radioactivity

Radioactivity – unstable atomic nuclei release subatomic particles. The phenomenon of radioactivity is observed in heavy elements such as uranium.

Radioactivity is the spontaneous loss of energy from an unstable atom, in the form of various nuclear byproducts (radiation). It helps the atom gain a relatively stabler configuration. This spontaneous loss, known as radioactive decay, continues till a stable (nonradioactive) configuration is achieved.

Radiation – The main types of emissions from radioactive substances are: Alpha Radiation, Beta Radiation, Gamma Radiation, and X-rays. Gamma and X-rays are very powerful and potentially very dangerous. They can pass through virtually anything, and are effectively shielded or absorbed only by materials of high atomic weight such as lead. Because of their penetrating ability, X-rays are used to see inside the human body, destroy cancer cells in radiation therapy, or analyze the internal structure of rocks and minerals, for instance.

Cosmic radiation – Gamma rays produced naturally by the sun and other bodies in outer space, and transmitted to earth

Radioactive earth minerals, Uranium and Thorium also emit Gamma rays.

Geiger counter is a device to detect radioactivity.

Radioactive waste disposal – reduce the radioactivity of the stored byproducts.

• vitrification (forming a mixture of the radioactive waste and glass and storing it in steel containers)
• reusing the radioactive waste until it becomes sufficiently benign
• storing spent nuclear fuel in dry casks after it has been treated in spent fuel pools for a long period, at least a year.

Good radioactivity

• Tracers are radioactive elements, which are used to follow their pathway through a chemical reaction. These elements are traced in a chemical reaction to find their course in a chemical reaction. Tracers are used in the medical field and in the study of plants and animals. For example, Iodine-131 is used to study the functioning of thyroid gland.

• Nuclear power stations commonly use uranium atoms as a fuel to produce energy. The heat that is released during the process of nuclear fission is used to generate steam, which in turn, rotates the turbine to produce electric energy.

• Sterilization of food and medical instruments harnesses radioactivity. By subjecting the instruments or the food materials to concentrated radiations, the microorganisms causing contamination can be killed. Radioactivity can also be used in the testing and inspection of materials.

• Radiotherapy – rays of radioactivity is used for the treatment of various diseases. It is an effective treatment for various forms of cancer. Here, a high dose of gamma rays are penetrated through the immature cancerous cells that are growing at a rapid pace in order to destroy them. Thus it will kill the malignant cells without affecting the normal ones. Similar kind of treatment is carried out for the elimination of tumors as well.

• Radioactivity is also used for the diagnosis of several diseases. Radioactive pills are used to check if the organs of the body are functioning normally. It helps in the detection of exact location of a tumor or a blood clot in various parts of the body. Radioactive iodine-123 is popularly used for the diagnosis of thyroid problems. Cobalt-67 is useful for diagnosing pernicious anemia.

• 3D printing replica tumors and organs – molecular radiotherapy – doctors give a patient a radioactive drug designed to target a tumor, and aim for a dose high enough to kill cancer cells but not so high that it damages healthy tissue. Known as ‘phantoms’ – made from a type of plastic and printed by researchers are based on scans taken during patient treatment. Then the phantoms were filled with the same radioactive liquid administered to patients and monitored to mimic the likely effects of radiotherapy in that individual patient.

• Carbon dating – technique to determine the age of archeological objects, fossils or any remnant from the past by comparing ratios of two isotopes of carbon – C-14 is radioactive while C-12 is not. Isotopes are elements with the same atomic number, but different atomic mass numbers. C-14 has a half life of approximately 5730 years. Age can be estimate based on laws of radioactive decay and the amount of radioactive carbon present now. The method was developed by Willard Libby and his associates in 1949. The impact of this technique on the world of science, led to Libby being awarded the Nobel Prize in Chemistry in 1960.

Radioactive waste, contamination

• When soil is contaminated by radioactive substances, the harmful substances are transferred into the plants growing on it. It leads to genetic mutation and affects the plant’s normal functioning. Some plants may die after such exposure, while others may develop weak seeds. Eating any part of the contaminated plant, primarily fruits, poses serious health risks.

• The impact of radioactivity on human beings can vary from mild to fatal; the magnitude of the adverse effects largely depends on the level and duration of exposure to radioactivity. Low levels of localized exposure may only have a superficial effect and cause mild skin irritation. Effects of long, but low-intensity exposures include nausea, vomiting, diarrhea, loss of hair, bruises due to subcutaneous bleeding etc. Skin cancer, lung cancer and thyroid cancer are some of the common types of cancers caused by radiation.

Because radiation provides great benefits of abundant clean energy and medical and scientific innovation but has potentially serious negative impact on the environment and life if not handled properly, radioactivity is a topic of considerable interest.

• Detecting radioactivity

Geiger counter is a device to detect radioactivity, or ionizing radiation. A typical Geiger counter consists of a Geiger-Mueller tube, a visual readout, and an audio readout.

The Geiger-Mueller tube or detector is the heart of a Geiger counter. It is a type of ionization chamber that counts particles of radiation. That count is read by the user through a visual readout in the form of a traditional analog meter, or an electronic LCD (liquid crystal display) readout.

• Ask – What type of radiation is measured? What units are used for measurement? Virtually all Geiger counters detect Gamma and X-rays, while some models detect Alpha and Beta radiation as well.These meters are available in different units, including mR/hr, or milli-Roentgens per hour (popular in the US and Israel), and µSv/hr, or micro-Sieverts per hour (popular in Canada and overseas ).
• Imagine – How can the user be altered to the amount of radiation? Most Geiger counters also have an audio readout that sounds one “click” for each particle count. These particles are emitted at random intervals, and a large number of particles produced in a short span of time sound almost like static from a radio. Sounds like this.
• Design, Build – What forms of output are available? What other features do users want?
  Digital Geiger counters not only offer visual digital readouts on an LCD display, but they typically also have audio ports for external speakers, as will as data ports for readout on computers and data loggers. What technologies are used today? In contrast to vintage 1950’s civil defense models, modern Geiger counters are built around transistorized, solid state electronics, and are powered by easily replaceable batteries.
• Improve – How can the Geiger counters design be changed to measure more types of radiation? Another feature found on some Geiger counters is an open window over the Geiger-Mueller tube. This allows for energy discrimination, that is, the determination of what type of radioactivity the unit is measuring, between Gamma and X-rays that are strong enough to pass right through the housing of the Geiger counter, versus Beta and Alpha radiation, which are too weak to pass through the housing, but can be read through the open window of the detector.

That’s engineering

• isotope – Different forms of an element that vary somewhat in weight (and potentially in lifetime). All have the same number of protons, but different numbers of neutrons in their nucleus. That’s why they differ in mass.
• radioactive – An adjective that describes unstable elements, such as certain forms (isotopes) of uranium and plutonium. Such elements are said to be unstable because their nucleus sheds energy that is carried away by photons and/or and often one or more subatomic particles. This emission of energy is by a process known as radioactive decay.

Engineering ideas

• audio port, data port, transistor, solid state electronics, batteries, units of radiation, analog, LCD, isotope, radioactive

Do it
Now it is your turn. Here are some challenges for you to work on…

• Radioactive Dating Game – Learn about different types of radiometric dating, such as carbon dating. Determine the age of different objects such as fossils and rocks by percentage of parent nuclei remaining. Understand how decay and half life work to enable radiometric dating. Play a game that tests your ability to match the percentage of the dating element that remains to the age of the object.

• find some specific uses of radioactive materials that are beneficial
• explore the subject of radioactive contamination and danger, and what can be done about it

Learn more…

• Geiger counters, Radiation
• Bomb: The Race to Build—and Steal—the World’s Most Dangerous Weapon – deep in the desert, one brilliant group of scientists was hidden away at a remote site at Los Alamos. This is the story of the plotting, the risk-taking, the deceit, and genius that created the world’s most formidable weapon. This is the story of the atomic bomb.