Predicting Nuclear-Reactor Accidents: 'The Problem Is One of
Hurricanes, floods, blizzards, and other natural disasters may not be predictable, but that they will somewhere occur sooner or later is inevitable. In the case of nuclear-reactor accidents, however, emergency planners must prepare for the worst without knowing whether the plans will be needed tomorrow, or ever.
"Nobody knows the likelihood of a serious nuclear accident," said James MacKenzie, a physicist who is a senior staff scientist for the Union of Concerned Scientists, a scientific public-interest organization. "There is no simple answer."
It is possible to develop statistical models that estimate the effects on the health of nearby residents given a particular malfunction of a nuclear reactor, Mr. MacKen-zie said, as was done in a mid-1970's nrc study known as the Rasmussen report. But it is not possible to determine in advance how likely it is that a given problem will occur in a reactor.
"That part is basically impossible," the scientist said. "There aren't enough data to confirm the model. The whole problem is one of major uncertainty."
Uncertainty and Disagreement
Uncertainty and disagreement remain also on questions of the special dangers that radiation from a reactor accident would pose to children in the area, according to Dr. Jacob Shapiro, director of radiation-protection programs at Harvard University and author of a widely used textbook on radi-ation protection. But there is no question, he said, that "there's more concern about radiation's effects on young children.''
At low levels of exposure, radiation leads to an increased risk of cancer. Hence, Dr. Shapiro said, many experts believe that the earlier in life one is exposed, the greater the risk that one will develop cancer later in life.
"There are some people who will challenge this," Dr. Shapiro said, but he added that the U.S. radiation-protection policy for workers operates on this theory. Individuals under 18, for instance, are not permitted to work around radiation.
Some researchers, he said, believe that the hypersensitivity ends after the child is one year old; according to this theory, schoolchildren would be subject to the same effects as adults.
In addition, Dr. Shapiro noted, there is concern that children's thyroids are more sensitive to the effects of the radioactive iodine that might leak during a nuclear-reactor accident. If this hypothesis is true, it could mean that children would be more likely to develop either cancerous or noncancerous thyroid tumors.
Unless a nuclear-reactor accident was truly catastrophic--a total meltdown, for example--it is highly unlikely that children or any other members of the general public in the vicinity of a reactor when an accident occurred would experience the acute, or immediate, effects of radiation sickness, Dr. Shapiro said.--S.W.