Надеина Л.В. Радиоэкология

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{+} Radioecology is

being studying this

semester.

{?} Is radioecology

being studying this

semester?

{–} Radioecology is

not being studying

this semester.

{+} Radioecology

was being study-

ing last semester.

{?} Was radio-

ecology being

studying last se-

mester?

{–} Radioecology

was not being

studying last se-

mester.

Perfect

(to have been +

Part II)

Have (has) been +

Part II (ed, V

3 )

________________

{+} Radioecology

has already been stu-

died.

{?} Has radioecology

been studied yet?

{–} Radioecology

has not been studied

yet.

Had been + Part

II (ed, V

3 )

______________

{+} Radioecology

had been studied

by December last

year.

{?} Had radio-

ecology been stud-

ied?

{–} Radioecology

had not been stud-

ied.

Shall (will) have

been + Part II

(ed, V

3 )

______________

{+} Radioecology

will have been

studied by next

year.

{?} Will radio-

ecology have been

studied?

{–} Radioecology

will not have been

studied.

6. Read the text «The Chernobyl accident» and in brackets choose the cor-

rect form of the verb in Passive Voice. (See the table «PassiveVoice», p. 9).

The Chernobyl accident

The increase of thyroid cancers among children in various districts of Belarus.

Early in the morning on 26 April 1986 at 1.24 local time a very severe

accident occurred at the fourth unit of the Chernobyl nuclear power plant in

the former Soviet Union. The operators made some serious errors which re-

sulted in a drastic increase of the effect and ended up in two explosions. The

buildings (had been severely damaged /were severely damaged) and fuel

fragments and burning graphite blocks (were found / had been found) out-

side them. Material from the reactor core, including large amounts of radio-

active material and smoke from the fire, (are ejected / were ejected) verti-

cally several kilometers into the air. The reactor core was open to the air and

in the following days sealing materials (were being dumped / were

dumped) into the core. However, this resulted in increased core temperature

and increased release of radioactive material. It was not until May 5 that they

managed to cool the reactor with liquid nitrogen and the release of radioac-

tive material (could be stopped / have been stopped or at least be reduced /

have been reduced) to a low amount. The unit 4 core contained an inventory

of 4x10

Bq and it (is being estimated / has been estimated) that at least

1x10

to 2x10

Bq was released. During these 10 days, a large part of the

inventory of radionuclides of the reactor (had been spread out / was spread

out) not only over a part of the Soviet Union but also over most of the coun-

tries in Europe and detectable amounts over nearly all parts of the northern

hemisphere. One of the biggest accidents in the world had occurred.

After the two explosions, large amounts of burning material (had been

spread out / was spread out) around the buildings and fires occurred on

several sites. Shortly after the accident, three fire-fighting teams arrived and

augmented the teams at the site. The main challenges were to prevent the fire

from spreading to unit 3 since the roof of the machine hall shared by units 3

and 4 was burning. The fire-fighters did not have appropriate protective

clothing and they received quite high radiation doses, both whole-body irra-

diation due to the high external dose rate and also high beta contamination

that caused severe beta skin burns. Many of them suffered from acute radia-

tion sickness, with vomiting and nausea already during the fire-fighting. Of

the on-site personnel, about 300 (were being hospitalized / were hospital-

ized) due to acute radiation syndromes and burns. Of these, 28 died due to

acute radiation injuries.

On April 27, the 45,000 inhabitants in Pripiat, the nearest town, (had

been evacuated / were evacuated), followed some days later by all 135,000

people living within a radius of 30 km. Probably none of them will return and

live within the 30 km zone. In addition to the people, some tens of thousands

of cattle (were being evacuated / were also evacuated) from the 30 km

zone.

(http://www.envimed.com/emb08.shtml)

UNIT II

History of Radioactivity

Warming-up

Look at the portraits of these well-known scientists.

Read the information about these scientists match the letters with the

numbers and answer the questions.

1) He was born into a family of scientists. His grandfather had made

important contributions in the field of electrochemistry while his father had

investigated the phenomena of fluorescence and phosphorescence. He not on-

ly inherited their interest in science, he also inherited the minerals and com-

pounds studied by his father. The material he chose to work with was potas-

sium uranyl sulfate, K2UO2(SO4)2, which he exposed to sunlight and placed

on photographic plates wrapped in black paper. When developed, the plates

revealed an image of the uranium crystals. He concluded «that the phospho-

rescent substance in question emits radiation which penetrates paper opaque

to light». Initially he believed that the sun's energy was being absorbed by the

uranium which then emitted X-rays. Further investigation, on the 26th and

27th of February, was delayed because the skies over Paris were overcast and

the uranium-covered plates he intended to expose to the sun were returned to

a drawer. On the first of March, he developed the photographic plates expect-

ing only faint images to appear. To his surprise, the images were clear and

strong. This meant that the uranium emitted radiation without an external

source of energy such as the sun. He had discovered radioactivity, the spon-

taneous emission of radiation by a material.

Later, he demonstrated that the radiation emitted by uranium shared cer-

tain characteristics with X-rays but, unlike X-rays, could be deflected by a

magnetic field and therefore must consist of charged particles. For his dis-

covery of radioactivity, he was awarded the 1903 Nobel Prize for physics.

2) He was a Professor at Wuerzburg University in Germany. Working

with a cathode-ray tube in his laboratory, he observed a fluorescent glow of

crystals on a table near his tube. The tube that he was working with consisted

of a glass envelope (bulb) with positive and negative electrodes encapsulated

in it. The air in the tube was evacuated, and when a high voltage was applied,

the tube produced a fluorescent glow. He shielded the tube with heavy black

paper, and discovered a green colored fluorescent light generated by a mate-

rial located a few feet away from the tube. He concluded that a new type of

ray was being emitted from the tube. This ray was capable of passing through

the heavy paper covering and exciting the phosphorescent materials in the

room. He found that the new ray could pass through most substances casting

shadows of solid objects. He also discovered that the ray could pass through

the tissue of humans, but not bones and metal objects.

(www:history.htm)

1. Can you name these scientists?

2. Were their researches connected with the topic of this unit?

3. Whose film of hand do you think it was?

1. Do you know that …?

History of the Radioactivity Warning Symbol

Did you know the original radiation warning symbol that was devised in

1946 at that University of California, Berkeley Radiation Laboratory was

magenta on a blue background?

☀ The colours were changed to a black trefoil on a yellow background,

with specific attributes regarding the relative diameter of the blades and their

orientation.

☀ The central circle has radius R, with the inner section extending for a

radius of 1.5 R.

☀ The fan blades are 5 R, separated from each other by 60°.

(www:History of the Radioactivity warning symbol-Did you know.htm)

1.1 This is a collection of radiation warning symbols and radioactivity

warning signs. What do the symbols and signs warn about?

1.2 Match the letters with the numbers.

1) This radiation symbol is a little fancier than your standard trefoil, but it is

easy to recognize the significance of the symbol.

2) This is the warning symbol for non-ionizing radiation.

3) This symbol warns of a radiation hazard.

4) This symbol warns of the risk of exposure to laser beams or coherent

radiation.

5) This sign warns of a radiation hazard.

6) The original radiation warning symbol was devised in 1946 at the

University of California, Berkeley Radiation Laboratory. Unlike the

modern black on yellow symbol, the original radiation symbol featured a

magenta trefoil on a blue background.

7) This trefoil is the hazard symbol for radioactive material.

8) This symbol indicates the presence of an optical radiation hazard.

9) The radiation symbol warning of an ionizing radiation hazard.

10) This is the US Army symbol for a radiation WDM or nuclear weapon.

11) This sign warns of laser radiation.

12) This is the IAEA ionizing radiation warning symbol.

2. Read the text and for questions 1-9 choose the best answer: A, B or C.

Three Types of Radioactivity

There are three types of radioactivity. Gamma rays come from the nu-

cleus of the atom of a radioactive isotope. They are the most energetic and

most penetrating of all radiation. Some radiation travel as particles not waves

and is also emitted by the radioactive isotope. One is alpha particles that lose

energy quickly. A hand or thin piece of paper stops it. Beta particles are high

speed electrons that travel close to the speed of light and can penetrate a hand

but not concrete.

When an atom undergoes radioactive decay, it emits one or more forms

of radiation with sufficient energy to ionize the atoms with which it interacts.

Ionizing radiation can consist of high speed subatomic particles ejected from

the nucleus or electromagnetic radiation (gamma-rays) emitted by either the

nucleus or orbital electrons.

Alpha Particles

Certain radionuclides of high atomic mass (Ra226, U238, Pu239) decay

by the emission of alpha particles. These alpha particles are tightly bound

units of two neutrons and two protons each (He4 nucleus) and have a positive

charge. Emission of an alpha particle from the nucleus results in a decrease of

two units of atomic number (Z) and four units of mass number (A). Alpha

particles are emitted with discrete energies characteristic of the particular

transformation from which they originate. All alpha particles from a particu-

lar radionuclide transformation will have identical energies.

Beta Particles

A nucleus with an unstable ratio of neutrons to protons may decay

through the emission of a high speed electron called a beta particle. This re-

sults in a net change of one unit of atomic number (Z). Beta particles have a

negative charge and the beta particles emitted by a specific radionuclide will

range in energy from near zero up to a maximum value, which is characteris-

tic of the particular transformation.

Gamma-rays

A nucleus which is in an excited state may emit one or more photons (packets

of electromagnetic radiation) of discrete energies. The emission of gamma

rays does not alter the number of protons or neutrons in the nucleus but in-

stead has the effect of moving the nucleus from a higher to a lower energy

state (unstable to stable). Gamma ray emission frequently follows beta decay,

alpha decay, and other nuclear decay processes.

(www:radiography/physics/gamma.htm)

1. They are the most energetic and most penetrating of all radiation.