On 26 April 1986, an accident occurred within the nuclear power station at Chernobyl, Ukraine, in the former USSR. The accident was caused by a sudden surge of nuclear power that destroyed the reactor and released massive amounts of radioactive material into the environment.  The consequences of the nuclear accident were catastrophic. As such the Chernobyl accident is commonly referred to as ‘The Chernobyl Disaster’.
The Chernobyl disaster caused many severe radiation effects almost immediately. Two Chernobyl plant workers died on the night of the accident, and a further 28 people died within a few weeks as a result of acute radiation poisoning. It also resulted in widespread contamination in areas of Belarus, the Russian Federation, and Ukraine inhabited by millions of residents.
Evidence suggests the accident was the result of a flawed reactor design that was operated with inadequately trained personnel and was due to a lack of safety culture.
Many lessons were learnt from the Chernobyl nuclear disaster. It dramatically demonstrated to the countries concerned that they had not been prepared for an accident on this scale. It also led to a review of reactor safety and emergency planning for plants in both the East and West.
It demonstrated that the cost of ensuring the safety of nuclear facilities is considerably lower than that involved in dealing with the consequences of a nuclear accident. Going forward, there was a recognised need for strict compliance with international safety requirements during the design, construction and operation of nuclear power plants.
No matter how much money and effort is spent on improving nuclear safety, however, the probability of a nuclear accident will never be zero, there will always be some risk of an accident occurring.  At the time of the Chernobyl disaster the medical services were not sufficiently equipped to deal with or to minimize the medical consequences of such a huge scale man-made accident. Analysis of the emergency response to the Chernobyl accident has provided a unique opportunity for making improvements to the emergency response system. 
There is now a recognised need to establish and support a high-level national emergency response system in order to minimize the suffering of people. Improvements to the emergency response system include well-defined procedures for action, the necessary instruments and equipment, trained personnel, criteria and mechanisms for decision-making developed in advance, and a system for training emergency workers.