Development of a nation and need for energy are synonymous. The thermal power generation units are facing the flak world over as they are packing the atmosphere with carbon dioxide. We all know the perils of this greenhouse gas and the resultant global warming. The environment experts all over are shouting from the rooftops pleading the governments to use nuclear energy as one of the main sources of energy, just in order to cut down the carbon dioxide emissions. How safe is the nuke power is a question that needs to be examined. Hazards of nuclear energy are quite forbidding. It has to be harnessed for practical use with great care and caution.
It was a big jolt to the human society in 1986 when the reactor number four of Chernobyl Nuclear Power Plant in Soviet Union exploded. The resulting fire released a plume of nuclear material that spread as far as North America. Worst affected were areas in Ukraine, Belarus and Russia. As per the Wikipedia the fall out of the 'leak' was stupendous. Though directly only 56 persons died which included nine children who died of thyroid cancer post disaster. As per the WHO estimates 4000 persons more could die of cancer out of 600,000 highly exposed people.
Exposure of living beings to nuclear radiation has long term effects. That is why the nuclear power generation and disposal of nuclear waste requires highly specialized people and treatment.
Generating electricity in the conventional manner needs a turbine and a mechanism to move that turbine. Either water or charcoal heat is used to move the turbine. Hydroelectric generation is one of the cleanest ways but unfortunately it has been experienced that large dams constructed in the mountain terrain for the purpose of power generation are becoming a source of hazard. The recent incidents of damages to dams, power houses and other structures including roads and habitations due to flash floods are still fresh in the memory. The power house at Nathpa-Jhakri on the bank of Sutlej river suffered heavily due to flash floods in the river in the year 2005.
We all know the use of charcoal for power generation and its effect on the environment. Yet we are helpless and power generation continues using coal. Apart from polluting the environment, the availability of coal is also limited.
Thus the choice falls on the third method-that is the nuclear power. Nuclear power generation uses radioactive material. A typical characteristic of radioactive elements is to break down to other elements. In the jargon of nuclear scientists the phenomena involves decay of parent element to daughter element. The decay takes place over a period of years, also known as the half life of the element. During the course of decay, particles of energy are released. For example, Uranium-238 decays to lead and the by-products are varieties of particles, gamma rays and energy. The energy released during the decay of radioactive element is used for generation of power. The process sounds simple but it has hazards too. The natural decay of the radioactive material becomes a natural radiation hazard. To add to the problem, like any other factory, the nuclear power generation requires the raw material. Power is the main produce but similar to other factories unwanted waste is also generated. From every day newspaper reports we are aware how hazardous the industrial waste is. The nuclear waste from the power plants is no exception.
Therefore for a nuclear power plant the first precaution taken is the selection of site. Nuclear power plants are preferably located in earthquake safe zones and on bed-rock. Earthquake sensors are a part of the plant and there are arrangements to stop operation of reactors in case of emergency, to cool down reactors to remove heat from nuclear fuel and to contain radioactive material. Locating such power plants on an active fault is hazardous.
In short any kind of tremble could produce a leak and that could be disastrous. That is why the precautions.
The nuclear waste generated by the plants needs a special treatment too. It can not be just dumped on the roadside or in the nearby streams like the industrial waste. The problems faced by the nuclear powerhouses about the waste disposal are multiple. Lot of research has been done on the types of nuclear wastes and their disposal methodology. Nuclear waste is grouped in to 'low level', 'intermediate level' and 'high level' waste on the basic type of radiation. The physical classification divides it into three categories, viz. liquid waste, solid waste and gaseous waste. The power plants follow the classification given by the International Atomic Energy Agency (IAEA) which is based on the radiological properties of the waste and specific activity.
While various techniques are used in handling and disposing the nuclear waste according to their radiation hazard, the nuclear waste management group of the plant has to ensure that the society is not endangered, people are not inconvenienced and natural resources are not harmed in any way.
The radioactive material in nature keeps releasing some amount of radiation in the atmosphere. Called as threshold value, it remains harmless to the living beings. The disposal philosophy keeps this fact in mind and ensures that the decay of the waste does not generate radiation beyond the threshold value.
Data published by nuclear scientist M.V. Ramana and his colleagues show that nuclear waste generation in India is on the increase. Low level waste amounts to over 232,000 cubic meters while intermediate and high level wastes measure about 40,280 cubic meters. Disposal technique involves conversion of the low and intermediate level wastes in to slurry and then stored in concrete-lined basins. These bins are entombed in shallow, concrete walled, land repositories. High level waste is first vitrified in borosilicate glass or synthetic rock and ten stored in concrete-lined steel tanks. These containers are kept in underground stores for 20 years before being disposed off in underground salt beds or abandoned salt mines.
Trenches in the abyss of oceans are one of the suitable sites for disposal high level nuclear wastes. Containers of high integrity are buried in such trenches. These containers are lowered through boreholes drilled specially for he purpose and stacked one above other separated by minimum 20 meter of thick clays pumped in at high pressure. These oceanic clays have a great capacity to hold radioactivity like a closely guarded secret and do not allow it to escape on to sea waters.
However, despite all precautions, chances of leakage of radioactive gases or liquids can not be ruled out.
The share of nuclear power is merely three percent of total power generation. Before becoming a self-sufficient or superpower in terms of electricity generation the cost-benefit ratio between other existing techniques and nuclear power needs to be examined. The proliferation of nuclear power plants in India, their operation and waste disposal will require special precautions. The unfounded fears that nuclear powers are toxic also need to be cleared.
Above all, while dealing with nuclear power generation quality of safety measures has to be kept above board; any slackness could be hazardous and toxic for generations to come.
James D. Werner an environment engineer from United States and expert on nuclear waste disposal rightly said in Scientific American in 1996:
"The stuff we are dealing with can't go away until it decays. You can containerize it, solidify it, immobilize it, but you can't make it go away".