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Radiation Protection & Shielding
The Radiation Protection and Shielding Division is developing and promoting radiation protection and shielding aspects of nuclear science and technology — including interaction of nuclear radiation with materials and biological systems, instruments and techniques for the measurement of nuclear radiation fields, and radiation shield design and evaluation.
Utility Working Conference and Vendor Technology Expo
August 8–11, 2021
Marco Island, FL|JW Marriott Marco Island
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Metz on Harold Denton: Memories of a life in nuclear safety
A number of years ago, historian and writer Chuck Metz Jr. was at the Bush’s Visitor Center in Tennessee’s Great Smoky Mountains when he ran into former Nuclear Regulatory Commission official Harold Denton and his wife. Metz was at the visitor center, which opened in 2010 and is now a tourist hotspot, because, as he explained to the Dentons at the time, he had overseen the development of its on-site museum and had written a companion coffee-table history book.
The chance meeting turned into a friendship and a fruitful collaboration. Denton, who in 1979 was the public spokesperson for the NRC as the Three Mile Island-2 accident unfolded, had been working on his memoir, but he was stuck. He asked Metz for help with the organization and compilation of his notes. “I was about to retire,” Metz said, “but I thought that exploring the nuclear world might be an interesting change of pace.”
Denton passed away in 2017, but by then Metz had spent many hours with his fast friend and was able to complete the memoir, Three Mile Island and Beyond: Memories of a Life in Nuclear Safety, which was published recently by ANS. Metz shared some of his thoughts about Denton and the book with Nuclear News. The interview was conducted by NN’s David Strutz.
Radiation is simply the transmission of energy from a source via waves or particles.
There are many kinds of radiation that move in waves, most of them very familiar to you, like radio waves, visible light, and x-rays. They are all part of the electromagnetic spectrum.
Radiation can also be described as non-ionizing or ionizing.
Non-ionizing radiation has enough energy to excite atoms, making them move more rapidly. Microwave ovens work by exciting water molecules, creating friction. The friction creates heat, and the heat warms the food. Other examples of non-ionizing sources include radio transmissions, cell phones, and visible light.
Ionizing radiation has enough energy to remove electrons from their orbits, creating ions. Examples of ionizing sources are high-level ultraviolet light, X-rays, and gamma rays.
Ionizing radiation happens when an unstable atom (a radioactive isotope of an element) emits particles or waves of particles to become more stable. This process is called radioactive decay.
Not all of the atoms of a radioactive isotope decay at the same time. Instead, the atoms decay at a rate that is characteristic to the isotope. The rate of decay is a fixed rate called a half-life.
The half-life of a radioactive isotope refers to the amount of time required for half of a quantity of a radioactive isotope to decay. For example, carbon-14 has a half-life of 5730 years, which means that if you take one gram of carbon-14, half of it will decay in 5730 years. Different isotopes have different half-lives.
Radioactive decay is random; we can't tell which atoms in an isotope sample will decay. But, it is also predictable and exponential, so we can determine how long it will take for a sample to completely decay based on its half-life.
There are four basic types of ionizing radiation--alpha, beta, gamma, and neutron--and each has unique properties.
Alpha radiation happens when the unstable atom emits two protons and two neutrons—basically a helium nucleus. The original atom, with fewer protons and neutrons, becomes a different element.
Compared to other forms of ionizing radiation, alpha particles are large and heavy. They can’t travel very far, so they are useful in things like smoke detectors. They can be stopped by a piece of paper, your skin, or even just a few inches of air.
Beta radiation is when a proton in an unstable atom becomes an electron. Because it loses a proton, the original atom becomes a different element.
Beta particles are much smaller than alpha particles, so they can travel farther and penetrate deeper. Beta particles are sometimes used in eye surgery.
Gamma radiation and x-rays, are high-energy waves that can travel great distances at the speed of light. Both can penetrate deeply into matter.
X-rays are stopped by dense materials like bone, tumors, or lead. This makes them useful for medical diagnosis.
Gamma rays can penetrate further with higher energy. Gamma radiation can be used to precisely target and eliminate tumors; it also has a number of uses in industry, agriculture, pest-control, and more. Gamma rays be stopped by several inches of lead.
Neutron radiation is created as a result of fission reactions and happens in nuclear reactors. Neutrons are extremely high energy, so need many feet of dense materials like water or concrete to stop them. Neutron radiation can make other materials radioactive and is used to create the radioisotopes used in medical treatments.
Learn about the beneficial uses of radiation
Learn about exposure to radiation
Last modified July 19, 2021, 3:07pm CDT