U.S. Reveals 204 Nuclear Tests, Plutonium Exposure : Weapons: Energy Department declassifies Cold War data. Radioactive matter was injected into 18 people.

Shedding a cloak of Cold War secrecy, the Energy Department revealed Tuesday that the United States conducted 204 secret underground nuclear tests over 45 years and deliberately exposed at least 18 Americans to dangerous levels of nuclear material.

Energy Secretary Hazel O’Leary said the revelations, made possible by the end of the nation’s nuclear rivalry with the Soviet Union, represent the most sweeping declassification of information in the department’s history. She promised additional disclosures as she tries to win new public confidence for the department, which took over the development and manufacture of the nation’s nuclear weapon stockpile in 1977.

“We’ve got to expose the impact of the Cold War, both in terms of its environmental health and safety impacts and also impacts on . . . the psyche of the nation,” O’Leary told reporters. “One of the benefits to openness will be to build public trust.”

O’Leary stressed that the disclosures will not aid Third World countries wishing to develop nuclear weapons. “While we are releasing information, we’re not putting other information in the hands of people from terrorist states who could design a very crude bomb and do damage,” she said.

O’Leary declared that she has been “shocked and amazed” at shortcomings in the management of the nation’s nuclear weapon complex under Cold War administrations. Among the effects of the department’s secretive leadership is an environmental cleanup bill that may reach hundreds of billions of dollars.

The department’s new willingness to reveal secrets is expected to aid many of the communities surrounding the 17 major facilities involved in the development, manufacture and testing of nuclear weapons. Those activities appear to have brought elevated levels of cancers and a wide range of environmental and health concerns to communities in Ohio, South Carolina, Washington and Nevada.

In disclosing the secret nuclear tests, O’Leary acknowledged that 34 of them released radiation into the atmosphere. The tests occurred from 1963 to 1990 at the department’s Nevada test range.

In recent years, independent experts have greatly underestimated the number of secret underground nuclear tests, calculating that about 118 took place instead of 204. The additional figures bring the total of American nuclear tests to 1,051 since the Nuclear Age began.

Arms control experts pressing for a total halt to U.S. nuclear tests noted Tuesday that the government’s ability to conduct the tests in recent years without being detected by modern monitoring devices raises questions about whether nations and watchdog groups would be able to verify any comprehensive international ban on nuclear weapons.

O’Leary said she plans to release more information in June about experiments in which 18 people were injected with plutonium in the 1940s. Those tests were among an estimated 800 various experiments involving more than 600 individuals over the years.

The experiments previously were disclosed in a congressional report and other documents, but few details are known. All 18 of the plutonium subjects have died, and laws assuring the privacy of government employees prevents the immediate release of their names and cause of death, O’Leary said.

The Albuquerque Tribune recently reported on the testing and named five people it said were among the 18. Those five were injected with plutonium as part of work being done by the Manhattan Project in the development of the atomic bomb, the newspaper said.

O’Leary said she was “appalled, shocked and deeply saddened” to learn of the experiments. Based on her own briefings, she said, “certainly by the standards of today, it is apparent that informed consent could not have taken place.”

In other disclosures, O’Leary reported that the department had produced 89 metric tons of plutonium--enough for nearly 15,000 crude nuclear warheads. The nation has built 70,000 nuclear weapons.

In a demonstration of environmental degradation linked to production of nuclear weapons, O’Leary reiterated a department finding that roughly 750,000 pounds of mercury have been dumped into a stream in Oak Ridge, Tenn. The mercury, associated with congenital disabilities and nervous system disorders, was dumped by the Energy Department’s Y-12 plant, which produced uranium components for nuclear weapons.

Energy officials also reported that government cleanup costs will be pushed higher still by the expense of disposing of millions of pounds of radioactive reactor fuel held in rusting storage pools.

The pools were intended to hold the fuel for less than two years--until it cooled sufficiently to allow extraction of plutonium and other materials at processing plants. But the plants were closed because of safety problems in the 1980s, stranding the fuels in temporary holding pools near Hanford, Wash.; Idaho Springs, Ida., and Aiken, S.C.