The Seattle Times Web Edition: 50 Years from Trinity


IMAGE: Three workers sitting on a bench, suiting up
Hanford workers suit up before entering radioactive areas to protect them from breathing and contacting airborne particles of radiation.

RADIATION IS INESCAPABLE, useful and dangerous, and understanding its benefits and risks is a necessary part of living in the atomic age.
   While the word "radiation" is a broad term that includes sunlight and heat, it is most commonly used to refer to ionizing radiation, which is caused by the decay of atoms that releases energetic particles capable of damaging living cells. Humans have been aware of this kind of radiation for only a century.
   We are exposed all the time to low levels of natural ionizing radiation. Our bodies are mildly radioactive, our bones having absorbed radioactive elements such as potassium-40 from food we eat. This, on average, contributes 11 percent of our annual background dose, or 39 millirems. We get cosmic radiation from outer space and radiation from the naturally occurring uranium, thorium, radium, radon and potassium atoms in the earth.
   Flying in an airplane slightly increases cosmic radiation by lessening the amount of atmospheric shielding from cosmic rays. Airline crews on the New York-Tokyo route get an amount estimated to be about three times normal background.
   Similarly, mile-high Denver residents get twice as much radiation from cosmic rays as Seattleites. Living in Spokane exposes residents to about five times the natural background radiation as here because of higher levels of radon in the Spokane area.
   Medical X-rays and diagnostic tests add to our exposure. There is even a tiny amount of fallout left from atmospheric nuclear testing.
   Our bodies repair some radiation damage. Healthy cells fix themselves all the time. But massive doses of radiation can destroy cells, killing quickly, and milder doses can occasionally overcome the body's repairs and cause DNA damage that can trigger cancer or other diseases.
   This damage and repair cycle makes assessing the risk from nuclear waste, nuclear-power plants and fallout from nuclear testing extremely difficult. Scientists can predict with some accuracy that exposing many people to radiation will result in some percentage of them being harmed. They can't say whether low-level exposure will trigger cancer or other diseases in any individual.
   For example, millions of Americans benefit each year from medical X-rays. In a tiny handful, the procedure triggers cancer. Most people believe the benefits of X-ray diagnosis outweighs the extremely remote risk of getting sick from it.
IMAGE: Testing gloves at Hanford, 1960    Even large radiation doses harm some people and not others. Studies of Hiroshima and Nagasaki victims showed elevated levels of several kinds of cancer, such as 3.5 times the risk of breast cancer and 1.8 times the risk of lung cancer. But many survivors have not contracted any cancer.
   One worker at the Hanford nuclear reservation in Eastern Washington received such a strong exposure after an explosive accident that he was dubbed "The Atomic Man" and could set off Geiger counters at 50 feet. But he lived 10 more years and died of heart disease.
   Still, numerous occupational and disease studies have resulted in scientists steadily increasing their estimate of radiation's risk and reducing the recommended maximum dose.
   Since 1968, nuclear-industry workers have been limited by the federal government to no more than 5,000 millirems per year, and usually by their employers to no more than 2,000 millirems.
   By comparison, the standard was 30,000 millirems per year in 1934.
   Natural background radiation averages about 360 millirems per year, or one a day.
   I wore radiation-monitoring devices at Hanford while visiting spent-fuel basins, plutonium-storage vaults and an open reactor being refueled. The accumulated recorded exposure from all this was about 1 millirem. I likely picked up about 2 millirems at the Trinity bomb test site in New Mexico. At the Nevada Test Site, radiation badges for visitors were dispensed with in January because of low remaining levels from most early bomb tests.
   Assessing radiation risk is further complicated because not all radiation is alike.
   For example, alpha radiation is blocked by human skin, but gamma rays and neutrons are extremely penetrating.
   Some radioactive isotopes are extremely dangerous in the short term but decay quickly and pose no long-term waste problem. The dangerous isotope of iodine, which may have caused thyroid disease among people living downwind from Hanford in the 1940s and 1950s, has a half-life of eight days and thus decays almost entirely in a few weeks.
   Other isotopes persist a long time but give off weaker radiation. Plutonium, for example, has a half-life of 24,000 years but emits only alpha radiation. It is possible, though not advised, to hold a "button" of purified plutonium in one's hand without harm; one scientist compared its warm feel to that of a live bunny.
   Plutonium is also unlikely to harm if it is swallowed. The body typically flushes it out of the digestive system before its weak radiation can have an effect. Plutonium is extremely dangerous if particles are breathed, however: They can lodge in the lungs and steadily give off radiation that could eventually trigger cancer.
   During World War II, the U.S. government allowed plutonium workers to inhale up to a millionth of a gram of plutonium but by 1950 had concluded there was no permissible lower limit.
   The differences in isotopes makes dealing with nuclear waste complex and, to the public, confusing. There are four primary kinds:

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