Nota: il plutonio è l'elemento più letale, basta un milionesimo di grammo per uccidere una persona. Sei chili, sei miliardi di persone. In Europa "loro" ne hanno stoccate 600 tonnellate, 6 milioni di chili, 6 milioni di miliardi di potenziali vittime. Tempo di dimezzamento: 25mila anni. Non si trovava in natura prima dell'era nucleare. Il suo nome viene da Pluto, il dio dei morti dell'antica Grecia.

WASHINGTON, Oct. 20 - The Energy Department has concluded that the amount of plutonium and other man-made radioactive elements released into soil or buried in flimsy containers in the first four decades of nuclear weapons manufacture was 10 times larger than it had estimated.

A private environmental group, the Institute for Energy and Environmental Research, complained in 1997 that government data on the volume and radioactivity of buried plutonium and similar materials "are inconsistent and contradictory." After more than two years of study, the department agreed.

Since the dawn of the nuclear age, the department and its predecessor agencies have processed nuclear materials to make weapons. The production, processing and shaping of the material produced huge quantities of waste. Some of that waste is in known, secure locations - and some of it was poured into the dirt or buried in shallow dumps.

The radioactive elements at issue are "transuranics," or elements heavier than uranium, produced in reactors by bombarding uranium with neutrons. Bombmakers did that to make plutonium for weapons.

But from the first efforts to make an atomic bomb in the early 1940's until the 1970's, much of the plutonium was not separated from wastes, and was instead dumped or buried.

Since 1987, the department has said that more than 97 percent of the plutonium and other related waste was locked up in "retrievable" storage, destined for deep burial at a new repository, and only about 3 percent was poured into the dirt or buried.

Now the department says that the material poured into dirt or buried contains much more of the more dangerous nuclear wastes. Using a standard measure of radioactivity, the officials now say there is 10 times the amount of those wastes in the soil and in flimsy containers than previously estimated.

In response to the institute's complaint, the department surveyed production and dumping records at its Hanford nuclear reservation, near Richland, Wash.; the Idaho National Engineering and Environmental Laboratory, near Idaho Falls; the Los Alamos National Laboratory, in New Mexico; the Oak Ridge National Laboratory, near the city of the same name in Tennessee; and the Savannah River Site, near Aiken, S.C. It also raised its estimate for the Nevada Test Site, near Las Vegas, where the transuranics are the result of nuclear test detonations.

The department has opened a permanent repository for plutonium and related wastes 2,150 feet below the desert in Carlsbad, N.M., for the wastes in retrievable storage. It is extremely difficult to gather the uncontained wastes, and little progress has been made on them.

In 1994 the department decided to dig up a one-acre, 25-year-old pit at the Idaho plant, to demonstrate whether retrieval was possible. But in 1998 it fired the contractor because of a disagreement over costs and methods; this year, the department expects to spend $6 million on legal costs in the dispute over the pit, and $2.5 million on cleanup. No waste has yet been retrieved.

It remains unclear how much material has leached into the soil at dump sites around the country, but if the radioactive elements concentrate in the food chain, they are believed to cause cancer if ingested even in small amounts.

Dr. Arjun Makhijani, the president of the institute, said new evidence indicated that the material spreads through soil far more readily than had been believed. Since the material remains radioactive for thousands of years, even slow movement through soil can ultimately threaten underground water supplies.

While the government is spending billions of dollars to stabilize and bury wastes at Carlsbad, those wastes are already well-controlled in retrievable form, he said, and the government is doing virtually nothing to take care of the wastes in the dirt and wastes in barrels that are now rusting and leaking.

Carolyn Huntoon, the assistant secretary for environmental management at the Department of Energy, said in a letter to Dr. Makhijani in July that it was "still appropriate" to manage the buried wastes the same way it has been, which is to gather information on them and review them on a case-by-case basis.

But, she said in the letter, "there is little or no information on volumes of soil potentially contaminated by leaching of buried solid wastes, nor is there information on hazardous waste components known to have been commingled with the radioactive components." Where enough is known, she said, "a mix of remedial alternatives is being considered."

Dr. Makhijani, in a phone interview, said the "shocking thing" about the department's response "is they have increased their estimates of radioactivity in dumped waste, and yet they don't want to revisit the policies that were based on the assumption there was very little radioactivity in these wastes."

He said that the barrels often contain chemical hazards and explosives, so that retrieving them would be difficult. But he and other environmentalists say that retrieval would be more useful than shipping barrels that have been stored in special buildings to New Mexico for underground storage.

In a statement today, Ms. Huntoon noted that the National Academy of Sciences had endorsed the department's approach to the wastes.

But, she said, "in light of this new information, the department will ask the National Academy of Sciences to review D.O.E. strategies."

She added that "no sites have identified transuranic wastes as an imminent risk. We also know that the risks from digging up the waste with currently available technologies far exceed the benefits."

But at the Snake River Alliance, an environmental group in Idaho, Beatrice C. Brailsford, the program director, said that the Snake River aquifer - the underground water supply that feeds the river - lies 590 feet below the surface, and that plutonium that was buried about 20 feet below the surface has already been found 240 feet down. It will take about 25 years to reach the aquifer, she estimated, at which point it will move with the water, about 10 feet a day. Americium, a radioactive substance created by plutonium when it gives off its radiation, has already turned up in the river, she said.

"In the mid-1960's, the Atomic Energy Commission said it would take 80,000 years, and now it's a generation," Ms. Brailsford said.

NEW YORK (Reuters) - The Energy Department has increased by 10 times its estimate of how much plutonium and other man-made radioactive material has been released in the ground or buried in poorly built containers, The New York Times said on Saturday.

The Times said that the department for years had stated that more than 97 percent of plutonium and related waste generated by the first four decades of nuclear weapons production was in ``retrievable'' storage awaiting burial at a new depository.

Only about 3 percent had been placed in soil or buried, it said.

Energy Department officials now say there is 10 times the amount of such wastes in the soil and in inadequate containers than previously estimated, the Times said.

The new estimate was said to come three years after an environmental group called the Institute for Energy and Environmental Research said the government's data was inconsistent and contradictory.

Dr. Arjun Makhijani, president of the group, told the Times that the government was doing little to address the problem of wastes in the dirt and in rusty, leaking barrels.

The Times cited a July letter to Makhijani from Carolyn Huntoon, assistant secretary for environmental management at the Energy Department, saying the department would not change the way it was managing the buried wastes.

The department's policy is to gather information on them and review them on a case-by-case basis, it said.

In a statement to the newspaper on Friday, Huntoon said the department would ask the National Academy of Sciences to review the Energy Department's strategies.

Huntoon added that the National Academy of Sciences backs the department's policies toward the wastes.

The Times said it was unclear how much material had leached into the ground at dump sites around the country.