Radiation Protection Basics
Three basic principles apply to all types of ionizing radiation. If we have rules or standards that limit the amount of radiation a person can receive in a given situation to develop, we examine how these concepts can affect the exposure of a person.
Time
The amount of exposure to radiation increases and decreases over time people spend near the source of radiation.
In general, we believe that the exposure time for how long a person close to radioactive materials. It is easy to understand how the external time (live) to minimize exposure. Gamma and X-rays are the main concern for external exposure.
However, if radioactive material gets into your body, you can not abandon it. You must wait until the expiry or until your body can eliminate. When this occurs, the biological half-life of radionuclide regulates the duration of exposure. Biological half the amount of time it takes the body half of the elimination of radionuclides originally present. The alpha and beta particles are the main concern for internal exposure.
How does EPA use the concept of time in radiation protection?
If we have a standard that increased radiation risk for a certain period, we apply the concept of time. For example, we often ExpressCard positions in terms of dose commitment. A committed dose is that which represents the continuous exposure over long time (like 30, 50 or 70 years). It refers to the exposure received from radioactive material that enters and remains in the body for many years.
Then, the risk of exposure in a position to judge, we consider the amount of time a person can spend in the field of pollution. For example, in assessing the potential exposure to radon in a home, we estimate how long people are likely to spend in the basement.
Distance
People who are farther from a radiation source, the lower their exposure.
How close to a radiation source can be obtained without a high exposure? It depends on the energy of radiation and the size (or activity) of the source. Distance is a major concern in the case of gamma rays as they travel long distances. The alpha and beta particles do not have enough energy to travel very far.
In general, if you double the distance, you reduce the risk by a factor of four. Reduce by half the distance to increase exposure by a factor of four.
Why does exposure change more rapidly than the distance?
The area of the circle depends on the distance from the center to the edge of the circle (radius). It is proportional to the square of the radius. Therefore, if the radius doubles the area four times larger.
Consider the radiation source and a bare bulb. The lamp emits light in all directions in a circle. The light energy is distributed evenly over the surface of the circle. If the radius doubles, the radiation is spread over four times more space, so that the dose is only one quarter as much. (Also, if the distance from the source increases, the likelihood that some gamma rays will lose their energy.
The exposure of an individual sitting 4 feet from a radiation source will be 1/4 the exposure of an individual sitting 2 feet from the same source
How does EPA use the concept of distance in radiation protection?
We also consider the distance in the analysis of potential risks of a source. If a person on a contaminated site, or working around radioactive materials, we evaluate how exposures vary as the person closer or further away from the radiation source.
Shielding
More shielding around a radiation source, the smallest of the exhibition.
Shielding simply means something that absorbs radiation between you and the source of radiation (but with another person to absorb the radiation are not considered as a shield). The amount of shielding required to protect against different types of radiation depends on the amount of energy they have.
(Alpha) A thin layer of lightweight materials such as paper, or even dead cells in the outer layer of human skin provides adequate protection of alpha particles, because it can not penetrate. However, living tissue in the body, does not protect against alpha emitters inhaled or ingested.
(Beta) Others include heavy clothing is necessary to protect against beta emitters. Some beta particles can penetrate and burn the skin.
(Gamma) Thick, dense shielding such as lead, are needed to protect against gamma radiation. More energy gamma rays, the thicker the line should be. X-rays are a similar challenge, if the radiology technicians often provide patients with medical and dental X-ray lead aprons in other parts of their bodies covered.
How does EPA use the concept of shielding in radiation protection?
We take into account the type of shielding can be provided by the ground when we sites that are contaminated or used for the disposal of radioactive material to evaluate. We also consider the shielding effect of buildings for a person living or working on a site that has been deleted.
Since antiquity, philosophers and scientists interested in the fundamentals of our physical universe. In fact, the ancient Greeks were the first to believe that all matter in the universe must be made of small building blocks - or atoms. Start with the first specialists in science throughout history and in this century, scientists have been eager to learn more about the atom and how to control it.
Significant Discoveries
It was not until the latter part of the 19th century that scientists really began to progress in the study of atomic structure and radiation.
During the 1600s, Sir Isaac Newton proved his theories of gravitation. Marie and Pierre Curie began their studies in chemistry and physics, and Dmitri Mendeleev presented the periodic table of elements. Just before the turn of the century, Wilhelm Conrad Roentgen discovered the fundamental properties of X-rays, the properties of ionizing radiation and the possibility of using radiation in medicine.
Finally, in 1896, Henri Becquerel announced the discovery of radioactivity in the Academy of Sciences in Paris. In the early 1900s the study of the radiation is a widely accepted scientific enterprise.
New Dangers Come with Discoveries
But these discoveries were not without price. Scientists learned that the radiation is a source of energy and medicine, it may be a potential threat to human health if not properly treated. In fact, the pioneers in the investigation late radiation radiation-induced diseases (overexposure). For example, Thomas Edison worker who died of radiation-induced cancer resulting from excessive exposure to X-ray As new uses of radioactive elements have been discovered, potentially fatal cases of excessive exposure increased. For example, during the First World War, radium-based paint (a mixture of radium and phosphorus) was used for military aircraft instruments to shine in the dark so they would be more visible to drivers at night.
After the war was over, the industry that supports that technology has changed their clocks painting business-to-the-dark and the watch face. Young women who worked in this mission would be an art form with their brushes by pulling the brushes cost of crossing between the lips before applying paint on watch dials. Unknowingly, they were eating small amounts of radium and damage their bodies.
Over a period of two years, nine women who had worked as a dial painters dead serious, unexplained anemia, accompanied by destructive lesions of the mouth and jaws. A dentist who had treated one of these women, and finally the link between inflammation of the bone marrow, and the radium dial painting.
Meeting the Need for Radiation Protection
In 1970, Congress created the Environmental Protection Agency (EPA) and radiation protection became a part of EPA's responsibility. Today, EPA's Radiation Protection Division (RPD) is responsible for protecting the public's health and the environment from undue exposure to radiation. This is accomplished by setting safety standards and guidelines. Now, organizations that deal with ionizing radiation must meet these standards to comply with the law.
In 1915 the British Roentgen Society adopted a resolution to protect people against excessive exposure to X-ray This was probably the first organized attempt to protect against radiation.
In 1922, British American organizations had rules of protection. Information and education have increased, and throughout the 1920s and 30 have been developed guidelines and many more organizations were formed for protection against radiation in the United States and the address abroad.
Radiation was based primarily non-government until the late 1940s. After the Second World War, the development of the atomic bomb and nuclear reactors caused the federal government playing politics with human exposure to determine. In 1959, the Federal Council adopted radiation. The Council was responsible for three things:
1. advise the President of the United States on matters of radiological consequences for public health.
2. provide guidance to all federal agencies to establish standards for radiation.
3. work with Member States on matters of radiation.
In 1970, Congress created the Environmental Protection Agency (EPA) and protection against radiation, which is part of the responsibility of the EPA. Today, EPA's Radiation Protection Division (RPD) is responsible for protecting public health and the environment from unnecessary exposure to radiation. This is achieved by setting safety standards and guidelines. Now, organizations dealing with ionizing radiation to these standards under the law.
