Надеина Л.В. Радиоэкология
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contributor to the absorption coefficient. The scattering occurs without the
loss of energy. Scattering is mainly in the forward direction.
Photodisintegration (PD) is the process by which the x-ray photon is
captured by the nucleus of the atom with the ejection of a particle from the
nucleus when all the energy of the x-ray is given to the nucleus. Because of
the enormously high energies involved, this process may be neglected for the
energies of x-rays used in radiography.
13.1 Find the answers to the following questions.
1) What types of interactions do you know?
2) What do the interactions include?
3) Does the subsequent emission of lower energy photons contribute to the
image making process?
4) Why does the x-ray photon lose energy?
5) What does the x-ray photon continue to do after losing energy?
6) What does the energy shift depend on?
7) Does scattering occur without the loss of energy?
8) Why may photodisintegration be neglected for the energies of X-rays used
in radiography?
13.2 Join the parts of sentences.
Pair production
Photoelectric absorp-
tion of x-rays
Thomson scattering
Compton scattering
Photodisintegration
occur(s)
is
when the x-ray photon interacts with
the whole atom so that the photon is
scattered with no change in internal en-
ergy to the scattering atom, nor to the x-
ray photon.
when the x-ray photon is absorbed,
resulting in the ejection of electrons
from the outer shell of the atom, and
hence the ionization of the atom.
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the process by which the x-ray pho-
ton is captured by the nucleus of the
atom with the ejection of a particle from
the nucleus when all the energy of the x-
ray is given to the nucleus.
when an electron and positron are
created with the annihilation of the x-ray
photon.
when the incident x-ray photon is de-
flected from its original path by an in-
teraction with an electron.
14. Choose the correct answer.
1. Who is given credit for the discovery of X-ray?
a) Henri Becquerel
b) Wilhelm Roentgen
c) Marie Curie
d) Pierre Curie
2. After traveling through two half-value layers, the incident radiation has
been reduced to
a) 50%
b) 35%
c) 20 %
d) None of the above
3. Who is given credit for the discovery of radioactive materials?
a) Henri Becquerel
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b) Wilhelm Roentgen
c) Marie Curie
d) Pierre Curie
4. Stationary lab or shop X-ray systems usually rely on what to limit expo-
sure to the radiation?
a) Distance controls
b) Time limits
c) Shielding
c) All of the above
5. X-rays and Gamma rays are a form of
a) Light
b) Particle radiation
c) Electromagnetic radiation
d) Both B and C
6. X-rays and Gamma rays have significant penetrating power due to their
a) Short wavelength
b) Medium wavelength
c) Long wavelength
d) Wide range of wavelengths
7. A specific radioactive source will always produce gamma rays at the same
a) Intensity
b) Activity
c) Energy levels
d) None of the above
8. Ionizing radiation can be used in industrial radiography because the health
hazards
a) Have been eliminated with controls and procedures
b) Are minimized through controls and procedures
c) Are worth the risk
d) Are being ignored
9. Higher energy radiation will have more
a) Speed
b) Incident intensity
c) Penetrating power
d) Both B and C
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10. Radiographic contrast describe
a) The sharpness of lines in a radiograph
b) The differences in photographic density in a radiograph
c) The average photographic density in a radiograph
d) The difference in density between two different radiographs
11. There are four types of radiation-matter interactions that can contribute to
the total attenuation. These are
a) Compton scattering, pair production, photoelectric absorption,
rayleigh scattering
b) Compton scattering, electron exchange, photoelectric absorption,
rayleigh scattering
c) Electron exchange, pair production, photoelectric absorption,
e) rayleigh scattering
f) None of the above
12. X-rays and Gamma rays are often referred to as photons because
a) They possess a charge
b) They have mass
c) They occur as small packets of energy
d) None of the above
13. Which of the following does not affect radiographic contrast?
a) Attenuation differences in the component being inspected
b) The wavelength of the radiation used
c) The amount of scattered radiation
d) The level of current used for the exposure
14. In comparison with lower-voltage radiographs, high voltage radiographic
images have
a) Less contrast sensitivity
b) Greater contrast sensitivity
c) Greater amounts of scatter radiation relative to primary beam
intensity
d) Less latitude
15. Film contrast is determined by
a) The type of film used
b) The process by which the film was developed
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c) The radiation energy used
d) Both A and B
16. Which two types of radiation-matter interactions account for the majority
of attenuation in typical industrial radiography?
a) Compton scattering and photoelectric absorption
b) Compton scattering and pair production
c) Pair production and photoelectric absorption
d) None of the above
17. A radiograph made with an exposure of 8mAm produces a density of 1.8.
The sensitometric curve shows a difference in relative exposure between a
density of 1.8 and the target density of 2.5 is 4. What must the new exposure
time be to produce a radiograph with a density of 2.5?
a) 4 mAminutes
b) 2 mAminutes
c) 32 mAminutes
d) None of the above
18. When using geometric magnification to produce a radiograph, the pe-
numbra will be reduced by
a) A longer exposure
b) A faster film speed
c) A smaller source spot size
d) More X-ray energy
19. When flaws are in unknown locations, radiography is best suited for the
detection of
a) Volumetric defects such as porosity
b) Tight linear defects such as cracks
c) Material delaminations
d) The flaw type does not matter
20. X-rays and Gamma rays present a health risk because they are a form of
ionizing radiation, which means that the radiation has enough energy to
a) Vibrate water molecules and generate heat
b) Break chemical bonds
c) Break physical bonds
d) None of the above
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15. Here some key phrases and words to do the presentation. Choose one of
four subjects below and give a presentation.
Let me start by saying just a few words about my own background. I am
………….
I’m going to inform you about ……..
We are here today to decide \ agree \ learn about……
I shall only take ( ) minutes of your time.
I have divided my presentation into X sections......
In the first section I will \ am going to describe.............
Then I will \ am going to go on to .........
After that I will am going to look at.........
Finally I will \ am going to..........
If we can now look at……….
If you have a look at this figure here.......
As you can see from the table.......
This particular slide shows.......
The main explanation for this is……
This is \ can be explained by two factors. First…. Second………..
Some of you may be wondering how can this be done?
This means that...........
As a result............
Are there any questions so far?
I welcome questions if at any point you don’t understand something.
So, we have looked at…. and we’ve seen that……
To summarize, I’d like to……..
I would like to thank you for your interest and attention
If you have any questions please I’m ready to answer them.
1) First therapeutic applications of X-rays.
2) Greek philosopher Anaxagoras states that matter cannot be created nor
destroyed
.
3) Discovery of radioactivity of thorium by G. Schmidt.
4) Thomas Edison reports eye injuries from X-rays.
16. To get the additional information read Appendix.
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Unit III
Radioactive materials in the environment: HOT PARTICLES
Warming-up
Fallout is the residual radiation hazard from a nuclear explosion, so
named because it "falls out" of the atmosphere into which it is spread during
the explosion. It commonly refers to the radioactive dust created when a nu-
clear weapon explodes. This radioactive dust, consisting of hot particles, is a
kind of radioactive contamination.
Picture 1
photo by Del Tredici, Burdens of Proof by Tim Connor,
Energy Research Foundation (1997)
Picture 2
«Hot» or radioactive particle in lung tissue»
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This is a photo of a «hot particle» (in this case it is a 1 micron particle of
plutonium, and it shows the alpha tracks emitted from that particle in one
year).
Look at the picture2 and answer the questions:
1. What does the dark, star-like image in this photograph show?
2. Can alpha radiation from plutonium and other alpha-emitting ra-
dionuclides be blocked by skin or even a piece of paper?
3. Is it the most biologically destructive form of ionizing radiation when
the alpha-emitting substance is deposited in the soft tissue of internal organs
like the lung?
4. How do you think what period of time the alpha tracks shown in pic-
ture 2 were captured?
1. Mind the meaning of the following words and use them to read the
text «Investigating fallout from nuclear testing».
English Russian
explosion взрыв, вспышка
disperse рассеивать
yield выход, отдача
precipitation выпадение, осаждение
fallout радиоактивные осадки
tiny крошечный, очень маленький
contamination загрязнение, заражение
trial испытание
fissile делящийся, расщепляющийся
encompass охватывать
tropopause тропопауза
irradiation иррадиация, излучение
ingestion всасывание
detonation детонация, взрыв
fireball ядерный гриб, ядерное облако
mixture смесь, смешение
coagulation свертывание, коагуляция
decay затухать
leakage утечка
eject извергать, выбрасывать
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altitude высота
binary бинарный, двойной
discrete дискретный
homogeneity однородность, гомогенность
debris осколки, обломки, руины
measure измерять
hazard риск, опасность
caution предостережение, предупреждение
fission деление атома ядра при цепной реакции
detectable обнаруживаемый
2. Pay attention to the pronunciation these chemical elements.
plutonium [plu:´təuniəm] nickel [´nikl]
aluminum [ə´lu:minəm] chromium [´krəumiəm]
potassium [pə´tæsiəm]
cobalt [´kəubɔ:lt]
calcium [´kælsiəm] carbonate [´ka:b(ə)neit]
iron [´aiən]
chlorine [´klɔ:ri:n]
uranium [juə´reiniəm] lead [led]
neptunium [nep´tj:niəm]
americium [ˏæmə´risiəm]
manganese [´mæŋgəni: z] titanium [tai´teiniəm]
3. Match the numbers with the letters and find out the meaning of word
combinations.
1)concentrations of certain
radionuclides
a) роль, которую играют горячие
частицы при оценивании радиаци-
онных рисков
2) tiny bits of materials contain-
ing radioactive chemical ele-
ments
b) те же современные аналитиче-
ские технологии, используемые для
исследования «горячих частиц»
3) further separation of the con-
densate
c) явления, ведущие к образованию
«горячих частиц»
4) because of the influence of
wind, gravity and the turbulence
d) крошечные частицы вещества,
содержащие радиоактивные хими-
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of the atomic cloud ческие элементы
5) analysis of radioactive mate-
rial deposited on the ground
e) из-за воздействия ветра, плотно-
сти и турбулентности атомного об-
лака
6) ingestion of contaminated
food
f) дальнейшее отделение
конденсата
7) the nature and concentrations
of radionuclides
g) морфологические свойства «го-
рячих частиц» и их поведение в ес-
тественной среде
8) the major elements identified
h) информация о «горячих
частицах», полученная посредст-
вом радиохимического, химическо-
го и физического анализов облом-
ков
9) the detonation point
i) анализ осажденного в почве ра-
диоактивного материала
10) the contamination of consid-
erable portions of land
j) прием зараженной пищи
11) the behaviour of the core of
nuclear devices under simulated
faulty detonation conditions
k) характер и концентрация радио-
нуклидов
12) the information on hot parti-
cles obtained through radio-
chemical, chemical and
physical analyses of debris
l) поведение активной зоны ядер-
ного устройства в условиях искус-
ственного взрыва
13) morphological properties of
hot particles and their behaviour
in the natural environment
m) загрязнение значительной части
территории
14) the phenomena leading to
the formation of hot particles
n) начало детонации
15) the same modern analytical
techniques used to investigate
o) большинство установленных
элементов