All technology and all human behaviour, to a greater or lesser extent, are prone to error. Nuclear facilities are not exempt from this.

The accident in Chernobyl in 1986 is an ongoing example. Besides the 6,000 deaths attributed to the accident, there was also:

• 8.4 million people exposed to radiation across Europe, particularly Belarus, Ukraine and Russia
• an increase of up to 34-fold in rates of thyroid cancer documented (with the highest in females up to 14 years old at the time of exposire)
• almost 400,000 people who needed to be resettled, and millions still living in an environment of continued excess radiation exposure
• contamination of 150,000 square kilometres
• agricultural areas covering almost 52,000 square kilometres unable to be used for decades
• In January 2003, the Ukraine government has registered almost 100,000 individuals with 'disabilities connected with the Chernobyl disaster'

Numerous other incidents and near misses underscore that the risks of serious nuclear accidents are not confined to specific types of reactors or particular countries. Some other notable examples are:

• 1999 criticality accident at the Tokai-mura nuclear power plant in Japan
• 1979 partial core meltdown at the Three Mile Island nuclear power plant in the United States
• 2002 accident at the Davis-Besse nuclear power plant in Ohio, USA, where boric acid corroded a hole within half a centimetre of breaching the steel reactor vessel head that contained the reactor coolant, risking meltdown of the nuclear core

Many nuclear power plants around the world were constructed in the 1960's and 1970's. Because nuclear power plants have relatively short life spans (~40 years), many of these early reactors are now nearing the end of their use, increasing the probability of reactor failure, and causing a new problem in how to effectively clean up and decommission the plants.