Name: Radiation Safety
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Construction

This course brings you back to radiation basics — from the atom to sources of radiation — and highlights how radiation can affect you in construction and how you can protect yourself against exposure. 

When we hear the word radiation, we often think of...


Yes, those are all related to radiation, but how is radiation truly defined?


It is the spontaneous breakdown of an atomic nucleus resulting in the release of energy and matter from the nucleus. 3
The time it takes for radioactive decay to reach half of its starting activity is called half-life, which is denoted by the symbol t½.
Radioactive decay usually happens in three different forms:
Alpha decay
Beta decay
Gamma Decay


What is radioactive decay?


Is there a difference between radioactivity and radiation?
Yes.
To differentiate, radiation is the energy or particles that are released during radioactive decay, while radioactivity of a material refers to the rate at which it emits radiation. 4


How Does Radiation Occur?

What are the types of Ionizing Radiation? 2


Alpha radiation (α) happens when the unstable atom emits two protons and two neutrons—basically a helium nucleus. The original atom, with fewer protons and neutrons, becomes a different element.


Beta radiation (β) is when a proton in an unstable atom becomes an electron. Because it loses a proton, the original atom becomes a different element


Photon radiation (gamma [γ] and X-ray)  are high-energy waves that can travel great distances at the speed of light. There are two types of photon radiation of interest for this course: gamma (γ) and X-ray.


Neutron radiation (n) consists of a free neutron, usually emitted as a result of spontaneous or induced nuclear fission.
Neutrons are, in fact, the only type of radiation that is able to turn other materials radioactive. 5


Our exposure come from two different kinds of sources:
Natural background radiation
Man-made (artificial) radiation
Learn more about each of them in the next slides.


All of us are exposed to a certain amount of ionizing radiation in our everyday lives.


Natural Background Sources of Ionizing Radiation


Cosmic Radiation
Cosmic radiation consists of high-energy charged particles, x-rays, and gamma rays coming from the sun and other celestial events in the universe.
The average annual dose or exposure from cosmic radiation is 0.33 mSv (33 mrem) or 11% of a person’s yearly exposure due to all natural sources of radiation. 8


Terrestrial Radiation
The composition of the earth’s crust is a major source of natural radiation. The main contributors are natural deposits of uranium, potassium and thorium which, in the process of natural decay, will release small amounts of ionizing radiation.


Internal Radiation
Yes, that's right: humans are innately radioactive. Through ingestion and inhalation,  people have internal radiation.
About 73% of a person’s yearly exposure to natural sources of radioactive material comes from inhalation, while 9% come from ingestion. 8


Types and Sources of Radiation

type of radiation (alpha, beta, gamma) ;
dose (amount) of radiation;
where the radiation concentrates in the body and how long it stays there;
how sensitive your body is to radiation; and


The amount of damage that exposure to radiation can cause depends on several factors, including


Most Tragic Radiation Accidents in History 2


Chernobyl, Ukraine (then Soviet Union) - 1986
Chernobyl is considered the world’s worst nuclear disaster to date. It occurred on April 26, 1986, when a sudden surge in power during a reactor systems test resulted in an explosion and fire that destroyed Unit 4.


Workers and the public were exposed to three main types of radionuclides: iodine-131, cesium-134 and cesium-137.
On the day of the accident, there were 600 workers onsite. 134 suffered acute radiation sickness, 28 of whom died in the first three months. For those who survived radiation sickness, recovery took several years.3


Fukushima Daiichi, Japan - 2011
The earthquake and tsunami that struck eastern Japan on March 11, 2011, caused a serious accident at the Fukushima Dai-ichi nuclear power plant on the northeastern coast of Japan.
Hydrogen explosions caused fuel in three of the reactor cores to melt, resulting to radiation releases from the damaged reactors and contaminating a wide area surrounding the plant.


The main radionuclides to which individuals were exposed included iodine-131 and caesium-137.
For the twelve workers who were estimated to have received the highest absorbed radiation doses to the thyroid, an increased risk of developing thyroid cancer and other thyroid disorders was estimated. 4


How Radiation Affects Cells 3
Radiation affects our health primarily through breakage of deoxyribonucleic acid (DNA) molecules. When it does, three things mainly happen:


The DNA is repaired properly
In this case, the cell is repaired properly and it continues to function normally. DNA breakage occurs normally every second of the day, and cells have a natural ability to repair that damage.


The DNA damage is so severe that the cell dies (deterministic effects)
When the DNA or other critical parts of a cell receive a large dose of radiation, the cell may die or be damaged beyond repair. If this happens to a large number of cells in a tissue or organ, deterministic effects may occur, such as burns, and, in extreme cases, death.


The cell incorrectly repairs itself, but it continues to live (stochastic effects)
In some cases, part of the DNA in the cell may be damaged by radiation and may not properly repair itself. The cell may continue to live and even reproduce itself.


However, during that process, errors that have not been repaired in the DNA chain will also be present in the cell descendents and may disrupt these cells’ functioning. This type of detrimental effect has a probability that is proportionate to the dose, and is called a stochastic effect.


Health Effects of Radiation Exposure

Absorbed dose
Equivalent dose
Effective dose
Learn more about each of them in the next slides.


Dose quantities are expressed in three ways:


Radiation Doses

Information System on Occupational Exposure in Medicine, Industry and Research (ISEMIR)
ISEMIR is a web-based tool for the collection and analysis of occupational exposure data in interventional cardiology (IC) and industrial radiography (IR) practices.
Safety in Radiological Procedures (SAFRAD)
SAFRAD is a voluntary international reporting system on the doses received by patients and other relevant data or events in fluoroscopically-guided diagnostic and interventional procedures.


Occupational Radiation Protection Networks (ORPNET)
ORPNET serves as focal point for the communication and exchange of information on occupational radiation protection and the ALARA networks that work in this field.
Personal Annual Radiation Dose Calculator
https://www.nrc.gov/about-nrc/radiation/around-us/calculator.html
You can use this tool by the US NRC to calculate your estimated personal annual average dose.


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