2. 考研
  3. All U.S. nuclear weapons production facilities are presently closed down, and if the various agreements are adhered to, those fa

All U.S. nuclear weapons production facilities are presently closed down, and if the various agreements are adhered to, those fa

admin2009-04-26  25
问题     All U.S. nuclear weapons production facilities are presently closed down, and if the various agreements are adhered to, those facilities will never be required except for one critical capability. All modern nuclear weapons use uranium(铀), plutonium(钚), and tritium(氚). Uranium and plutonium have very long half-lives, and there is large surplus of these materials.
    Tritium, however, has a relatively short half-life of about 12.6 years, so about 5 percent of the amount on hand must be replaced each year to maintain the current inventory. (46)Because of the large retirement of nuclear weapons by the United States in compliance with early agreements and national policy, tritium from retired weapons has been used to make up that lost through natural decay. (47)However, in about 10 to 15 years, depending on future negotiations, the United States will need a guaranteed supply of tritium to maintain its stockpile at whatever level is agreed on.
    In anticipation of this future need to produce tritium, Defense Office Executive is pursuing two technologies. One uses a nuclear reactor that could also produce electricity whose sale would recover not only the capital cost of the reactor but also its annual operational cost. (48)Unfortunately, the present Administration has a definite bias against nuclear power, so an alternative method is also being pursued even though it is agreed that it will cost twice as much as a reactor and use as much electricity as a reactor would produce. This technology uses an accelerator to produce high-energy protons that in turn produce neutrons.
    The main argument for the accelerator is that it produces no conventional nuclear wastes. (49)Proponents readily admit that it will produce radioactive materials, but with a relatively short half-life compared with that of wastes from spent nuclear fuel. The fact that the accelerator will require the equivalent of a nuclear power plant to supply its electricity is ignored.
    (50)Proponents ’also neglect to mention that about 22 percent of all electrical energy generated in the United States comes from nuclear power plants, so that 22 percent of the power used by the accelerator will generate conventional nuclear wastes, in addition to those the accelerator produces. There is an alternative to either the reactor or the accelerator, which is simply to buy the required tritium from Canada or Russia.

选项
答案支持者们欣然承认，这种加速器会产生放射性物质。不过与使用过的核燃料废料相比，放射性物质的半衰期相对较短。
解析
转载请注明原文地址:https://kaotiyun.com/show/6Ga4777K
0

考研英语一

相关试题推荐
随机试题
最新回复(0)