Chapter 5: Harnessing the Secrets of the Nucleus Nuclear Energy, Nuclear Medicine, and a Nuclear CalendarNuclear Medicine © 2003 John Wiley and Sons Publishers Courtesy Roger Ressmeyer/Corbis Images

Enrico Fermi built the first atomic pile and produced the first controlled chain reaction on December 2, © 2003 John Wiley and Sons Publishers Courtesy University of Chicago/AIP Neils Bohr Library

A depiction of the dawn of nuclear power as the first chain reaction begins beneath Stagg Field, Chicago. © 2003 John Wiley and Sons Publishers “Birth of the Atomic Age by Gary Sheahan/Chicago Historical Society.

Figure 5.1: Schematic diagram of a nuclear power plant. © 2003 John Wiley and Sons Publishers

Cooling towers of a nuclear power plant. © 2003 John Wiley and Sons Publishers Courtesy David Bartruff/Corbis Images

The nuclear power plant at Chernobyl, after the accident of April 16, © 2003 John Wiley and Sons Publishers Courtesy Sipa Press

Disposal of radioactive wastes by burial in a shallow pit. © 2003 John Wiley and Sons Publishers Courtesy Matthew Neal McVay/Stone/Getty Images

Figure 5.2: Graphical representation of the disappearance of a radioisotope. © 2003 John Wiley and Sons Publishers

Half-life is the time for the radiation level to decrease (decay) to one-half of the original value. Half-Life decay curve

Half-Lives of Some Radioisotopes

After one half-life, 40 mg of a radioisotope will decay to 20 mg. After two half-lives, 10 mg of radioisotope remain. 40 mg x 1 x 1 = 10 mg half-life 2 half-lives Initial 40 mg 20 mg 10 mg Half-Life Calculations

The half life of I-123 is 13 hr. How much of a 64 mg sample of I-123 is left after 26 hours? 1) 32 mg 2) 16 mg 3) 8 mg Learning Check

2) 16 mg Half life = 13 hrs Number of half lives = 2 Amount remaining = 64 mg x 1 x 1 = 16 mg hrs 13 hrs 64 mg 32 mg 16 mg Solution

Medical Applications Radioisotopes with short half-lives Are used in nuclear medicine. Have the same chemistry in the body as the nonradioactive atoms. In the body give off radiation that exposes a photographic plate (scan), which gives an image of an organ.

23.6 Radioisotopes in Medicine 1 out of every 3 hospital patients will undergo a nuclear medicine procedure 24 Na, t ½ = 14.8 hr,  emitter, blood-flow tracer 131 I, t ½ = 14.8 hr,  emitter, thyroid gland activity 123 I, t ½ = 13.3 hr,  ray emitter, brain imaging 18 F, t ½ = 1.8 hr,   emitter, positron emission tomography 99m Tc, t ½ = 6 hr,  ray emitter, imaging agent Brain images with 123 I-labeled compound

An image of a thyroid gland obtained through the use of radioactive iodine. © 2003 John Wiley and Sons Publishers Courtesy Custom Medical Stock Photo

Images of human lungs obtained from a γ-ray scan.γ-ray scan. © 2003 John Wiley and Sons Publishers Courtesy CNRI/Phototake

Some Radioisotopes Used in Nuclear Medicine

Learning Check Which of the following radioisotopes are most likely to be used in nuclear medicine? 1) 40 K half-life 1.3 x 10 9 years 2) 42 K half-life 12 hours 3) 131 I half-life 8 days

Solution Which of the following radioisotopes are most likely to be used in nuclear medicine? Radioisotopes with short half-lives are used in nuclear medicine. 2) 42 K half-life 12 hours 3) 131 I half-life 8 days

Construction of a tunnel that will be used for burial of radioactive wastes deep within Yucca Mountain, Nevada. © 2003 John Wiley and Sons Publishers Courtesy Yucca Mountain Project

A cancer patient receiving radiation therapy. © 2003 John Wiley and Sons Publishers Courtesy Kelley Culpepper/Transparencies, Inc. Youtube.com

Figure 5.4: Positron emission by fluorine-18. © 2003 John Wiley and Sons Publishers

The image on the Shroud of Turin.Shroud of Turin © 2003 John Wiley and Sons Publishers Courtesy Patrick Mesner/Liaison Agency, Inc. /Getty Images

A medical worker wearing a film badge. © 2003 John Wiley and Sons Publishers Courtesy Yoav Levy/Phototake

Figure 5.6: The Geiger counter. © 2003 John Wiley and Sons Publishers

Detecting Radiation A Geiger counter detects radioactive radiations. Ions produced by radiation create an electrical current.

28 Geiger counter

29 Chapter 22Slide 29 A Geiger counter determines the amount of ionization by detecting an electric current. A thin window is penetrated by the radiation and causes the ionization of Ar gas. The ionized gas carried a charge and so current is produced. The current pulse generated when the radiation enters is amplified and counted.

30 Chapter 22Slide 30 Biological Effects of Radiation The penetrating power of radiation is a function of its mass:  -rays >  -particles >>  -particles. When ionizing radiation passes through tissue it removes an electron from water to form H 2 O + ions. The H 2 O + ions react with another water molecule to produce H 3 O + and a highly reactive OH radical. Free radicals generally undergo chain reactions, producing many radicals in the biomolecules.

31 Radiation Measurement Curie: 1 Ci = 3.7 x disintegrationsThe Curie measures the number of atoms that decay in one second. Curie: 1 Ci = 3.7 x disintegrations The rad (radiation absorbed dose) measures the radiation absorbed by the tissues of the body. The rem (Roentgen equivalent for man (rem) ) measures the biological damage.

Girl being scanned with a Geiger counter after a nuclear accident. © 2003 John Wiley and Sons Publishers Courtesy AP/Wide World Photos

Receiving radiation from a dental X-ray. © 2003 John Wiley and Sons Publishers Courtesy PhotoDisc, Inc./Getty Images

34 Background Radiation A person is exposed to radiation from naturally occurring radioisotopes and medical X rays.

35 Effects of Radiation

© 2003 John Wiley and Sons Publishers (a) What percentage of the world’s nuclear power plants are located in the United States? (b) Rank the countries of Table 5.1 in terms of the percentage of electric power produced from nuclear plants. Where in this ranking does the United States stand? QUESTION

© 2003 John Wiley and Sons Publishers What is the most serious form of damage that could occur if a natural disaster such as a hurricane, a tornado, or an earthquake struck a nuclear power plant? Explain. QUESTION

© 2003 John Wiley and Sons Publishers Describe one advantage of a breeder reactor over a conventional nuclear reactor. Describe one disadvantage. QUESTION

© 2003 John Wiley and Sons Publishers What is the ultimate fate of every radioactive atom now in existence? QUESTION

© 2003 John Wiley and Sons Publishers If each of the radioisotopes of Table 5.3 were stored at the Yucca Mountain site, which would still be present after 10,000 years at a level of 10% or more of the original amount? QUESTION

© 2003 John Wiley and Sons Publishers (a) What is one cost of electric power production by nuclear power that is not a factor in the use of coal, petroleum, or natural gas? (b) What is one cost of electric power production by these fuels that is not a factor in the use of nuclear power? QUESTION

© 2003 John Wiley and Sons Publishers Name and describe two types of biological damage caused by ionizing radiation. QUESTION

© 2003 John Wiley and Sons Publishers How is each of the following used in medical diagnosis and/or therapy? (a) I-131; (b) Tc- 99m; (c) Co-60. QUESTION

© 2003 John Wiley and Sons Publishers Into what element is an atom of nitrogen-13 transformed when it emits a positron? QUESTION

© 2003 John Wiley and Sons Publishers What would the ratio of Pb-206 to U-238 atoms be if the sample of meteorite in the exercise were 18.0 x 10 9 years old? QUESTION

© 2003 John Wiley and Sons Publishers Which of the following can be dated by radiocarbon techniques: (a) a rock; (b) a leather slipper; (c) a wooden boat; (d) a mummified body; (e) a silver spoon. Describe your reasoning. QUESTION

© 2003 John Wiley and Sons Publishers Which one or more of the detection devices described in this Section would you use if you wished to determine immediately whether the residue left by a spilled chemical is radioactive? Which would you use if you wanted to determine the total, cumulative amount of radiation you might be exposed to in the course of an entire month? QUESTION

© 2003 John Wiley and Sons Publishers Assign the data of each of the sources of Table 5.6 into one of two categories: (a) originates in human activities; (b) natural, not dependent on human activities. What total percentage of exposure is associated with each of the two categories? QUESTION