。 接着谈“with”结构的形容词功能，有下列五种： 一、“with+宾语+现在分词或短语”，如： (10) The body with a constant force acting on it. moves at constant pace. (11) Can you see the huge box with a long handle attaching to it ? 二、“with+宾语+过去分词或短语” (12) Throw away the container with its cover sealed. (13) Atoms with the outer layer filled with electrons do not form compounds. 三、“with+宾语+形容词或短语”，如： (14) Put the documents in the filing container with all the drawers open.
双宾语 to for的用法
1.两者都可以引出间接宾语，但要根据不同的动词分别选用介词to 或for：(1) 在give, pass, hand, lend, send, tell, bring, show, pay, read, return, write, offer, teach, throw 等之后接介词to。 如： 请把那本字典递给我。 正：Please hand me that dictionary. 正：Please hand that dictionary to me. 她去年教我们的音乐。 正：She taught us music last year. 正：She taught music to us last year. (2) 在buy, make, get, order, cook, sing, fetch, play, find, paint, choose,prepare, spare 等之后用介词for 。如： 他为我们唱了首英语歌。 正：He sang us an English song. 正：He sang an English song for us. 请帮我把钥匙找到。 正：Please find me the keys. 正：Please find the keys for me. 能耽搁你几分钟吗(即你能为我抽出几分钟吗)? 正：Can you spare me a few minutes? 正：Can you spare a few minutes for me? 注：有的动词由于搭配和含义的不同，用介词to 或for 都是可能的。如：do sb a favour＝do a favour for sb 帮某人的忙 do sb harm＝do harm to sb 对某人有害
介词at的基本用法
介词at的基本用法： 一、at引导的时间短语通常可表示： 1.在几点几分，例如：at one o’clock(在一点钟) I usually make the bed at one o’clock.. 2.在用餐时间，例如：at lunchtime（在午餐时间） 3.在某个节日，例如：at Christmas 在圣诞节的时候 4.在某个年龄的时候，例如：at the age of 12。在12岁的时候 5.一天中的某段较短的时间，例如：at noon在中午at night在夜里 二、at也可引导地点短语，常用于小地点之前，例如： at the bus stop在汽车站at the butcher’s 在肉店里at school在学校里at home在家里 介词on的基本用法： 一、on可引导地点短语，表示“在…上面”，例如：on the table在桌子上 二、on也可引导时间短语，通常有以下用法： 1.用于“星期”和“月份”中的任何一天之前，例如：On Monday在星期一on April 1st. 2.用于某个“星期几”当天的某段时间，例如：on Monday morning在星期一上午 3.用于具体某一天之前，例如：on that day在那一天On my birthday在我的生日那天 On Christmas day在圣诞节那天 介词in的基本用法： 一、in可引导地点短语，常表示“在…里面”，例如：in the bag在袋子里 二、in引导的时间短于通常有以下用法： 1.在某个世纪，例如：in the 21st century在21世纪 2.在某一年，例如：in 1995在1995年 3.在某一个季节，例如：in spring在春季 4.在某一个月份，例如：in March在三月里 5.在某段时期，例如：in the holidays在假期里 6.在某个持续几天的节日里，例如：in Easter Week在复活周 7.在一天中的某段时间，例如：in the morning在上午（早晨）
初中 英语 介词“with”的用法
介词“with”的用法 1、同, 与, 和, 跟 talk with a friend 与朋友谈话 learn farming with an old peasant 跟老农学习种田 fight [quarrel, argue] with sb. 跟某人打架 [争吵, 辩论] [说明表示动作的词, 表示伴随]随着, 和...同时 change with the temperature 随着温度而变化 increase with years 逐年增加 be up with the dawn 黎明即起 W-these words he left the room. 他说完这些话便离开了房间。2 2、表示使用的工具, 手段 defend the motherland with one s life 用生命保卫祖国 dig with a pick 用镐挖掘 cut meat with a knife 用刀割肉3
3、说明名词, 表示事物的附属部分或所具有的性质]具有; 带有; 加上; 包括...在内 tea with sugar 加糖的茶水 a country with a long history 历史悠久的国家4 4、表示一致]在...一边, 与...一致; 拥护, 有利于 vote with sb. 投票赞成某人 with的复合结构作独立主格,表示伴随情况时，既可用分词的独立结构，也可用with的复合结构： with +名词(代词)+现在分词/过去分词/形容词/副词/不定式/介词短语。例如： He stood there, his hand raised. = He stood there, with his hand raise.他举手着站在那儿。 典型例题 The murderer was brought in, with his hands ___ behind his back A. being tied B. having tied C. to be tied D. tied 答案D. with +名词(代词)+分词+介词短语结构。当分词表示伴随状况时，其主语常常用
for和of的用法
for的用法： 1. 表示“当作、作为”。如: I like some bread and milk for breakfast. 我喜欢把面包和牛奶作为早餐。 What will we have for supper? 我们晚餐吃什么? 2. 表示理由或原因,意为“因为、由于”。如: Thank you for helping me with my English. 谢谢你帮我学习英语。 Thank you for your last letter. 谢谢你上次的来信。 Thank you for teaching us so well. 感谢你如此尽心地教我们。 3. 表示动作的对象或接受者,意为“给……”、“对…… (而言)”。如: Let me pick it up for you. 让我为你捡起来。 Watching TV too much is bad for your health. 看电视太多有害于你的健康。 4. 表示时间、距离,意为“计、达”。如:
I usually do the running for an hour in the morning. 我早晨通常跑步一小时。 We will stay there for two days. 我们将在那里逗留两天。 5. 表示去向、目的,意为“向、往、取、买”等。如: Let’s go for a walk. 我们出去散步吧。 I came here for my schoolbag.我来这儿取书包。 I paid twenty yuan for the dictionary. 我花了20元买这本词典。 6. 表示所属关系或用途,意为“为、适于……的”。如: It’s time for school. 到上学的时间了。 Here is a letter for you. 这儿有你的一封信。 7. 表示“支持、赞成”。如: Are you for this plan or against it? 你是支持还是反对这个计划? 8. 用于一些固定搭配中。如:
for和to区别
1.表示各种“目的”，用for （1）What do you study English for 你为什么要学英语？ （2）went to france for holiday. 她到法国度假去了。 （3）These books are written for pupils. 这些书是为学生些的。 （4）hope for the best, prepare for the worst. 作最好的打算，作最坏的准备。 2．“对于”用for （1）She has a liking for painting. 她爱好绘画。 （2）She had a natural gift for teaching. 她对教学有天赋/ 3．表示“赞成、同情”，用for （1）Are you for the idea or against it 你是支持还是反对这个想法？ （2）He expresses sympathy for the common people.. 他表现了对普通老百姓的同情。 （3）I felt deeply sorry for my friend who was very ill. 4. 表示“因为，由于”（常有较活译法），用for （1）Thank you for coming. 谢谢你来。
（2）France is famous for its wines. 法国因酒而出名。 5．当事人对某事的主观看法，“对于（某人），对…来说”，（多和形容词连用），用介词to，不用for. （1）He said that money was not important to him. 他说钱对他并不重要。 （2）To her it was rather unusual. 对她来说这是相当不寻常的。 （3）They are cruel to animals. 他们对动物很残忍。 6．和fit, good, bad, useful, suitable 等形容词连用，表示“适宜，适合”，用for。（1）Some training will make them fit for the job. 经过一段训练，他们会胜任这项工作的。 （2）Exercises are good for health. 锻炼有益于健康。 （3）Smoking and drinking are bad for health. 抽烟喝酒对健康有害。 （4）You are not suited for the kind of work you are doing. 7. 表示不定式逻辑上的主语，可以用在主语、表语、状语、定语中。 （1）It would be best for you to write to him. （2） The simple thing is for him to resign at once.
高中常见介词的基本用法
介词 介词不能单独作句子成分，而是用来表示名词或代词等和句中其他词的关系，通常放在名词或代词之前，构成介词短语。介词短语作为一个成分在句中可用作定语，表语，状语等。When shall we have the talk on the history of the Party我们何时听党史报告（定语）His elder brother is in the army.他的哥哥在部队。（表语） I went to school at half past seven yesterday.昨天我7：30 上学。（状语） 《 Will you please come along with me跟我一起走好吗（状语） ※同一个汉语词可以译成不同的英语介词。例如： 一幢石头的房子 a house of stone 这个房间的钥匙 the key to this room 明天的票 the ticket for tomorrow 《 （一）About 1．表示地点：在。。。周围；在。。。附近 We took the foreign guests about the campus. 我们带领外宾在校园里各处看看。 2．表示时间：大约。。。；近于。。。时刻前后We left there about six o’clock 我大约在六点左右离开那个地方。 3．表示客体关系：对于；关于；有关。例如：1) I must see him, I’ve heard so much about him 我必须要见他，我听到很多关于他的事情。2) What do you know about China 关于中国你知道些啥 （二）Above 表示位置，职位，数量，年龄等：在。。。上方；在。。。之上；超过。。。 1) Henry’s work is well above the average.亨利的功课大大超过一般水平。 2) A bird is flying above the woods. 一只鸟在树林上飞。 3) The portrait is above the blackboard.一幅肖像挂在黑板的上方。 4) It weighs above five tons. 这东西有5 吨多重。 （三）Across 1．表动作方向/位置：横过；穿过。（在表面）1）The boy helped the old lady across the street. 男孩扶老大娘穿过马路。2) The tree had fallen down across the railway line.树倒啦，横在铁路上。 2．表示地点：在对面；在。。。的另一边。 1）The church is across the river. 教堂在河的对面。 （四）After 1.表示时间或位置：在。。。之后。 1）Please line up one after another. 请一个挨一个排好对。 He goes on working day after day ,week after week without any change. 他继续日复一日地工作，没有丝毫改变。Shut the door after you. 随手关门！ 2．引伸意义：仿照；按照。 Please make sentences after the model. 请照示例造句。 ※（五）Against 1．表示位置：依着；紧靠；撞击；碰着。 1) He rested his bike against the wall.他把自行车靠在墙上。 2) The rain was beating against the windows. 雨敲打着窗户。 2．引伸意义：反对；禁止。 1）Are you for it or against it 你是赞成还是反对 2) Is there a law in this country against spitting right and left 你们国家有没有反对随地吐痰的规定