제  목 : The Role of Radioactivity in Everyday Life
  일  자 : 1998년 07월
  제공처 : Internet

          The Role of Radioactivity in Everyday Life
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  New Orleans ？？Radiation is not a modern creation of man？s tinkering
  with the atom. Radiation is a natural energy force that has existed on
  Earth and in the universe since the beginning of time. People disagree
  widely about the merits and dangers of nuclear energy, but the fact is
  there are many benefits of nuclear technology that are embedded in our
  daily lives,？ said Captain William F. Holcomb, of the U.S. Public Health
  Service at the National Institutes of Health Radiation Safety
  Branch/Radiation Safety Training Unit in Bethesda, Maryland, speaking
  here today at the Spring National Meeting of the American Institute of
  Chemical Engineers (AIChE). Holcomb？s session offered an overview
  of many of nuclear energy？s uses and misuses since the discovery of
  naturally occurring radium and uranium and the advent of man-made
  radionuclides.

  ？In the health arena, nuclear technology can be used in a variety of
  techniques to prevent, diagnose, and treat disease,？ Holcomb said. ？The
  discovery of x-rays in 1895 was a major turning point in diagnosing
  disease because physicians finally had a way to see inside the body
  without having to operate.？ According to Holcomb, one-third of
  Americans hospitalized each year undergo some sort of medical
  procedure that uses radiation. ？Some ten million nuclear medicine
  procedures and more than 100 million nuclear medicine tests are
  performed each year in the US,？ Holcomb said, explaining that ？most
  are devoted to diagnostics, i.e., studying the processes of organs and
  diseases as they work on those organs.？ ？Visualization, function, and
  blood flow measurements of essentially all body organs makes up more
  than 90 percent of clinical practice of nuclear medicine,？ he reported.
  The diagnostic use of radiation, such as mammography, has led to major
  improvements in the detection and treatment of cancer. Such
  innovations have resulted in increased survival rates and improved
  quality of life for many patients.

  Radiation also has many industrial uses, for example, allowing industry
  to develop highly sensitive gauges, using radioisotopes, to measure the
  thickness and density of numerous materials, and imaging devices to
  inspect finished goods for weaknesses and flaws. Some of the
  examples Holcomb gave included safety tests on airplanes to detect
  cracks or the spreading of cracks; testing the integrity of pipeline welds;
  measuring the dust and pollutant levels on filter paper; inspecting airline
  luggage for hidden explosives,

  weapons, or drugs; sterilizing surgical instruments; smoke detectors
  used in factories, shops, and offices; and even the Pioneer 10
  spacecraft, which was launched in 1972 and is now more than 3 billion
  miles from Earth and still sending back radio transmissions using a
  nuclear-powered generator.

  ？Manufacturers who use radioactive materials do so only under strict
  guidelines and must be licensed and regulated for safety by either the
  federal or state government,？ Holcomb cautioned. ？Radiation？s
  versatility is a major reason why the number of organizations using
  nuclear materials with federal licenses increased from 7,000 in 1962 to
  25,000 in 1992,？ he added.

  Food preservation is another prime use of radiation. ？Foods preserved
  by irradiation procedures do not become radioactive or toxic as a result
  of the radiation,？ Holcomb said. ？The technical feasibility of safely
  preserving certain foods by irradiation has existed since the 1950s, and
  is firmly established by experimental evidence and experience,？ he
  explained, saying that irradiated beef steaks are routinely consumed by
  the Space Shuttle crew.？

  Radiation is already used to control insects in wheat and flour; inhibit
  sprout development in potatoes, onion, and garlic; inhibit trichinosis in
  pork; slow growth and ripening, plus control insects in fresh fruits and
  vegetables; kill insects and control microorganisms in dry herbs, spices,
  seeds, and vegetable seasonings; and eliminate spoilage and pathogenic
  microorganisms in seafood, poultry, and meat. ？Radiation pasteurization
  can protect the public from diseases such as salmonellosis, and
  hemorrhagic diarrhea caused by e-coli and gastroenteritis,？ Holcomb
  cautioned. ？Other consumer products that are irradiated for sterilization
  purposes, include baby bottle nipples, pacifiers, bandages, hair brushes,
  ointments, latex gloves, and surgical gowns,？ he said.

  ？It is a common error to believe that nuclear power plants can explode
  like nuclear bombs. Because of design configuration and nuclear fuel
  characteristics, such explosions are impossible,？ Holcomb said.

  However accidents do, and have, occurred at nuclear reactors and
  other facilities, with varying consequences. In 1961, the Enrico Fermi
  Breeder Reactor in Michigan experienced a partially blocked coolant
  flow, and portions of the core overheated and melted. The reactor was
  promptly shut down and no radiation escaped.

  In 1979, the U.S. experienced its worst commercial nuclear power plant
  accident when Unit 2 of the Three Mile Island reactor in Pennsylvania
  ？experienced mechanical malfunctions and human misjudgments in
  responding to them that resulted in major damage to the reactor plant.
  No one was injured and the releases were far too low to result in future
  health effects,？ Holcomb reflected.

  But, the most serious accident in the history of the nuclear industry took
  place in 1986, when an explosion occurred in Unit 4 of the Chernobyl
  Nuclear Power Station in the eastern part of the former Ukrainian
  Republic of the former Soviet Union, ？in which large amounts of
  radioactive materials were released to the environment.？

  ？The Chernobyl disaster was the product of a severely flawed reactor
  design and serious mistakes made by the plant operators, who violated
  procedures intended to ensure safe operation of the plant,？ Holcomb
  explained. ？The Chernobyl accident, not only because of its severity,
  but especially because of the presence of radiation, has had a
  significant impact on human society. Not only has it produced health
  effects and physical, industrial and economic damage in the short term,
  but, long-term consequences in terms of socio-economic disruption,
  psychological stress, and the damaged image of nuclear energy, which
  are expected to be long-standing,？ he said.

  Over the years, accidents in the nuclear industry have become a source
  of concern and apprehension to the public. ？Most, however, have
  allowed regulatory agencies to develop additional safety rules and
  requirements to decrease the possibility of fatal accidents,？ Holcomb
  noted. Despite the popular perception of radiation associated with
  bombs and death, radioactive materials have become a vital part of
  medicine, industry, and science, and ？nuclear technology has the
  potential to save lives,？ Holcomb concluded.