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  3. In the United States, there is some disagreement (to say the least) over the risks and benefits .of nuclear power. There can be

In the United States, there is some disagreement (to say the least) over the risks and benefits .of nuclear power. There can be

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问题   In the United States, there is some disagreement (to say the least) over the risks and benefits .of nuclear power. There can be no question that with our electrical power needs increasing rapidly, we cannot rely indefinitely on the earth’s remaining fossil fuel supply. The question is, can we safely shift our reliance to nuclear fission power plants—considering the present state of our knowledge and technology? The American public has, in the past few years, developed a rather strong consensus regarding this question. Nuclear power has fallen into disfavor. The risks seem too great, the reward too small—at least for the immediate future.
  It is not likely that an explosion of the type produced by atomic bombs can occur in the kinds of nuclear reactors being used today. However, we still don’t know how close we came to a major tragedy at Three Mile Island. A far greater tragedy occurred at a nuclear plant at Chernobyl, in the Soviet Union’s Ukraine in 1986. The risks associated with nuclear power, however, are not always so spectacular. Some are of a far subtler nature. For example, radioactivity could be released into the environment from activities related to mining and processing nuclear fuel, from the transportation and recycling of the fuel and from storage of the radioactive wastes. We frequently hear of steam or gas leaks from the reactors themselves. ;And even the safest reactors normally leak small amounts of radiation into their immediate environment. (The problem with this is that there are no "safe" levels of radioactivity--only "acceptable" levels. )
  We could probably greatly reduce the risks associated with nuclear power by simply exercising more care and common sense. There are numerous published accounts that attest to our carelessness, however. For example, it has been revealed that the Diablo Canyon nuclear power plant in California was built on an earthquake fault line. At the WNP-2 plant in Washington State, the concrete contained air bubbles and pockets of water as well as shields that had been incorrectly welded. In 1981, the Nuclear Regulatory Commission inspected forty-three plants that were under construction and rated seven "below average" and thirty-six "average". None were rated even "above average".
  Completely apart from the possibility of accidents, there is the unsolved problem of what to do with the radioactive wastes generated in the course of normal nuclear plant reactions. The problem is a tough one since such wastes can only be rendered safe by the passage of time. The waste radioactivity is .generated in the fuel system of the reactors because only a part of the fuel is fissionable and, for technical reasons, not all of the fissionable elements are spent. Much of the spent fuel materials removed from the reactor can be reused. However, some of the radioactive fuel in the spent elements cannot be removed, and this material adds to the radioactive waste.
  We have already generated over 10,000 tons of nuclear waste, with another 47,000 tons expected by 19951 Most of the waste is in the form of fuel rods which are, for now, stored in baths filled with a solution of neutron-absorbing boric acid. The problem is that these are only temporary repositories and,’ unless new space is found, existing plants must begin closing for lack of space. The rods can be reprocessed, but the technology could lead to the fuel for nuclear weapons.
  The reprocessing also leaves "high-level liquid waste" that must be stored. The prevailing idea at the moment is to dry the liquid and mix it with molten glass that, when it hardens, can be stored in tanks. Suggestions range from burying it in the Antarctic to sending it into space.
Which of the following facts from the selection best supports the statement that the radioactive waste is an unsolved problem?
选项 A、We have already generated over 10,000 tons of nuclear waste.
B、Radioactivity could be released into the environmental from activities related to mining and processing nuclear fuel.
C、Only a part of nuclear fuel is fissionable.
D、A location for stainless steel tanks containing "high-level liquid waste" mixed with molten glass has not been found.
答案D
解析 这是一个反向的归纳问题，要求用事实来证明观点。纵观四个答案，前两项仅仅是阐述事实，与问题无关。第三个选项不属于具体事例，只有第四个才是正确选项。
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