|
Exercise 5. Match the pairs of synonyms below. |
||
1) |
To liberate |
a) To be destroyed |
|
2) |
It is apparent |
b) Quantity |
|
3) |
To lead to |
c) To remove |
|
4) |
To maintain |
d) To release |
|
5) |
To generate |
e) To split |
|
6) |
To disintegrate |
f) To moderate |
|
7) |
Amount |
g) To result in |
|
8) |
To break up |
h) To sustain |
|
9) |
To enable |
i) To produce |
|
10) |
To induce |
j) To reduce |
|
11) |
To decrease |
k) To permit |
|
12) |
To slow down |
l) To drive |
|
13) |
To control |
m) It is obvious |
|
14) |
To take away |
n) To initiate |
|
15) |
To power |
o) To regulate |
|
Exercise 6. Replace the underlined words with their synonyms from the list below. Use the appropriate form of the verb.
To remove, to release, to disintegrate, to moderate, amount, to regulate, to reduce, to lead to, to maintain, to generate.
1.When the nucleus is split, tremendous energy is liberated.
2.235U is mixed with a much greater quantity of 238U.
3.The size of the reactor core can be decreased.
4.Neutron capture in 238U may result in the formation of 239Рu.
5.233U does not occur in nature but may be produced by exposing 232Th to neutron bombardment.
6.This cross-section is not adequate to sustain a chain reaction in a structure of reasonable size.
7.The function of the cooling system is to take away the heat produced by the fission process.
8.But for the cooling fluid, the reactor would be destroyed as a result of thermal stresses.
9.To maintain a steady chain reaction, it is necessary to control the rate of neutron production.
56
10. The fuel in а natural uranium reactor is surrounded by the material which slows down neutrons rapidly to improve their chances of inducing fission
Exercise 7. Use Reading 5-A to decide if the statements below are true or false. If they are false, correct them. Use expressions of agreement and disagreement below.
I agree with you.
That sounds like a good idea. That's right/true.
You are right! Absolutely!
I don't (really) agree with you. I am not sure about that. That's wrong, I am afraid.
Yes, but…
1.There is a great difference in the operation of a NPP and a coalburning plant.
2.The fission cross-section is the probability that a fission event will occur.
3.Fission is more likely to occur if it is caused by fast neutrons.
4.Water, heavy water and graphite are moderators which are commonly used in fast neutron reactors.
5.The most urgent function of the coolant is to prevent the destruction of the reactor as a result of thermal stresses.
6.The NPP consists of two principal systems: the Nuclear Steam Supply System and the turbogenerator system.
7.Control rods keep the chain reaction from «dying out», but they
cannot prevent it from «running away».
8. Control rods are made of neutron-moderating materials such as boron.
Reading 5-B
Chicago Pile-1
You are going to read a passage about the world's first man-made nuclear reactor. Five sentences or parts of sentences have been removed from the text. Choose from the phrases and sentences A-F the one which fits each gap (1-5). There is one extra sentence which you will not need to use.
A. led to the atomic pile (nuclear reactor) and the first controlled nuclear chain reaction.
57
B.who actually made uranium "burn".
C.a new fissionable element was produced inside the pile during operation.
D.nor could it be very useful as а power source.
E."The atomic pile works successfully. The nuclear chain reaction has been achieved."
F.it was necessary to mix natural uranium with a large amount of carbon in the form of graphite.
The Italian-American physicist Enrico Fermi is sometimes called the Architect of the Atomic Age. It was Enrico Fermi 1). ________. Не was able to do so by utilizing the fact that the effectiveness of fission neutrons in producing the fission оf U235 nuclei increases considerably when they are slowed down. То slow down the original fission neutrons, 2)._______. А large "pile" of graphite bricks with small pieces of natural uranium included in the structure was constructed in great secrecy under the grandstand of the University of Chicago Stadium.
And on December 2, 1942, Professor A. Compton telegraphed to Dr. V. Bush in Washington, D.C. "The Italian navigator has landed in the New World. The natives are friendly." In the secret language of the Manhattan Project this meant: 3).________.
In the Fermi-pile the natural uranium was so highly diluted by carbon that high efficiency in energy production could not be achieved. Owing to the presence of inactive U238 the chain reaction in the pile could not result in an explosion, 4). ________. But although the energy released in the fission of U235 nuclei was less than the amount necessary to light a small electric bulb, 5). _______. This element was plutonium.
Do you know why the first reactor was called a pile? Read the passage below and find out.
The Chicago Pile-1was named so because the reactor was more or less a pile of elements stacked on top of one another, primarily made of uranium pellets separated by graphite blocks. Rods coated with cadmium were used to control the reaction. The pile of blocks was held together by wood. An "atomic pile" was a code word for a device that in peacetime would be known as a "nuclear reactor".
58
Reading 5-C
Reactor Types
Put each of the following words in its correct place in the passage below.
Breeder, light water, boiling, thermal reactors, pressurized, rare, heavy, coolant, fertile, fast-neutron reactors, gas, fissile.
There are many types of nuclear reactors. Basically, they fall into two broad classes: (a) ______ in which the chain reaction is supported by thermal neutrons, and (b) ______ in which fission is produced by fast neutrons.
Thermal reactors are classified according to the type of (c) ______
used. 80% of the commercial reactors in use are cooled and moderated by ordinary water and are known as (d) ______ reactors. Two major types of light water reactors are (e) ______ water reactors, including a Russian version (VVER), and (f) ______ water reactors. The water-cooled graph- ite-moderated channel type reactor (RBMK, the Chernobyl reactor) is also a light water reactor. Most of the remaining 20% of reactors are cooled by
(g) ______ water, like CANDU (the Canadian Deuterium-Uranium reactor), or (h) ______, like the high-temperature gas-cooled reactor.
Thermal reactors use only one uranium isotope – U235, which is very
(i) ______. Besides, they extract only 1-2 % of the energy from uranium. That is why Russia is interested in fast-neutron reactors which make
full use of natural uranium. Fast-neutron reactors can convert (j) ______
materials Th232 and U238 into (k) ______ U233 and Pu239 and produce (or breed) more fuel than they consume. That is why they are called fast
(l) ______ reactors. Fast breeder reactors, by creating fuel from nonfissile isotopes, can increase available world nuclear fuel resources. The general trend in the future development of Russian nuclear power is toward the construction of fast reactors.
Reading 5-D
What is in Nuclear Power?
Read the text and choose a suitable heading for each part. There is one extra heading. Translate Parts 5 and 6 in writing.
ATo err is human
BThe rest is easy
CThe fuel
59
DSupport and opposition
EBe in control
FWhy the whole is more than the sum of its parts
GEinstein was right
1
Commercial nuclear power has been around for nearly half a century. In 1956, the reactor at Calder Hall in north-west England became the first in the world to supply electricity to a national grid. A year later, in Shippingport, Pennsylvania, the US opened its first commercial plant, while France followed suit in 1959 and the Soviet Union in 1964. From the start, great claims were made for the industry: it was going to produce cheap, clean and reliable power. But its critics saw it as costly, polluting, dangerous in the event of an accident, and closely linked to nuclear proliferation.
2
All nuclear power plants use uranium as fuel. With an atomic number of 92 (the number of protons in its nuclei), uranium is the heaviest element found in considerable amounts in nature. It's radioactive.
All the uranium on Earth was formed from lighter elements during supernova ехрlоsions billions of years ago. Material from these exploded stars was strewn across space, and eventually some was incorporated into new stars and their orbiting planets. So nuclear power here on Earth harnesses energy that has been stored in uranium for more than 4.5 billion years. Uranium is fissile - its atomic nuclei can be split to release energy. Its most common isotopes are U-238 and U-235.
3
In fission, the nucleus of а heavy element splits and energy is liberated. То trigger the fission of а uranium nucleus, it must be struck by а neutron. This particle is temporarily absorbed, making the nucleus unstable. The nucleus then splits to form two smaller nuclei, releasing two or three more neutrons in the process. Some of the energy of the nucleus is liberated in the form of the kinetic energy of the particles and gamma radiation.
Einstein’s famous equation Е= mc2 expresses this fact. The mass of the initial nucleus and the neutron that strikes it is greater than that of the split nuclei and released neutrons, because the missing mass was converted into energy.
60