Radiation Protection

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What is ionizing radiation?

A material is defined as a substance (most often a solid, but other condensed phases can be included) intended for certain applications. There is a myriad of materials around us – they can be found in anything from buildings to spacecraft.

Key Facts

  • Ionizing radiation has different ionization mechanisms and may be grouped as:
    • Directly ionizing. Charged particles (atomic nuclei, electrons, positrons, protons, muons, etc.) can ionize atoms directly through fundamental interaction through the Coulomb force if they carry sufficient kinetic energy.
    • Indirectly ionizing. Indirect ionizing radiation is electrically neutral particles and therefore does not interact strongly with matter.
      • Photon radiation (Gamma rays or X-rays). Photon radiation consists of high-energy photons. According to the currently valid definition, X-rays are emitted by electrons outside the nucleus, while gamma rays are emitted by the nucleus. The production of gamma rays is termed gamma decay.
      • Neutron radiation. Neutron radiation consists of free neutrons at any energies/speeds. This type of radiation can be produced by nuclear reactors or in flight. Neutrons contribute 40 – 80% of the equivalent dose.
  • There are three main types of radiation detectors, which record different types of signals.
    • Counter. The activity or intensity of radiation is measured in counts per second (cps).
    • Radiation Spectrometer. Spectrometers are devices designed to measure the spectral power distribution of a source.
    • Dosimeter. A radiation dosimeter is a device that measures exposure to ionizing radiation.
  • In general, there are two broad categories of radiation sources:
    • Natural Background Radiation. Natural background radiation includes radiation produced by the Sun, lightning, primordial radioisotopes, supernova explosions, etc.
    • Man-Made Sources of Radiation. Manufactured sources include medical uses of radiation, residues from nuclear tests, industrial uses of radiation, etc.

Radiation Measuring and Monitoring - Quantities and Limits

Fear of Radiation – Is it rational?
Fear of Radiation – Is it rational?

Radiation is all around us. We are continually exposed to natural background radiation, and it seems to be without any problem. Yes, high doses of ionizing radiation are harmful and potentially lethal to living beings, but these doses must be high. Moreover, what is not harmful in high doses? Even a high amount of water can be lethal to living beings.

The truth about low-dose radiation health effects still needs to be found. It is unknown whether these low doses of radiation are detrimental or beneficial (and where is the threshold).

But finally, if you compare risks, which arise from the existence of the radiation, natural or artificial, with risks that arise from everyday life, you must conclude that fear of radiation is irrational. Humans are often inconsistent in our treatment of perceived risks. Even though two situations may have similar risks, people will find one permissible and another unjustifiably dangerous.

See also: Fear of Radiation – Is it rational?

What are the 4 types of radiation?
What are the 4 types of radiation?
  • Ionizing radiation has different ionization mechanisms and may be grouped as:
    • Directly ionizing. Charged particles (atomic nuclei, electrons, positrons, protons, muons, etc.) can ionize atoms directly through fundamental interaction through the Coulomb force if they carry sufficient kinetic energy.
    • Indirectly ionizing. Indirect ionizing radiation is electrically neutral particles and therefore does not interact strongly with matter.
      • Photon radiation (Gamma rays or X-rays). Photon radiation consists of high-energy photons. According to the currently valid definition, X-rays are emitted by electrons outside the nucleus, while gamma rays are emitted by the nucleus. The production of gamma rays is termed gamma decay.
      • Neutron radiation. Neutron radiation consists of free neutrons at any energies/speeds. This type of radiation can be produced by nuclear reactors or in flight. Neutrons contribute 40 – 80% of the equivalent dose.
What are typical doses of radiation?
What are typical doses of radiation?

We must note that radiation is all around us. In, around, and above the world we live in. It is a natural energy force that surrounds us. It is a part of our natural world that has been here since the birth of our planet. In the following points, we try to express enormous ranges of radiation exposure, which can be obtained from various sources.

  • 0.05 µSv – Sleeping next to someone
  • 0.09 µSv – Living within 30 miles of a nuclear power plant for a year
  • 0.1 µSv – Eating one banana
  • 0.3 µSv – Living within 50 miles of a coal power plant for a year
  • 10 µSv – Average daily dose received from natural background
  • 20 µSv – Chest X-ray
  • 40 µSv – A 5-hour airplane flight
  • 600 µSv – mammogram
  • 1 000 µSv – Dose limit for individual members of the public, total effective dose per annum
  • 3 650 µSv – Average yearly dose received from natural background
  • 5 800 µSv – Chest CT scan
  • 10 000 µSv – Average yearly dose received from a natural background in Ramsar, Iran
  • 20 000 µSv – single full-body CT scan
  • 175 000 µSv – Annual dose from natural radiation on a monazite beach near Guarapari, Brazil.
  • 5 000 000 µSv – Dose kills a human with a 50% risk within 30 days (LD50/30) if the dose is received over a very short duration.
ionizing radiation - hazard symbol
ionizing radiation – hazard symbol

Radiation protection is the science and practice of protecting people and the environment from the harmful effects of ionizing radiation. The International Atomic Energy Agency (IAEA) defines radiation protection as:

“The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this”

It is a serious topic not only in nuclear power plants but also in industry or medical centers. According to the IAEA, radiation protection can be divided into three groups:

  • occupational radiation protection, which is the protection of workers in situations where their exposure is directly related to or required by their work
  • medical radiation protection, which is the protection of patients exposed to radiation as part of their diagnosis or treatment
  • public radiation protection, which is the protection of individual members of the public and the population in general

According to the ICRP (Publication 103), the System of Radiological Protection is based on the following three principles:

  1. Justification. “Any decision that alters the radiation exposure situation should do more good than harm.”
  2. Optimization of Protection. “Doses should all be kept as low as reasonably achievable, taking into account economic and societal factors.” (known as ALARA or ALARP)
  3. Dose Limitation. “The total dose to any individual … should not exceed the appropriate limits.”

See also: ICRP, 2007. The 2007 Recommendations of the International Commission on Radiological Protection. ICRP Publication 103. Ann. ICRP 37 (2-4).

The International Commission on Radiological Protection (ICRP) is an independent, international, non-governmental organization created by the 1928 International Congress of Radiology to advance the science of radiological protection for the public. The ICRP is a sister organization to the International Commission on Radiation Units and Measurements (ICRU), which is a standardization body and develops concepts, definitions, and recommendations for the use of quantities and their units for ionizing radiation and its interaction with matter, in particular for the biological effects induced by radiation.

“What
Most general definition of radiation is radiation that comes from a source and travels through some material or space. This is a very general definition, the kind of radiation discussed in this article is called ionizing radiation. Ionizing radiation is characterized by the kinetic energy of particles (photons, electrons, etc.). The particle can ionize (to form an ion by losing electrons) target atoms to form ions, so ionizing radiation is sufficient. Ionizing radiation can knock electrons from an atom.

External Dose Uptake

External exposure is radiation that comes from outside our body and interacts with us. In this case, we analyze exposure predominantly from gamma rays since alpha and beta particles, in general, constitute no external exposure hazard because the particles generally do not pass through the skin. The source of radiation can be, for example, a piece of equipment that produces the radiation, like a container with radioactive materials or an x-ray machine. In radiation protection, there are three ways how to protect people from identified external radiation sources:

  • radiation protection pronciples - time, distance, shielding
    Principles of Radiation Protection – Time, Distance, Shielding

    Limiting Time. The amount of radiation exposure depends directly (linearly) on the time people spend near the radiation source. The dose can be reduced by limiting exposure time.

  • Distance. The amount of radiation exposure depends on the distance from the source of radiation. Like heat from a fire, if you are too close, the intensity of heat radiation is high, and you can get burned. If you are at the right distance, you can withstand there without any problems and are comfortable. If you are too far from the heat source, the insufficiency of heat can also hurt you. This analogy, in a certain sense, can be applied to radiation also from radiation sources.
  • Shielding. Finally, if the source is too intensive and time or distance does not provide sufficient radiation protection, the shielding must be used. Radiation shielding usually consists of barriers of lead, concrete, or water. Many materials can be used for radiation shielding, but there are many situations in radiation protection. It depends on the type of radiation to be shielded, its energy, and many other parameters. For example, even depleted uranium can be used as good protection from gamma radiation, but on the other hand, uranium is absolutely inappropriate shielding of neutron radiation.

Internal Dose Uptake

If the source of radiation is inside our body, we say it is internal exposure. The intake of radioactive material can occur through various pathways, such as ingesting radioactive contamination in food or liquids. Protection from internal exposure is more complicated. Most radionuclides will give you much more radiation dose if they can somehow enter your body than they would if they remained outside.

Public Exposure and Nuclear Power Plants

It must be noted that radiation is all around us. In, around, and above the world we live in. It is a part of our natural world that has been here since the birth of our planet. There are radioactive isotopes in our bodies, houses, air, water, and in the ground – and we are exposed to radiation from outer space. This radiation is called natural background radiation.

Exposure from nuclear power plants and their fuel cycle belongs to manufactured sources of radiation. By far, the most significant source of manufactured radiation exposure to the public is from medical procedures, such as diagnostic X-rays and nuclear medicine. Moreover, according to the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), public exposure to radiation resulting from electricity generation by nuclear power plants is just a fraction of that from coal-powered plants.

See also: SOURCES, EFFECTS, AND RISKS OF IONIZING RADIATION, UNSCEAR 2016. ISBN: 978-92-1-142316-7.

References:

Radiation Protection:

  1. Knoll, Glenn F., Radiation Detection and Measurement 4th Edition, Wiley, 8/2010. ISBN-13: 978-0470131480.
  2. Stabin, Michael G., Radiation Protection, and Dosimetry: An Introduction to Health Physics, Springer, 10/2010. ISBN-13: 978-1441923912.
  3. Martin, James E., Physics for Radiation Protection 3rd Edition, Wiley-VCH, 4/2013. ISBN-13: 978-3527411764.
  4. U.S.NRC, NUCLEAR REACTOR CONCEPTS
  5. U.S. Department of Energy, Nuclear Physics and Reactor Theory. DOE Fundamentals Handbook, Volume 1 and 2. January 1993.

Nuclear and Reactor Physics:

  1. J. R. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed., Addison-Wesley, Reading, MA (1983).
  2. J. R. Lamarsh, A. J. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 0-201-82498-1.
  3. W. M. Stacey, Nuclear Reactor Physics, John Wiley & Sons, 2001, ISBN: 0- 471-39127-1.
  4. Glasstone, Sesonske. Nuclear Reactor Engineering: Reactor Systems Engineering, Springer; 4th edition, 1994, ISBN: 978-0412985317
  5. W.S.C. Williams. Nuclear and Particle Physics. Clarendon Press; 1 edition, 1991, ISBN: 978-0198520467
  6. G.R.Keepin. Physics of Nuclear Kinetics. Addison-Wesley Pub. Co; 1st edition, 1965
  7. Robert Reed Burn, Introduction to Nuclear Reactor Operation, 1988.
  8. U.S. Department of Energy, Nuclear Physics and Reactor Theory. DOE Fundamentals Handbook, Volume 1 and 2. January 1993.
  9. Paul Reuss, Neutron Physics. EDP Sciences, 2008. ISBN: 978-2759800414.

See above:

Nuclear Engineering