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ROBERT BURKE
Published: January 1996

Radioactive materials (hazard class 7) are a part of everyday life. Uranium is used in nuclear reactors to produce electricity and in the production of nuclear weapons systems. Medical uses include sterilization, implants using radium, scans using iodine, and therapy using cobalt. X-rays are used in diagnostic medical procedures. In addition, radioactive materials may be found in research laboratories, educational institutions, industrial applications, and hazardous waste sites as well as in transportation. Radioactive materials are heavily regulated and their containers are well constructed. Local emergency responders such as fire departments, EMS units, and police do not handle most incidents involving radioactive materials; other agencies are responsible for and respond in such cases. Emergency responders however, must be aware of radioactive materials and know how to protect themselves from them.

Radiation Sickness Values 25 REM Maximum lifetime exposure from a single incident for emergency responders. 20 to 100 REM Some chromosomal damage; alteration of white blood cell (WBC) counts. 100 to 200 REM Nausea, vomiting, WBC count reduction. 200 to 400 REM Severe WBC reduction, hair loss, some deaths from secondary infections. 500 to 1000 REM 50 percent death rate in 30 days. 1000 to 2000 REM Death within 4 to 14 days. 2000 or more REM Immediate death due to edema of brain and central nervous system damage.

What is Radioactivity?

A radioactive material, according to the U.S. Department of Transportation (DOT), is one "having a specific activity greater than 0.002 microcuries per gram." Specific activity of a radionuclide is "the activity of the radionuclide per unit mass of that nuclide." Simply stated, a microcurie is a measurement of radioactivity. When the radioactivity of a material emits more than 0.002 microcuries per gram of material, which is a term of weight, the material is regulated in transportation by the DOT. Radiation is an ionizing energy spontaneously emitted by a material or combination of materials. A radioactive material, then, is one that spontaneously emits ionizing radiation. Three types of labels are used to mark radioactive packages: radioactive I, II, and III, determined by the radiation level at the package surface. Radioactive I materials measure <0.5 millirem per hour (mR/hour), radioactive II is >0.5 and < 50 mR/hour, and radioactive III is >50 and < 200 mR/hour. Only materials labeled radioactive III require placarding.

Gamma Radiation Electromagnetic-Energy Waves

Elements above lead (atomic numbers 83 and above) on the Periodic Table are all radioactive. There are radioactive isotopes of many of the elements below 83 also. Some occur naturally; others are man made. Each symbol on the Periodic Table represents one atom of that element. An atom is made up of a nucleus with varying numbers of electrons in orbits circling around the nucleus. Inside the nucleus are protons and neutrons. The number of protons also reflects the atomic number of the element and cannot change without changing the element. The number of neutrons varies from one element to another. Radioactivity involves the nucleus of an atom of an element. Normally, a "strong force" holds the nucleus together. There are some nuclei of elements that the force cannot hold together and the nuclei begin to disintegrate. A basic law of nature says an unstable material may not naturally exist for long, but must do whatever it can do to achieve stability. Elements that throw off particles from the nucleus to reach stability are said to be radioactive; the process is known as nuclear decay. These particles are sometimes referred to as sub-atomic particles because they are smaller than atoms.

Types of Radiation

Radioactive Labels

There are two types of radiation: ionizing and non-ionizing. Ionizing radiation involves particles traveling in a wave like motion. Non-ionizing radiation is made up of waves of energy. All radioactivity travels in a straight line. Gamma radiation is a naturally occurring, high-energy electromagnetic wave. It is not particulate in nature and has high penetrating power. Gamma rays have the highest energy level known. Examples of other electromagnetic energy waves include ultraviolet, infrared, microwave, visible light, radio, and X-rays. Gamma rays travel at the speed of light - more than 186,000 miles per second - and will penetrate the skin and injure internal organs. No type of protective clothing will protect against gamma radiation. Shielding from gamma radiation requires several inches of lead or other dense metal, or several feet of concrete or earth. Gamma radiation does not result in contamination because there are no radioactive particles, only energy waves. There is little difference between gamma rays and X-rays, which are produced by cathode ray tube. To be exposed to X-rays, however, there must be electrical power to the X-ray machine and the machine must be turned on. If there is no electrical power, there is no radiation.

Two types of radioactive particles are emitted from the nucleus of an atom: alpha and beta. The alpha particle looks much like an atom of helium stripped of its electrons, with tow protons and two neutrons remaining. Positively charged, the alpha particle is large in size and therefore will not penetrate as much or travel as far as beta or gamma radiation. Alpha particles travel three to four inches and will not penetrate the skin. However, if alpha particles are ingested or enter the body by some other means they can cause a great deal of damage to internal organs. The beta particle, at 1/1,800th the size of a proton, is smaller than the alpha particle. It will penetrate the skin and travel fro three to 100 feet. Full turnout gear and self-contained breathing apparatus (SCBA) will protect against penetration of alpha particles, but will not provide full protection from beta particles. Particulate radiation results I contamination of personnel and equipment where the particles come to rest.

A third type of radioactive particle exists, but does not occur naturally; the neutron particle. It is the result of an atom being split in a nuclear reactor or accelerator; it can also occur in a thermal nuclear reaction. When an atom is split neutron particles are thrown out. You would have to be inside a reactor or experience a thermal nuclear explosion to be exposed to neutron particles. Even if you were to be exposed to neutron particles from a thermal nuclear blast you wouldn't need to worry - you would be torn apart by the blast pressure or vaporized by the heat! When the nucleus of an atom of an element contains more neutrons than the "normal" atom of that element it is said to be an isotope of that element. There are also protons in the nucleus but this is the atomic number of the element and cannot be changed. If you change the number of protons, you have a different element. All atoms have from 3 to 25 isotopes; the average is 10 per element. Not all isotopes are radioactive.

Hydrogen has three important isotopes. Hydrogen 1, sometimes called protonium, has one proton in the nucleus and no neutrons. Hydrogen 2, also called deuterium or heavy water, has one proton in the nucleus and two neutrons. Hydrogen 3, or tritium, has one proton in the nucleus and three neutrons. (Tritium is used in some "exit" signs because it glows in the dark without batteries or electricity.) Carbon has several isotopes. Normal carbon is known as carbon 12 and has six protons and six neutrons I the nucleus. Carbon 12 is not radioactive. Carbon 13 has six protons and seven neutrons in the nucleus and is not radioactive. Carbon 14 has six protons and eight neutrons and is naturally radioactive. Carbon 14 is a beta emitter produced in the atmosphere by the action of cosmic radiation on atmospheric nitrogen. In the process a proton is forced from the nucleus of nitrogen, which then becomes Carbon 14. The human body is made up of 1/10,000th of 1 percent of carbon 14. Every breath you take contains carbon 14. The amount of carbon 14 present indicates age of organic materials because it takes years to disappear. Three other carbon isotopes are man made: carbon 11, with six protons and 11 neutrons; carbon 15, which has six protons and 15 neutrons; and carbon 16, with six protons and 16 neutrons. All are radioactive. Radioactive materials are regulated in transportation by the DOT and by the Nuclear Regulatory Commission, part of the Department of Energy, in other situations. The design and construction of packaging for radioactive materials in transportation makes the likelihood of a release very small. The packaging undergoes rigorous testing before it is approved for use. The casks used for high-level radioactive materials have never been involved in an accident where a serious release occurred.

Nuclear Power Plants

The human senses cannot detect radioactivity. Responders will know whether radioactive materials are present only by using instruments designed to detect radioactivity. Two types of civil defense meters are widely available to emergency responders. These are the CDV-700 and CD V-715. Neither of these instruments can detect alpha radiation. The CDV-700 survey meter has a range of 0 to 50 mR/hour. An experienced operator can detect beta radiation with the CDV700 though a process of elimination. If you check for radiation with the Geiger-Mueller (GM) tube on the CDV-700 with windows closed and no radiation exists beyond background, than no gamma is present. If windows are opened, another reading taken and radiation is detected, it is beta radiation. Dosimeters are used tin conjunction with survey meters to monitor the levels of exposure to personnel. There are two types of civil defense dosimeters with different monitoring scales. The CDV - 138 is used for monitoring relatively low levels of exposure and has a minimum scale reading of 200 mR. The CDV - 742 has a range up to 200 R (200,000 mR) and is used for high levels of personnel exposure. Both meters should be worn. Similar commercial instruments are also available.

Several terms are used to express the intensity of radiation. A curie - 37 billion disintegrations per second - is a physical amount of material required to produce a specific amount of ionizing radiation. It may take several hundred pounds of one radioactive material to produce the same amount of curies as one pound of another radioactive material. A roentgen is a measure of the ionization produced by a specific material. It is the amount of X-ray or gamma radiation that produces 2 billion ionizations in one cubic centimeter (cm3) of dry air. The radiation-absorbed dose (RAD), roughly equal to a roentgen, indicates how much radiation someone has been exposed to. The radiation equivalent in man (REM), also roughly equal to a roentgen, measures how much radiation has been absorbed or the biological effect as a result of the dose.

X – Ray Machines

The health effects of exposure to radiation vary. Non-ionizing radiation comes from ultraviolet and infrared energy waves. This type of radiation causes sunburn and is not a major concern for hazardous materials responders. Ionizing radiation comes from alpha, beta, and gamma sources, and its damage occurs at the cellular level. Short-term effects can include: repairable damage to cells; irreparable damage to cells, but not causing death; and destruction of cells. There are also long-term effects from ionization radiation. Exposures can cause cancer and birth defects of teratogenic or mutagenic nature. Teratogenic birth defects result from the fetus being exposed and damaged by the radiation. The child is born with a defect as a result of the exposure. Provided no further exposures occur, later children can be normal. Mutagenic damage occurs when the DNA or other part of the reproductive system is damaged. The ability to produce normal children is lost because the damage is permanent.

The routes of entry for radioactive materials are much the same as for poisons. However, the radioactive source or material does not have to be directly contacted for radiation exposure to occur. Once a radioactive material enters the body it is very dangerous because the source now becomes an internal source rather than an external one. You cannot protect yourself by time, distance, or shielding from a source that is inside your body. Contact with a radioactive material or ingestion of a radioactive material does not make you radioactive. You may become contaminated with radioactive particles, but with proper decontamination they can be removed and unable to cause further damage. There are no truly safe levels of exposure to radioactive materials. Symptoms of radiation exposure may be the same as those from exposure to cancer-causing materials. The tolerable limits for exposure to radiation that have been proposed by some scientists are very arbitrary. The maximum annual radiation exposure for an individual in the United States is 0.1 REM. The maximum for workers in the nuclear industry is five REMs per year. An emergency exposure of 25 REMs has been established by the National Institute of Standards and Technology. This type of exposure should be attempted under only the most dire circumstances and should occur only once in a lifetime. The effects of exposure to radiation on the human body depend on the amount of material the body was exposed to, the length of exposure, the type of radiation, the depth of penetration and the frequency of exposure. Radiation injuries frequently do not present themselves for a long time- years, even decades - after exposure. Cancer is one of the main long-term effects of exposure t radiation. Leukemia may take from 5 to 15 years to develop. Lung, skin and breast cancer may take up to 40 years to develop.

How to Protect Yourself

Lead Bricks for Shielding

Because of the physical characteristics of radioactives, protection can be provided by time, distance, and shielding. Time refers t the length of exposure to the radioactive source. Time also refers to the half-life of a radioactive material. A half-life is the time necessary for an unstable element or nuclei to lose one-half of its radioactive intensity in the form of alpha, beta, or gamma radiation. As previously mentioned, radiation travels in a straight line and only for short distances. Therefore, the greater the distance from the radioactive material the less the intensity of the exposure. Shielding simply means that if there is enough mass between personnel and the radiation, they will be protected from the radiation. In the case of alpha particles, your skin or a sheet of paper will produce enough shielding and turnouts will provide extra protection. Ingestion is the major hazard, but can be prevented by wearing SCBA. Beta particles require more substantial protection. A 1/24th inch piece of aluminum will stop beta radiation, but turnout s may not provide adequate protection. Gamma radiation requires three to nine inches of lead or several feed of concrete or earth.

Each state has a special team that responds to radiation emergencies. A team may be a part of an emergency management agency or a department of health or environmental protection. Federal interests are represented by the Nuclear Regulatory Commission, 301-492-7000. The Department of Defense Joint Nuclear accident Center, 703-325-2102, handles incidents involving weapons.

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