Americans’ average radiation exposure

We live with radiation every day. We receive radiation exposures from cosmic rays, from outer space, from radon gas, and from other naturally radioactive elements in the earth. This is called natural background radiation. It includes the radiation we get from plants, animals, and from our own bodies.

We also are exposed to man-made sources of radiation, including medical and dental treatments, television sets and emissions from coal-fired power plants. Generally, radiation exposures from man-made sources are only a fraction of those received from natural sources. One exception is high exposures used by doctors to treat cancer patients.

Each year in the United States, the average dose to people from natural and man-made radiation sources is about 360 millirem. A millirem is an extremely tiny amount of energy absorbed by tissues in the body.


Where you live contributes to your exposure

One of many factors contributing to radiation exposure is where you live. The level of radiation exposure in Nevada varies, being lower in the valley areas and higher in the elevated areas. The atmosphere is thinner at higher altitudes and allows more cosmic radiation exposure. The current average annual radiation dose to persons living in the Amargosa Valley is around 400 millirem, some 40 millirem more than the national average.


Protecting the public from repository radiation

Protection of the public is of utmost importance to the United States Department of Energy. The repository design is intended to meet or exceed strict federal regulatory standards for radiation exposures.

There are primarily two different radiation exposures to the public that might be possible from having a repository for spent nuclear fuel and high-level radioactive waste. The first is from transporting the materials and the second is from the repository for the materials.


Exposures from transportation are very low

Estimates for radiation dose from transportation, based on the exposure of a person standing 100 feet from a vehicle that is carrying waste and moving 15 miles per hour, is about 0.0004 millirem. A person would receive 5,000 to 12,500 times more radiation dose on a round-trip flight from Los Angeles to New York on a commercial airline (2.5 millirem).

Once the repository opens, the estimated number of rail casks shipped would range from 190 to 317 per year, on trains carrying 3-5 casks. Annual truck shipments could range from 53 to 89 per year, with one cask per truck. However, if all shipments were sent via truck, it would result in about 50,000 shipments over the 24-year period. If a person were to stand 100 feet from a transportation route 24 hours a day for 24 years, and were exposed to all 50,000 truck shipments, that person would receive a total whole-body radiation dose of about 20 millirem. During the same 24-year timeframe, that same person would receive over 7,000 millirem from natural background radiation.


Exposures from a repository

Radiation exposures from a repository are estimated by the Department of Energy as follows:

• During the first 10,000 years following the closing of the proposed repository, persons living in Amargosa Valley would receive little or no increase in radiation exposure from the repository. (This community is referenced because water from Yucca Mountain flows toward the Amargosa Valley. Water is expected to be the vehicle that would move radioactive particles from a repository to the water table and from there to contact with people and the environment.)
  
  
• The Department estimates the maximum exposure to occur some 300,000 years after the repository is closed. At that time, it is possible that some people living in the Amargosa Valley could receive an additional 260 millirem per year. This would bring their total radiation dose to around 660 millirem per year.
  
  To put this dose in perspective, 660 millirem is somewhat higher than the 360 millirem national average on a yearly basis but well below levels received by people living in other parts of the United States.
  
  For example, people living in the northwest region of Washington state receive about 240 millirem per year, on average, from natural and man-made sources, whereas residents of the southeast region of Washington state receive about 630 millirem per year, on average, from natural and man-made sources. The highest levels of exposure in Washington state are experienced by residents in the northeast region who receive doses of about 1,700 millirem per year, most of it from radon in the rock and soil.

Even though the projections for possible radiation exposure from a repository in the distant future are modest, Department of Energy scientists and engineers are continuing to look at ways to improve radiation protection from a repository.

The Department has been studying Yucca Mountain for more than 20 years, and will continue to study it. Moreover, if the site is licensed, for at least 50 years, and according to current plans up to 300 years, scientists will keep an ongoing check that everything is functioning the way they predicted it would.

For continuing updates on repository efforts, call 1-800-225-6972 or visit our Web site at www.ocrwm.doe.gov.