Text b boiling water reactors

Pre-reading tasks

1. The text you are to read is headlined “Boiling water reactors”. In your opinion, what problems are discussed in this text?

2. If you were to make a report on this theme what would you speak about? What information would you include in your report? Write down 5-6 key sentences.

3. Think of 4-5 questions the answers to which you would to find in the text below.

4. In pairs, discuss these questions. In case you can’t answer your groupmate’s questions, give your opinion. ( How many of the questions did you manage to answer using the information of the text?)

5. The definitions of the words given in bold type in the text are in the box below. Match these words and their definitions.

round plate or short cylinder of wood or metal, fitting closely inside another cylinder or tube in which it moves up and down or backwards and forwards used in engines, pumps, etc.

apparatus for the controlled production of nuclear energy.

set of toothed wheels working together in a machine, esp. such a set to connect the engine of a motor vehicle with the road wheels.

mechanical device for controlling the flow of air, liquid, gas or electrons in one direction only.

(the amount of) force exerted continuously on or against smth by smth which touches it.

material for producing heat or other forms of energy.

to place (to fix) apparatus in position for use.

violent, rushing steam of liquid (esp. water).

bar or rod joining parts of a machine, or transmitting power.

engine or motor whose driving-wheel is turned by a current of water, steam or air.

Reading

Read the text and fulfill the tasks to follow.

Boiling water reactors

Consider the simplified schematic of one of the most common types of nuclear reactor, a boiling water reactor. (See the accompanying illustration.) Boiling water reactors were first pioneered in the United States, where a number of them continue to produce electricity. Japan has recently installed several boiling water reactors of a more advanced design.

A boiling water reactor is, in the end, a type of steam engine, and has much in common with other steam engines.

But while many of the design concepts employed in these reactors are the same as what one finds in the early steam engines, the technology employed in nuclear reactors has, not surprisingly, been greatly modified to make better use of the tremendous steam temperatures and pressures that these plants are capable of producing.

Apart from the fuel used by these reactors and the scale on which they operate, the most obvious difference between Newcomen’s and Watt’s engines and contemporary boiling water reactors is the turbine. The turbine is the analogue of Watt’s sun and planet gear system. It converts the linear or straight-line motion of flowing steam into rotary motion. Turbines are designed to rotate continuously in one direction and at a steady speed and are driven by the high-pressure steam that flows in a continual torrent out of the pressure vessel, the analogue of Newcomen’s boiler. Designers prefer to use turbines because they have found that the back-and-forth motion of pistons, the continual opening and closing of valves, and the sun and planet gear systems are poorly suited for electrical power generation, a process in which all components must operate for prolonged periods of time under conditions of high temperature, high pressure, and other large forces.

For boiling water reactors, the cycle by which electricity is produced works as follows:

1. Upon passing through a valve, the expanding steam pushes against the blades of the turbine, causing the turbine to spin. The turbine is connected to the electrical generator, the device that actually produces electricity, by a shaft. (The entire purpose of any power plant is to drive the generator.)

2. Water is pumped into the reactor vessel, where some of it is converted to high-temperature, high-pressure steam.

3. After exiting from the turbine, the steam enters the condenser, where it is cooled and in the process condenses back to the liquid state. Cooling occurs when the steam comes into contact with a device called a heat exchanger. The heat exchanger is kept cool by water that circulates through it continuously. The water that cools the heat exchanger is physically separate from the water that passes through the pressure vessel. Only heat, not water, is exchanged inside the condenser. One purpose of the condenser is to reduce the back pressure of the steam after it has exited the turbine. In a way that is conceptually similar to the function of Watt’s condenser, the condenser in the boiling water reactor enables the turbine to make maximum use of the steam.

4. Heat is generated by the nuclear fuel, which is located in the reactor vessel.

5. From the condenser the liquid water is pumped back into the pressure vessel, and the cycle repeats.

6. The steam, which leaves the pressure vessel at about 550°F (290°C) and at a pressure of about 71 atmospheres, travels along the steam line until it reaches the turbine.

Boiling water nuclear power plants have a great deal in common with their Age of Steam predecessors. They are machines that use thermal energy to create steam to do mechanical work. The characteristic that most distinguishes these nuclear power plants from other types of heat engines is the fuel that they use to generate thermal energy, but the consequences of using nuclear fuel are profound.

Tasks

1. The derivatives of the words given in the box are in the text. Find and name them.

to boil	nucleus	scheme	to condense	to design	to differ
to react	to cool	to press	to continue	to open	to generate

2. Make up collocations using the words of two columns. Each word can be used once only. (Make use of the text if necessary). Think of and write down 2-3 sentences where these collocations can be used.

to produce	reactor
advanced	poorly
to condense to	use of
to install	electricity
to suit	water
to employ	continuously
to pump	liquid state
to make	design
to rotate	technology

3. Replace the word in italics with a suitable word from the box.

function	revolves	makes	set up	generated
except for	differentiates	conventional	placed	applied

1. The most common type of nuclear reactor is a boiling water reactor.

2. Japan has installed several boiling water reactors.

3. Technology employed in nuclear reactors has changed greatly.

4. Apart from the fuel used by these reactors there are some other differences between them and Watt’s engine.

5. It rotates continuously.

6. All these components must operate for long periods of time.

7. Electricity is produced in accordance with a certain cycle.

8. Nuclear fuel is located in the reactor vessel.

9. It causes the turbine to spin.

10. This is the characteristic that distinguishes nuclear power plants from other types of heat engines.

4. The sentences describing the cycle by which electricity is produced are jumbled. Arrange them in the logical order.

5. Give answers to the following questions.

1. What is the most common type of nuclear reactors?

2. Where were boiling water reactors first used?

3. Are they still used?

4. Do modern nuclear reactors employ the same technology as the early steam engines?

5. How do turbines function?

6. Why do designers prefer to use turbines?

7. Under what conditions must all parts of a water boiling reactor operate?

8. How many stages does the cycle of electricity production include?

9. Why can we say that boiling water reactors have much in common with their steam predecessors?

6. Enumerate differences and similarities between boiling water reactors and their steam predecessors comparing

• the fuel used,

• the turbine and its analogue – Watt’s sun and planet gear system,

• service conditions.

(If there is not enough information in the text for making a comparison, find some other facts that help you to fulfill the task).

7. Describe the cycle by which electricity is generated. Make use of the following key words and expressions.

• heat, to generate, nuclear fuel, to locate, reactor vessel;

• to pump water, to convert to, high-pressure steam;

• steam, to travel, to reach, turbine;

• turbine, to spin, to connect, electrical generator, to produce electricity;

• to exit the turbine, steam, to enter, condenser, to cool, liquid state, to come into contact, heat exchanger, to circulate, , heat to exchange, purpose, to reduce, steam back pressure;

• liquid, to pump back, pressure vessel, to repeat the cycle.

8. Write a short essay about advantages and shortcomings of boiling water reactors.