单项选择题

Every time there’s an accident, proponents of nuclear power point out that risks are also associated with other forms of energy. Coal mining (31) mining disasters, and the pollution from coal combustion results (32) some ten thousand premature deaths in this country each year. Oil rigs explode, sometimes spectacularly, and so, on occasion, (33) natural-gas pipelines. Moreover, burning any kind of fossil fuel produces carbon-dioxide (34) , which, (35) changing the world’s climate, alter the chemistry of the oceans. Among those who argue most passionately for nuclear power these days are some (36) , who see the uncertain threat that it presents as (37) to the certain harm of climate change. An objective comparison might (38) suggest that a well-designed and vigorously regulated nuclear power plant (39) less danger than, say, a coal-fired plant of comparable size. Such a comparison, (40) , ignores the fact that the regulation of nuclear power in the U.S. still relies on wand-waving.
Consider the prospect of a terrorist attack. After 9/11, it would seem only prudent for nuclear plants to be prepared for an (41) by a large, well-armed group. But the Nuclear Regulatory Commission, in revising its security rules, decided not to require that plants be able to defend themselves against groups (42) the most dangerous sort of weapons, even though these were just the sort of weapons the N. R. C. ’s staff had concluded that terrorists could be (43) to possess. (The exact weapons in question are classified information.) According to a study by the Government Accountability Office, the N. R. C. appeared to have based its revised rules "on (44) the industry considered reasonable and feasible to defend against rather than on an assessment of the terrorist threat itself. "
Or consider the problem of spent fuel. After several decades and billions of dollars’ worth of studies, the U.S. still does not have a plan for developing a long-term storage facility for radioactive waste, much of (45) will remain dangerous for millennia. Instead, spent-fuel rods are stored at each of the country’s hundred and four nuclear power plants. More than two dozen reactors in the U. S. have aboveground storage pools (46) to those that have failed at Fukushima—the only difference is that the American pools contain far more waste than their Japanese (47) . In a conference call with reporters the other day, David Lochbaum, a nuclear engineer and the director of the Nuclear Safety Project of the Union of Concerned Scientists, called the risks currently posed by spent-fuel pools in the U. S. "about as high as you could (48) make them. "
As the disaster in Japan illustrates, so starkly and so (49) , people have a hard time planning for events that they don’t want to imagine happening. But these are (50) the events that must be taken into account in a realistic assessment of risk. We’ve more or less pretended that our nuclear plants are safe, and so far we have got away with it. The Japanese have not.