A Lecture on Nuclear Fusion - IELTS Listening Sample Answer

IELTS Listening section comprises four sections - two conversations and two monologues. The candidates need to properly listen to IELTS listening audio as it is played only once. This topic - A lecture on Nuclear fusion is IELTS listening section four. Candidates need to answer the following IELTS listening question types:

• Write the correct answer
• No more than two words/ a number

Topic: A Lecture on Nuclear Fusion

Audio Transcript:

You'll hear a man giving a lecture on nuclear fusion. First, you have some time to look at questions 31 to 33.

Now listen carefully and answer questions 31 to 33.

I'd like to start by thanking so many of you for attending this, my first public lecture, at this magnificent university. I'm going to be talking to you today about nuclear fusion. Before I proceed further, I would like to apologize on behalf of some of our newspapers for the sensationalist and hopelessly inaccurate articles that have been published on the subject over the years. I must confess that my own interest in the subject was actually stimulated by an article, published more than 50 years ago in a popular Sunday tabloid with the impressive title “Power from the sea”. Today, most people would probably interpret such a title as an introduction to a discussion on the latest developments in renewable energy sources such as wave technology or generating electricity from tidal flows, but back then, little, if any, progress had been made in these fields since the invention of the water wheel.

As I recall, following coverage of the opening of the world's first commercial nuclear power station more than 50 years ago, now at Calder hall in 1956, the article promised that we would have limitless, almost free electricity within 10 years. It claimed that we could do this using an isotope of water, deuterium from the sea. This would be used in reactors to combine simple molecules of hydrogen to form helium, releasing energy in the process. Of course, this is different from the process of nuclear fission, which today's nuclear reactors use.

I wouldn't like to say that the article I read is a boy was totally inaccurate. It's true that the concept of producing energy from nuclear fusion, essentially reproducing the reactions by which our sun and other stars produce energy depends on fusing atoms of hydrogen, but the time scale suggested was hopelessly wrong. To this day, despite some very embarrassing false claims from scientists who should have known better we have not been able to produce energy from nuclear fusion in a controllable way. Let me make clear what I mean by this statement. Before some journalists in the audience gets hold of the wrong end of the stick. Yes, we have been able to fuse hydrogen atoms to produce helium and the release of energy, but the balance account has always been negative. We've always had to put more energy into the reaction than we've ever succeeded in getting out. We know the theory works, but we still do not know if we can get fusion to work for us and solve the problem of our energy needs.

Before you hear the rest of the talk, you have some time to look at questions 34 to 40.

Now listen and answer questions 34 to 40.

Here, I will briefly explain these problems before going on to give you a summary of the innovative ways being tested to overcome. First of all, we have to try to understand the incredible physical conditions that exist inside a natural nuclear fusion reactor such as the sun. To start with, we have to create temperatures never experienced on our planet. Indeed, if we had experienced the temperatures required then our planet would never have formed. We have to generate temperatures of at least 100 million degrees celsius in a carefully controlled environment, before we can even hope to produce a fusion reaction. The problems are immense, but it can be done. Many of you will know that you can put your hand into a very hot oven and not get burnt, provided you do not touch any of the surfaces. I won't go into the reasons for this phenomenon, here. But we are applying roughly the same principles in designs for fusion reactors. I think, I can promise you that the heat will be confined to a very small area.

The other major problem we have to find a solution to is, pressure. The pressures in a massive body like the sun are vast, and this is what brings the hydrogen atoms into such close proximity to one another that they fuse into helium. We may not have to achieve the same pressures in a fusion reactor, but even so, it is a huge technological problem.

What then makes me hopeful about the future of energy from nuclear fusion? Perhaps surprisingly, it is developments in laser technology. We can now use lasers to control the nuclear fuel pellets so that they remain suspended inside the reactor without touching the sides. Remember that these pellets are quite small and because they contain atoms of deuterium and tritium, the two isotopic forms of hydrogen that can be used in these reactions, they are quite light. The lasers will also compress the fuel pellet to raise the pressure to that required to initiate the fusion reaction. Another far more powerful laser will be used to heat the fuel pellet to the temperature required. This laser, if you like, will act as the trigger to start the reaction. Once started, it is hoped that the reaction will produce enough energy to maintain itself and also that it will produce a surplus in the form of heat that can be used to produce the steam needed to drive turbines, in order to generate the electricity the world needs.

To give you some idea of how much energy we can produce, it has been calculated that just one kilogram of fusion fuel is capable of producing the same amount of energy as 10,000 tons of fossil fuel. I think you would agree that such an objective is worth, working towards. I believe and I am not alone in this that nuclear fusion could supply the world's energy needs for centuries to come.

Questions 31-40

Q.31-33

Choose the correct answers A-C and write them next to 31-33 on your answer sheet.

31. What does the speaker say about newspapers?

1. they never report developments in science accurately
2. he became interested in his subject because of a newspaper report
3. they only report developments in renewable energy technology

Answer: B

Explanation: The speaker says about newspapers he became interested in his subject because of a newspaper report.

Also check:

32. What significant event took place in 1956?

1. scientists discovered a new source of energy
2. a new type of power station came into service
3. Helium was first produced from hydrogen

Answer: B

Explanation: The opening of the world's first commercial nuclear power station more than 50 years ago, now at Calder hall in 1956, the article promised that we would have limitless, almost free electricity within 10 years.

33. What does the speaker consider to be the main problem with nuclear fusion?

1. irresponsible scientists make false claims on the subject
2. it takes too long to produce the required reaction
3. the reaction has not produced usable quantities of energy

Answer: C

Explanation: The speaker considers to be the main problem with nuclear fusion is the reaction has not produced usable quantities of energy.

Q.34 and 35

Complete the sentences below.

Write NO MORE THAN TWO WORDS AND/ OR A NUMBER for each answer.

34. Temperatures of at least____________ degrees are needed for fusion to take place.

Answer: 100 million

Explanation: to generate temperatures of at least 100 million degrees celsius in a carefully controlled environment, before we can even hope to produce a fusion reaction

35. Creating the pressure required in a ____________ is a major technological problem.

Answer: fusion reactor

Explanation: The incredible physical conditions that exist inside a natural nuclear fusion reactor such as the sun.

Q.36-40

Complete the summary below.

Write NO MORE THAN TWO WORDS for each answer.

In order for nuclear fusion to produce useful quantities of energy isotopes of hydrogen must be brought together at extremely high temperatures and pressures. A number of 36____________ will suspend the fuel so that it does not come into contact with the sides of the 37 ____________ Another one will raise the temperature of the fuel pellet to that required to start the 38 ____________Extra energy released in this process will be used to produce 39 ____________ that can be used to generate electricity. It is believed that the amount of energy that can be produced from

40____________ of fusion fuel is equivalent to that which can be produced from 10000 tonnes of fossil fuel.

Answer 36: lasers

Explanation: The use of lasers to control the nuclear fuel pellets so that they remain suspended inside the reactor without touching the sides.

Answer 37: reactor

Explanation: The use of lasers to control the nuclear fuel pellets so that they remain suspended inside the reactor without touching the sides.

Answer 38: reaction

Explanation: the reaction will produce enough energy to maintain itself and also that it will produce a surplus in the form of heat that can be used to produce the steam needed to drive turbines, in order to generate the electricity the world needs

Answer 39: steam

Explanation: Energy will produce a surplus in the form of heat that can be used to produce the steam needed to drive turbines, in order to generate the electricity the world needs.

Answer 40: 1 kg

Explanation: To give you some idea of how much energy we can produce, it has been calculated that just one kilogram of fusion fuel is capable of producing the same amount of energy as 10,000 tons of fossil fuel.