Nuclear power has become an important source of energy in several countries, especially in Europe and Japan. Nuclear power supplies one-third of all electricity in Europe, including two- thirds in Belgium and France, one-half in Hungary and Sweden, and one-third in Finland, Germany, Spain, and Switzerland. Outside of Europe,' Japan, South Korea, and Taiwan also rely on nuclear power for much of their electricity. The United States and Canada are less dependent than Europeans on nuclear energy, in part because of more abundant coal reserves. Nuclear power generates approximately 20 percent of the electricity in North America as a whole with New England drawing most of its electricity from nuclear power. Five interrelated problems severely restrict the use of nuclear power instead of coal to generate electricity. The first problem associated with nuclear power is the danger of an accident. A nuclear power plant produces electricity from energy released by splitting uranium atoms in a controlled environment, a process known as fission. One of the products in a nuclear reaction is radioactive waste, which is lethal to people: exposed to it. Elaborate safety precautions must be taken to prevent the fuel from leaking out of the power plant. The second problem with nuclear power is the need to store waste products following the reaction. The spent fuel and other radioactive waste products must be stored for several thousand years, until they are no longer lethal. But no country has devised an effective storage system for the radioactive waste products. The third problem with nuclear power is that a bomb can be made from the material. Nuclear power has been used in warfare twice. Even if we are confident that government will not use nuclear weapons, can we be as confident about terrorist organizations? Terrorists could steal a small amount of nuclear fuel and construct their own nuclear weapons. A few years ago, a Princeton undergraduate wrote a term paper that outlined how to make a nuclear weapon. He was accused at first of leaking government secrets, but the student showed that most of his information came from the encyclopedia and a few unclassified government documents. Following publicity about the term paper, several organizations and foreign governments contacted the student for technical assistance in making a bomb. A fourth problem with nuclear power is the scarcity of uranium. Like the fossil fuels, uranium ore is a nonrenewable resource, and proven reserves will be depleted in less than a century at the current rate of use. Proven uranium reserves are not distributed uniformly across the earth's surface. The United States, Canada, South Africa, Australia, and the former Soviet Union rank among the world' s leaders. One-fifth of the world' s proven reserves are concentrated in South Africa, but access to that supply is uncertain because of the country's racial problems. The final problem with using nuclear power is its high cost. Nuclear power plants cost several billion dollars to build, primarily because of elaborate safety measures. Without double- and triple-backup systems, nuclear energy would be too dangerous to use. As a result, the cost of generating electricity is much higher from nuclear plants than from coal plants. The future of nuclear power has been seriously hurt by the combination of high risks and costs. Most countries in North America and Western Europe have curtailed construction of new plants. Sweden, which received nearly half of its electricity from nuclear power in the t980s, plans to begin' shutting plants by 1995 and to abandon its nuclear power plants completely by the year 2010. Why does Canada depend less on nuclear energy than European countries? Because ______.