Radiation Passes Over Midwest

May 07, 1986|By John N. Maclean, Chicago Tribune.

WASHINGTON — Traces of radiation from the Soviet nuclear accident at Chernobyl have shown up at ground level in the Pacific Northwest for the first time, it was announced Tuesday, but U.S. officials said they pose no danger to public health.

The atmospheric clouds carrying the radioactivity now have passed over the Midwest, the officials said, and trace amounts may be showing up after rains there.

``My guess is that radioactivity will be detected (in the Midwest),``

said Lester Machta, director of the air resources laboratory for the National Oceanic and Atmospheric Administration and a member of the federal task force on the Soviet accident.

Lee Thomas, administrator of the Environmental Protection Agency and task force head, told reporters, ``We are way, way below anything that would trigger any kind of action.``

Samples of rainwater at Richland, Wash., and Portland, Ore., showed increased levels of radiation attributable to the April 26 disaster in the Ukraine, according to the government task force.

Ian McDonald, director of the Public Health Service, was asked if he would drink the water.

``It would really depend on how thirsty you are,`` he said. ``I would drink it. I would prefer not to drink it.``

A statement by the task force added: ``This level poses no danger to residents in the area. The radiation dose to an individual drinking one liter of rain water at this level would be less than 1 percent of the average annual background radiation dose and is comparable to less than half the radiation dose received from a single chest X-ray.``

The amount measured at Richland was 500 picocuries of iodine-131 per liter of water, but the level of accuracy meant the actual amount could be anywhere from 250 to 1,000 picocuries per liter. At Portland, the level measured was 630 picocuries per liter.

In Japan, radioactivity levels of 10,000 picocuries have been measured in recent days.

A curie is unit for measuring radioactivity, and a picocurie is a trillionth of a curie. A picocurie is equal to the quantity of any radioactive material in which the number of atomic disintegrations is about two per minute.

Iodine-131, the only radioactive isotope found so far in rainwater, has a half life of 8.1 days, which means half its radioactivity is lost every 8.1 days.

(The EPA`s overall drinking-water standard permits only 3 picocuries per liter, which would translate to an annual dosage of 4 millirems per year for anyone drinking two liters of water a day. Short-term, however, much higher concentrations are permitted. For example, the Food and Drug Administration allows 15,000 picocuries per liter of milk in fallout episodes that occur no more frequently than once a year.

(A rem--which stands for roentgen equivalent man--is a dosage of any ionizing radiation that will produce a biological effect approximately equal to that of a roentgen of X-ray or gamma-ray radiation. Scientists say exposure to 200 roentgens can be fatal.)

The EPA has begun daily radiation monitoring at 68 sites across the country since the Soviet accident, but other reporting stations in the U.S. and Canada have shown no increases, the task force reported.

In another development, the Department of Energy is accelerating a safety evaluation of five U.S. nuclear reactors that lack containment buildings and expects to have one review completed within 10 days.

DOE Undersecretary Joseph Salgado told a congressional subcommittee he does not believe it will be necessary to close the most controversial of the five, a reactor at Hanford, Wash., which uses graphite--as did the Chernobyl reactor. Salgado said there are major differences between the two, and he believes the Hanford site, where the early review is underway, is safe.

``We are extremely confident in our safety features,`` Salgado said.

DOE has control of reactors used to make nuclear weapons; the NRC has control of those used for generating electrical power.

The Hanford site is one of only two in the U.S. that use graphite to slow the nuclear reaction. The other is the Ft. St. Vrain generating plant near Platteville, Colo.

A coalition of environmental and public interest groups Tuesday filed a petition with the NRC asking suspension of licenses for reactors not yet completed. The coalition also asked for the immediate closing of the Hanford reactor and four other DOE reactors, all at Savannah, Ga.

``The facilities lack the containment domes required for commercial nuclear reactors and otherwise fall far short of the minimal safety requirements imposed by the Nuclear Regulatory Commission,`` said Scott Denman, spokesman for the Safe Energy Communication Council. ``They are regulated by the Department of Energy, which, like the Soviet Union, provides no forum for public input in the licensing or operation of its facilities.``

A spokesman for the NRC said the petition had been received, but it was too early to comment on it.