Radioactive Decay and Dating Methods

This assignment delves into the world of radioactivity and dating techniques, specifically focusing on carbon-14 (C-14) production and its incorporation into the environment through nitrogen atoms. It also explores radiocarbon dating and compares it with potassium-argon dating, highlighting their differences in assessing time intervals for origin of rocks and organic material.

RADIATION PHYSICS

TABLE OF CONTENTS
INTRODUCTION...........................................................................................................................3
1). Do you think radio towers located near houses or schools are safe for residents and
students? Explain why............................................................................................................3
2). By comparing natural and artificial sources of radiation, discuss the likely levels of
radiation that may be experienced by the average Australian, and compare it with exposure
levels for an average Finnish and an average Swedish. Do you think this may change in the
future?.....................................................................................................................................4
3). Assume the WA government has approved to build a nuclear power plant near
Rockingham close to the ocean. As the responsible health physicist what are your concerns
and planning strategies...........................................................................................................5
4). b). Write a balanced equation for a likely decay mechanism of 131I...............................6
5). Which of alpha and gamma 2 radiation is better suited for medical imaging? Give reasons.
................................................................................................................................................6
10). If there were only two modes of decay for a substance, what would the formula for the
half-life be?.............................................................................................................................8
12.A mass of 1-μg radium is found to emit 3.7 × 104 alpha particles per second. If each of
these alphas represents a radioactive transformation of radium, what is the transformation rate
constant for radium?...............................................................................................................8
13. A solution of Hg(NO3)2 tagged with 203Hg has a specific activity of 1.5 × 105 Bq/mL (4
μCi/mL). If the concentration of mercury in the solution is 5 mg/mL, .................................8
14). How is 14 C generated in the environment and incorporate into living things? What is
radiocarbon dating? Compare it with Potassium/Argon dating.............................................9
15). Consider a sample of organic material that contains 1 mg of C. Suppose it has a 14C/ 12C
atom ratio of 1.2×10-14. ......................................................................................................10

INTRODUCTION
This report will explain basic explanation related to radiations emission and its effect on
human health. It will lay emphasis on some consideration related to radiation emitted through
radio towers. It will also cover some planning and strategies that need to be followed and
planned by health physicist while constructing a nuclear power plant.
1). Do you think radio towers located near houses or schools are safe for residents and students?
Explain why
Generally radio towers located near houses or schools are not safe for residents and
students if there is a continuous and long term exposure of radioactive waves. As radio towers
emits radiations and high frequency radioactive waves it may cause warming of human body
tissues. Along with it, there are numerous of other health problems too which can cause severe
damage to human body due to radio tower radiations.
Water is a bipolar liquid which is consists of two poles one is positive pole (Hydrogen)
and another one is negative pole (Oxygen).Human body contains 60% water in it. The
microwaves are used in the telecommunication process. This waves can produce alternating
electric field in the human body. This alternating field attracts the dipole and the direction of the
field force the water molecule to rearrange its position. The positive pole and negative pole
rotates because of the attraction and repulsion. The direction of the field is continuously
changing, this alternate field keeps the dipole rotating. This rotation of water molecule generate
heat cause of the friction. The heat generated by the friction and vibration of water molecule
increases the temperature of the body tissue, which are in contact with the radiation. This
increased temperature can damage the tissues permanently.
Other evidences have shown that the energy of radio frequency waves have relatively low
level of energy which is not sufficient to harm human body organ or cells. There are fewer
evidences related with the fact that radio towers causes health issues like cancer, cell damage or
other brain related issues. Apart from this, there are some laboratory tests that were conducted on
rats showed that high exposure to radio waves my increase the risks of brain tumours. As far as
the radio towers located near schools and residential area is concerned, there are certain
significant reports are there which shows that such radiations do not cause severe health
problems. Therefore, radio towers near schools and residential area do not cause significant harm
to human health.

Cell phone towers. 2018. [Online]. Available through: <https://www.cancer.org/cancer/cancer-
causes/radiation-exposure/cellular-phone-towers.html>.
2). By comparing natural and artificial sources of radiation, discuss the likely levels of radiation
that may be experienced by the average Australian, and compare it with exposure levels for
an average Finnish and an average Swedish. Do you think this may change in the future?
Radiation is a type of energy transmitted by various modes that may be harmful or
effective to human health depending upon its properties. There are basically two types of
Radiations, ionizing and Non- Ionizing. Ionizing radiations are generally, alpha, gamma and beta
radiation, X rays and neutron radiations. Sources of these radiations have been classified as the
natural and Artificial sources.
 Cosmic Radiation- The radiation coming from the sun and cosmic activity in the space
is considered as the cosmic radiation.
 Terrestrial Radiation- This type of radiation is emitted by the radioactive element
present in the environment of earth naturally. The element like Uranium, Thorium, and
Radon are main source of radiation.
 Inhalation Radiation- The gases produces by the natural radioactive element are the
main sources for this kind of radiation.
Further, natural sources of radiation are classified as external and internal sources and
external sources of radiation can be Terrestrial and cosmic. The main components of radiation
that found within earth are Uranium, Thorium and Potassium. Earth has inhibits high number of
radio active substances that are present for a considerable long time period. These radiations may
have adverse effect on human health. Over exposure to natural UV radiation have increased the
risk of skin cancer and health issues such as hyperpigmentation.
As per reports, average American people are likely to have high risk of cancer due to
solar radiations. Australian population have high risks of getting exposed to terrestrial
radioactive material such as Radon, which is not harmful for heath if breathed out in small time
frame. But it can be a hazardous if it gets accumulated on the epithelium bronchial and thus,
creating severe health issues.
As far as the exposure level of Swedish population is concerned, they are being greatly
affected by Chernobyl radiations. Northern and central Swedish people are getting severely
affected by radiation which is increasing the rate of cancer. As described by The Swedish

Radiation Authority, soil and water of the country inhibits different level of radiations.
Furthermore, Swedish population are facing severe problems in pineal gland due to the exposure
of electromagnetic radiations. They are continuously being introduced by the issues of
hyperactivity and serious sleeping problems also. Ton reduce such instances, European council
have also laid down certain recommendations which include, conduction of campaigns to raise
awareness among public about radiation hazards.
Swedish Radiation Protection Foundation. 2019. [Online]. Available through:
<https://www.stralskyddsstiftelsen.se/english/>.
3). Assume the WA government has approved to build a nuclear power plant near Rockingham
close to the ocean. As the responsible health physicist what are your concerns and planning
strategies
There is continuous requirement of maintaining and updating the safety standards before
building any nuclear power plant. Health physicist is the responsible person to regulate and
measure the all the health risks that the population may posses due to the construction of a
nuclear power plant.
As a health physicist an elementary procedure of planning must be prepared and the level
of radiation which is going to be emitted by the plant must be assessed.
Strategic planning regarding the classification of emergency area or zone with the highest
level of risks must be evaluated and monitored. Health physicists need to be highly attentive and
design advanced plans for controlling health hazards in case of emergencies.
11 Team of health physicists need to be highly engaged with the activities of regulating and
monitoring the effect of radiation on environment.11 Related planning and preparedness will include certain specified health assessments
which need to be based on the principle of ALARA. There need to be some measures to
assess credibility of respiratory protection systems. Team of health physicists need to
check the waste disposal system of the plant to assure safety of aquatic life.11 Emission control devises need to be installed and monitored regularly by health
physicists as well other technicians. Human life must be safeguarded by the radiation
exposure by the application of safety standards proposed by International radiation safety
agencies.

11 Airborne risks need to be priorly assessed that can take place during mining, crushing and
other related activities.11 Health physics programs also need to be planned and implemented during construction
process to deliver a sense of clarity to the workforces related to the severe health risks.11 Health reports and clinical assessments plan of the employees and ground level workers
need to be checked within a fixed time interval.
Basic strategies of public protection in a nuclear power plant beyond—Design basis accident.
2016. [Online]. Available through:
<https://www.sciencedirect.com/science/article/pii/S2452303816300061>.
4). b). Write a balanced equation for a likely decay mechanism of 131I
606.3 KeV max 364.489 KeV max
131 53 I ―› Xe ―> Xe
8 days 89.9% 81.7%
5). Which of alpha and gamma 2 radiation is better suited for medical imaging? Give reasons.
Medical imaging is a process of treating specific health problems with the help of
radiations. Medical and clinical imaging which is dome by the help of X-rays are computed
tomography, mammography, angiography
The penetration capacity of the alpha and gamma rays is used for the medical imaging
process. The alpha ray which is used in the medical imaging is known as X-ray. X-rays are
produced when a highly energised electron losses its energy it releases the alpha particles and
this particle are highly mobile and have enough energy to penetrate the thin metal sheet. This
penetration capacity of alpha particle is used in the medical imaging process. According to the
property of alpha ray, it can easily penetrate the body tissues and not capable to passing through
the bones. This quality of the alpha ray is used for the imaging of bones.
Advantages of X-ray
1. This process is faster and easier to view and analyse to bone injuries.
2. High accuracy
3. This is not expensive and easily available in the hospitals.

4. No radiation remain in the human body after the imaging process.
5. It doesn't have any side effect.
Disadvantages of X-ray
1. Excessive exposure have risk of cancer.
The gamma rays are also used in the medical imaging. Imaging using gamma ray have wide
range. Gamma ray imaging can be used examine tumour imaging, internal infection , bone
structure, thyroid gland, cardiac function, brain imaging and Alzheimer. By using the gamma ray
emitting machine 2D and 3D imaging is possible. This rays are used for the specific study of the
organs like lungs, heart, brain and bones.
Advantages of Gamma Rays
1. High speed and high penetration power leads to less scattering in the imaging process.
2. Equipment are not too much expensive.
3. Grater penetration power.
4. High portability.
5. Size of the machine is smaller and lighter.
Disadvantages of Gamma Rays
1. Poor image quality.
2. Takes much time for scanning of organs.
3. The ray emitter need to change regular cause it looses its efficiency after some time.
4. Images are not clear as X-ray.
5. Emission of Radiation is continuous which is harmful.
Use of alpha ray and gamma ray in the medical imaging has huge scope. The imaging
process using X-ray is better than gamma ray because the image quality of alpha ray process is
more clear and sharper than the gamma ray method. The radiation used in the gamma ray process
is harmful and unstoppable. For the medical imaging alpha ray process is more efficient and
productive.
Available through:
<https://www.texasgateway.org/resource/225-medical-applications-radioactivity-diagnostic-
imaging-and-radiation>.

10). If there were only two modes of decay for a substance, what would the formula for the half-
life be?
General formula for calculating half life for in a branching decay is
λ total =λ 1 +λ 2
(1/T ½) total = (1/T ½) 1 + (1/T ½) 2
12.A mass of 1-μg radium is found to emit 3.7 × 104 alpha particles per second. If each of these
alphas represents a radioactive transformation of radium, what is the transformation rate
constant for radium?
As per the given data,
N= 3.7 x 10 4, t= 1 s, therefore, number of radium atoms per microgram is N= 6.02 x 10 23
atoms/mol x Wg, A g/mol
N= 6.02 X 10 23 atoms/ mol x 10 -6 g= 2.66 x 10 15 atoms 2.26 x 10 2 g/mol
Therefore, Transformation rate of constant is 3.4 x 104 atoms/ 2.66 x 10 15 atoms 1 N/N = 1.27 x
10 -11 t
On per year basis transformation rate is
1.27 x 10 -11 s -1 x 8.64 x 10 4 s d x 2.65 x 10 2 d yr
= 4.02 x 10 -4 per yr
13. A solution of Hg(NO3)2 tagged with 203Hg has a specific activity of 1.5 × 105 Bq/mL (4
μCi/mL). If the concentration of mercury in the solution is 5 mg/mL,
(a) what is the specific activity of the mercury?
SA (Hg) = 1.5 x 10 5 Bq/mL
5 mg Hg/mL
= 0.3 x 10 5 Bq/mg Hg

(b) what fraction of the mercury in the Hg(NO3)2 is 203Hg?
The fraction of mercury is given by
SA (Hg)/ SA (203 Hg)
SA (203 Hg)= 3.7 x 10 10 x (226 x 1600 yr x 365 d/yr)/ 203 x 46.5 days = 5.2 x 10 14 Bq/ g (1.4 x
10 4 Ci/g)
therefore the weight fraction of 203 Hg is,
0.3 x 10 8 Bq/g Hg/5.2 x 10 14 Bq/g 203 Hg
= 5.8 x 10 -8 (g 203 Hg/ g Hg)
(c). what is the specific activity of the Hg(NO3)2?
It may be assumed that formula weight of Hg(NO3)2 is 324. 63 due to the presence of
small fraction of mercury 203 Hg. Therefore, the concentration of Hg(NO3)2 may be calculated as
(324. 63 mg Hg (NO3)2 /200.61 mg Hg) x 5 mg Hg/ mL= 8.1 mg Hg(NO3)2/ mL
The specific activity of Hg(NO3)2 is
(1.5 x 10 5 Bq/mL)/ 8.1 mg Hg (NO3)2 = 1.9 x 10 4 Bq/mg Hg (NO3)2 [0.5 μCi/ mg Hg (NO3)2]
14). How is 14 C generated in the environment and incorporate into living things? What is
radiocarbon dating? Compare it with Potassium/Argon dating
Carbon 14 used to be generated in stratosphere and upper layer of atmosphere with the
help and action of neutrons of cosmic rays on nitrogen atoms. It forms carbon dioxide by getting
oxidized in the air. The rate of carbon 14 depends vary with the fluctuations in cosmic rays
intensity. The whole process of C 14 production starts with the collision of secondary cosmic
rays wityh nitrogen atoms. This collision form C 14 atoms and hydrogen atom. There is large
amount of nitrogen present in the atmosphere which form a considerable amount of C 14. After
production with nitrogen atoms, it also gets combine with O2 to form, Carbon dioxide gas. CO2
is absorbed by plants by the help of photosynthesis process and incorporated into human cyccle
through direct consumption of vegetation.

Radiocarbon dating or carbon dating is a technique or method which is used by scientist
to measure the age of carbon containing objects. This method generally done by Accelerator
Mass Spectrometer and Liquid Scintillation Counter.
Potassium argon dating is method to detect the content of radio-potassium and radio-
argon ratio present in rocks. The main difference between carbon dating and potassium- argon
dating is that potassium- argon dating asses the time interval of origin of rocks.
Carbon-14 and the environment. 2012. [Online]. Available through:
<https://www.irsn.fr/EN/Research/publicationsdocumentation/radionuclidessheets/
environment/Pages/carbon14-environment.aspx>.
15). Consider a sample of organic material that contains 1 mg of C. Suppose it has a 14C/ 12C
atom ratio of 1.2×10-14.
(a) How many 14C atoms are present?
N= 10- / 12 g/g-atom * 6.02 X10 atoms/ g-atom = 5.02 X 1019 atoms.
14 C atoms = (1.2x 10 -14) (5.02 x 10 19) = 6.02 x 10 5
(b) What would be the expected 14 C disintegration rate for this sample?
A= λN= ℓn2/ [(5730y) (3.15x 10 7 s/y) (6.02x 10 5)]
= 2.3 x 10 -6 Bq= 0.2 dis/day
(c) What is the age of this sample?
Age = ℓn (227 x 10 -6)/(2.3 x 10 -6)
ℓn2/ 5730 y
= 38,000 y