Further Fallout

And further lessons

More than a month after the nation's worst nuclear accident, at Pennsylvania's Three Mile Island Unit 2 reactor, the lessons and the consequences continued to be explored. Items:

> Secretary of Health, Education and Welfare Joseph A. Califano Jr. backed away from his original estimate that the Harrisburg nightmare would cause no cancer deaths among the 2 million people living within a 50-mile radius of Three Mile Island. Appearing before Ohio Senator John Glenn's nuclear proliferation and energy subcommittee, Califano predicted at least one death and acknowledged that some scientific investigators were estimating up to ten deaths. The revision was necessary because it turns out that the initial levels of radiation released in the accident were higher than thought at the time.

> The Nuclear Regulatory Commission provided disturbing new details on the initial performance of Metropolitan Edison Co., the plant's beleaguered operator. Midway through the first critical day, the hot, uranium-filled core, normally bathed in pressurized cooling water, was left dangerously uncovered for as long as 50 minutes; controllers had shut off the emergency core cooling system, probably because of ambiguous or misleading instrument readings. It was during this period that much of the damage was done to the fuel rods, causing a release of radiation.

On that day there was also a small fire or explosion of hydrogen gas, created when the reactor's high temperatures disassociated the cooling water's molecules. But the NRC team did not learn of it until two days later, the investigators disclosed, because of another snafu: harried by what one official called the "hassle factor," controllers had apparently rolled up a crucial recorder sheet at the height of the accident, thereby inadvertently concealing key information.

> The NRC admitted that it may have overestimated the seriousness of the large hydrogen bubble that formed in the reactor vessel. Despite that small explosion, investigators now believe there was never any danger of a bigger blast, which could have ruptured the reactor vessel and containment building, spreading deadly radiation. The false alarm was caused by incorrect speculation about free oxygen in the vessel.

> NRC officials also said that radiation levels inside the containment building are now at least as high as 30,000 rems, enough to kill anyone who enters almost instantly, and possibly as high as 50,000. The latter reading may be erroneous--possibly due to a "hot" particle on one device. By the NRC's reckoning, almost all the core's fuel elements are damaged, and even more radioactive material is exposed. New target date for entering the building: at least a year from now.

> The National Academy of Sciences issued two statistics-laden reports on possible radiation hazards until the end of the 20th century. One study, titled "Risks Associated with Nuclear Power," while largely reassuring, estimates that some 2,000 Americans are likely to develop fatal cancers as a result of nuclear power in the period from 1975 to 2000. The second report, "Biological Effects of Ionizing Radiation," projects a death toll, from all kinds of radiation, of 220,000 Americans who are now alive. But half of these deaths would come from cosmic rays and other sources of natural background radiation, like coal and granite. Most of the rest would come from man-made sources other than nuclear power, like X rays. Said Physiologist Edward Radford, panel chairman: "I don't think that the present alarm about radiation is entirely justified." Indeed, five of the 16 panelists argued that present ideas on effects of low-level radiation--extrapolated from such high-radiation dosages as those suffered by Japanese A-bomb victims--are questionable and that the panel's conclusions are exaggerated. The deaths, they said, will be far fewer.

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