RADıOACTıVıTY RADIOTHERAPY TRANıNG NURSE SELMA GÜÇLÜ Radioactivity is the process by which unstable nuclei within atoms spontaneously decompose to RADIOACTIVITY form nuclei with greater stability. Elements in nature always prefer to exist in stability, so radioactive elements simply go through this process in order to exist in stable form. To be stable, a nucleus has to have a good balance of protons and neutrons inside,as well as a weight that is not too heavy. Most elements, like carbon, have both stable and radioactive isotopes (isotopes are different types of the atom that have different atomic weights, which are determined by the number of neutrons within an element). Heavier elements like uranium are never stable, and are therefore always radioactive.

During the process of nuclear decay, energy and particles are released from radioactive materials. This is what we call radiation. It can be dangerous or harmless to humans depending on the amount and type. There are actually three types of radiation: alpha,beta, and gama.

RADIOACTIVITY RADIOACTIVITY ALPHA DECAY Alpha radiation is a stream of positively charged particles(called alpha particles) that each consist of two protons and two neutrons bound together. Alpha decay is the process that creates this radiation, and also by which an element becomes lighter. Since nuclei don’t like to be too heavy(that is, have too many neutrons and protons), a heavy nucleus will eventually lose some weight by emitting alpha particles. These particles are heavy and slow-moving compared to other particles that can be emitted, which is why they can only travel ashort distance and cannot penetrate the skin. This makes alpha radiation easier to manage than some other forms,but it is actually the most dangerous form of radiation if it does come in contact with living tissue-especially internally. This makes elements going through alpha decay highly dangerous to swallow or inhale. Probably the most common human health risk related to alpha decay is naturally occuring Radon gas (which is a good reason to get your house tested). Radon is a naturally occurring radioactive gas produced by the decay of uranium 238, which is present throughout the Earth's crust.

RADIOACTIVITY BETA DECAY Beta radiation is composed of a stream of high-energy lightweight positrons or electrons (called beta particles) that are created during beta decay.beta decay is the process by which the number of neutrons and protons within a nucleus are balanced. There are two ways this happens. Sometimes a nucleus has relatively too many more neutrons than protons. In this case, positive beta decay occurs. In the case that a nucleus has relatively too many more protons than neutrons, the reverse process of negative beta decay happens. Due to their lower mass and higher speed, beta particles can penetrate the skin more easily than alpha particles. However, a thin layer of metal can protect against beta radiation.

RADIOACTIVITY

GAMMA DECAY During alpha and beta decay, the transformation of the nucleus still leaves behind an excess of energy. This energy is released when the nucleus releases gama rays, also known as gamma radiation. Gamma rays are simply high- energy photons that is, a very high-frequency form of electromagnetic radiation. Gamma rays have no mass and move at the speed of light. Because of this, gamma rays can penetrate the body easily. They can even travel through several centimeters of lead. Although a small dose of gamma radiation passes through the body without harming it,larger amount can do serious damage.

RADIOACTIVITY HALF-LIFE

The half-life (abbreviated t1/2 ) is the amount of time it takes for half of the unstable atoms in a sample to decay. The half-life for a given isotope is always the same no matter how many particles you have or what happened in the past. For example, if an element has a half-life of 4 days and starts off with 16g of unstable particles, then after the first 4 days, 8g will remain. After the next 4 days, 4g will remain. After 4 more days, 2g will remain etc.

16 4 days 8 4 days 4 4 days 2

RADIOACTIVITY

RADIOACTIVE DECAY CHAİNS Some go through a serious of transformation before they reach a stable state. For example, uranium-238 ultimately transforms into a stable atom of lead. But in the process, several types of radioactive atoms are generated. This is called a decay chain. When uranium-238 decays, it produces several isotopes of:

RADIOACTIVITY URANIUM THORIUM

LEAD BISMUTH RADON

URANIUM DECAY CHAIN RADIOACTİVİTY HOW DANGEROUS IS RADIOACTIVITY? We are exposed to all forms of radioactivity in some form every day without incident, yet each type of radiation is potentially hazardous. The key to knowing how dangerous radiation is relates to the amount and the type of exposure. This danger to the human body is measured in sieverts, which take into account the power of the radiation(for example, alpha radiation has a negative health effect 20 times worse than gamma radiation) and the amount of radiation released. Radiation illness can be felt when a person is exposed to 1 sievert in one dose. Six sievert can be fatal.

RADIOACTIVITY HOW DANGEROUS IS RADIOACTIVITY?(continue) Top up it into context, though, a chest x-ray only exposes you to about 0,0001 sievert of radiation. Generally, proper safety procedures allow us to entirely negate (or at least mitigate) the negative effects of radiation. In fact, breathing the air exposes us to an average of 0,00365 sieverts of radiation per year. The body can generally heal any damage done by radiation at these levels.

RADIOACTIVITY WHAT IS RADIOACTIVITY USED FOR? Despite potential dangers, radioactivity has tons of everyday uses. By making technologies from x-rays to the sterilization of foods and medical instruments possible, it helps us to lead safer lives. Radiation has allowed us to develop the nuclear fission protocols to create nuclear power. Radiation sources are even extremely important for manufacturing industries around the world. Sure, radiation is not something we should take lightly, as it can be incredibly damaging under certain circumstances, but radioactivity itself is nothing we need to worry too much about either.

RADIOACTIVITY RADIOACTIVE SUBSTANCES Co-60 (-60) Cobalt-60 is a man-made isotope with a half-life of 5.27 years. The main advantage of Co-60 is that it is a high intensity gamma-ray emitter with a relatively long half-life. The main uses for Co-60 are:

 As a tracer for cobalt in chemical reactions

 Sterilization of medical equipment.

 Radiation source for medical radiotherapy. Cobalt therapy or cobalt-60 therapy is the medical use of gamma rays from the radioisotope cobalt-60 to treat conditions such as cancer. Beginning in the 1950s cobalt-60 was widely used in external beam radiotherapy (teletherapy) machines, which produced a beam of gamma rays which was directed into the patient's body to kill tumor tissue. Because these "cobalt machines" were expensive and required specialist support, they were often housed in cobalt units. Cobalt therapy was a revolutionary advance in radiotherapy in the post-World War II period but is now being replaced by other technologies such as linear accelerators.

RADIOACTIVITY Co-60(continue)

 Radiation source for industrial radiography.

 Radiation source for leveling devices and thickness gauges.

 Radiation source for pest insect sterilization.

 As a radiation source for food irradiation and blood irradiation.

 As a radiation source for laboratory mutagenesis use.

RADIOACTIVITY Cs-137 (caesium or cesium) Cs-137 is produced by nuclear fission for use in medical devices and gauges. Cs-137 is used in small amounts for calibration of radiation-detection equipment. In larger amounts, Cs-137 is used in medical devices for treating cancer; in industrial gauges that detect the flow of liquid through pipes; and in other industrial devices to measure the thickness of materials, such as paper, photographic film, or sheets of metal.

RADIOACTIVITY Ir-192 (iridium) Ir-192 is a man-made radioactive element that is formed from nonradioactive iridium metal in a . Ir-192 is used in industrial gauges that inspect welding seams and in medicine to treat certain cancers.

RADIOACTIVITY I-131 (iodine) I-131 is produced commercially for medical and industrial uses through nuclear fission. It also is a by product of nuclear fission processes in nuclear reactors and weapons testing. I-131 is used in medicine to diagnose and treat cancers of the thyroid gland.

RADIOACTIVITY Radium Radium (chemical symbol Ra) is a naturally occurring radioactive metal. Radium is a formed by the decay of uranium and thorium in the environment. . The most common isotopes of radium are ra-226 and ra-228. ra- 226 is part of the uranium decay serious.Radium-228 and Ra-224 are part of the thorium decay series. All isotopes of radium are radioactive. Radium decays to produce radon gas. Chronic exposure to high levels of radium can result in an increased incidence of bone, liver or breast cancer.

RADIOACTIVITY Radioactive wastes are usually by-products of nuclear power generation and other applications of nuclear fission or nuclear technology, such as research and medicine. Radioactive waste is hazardous to human health and the environment, and is regulated by government agencies in order to protect human health and the environment. So for the disposal of this adioactive waste lot of steps are needed.

RADIOACTIVITY TYPE OF RADIOACTIVE WASTE High level waste Intermediate waste Low level waste

RADIOACTIVITY LOW LEVEL WASTE Low level waste (LLW) is generated from hospitals and industry, as well as the nuclear fuel cycle. LLW typically exhibits no higher radioactivity. Low level nuclear waste represents about 90% of all radioactive wastes. Low level wastes include paper, rags, tools, clothing, filters, and other materials which contain small amounts of mostly short-lived radioactivity. LLW are less dangerous than the chemical and organic wastes from our homes that are sent to municipal landfills.

RADIOACTIVITY INTERMEDIATE WASTE It contains higher amounts of radioactivity and in some cases requires shielding. It typically comprises resins, chemical sludges and metal fuel cladding, as well as contaminated materials from reactor decommissioning. It makes up some 7% of the volüme and has 4% of the radioactivity of all radioactive waste.

RADIOACTIVITY HIGH LEVEL WASTE (HLW) It is produced by nuclear reactors. It contains fission products and transuranic elements generated in the reactor core. It is highly radioactive and often thermally hot. It is very radioactive and, therefore, requires special shielding during handling and transport. The amount of HLW worldwide is currently increasing by about12,000 metric tons every year, which is the equivalent to about 100 double-decker buses.

RADIOACTIVITY RADIATION PROTECTION There are three general guidelines for controlling exposure to ionizing radiation:

 Minimizing exposure time

 Maximizing distance from the radiation source

 Shielding yourself from the radiation source

RADIOACTIVITY TIME is an important factor in limiting exposure to the public and to radiological emergency responders. The amount of radiation exposure increases and decreases with the time people spend near the source of radiation. DISTANCE can be used to reduce exposure. The farther away people are from a radiation source, the less their exposure. How close to a source of radiation can you be without getting a high exposure? It depends on the energy of the radiation and the size (or activity) of the source. Distance is a prime concern when dealing with gamma rays, because they can travel at the speed of light. Alpha particles can only travel afew inches and beta particles around 10 feet. SHIELDING: As ionizing radiation passes through matter, the intensity of the radiation is diminish. Shielding is the placement of an ‘absorber’ between you and the radiation source. An absorber is a material that reduces radiation from the radiation source to you. Alpha, beta, or gamma radiation can all be stopped by different thicknesses of absorbers. Shielding materials can include barrels, boards, vehicles, buildings,gravel, water, lead or whatever else is immediately available.

RADIOACTIVITY