Listen to the text and fill in the gaps in the passage below

FORGET NUCLEAR FISSION, HOW ABOUT FUSION?

The sun pumps out some 383 quadrillion watts of energy every second 1__________. So, it's not surprising we've been trying for the last 50 years to harness the abundant clean energy from that process.

2__________ two hydrogen atoms together to produce a helium atom--and liberates energy in the process.

But it takes the Sun's powerful gravity and temperatures of around 14 million degrees Celsius to get these hydrogen atoms stripped down to just their nuclei and able 3_________ known as plasma.

In fact, it will take temperatures of 100 million degrees C to get fusion going on a scale that could fit on our planet. Plus, there's 4_________.

Like the Earth's atmosphere, plasma likes to swirl because of 5_________ from point to point. The result is storms that can cool the plasma and halt fusion.

The International Thermonuclear Experimental Reactor or ITER to be built in Cadarache, France will rely on magnetic fields roughly 100,000 times stronger than the Earth's to contain the plasma and 6_________. At the right density, pressure and temperature, voilà, fusion!

Unfortunately, 7__________ require more energy to operate than they produce. And ITER will cost at least $15 billion to build.

Fusion may have been going on in the Sun for more than four billion years but it still remains just 8__________.

Explain the meanings of the underlined verbs.

3. Do you agree with the author’s point of view? Discuss in a group.

PRESENTATION

Make up a presentation on one of the topics below.

1. The concept of mass defect and its relativistic explanation.

2. Practical examples of mass-energy equivalence.

3. Nuclear weapons based on fission.

4. H-bomb.

5. History of nuclear fusion research and achievements to date.

6. Fission reactors (main types, functioning)

7. Perspectives of nuclear fusion.

(See appendix 4)

SECTION 4

MODES OF RADIOACTIVE DECAY