Emergencies
There are already well developed and tested arrangements in place for responding to any nuclear emergency at UK civil nuclear sites. These are part of the licensing requirements imposed by the Health and Safety Executive's Office for Nuclear Regulation (ONR).
International notification requirements
In the event of a UK nuclear accident, DECC is responsible for notifying the international community under the:
There are also bilateral arrangements between the UK and Denmark, France, the Netherlands, Norway, the former Soviet Union (Russian Federation) and Ireland.
International Nuclear Event Scale
To help inform the public about the consequences of nuclear events, the IAEA and the Nuclear Energy Agency of the OECD have developed the International Nuclear Event Scale (INES).
The levels and criteria below can be applied to any event associated with radioactive material and / or radiation:
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Level 0
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Below scale. No safety significance.
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Level 1
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Anomaly. Variation from permitted procedures.
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Level 2
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Incident with potential safety consequences on site but with sufficient safety defences remaining. Insignificant release of radioactivity off site.
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Level 3
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Serious incident. Very small release of radioactivity. Radiation exposure off site a fraction of the prescribed limits. Local protective measures unlikely except for some food monitoring and control. Possible acute health effects to a worker.
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Level 4
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Accident with minor release of radioactivity. Radiation exposure off site of the order of prescribed limits. Local protective measures unlikely except for some food monitoring and control. Significant plant damage. Fatal exposure of a worker.
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Level 5
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Accident with off site risks. Release of radioactivity. Severe plant damage. Partial implementation of local counter measures.
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Level 6
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Serious accident. Significant release of radioactivity. Full implementation of local counter measures.
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Level 7
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Major accident. Major release of radioactivity. Acute health and long-term environment effects.
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As shown in the table, only events at Level 4 and above would lead to significant off-site radioactivity.
The accident at the Fukushima Dai-Ichi nuclear power plant in Japan, in 2011, was rated as Level 7 following an earthquake and tsunami which damaged 4 of 6 reactors at the site, resulting in the release of radioactive material into the atmosphere.
The accident at an RBMK reactor at the Chernobyl nuclear power plant in the former Soviet Union, in 1986, had widespread environmental and human health effects, and was rated as Level 7.
The accident at the Three Mile Island nuclear power plant in the United States in 1979 resulted in a severely damaged reactor core, and was a Level 5.
In 1957, in the early stages of development of the UK nuclear programme, an accident occurred at the United Kingdom Atomic Energy Authority's (UKAEA) site at the Windscale (now Sellafield) facility in Cumbria, which involved an external release of radioactive fission products. On the basis of the off-site impact, it was rated at Level 5, and is the highest rated accident to have happened in the UK.
You can find more information about the International Nuclear Event Scale on the International Atomic Energy Agency (IAEA) website.
Ministerial reporting arrangements
In April 1987, Alastair Goodlad (then Parliamentary Under Secretary for Energy) announced voluntary arrangements for reporting nuclear incidents at civil nuclear installations in England, Scotland and Wales.
These are generally referred to as the 'Goodlad' arrangements, and set out the approach agreed with the nuclear operators for reporting nuclear incidents occurring on their sites which, although not requiring the emergency plans to be invoked, have possible implications for the safety of the site.