Sovacool (2010) has documented 99 accidents at nuclear power plants. He states: “No less than 99 nuclear accidents (defined as incidents that either resulted in the loss of human life or more than US$50,000 of property damage, the amount the US federal government uses to define major energy accidents that must be reported), totalling US$20.5 billion in damages, have occurred world-wide from 1952 to 2009. These numbers translate to more than one incident and US$330 million in damages every year for the past three decades. … Fifty-seven accidents have occurred since the Chernobyl disaster in 1986, and almost two-thirds (56 out of 99) of all nuclear accidents have occurred in the USA, refuting the notion that severe accidents are relegated to the past or to countries without US modern technology or industry oversight.” (Sovacool 2010; see also Sovacool, 2008)
The Los Alamos National Laboratory lists 60 criticality accidents − accidental nuclear chain reactions in fissile material such as enriched uranium or plutonium. (Monahan et al., 2000) Of the 60 accidents, 38 occurred at research or experimental facilities such as research reactors, while 22 occurred in commercial nuclear facilities.
Abnormal events in nuclear plants are triggered by a variety of reasons (Schneider et al., 2007):
- design errors
- construction, manufacturing and materials faults and/or deficiencies that have remained hidden in the plant
- unforeseen and unprepared for external events that unexpectedly challenge the plants and their safety systems
- ‘internal events’ such as fires
- the human dimension, including slip ups, omissions and misunderstandings, or more complex and deeply rooted institutional errors and the possibility of malicious acts against nuclear plants.
Schneider et al. (2007, ch.9) discuss 16 power reactor accidents in common light-water reactors since 1986. The accidents are categorised according to cause of failure:
- Advanced Material Degradation (before break)
- Significant Primary Coolant Leaks
- Reactivity Risks
- Fuel Degradation (outside reactor core)
- Fires and Explosions
- Station Blackout
- Generic Issues – Reactor Sump Plugging
- Natural Events
- Security Events and Malicious Act
Numerous lists of nuclear accidents can be found at Wikipedia, e.g.:
- List of civilian nuclear accidents
- Lists of nuclear disasters and radioactive incidents.
The Australian Radiation Protection and Nuclear Safety Agency publishes lists of radiation incidents in Australia:
The IAEA’s International Nuclear Event Scale (INES) provides some information on nuclear accidents − but not a great deal. The scale defines events as “deviations” (Level 0), “anomalies” (Level 1), “incidents” (Level 2) “serious incidents” or “near accidents” (Level 3) and “accidents” (Levels 4 to 7). INES is problematic for various reasons (Schneider et al., 2007):
- a small number of the most recent events is available online with short descriptions at the IAEA’s website but the selection and publication criteria remain unclear.
- it is reliant on information provided by the operators of the affected plants or of the national regulatory authorities − there is no system of independent evaluation, and national governments have radically different approaches to the classification and reporting of nuclear incidents and accidents.
- the INES system is poorly placed to appropriately register the importance of ‘near misses’, events where there was little or no radiological release but a catastrophe was narrowly averted.
- the INES database is confidential (as is the accident database of the OECD’s Nuclear Energy Agency).
Accident reporting templates vary dramatically between countries. There are no clearly established benchmarks to describe, categorise and assess events from one country to another. Schneider et al. (2007) state: “In recent years the French nuclear power plant operator, EDF, has reported annually between 600 and 800 ‘significant incidents’ … to the nuclear safety authorities. Of over 10,000 events that were reported between 1986 and 2006, most were considered below the INES scale or Level 0 while 1,615 incidents were rated INES Level 1 and 59 Level 2. One event has been given a Level 3 rating. In comparison, since the implementation of INES in 1991 Germany reported over 2,200 events as Level 0 or below, while 72 events were rated Level 1 or higher. On its part, the US Nuclear Regulatory Commission, over the same time period, has only reported 22 events to the IAEA and rated them on the INES scale, of which 6 below scale, 7 Level 0, 3 Level 1, 5 Level 2 and 1 Level 3.”
Sometimes non-government organisations try to plug information gaps; for example the Union of Concerned Scientists has an online ‘Nuclear Power Information Tracker’ for US reactors: