Nuclear Disasters and Mitigation Measures
There is a lot of debate on installation of new nuclear power stations. There is a lot of opposition to setting up power plants. The main reason is the nuclear radioactive radiation that is harmful to both life and environment. Unfortunately the nuclear radiation seems to have long term effects, in addition to immediate impacts. But the use nuclear power is increasing world wide as the time passes. About 350 Giga Watts of power is produced by nuclear reactors all over the world. In India we have only about 5 Giga Watts of nuclear power. There are more than half a million people working in nuclear energy field or other industry. Hence, mitigation measures assume very high importance. Mitigation measures relate to prevention of disasters or to reduce the bad effects or impacts of a disaster.
The nuclear materials are used in military, medical, electric power, and some other industries. In many western countries, the nuclear safety has been better ensured by use of latest technology and continuous upgradation. It seems that there have been very few disasters in those countries. Nuclear safety measures are part of the mitigation measures.
Nuclear Regulatory commissions in various countries form guidelines for mitigation of impacts due to disasters and monitors them. International Atomic Energy Agency monitors the plants.
What are mitigation measures:
The mitigation measures could be in terms of reduction of loss of life, damage to property, consequential impact on future generations, radiation effects on various biological forms of life - on humans, animals, plants. Any action to prevent use of nuclear weapons in wars could also be part of the mitigation measures. Nuclear weapons nonproliferation community takes care of this.
However careful the design, installation, operation are done in nuclear reactors, there is a possibility of small mistakes. A nuclear reactor is the most sophisticated way of heating water to very hot steam. It uses the heat energy from a nuclear fission chain reaction. Some times unknown and unanticipated incidents occur like in Fukushima in Japan in 2011. Some fear also exists due to terrorism, if terrorists sabotage a reactor or cause disaster. As per record. there has been a major accident in each decade in the last 5 decades. There have been about 100 nuclear accidents small or big so far.
Where do we need them:
The mitigation measures are to be applied in any nuclear power plants or nuclear facility in all stages: the mining of uranium or other substance, in transportation of nuclear materials, processing of nuclear fuels, using them and storage of the raw materials as well as storage of nuclear wastes. That is during the entire nuclear fuel chain (cycle).
Environment is affected due to mining process. There are emissions (radiations) from radioactive effluents. Serious health risks exist during mining stage. There is also a lot of (rejected/ unutilized) waste heat that goes in to environment.
Decommissioning a reactor:
When the life of a nuclear reactor/power plant is over, the plant is decommissioned. The cost of that operation is high. Both the reactor and the uranium enrichment facility in the plant are to be decommissioned so that the radiation levels are very low. Some times the cooling off period is more than decades. Cutting, dismantling reactors, dismantling, packing and disposing off the parts of reactors is expensive, time taking. Not only that it is a health threat to the people doing those jobs. Further there are threats to the environment too. Thus disaster mitigation is important in decommissioning. The costs are high.
Radioactive waste management:
It seems about ten thousand metric tonnes of spent high level nuclear fuel waste is produced each year in the whole world. The radio active wastes have long half life times like thousands of years and more; technetium-99, iodine-129, neptunium-237 and plutonium-239 are such examples. These need careful and elaborate management strategy that includes storage, and disposal or treatment to convert them into non-toxic form. One of the ways is to bury them deep inside Earth. Risks due to wastes are still not solved satisfactorily.
Limits to mitigation measures:
Nuclear reactor designs should be upgraded with newer safety standards. Many types of expected failures can be taken care of in the design, implementation and operation. However, there are some multiple failures which are unexpected (with very less probability). These cannot be easily taken care of or worked around by some solution.
There are books and articles written on nuclear disaster, their causes, consequences, and improved safety and mitigation measures at different levels. The subject is debated a lot in many conferences. National Disaster
Management Authority has an important role in this activity.