Major developments in the field of nuclear technology were made in the 1940s. Post World War II, the focus shifted towards peaceful use of energy obtained by nuclear fission and its controlled use for the generation of power. Thus, the first commercial nuclear power station became operational in the 1950s. Now, 31 countries world-over have operational nuclear power plants catering for around 10% of electricity requirements from about 440 power reactors.
On 26 April 1986, a nuclear accident occurred in the Number 4 reactor of the Chernobyl Nuclear Power Plant. It is located near the city of Pripyat in northern Ukraine. This accident could easily be termed as one of the worst nuclear disasters in history, both in terms of casualties and cost. One can understand the severity of the accident because it is one of the ONLY TWO nuclear energy accidents rated at maximum severity level ie SEVEN – the other being the Fukushima Daiichi Nuclear Disaster that happened in 2011 in Japan post the Tsunami. The gravity of the situation can be understood by the involvement of half a million personnel and about US $ 70 billion (current value) for the immediate response and subsequent decontamination of the environment.
The International Atomic Energy Agency (IAEA) and Nuclear Energy Agency of the Organisation for Economic Cooperation and Development introduced International Nuclear and Radiological Event Scale (INES) in 1990, classifying the nuclear events on a scale of zero to seven, also dividing them into accidents, incidents, and anomalies. The Chernobyl event was classified as an accident. Level seven indicates a ‘major accident’ which implies ‘major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures’.
Recounting the accident
An electric power outage was being simulated to help create a safety procedure for maintaining reactor cooling water circulation till the time the electricity was restored using the backup electrical generators. Since 1982, three such tests had already been conducted which had failed. However, an unexpected delay of 10 hours occurred while the shift changed. The operators could restore the specified test power only partially. When the test was completed, a reactor shutdown was triggered by the operators. But, a combination of unstable conditions and flawed reactor design initiated an uncontrolled nuclear chain reaction.
Consequently, a tremendous amount of energy was released all of a sudden thereby rupturing the reactor core and destroying the reactor building. The two explosions were followed by an open-air reactor core fire which resulted in the precipitation of radioactive contamination onto parts of the erstwhile USSR and Western Europe in about nine ensuing days. The most affected was Belarus where nearly 70% of the contaminants landed. The fire was finally contained on 04 May 1986.
Within 36 hours of the accident, an exclusion zone of a 10 km radius was created since the ambient radiation levels had increased to a dangerous level. A little less than 50000 people had to be evacuated from the areas near the site. The numbers later rose to around 68000 when the radius of the exclusion zone was increased to 30 km. Eventually, the exclusion zone was made permanent.
Though it is extremely difficult to ascertain the exact number of fatalities directly assigned to this accident or it’s after effects, suffice to say that a number of lives were lost.
The nuclear clean-up of the area may take up around four and a half decades more to complete ie by around 2065.
Lessons from Chernobyl
It would be no good if a few lessons are not learned from this heart-wrenching saga to avoid any such accident in the future. It is heartening to note that some tangible practical benefits have resulted from the Chernobyl nuclear accident.
With increased collaboration between the East and the West towards the development of a culture of nuclear safety, the safety of Soviet-designed nuclear reactors has improved considerably. The necessary boost has been provided due to substantial investments in improving the reactors. The design deficiencies in the RBMK Reactors have been improved upon. Changes have been made in the control rods by adding neutron absorbers thus resulting in fuel enrichment. Hence, the reactors have become more stable at low power. The safety mechanisms, including automatic shutdown, have been improved. For inspection of the reactors, automated equipment has been installed. Under the aegis of the World Association of Nuclear Operators (WANO), which was formed in 1989 to link the 130 operators of nuclear power plants spanning more than 30 countries, reciprocal visits have been organized between the engineers and operators of the East and the West to understand and improve upon the safety mechanisms. Various international agencies like IAEA, Nuclear Safety Assistance Coordination Centre have come together to initiate the processes in improving safety and cater for the required financial assistance.
Another important development post-Chernobyl has been the adoption of the Convention on Nuclear Safety, in Vienna in June 1994.
Imperatives for India
Soon after independence, in 1948, the Atomic Energy Commission was established as a policy body. Then, in 1954, the Department of Atomic Energy (DAE) came up to cover research, development of technology, and operation of commercial reactors. Then various other organizations like NPCIL, UCIL, Electronics Corporation of India, BHAVINI, and Atomic Minerals Directorate for Exploration and Research- came up to function under DAE. In 1983, the Atomic Energy Regulatory Board was set up and a Council of Nuclear Safety, with the Prime Minister as the Chairman, was formed after the Fukushima Daiichi accident in 2011.
The Government of India is committed to the peaceful use of nuclear power. India does not form a part of the nuclear Non-Proliferation Treaty. This held back India’s progress in this field till the first decade of the current century. Yet, India is well on its path of progress in the field of peaceful use of nuclear energy. There are seven nuclear power plants under operation in India with 22 operating reactors. Their installed capacity is 6.7 GWe. The concerned agencies are making advancements in the R&D and many power plants are in different stages of planning, design, and construction. The earlier restrictions on India have nothing but helped its cause of being more self-reliant, though, various countries – mainly Russia, are collaborating to provide designs of reactors and their construction.
The nation needs to progress on this front without overlooking the lessons learned from Chernobyl. The INSAG reports adequately highlight the causes of the accident to include faulty reactor design, violations in the safety protocols and negligence of the operators, etc. These should help India frame stringent policies and equally strict adherence to the safety norms in operation and maintenance of the nuclear power plants, as now it is known that what kind of havoc a nuclear accident can cause.
The risks involved in nuclear criticality and release of radioactive materials while harnessing nuclear power for the generation of electricity have always been known to the world. The fact that there have been only two major reactor accidents in the history of over 18,500 cumulative reactor-years in the last seven decades, spread over more than 30 countries goes on to prove the care being taken in the design and operation of nuclear power plants thus making it safe. However, no industry is immune to accidents and, thus, the highest level of safety and security in design, construction, operation, and maintenance needs to be adopted while using nuclear sources for power generation.