Nuclear waste accidents

Nuclear reactors are useful in the production of electricity, but they are not without their problems. These problems include disposal of nuclear wastes, accidents, and sabotage. The eventual answer may lie in nuclear fusion. 

The fear of accidents like Chernobyl, and the high cost of nuclear waste disposal, halted nuclear power plant construction in the United States m the 1980s, and in most ol the rest ol the world by the 1990s. Because nuclear fusion does not present the waste disposal problem of fission reactors, there is hope that fusion will be the primary energy source late in the twenty-first centuiy as the supplies of natural gas and petroleum dwindle. 

There is now a marked pause in the construction and deployment of new nuclear power plants. Although some construction of reactors continues in Asia and Eastern Europe, a de facto moratorium exists in the United States and in most of Europe, while in Sweden and Gennany the governments plan to shut down operating plants before the end of their normal lifetimes. The inhibitions on nuclear power development stem in large measure from environmental concerns, particularly concerns relating to reactor accidents and nuclear wastes. 

The induction periods for the reaction of sodium nitrate—bitumen mixtures (43 57 wt) heated at 195, 234 or 260°C are 44, 2 and 0.5 h, respectively. Further study of sodium nitrate/bitumenised waste systems held at these temperatures showed an initial weak exotherm around 260°C and a larger exotherm (0.96—1.21 kJ/g) accompanied by 50% wt loss around 430°C [1]. Following an actual accident while encapsulating nuclear waste the system has been re-examined. With small nitrate crystal size, the mixing process can potentially give runaway from little above 160°C, by initial surface reaction slowly warming until the salt melts, whereupon exother-micity sharply increases [2]. 

Radioactive substances The principal sources of radionuclides released into the environment include nuclear weapon testing fallout from accidents such as the Chernobyl accident in 1986 or from foundering of nuclear submarines from the dumping of nuclear waste into the deep ocean and from discharges from nuclear power plants and nuclear reprocessing plants. 

Quite often you hear only negative stories about nuclear reactions and radioactivity. Radioactivity can mutate DNA molecules and cause cancer. The use of nuclear reactors to produce energy can create nuclear waste, which can harm the environment. Nuclear power plants have been known to have accidents and expose many people to radioactive particles. Radioactive radon gas can be found in the homes that people live in. Nuclear warheads and nuclear weapons can cause mass destruction. On the other hand, there are many uses for radioisotopes that can be beneficial to our lives. In order for a radioisotope to be effective, it must be used properly and in the proper dosages. Some benefits of radioisotopes are described in the following chart. 

The following section provides detailed information concerning the transport of radionuclides associated with two very different field analogues the Chernobyl reactor accident and the Oklo Natural Reactor. These examples span wide temporal and spatial scales and include the rapid geochemical and physical processes important to nuclear reactor accidents or industrial discharges as well as the slower processes important to the geologic disposal of nuclear waste. 

All methods of producing electricity have serious environmental impacts. The main objections to nuclear power plants are the fear of possible accidents, the unresolved problem of nuclear waste storage, and the possibility of plutonium diversion for weapons production by a terrorist group. The issue of waste storage becomes particularly emotional because leakage from a waste depository could contaminate ground water. Chemical dump sites have leaked in the past, so there is distrust of all hazardous wastes. 

Nuclear waste treatment and accident legacy solutions... 

Usually one distinguishes between "near field" and "far field" effects of radioactivity releases. Near field effects are observed close to the release source, as for example the nuclear power plant or nuclear waste storage facility. The dissolution of nuclear waste by rain or ground water is a typical near field problem. As the source is known, it can be controlled and its environment monitored. If the radioactivity exceeds permitted levels, access to the contaminated area can be restricted. Far field effects involve the behavior of radionuclides which have spread out of such a restricted area, caused either by nuclear power accidents and weapons tests or by leakage from nuclear power plants. 

In this paragraph we briefly describe some of the largest anthropogenic sources causing far field effects, i.e. nuclear weapons tests and nuclear power plant accidents. The cause of the releases is discussed in Chapter 19. Chapter 22 discusses both near and far field effects in further detail, particulary with regard to chemical properties liquid releases from nuclear power plants, dissolution of solidified nuclear waste and of fall-out particles, migration in the environment, and possible consequences. 

Actually, the United States has demonstrated an ability to deal successfully with the long-term storage of nuclear wastes. The Waste Isolation Pilot Plant (WIPP) in New Mexico has been receiving nuclear wastes since 1999 with no accidents in either transporting or storing the wastes. WIPP uses tunnels carved into the salt beds of an ancient ocean. Once a repository room becomes full, the salt will collapse around the waste, encapsulating it forever. 

Strontium-90 is also found in waste from nuclear reactors. It is considered one of the more hazardous constituents of nuclear wastes. The accident at the Chernobyl nuclear power plant al.so introduced a large amount of Sr-90 into the environment. A large part of the Sr-90 was deposited in the Soviet Republics. The rest was dispersed as fallout over Northern Europe and worldwide. No significant amount of stronium-90 reached the U.S. 

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