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Welcome to the Katmal Wiki

This WIKI is intended to be a useful resource for helping the public understand how to stay safe in a nuclear emergency.

It is intended to start with a very simple overview of the protective actions that can be taken should a nuclear emergency happen and then explain in ever more detail the reasons for these protective actions.

It will initially be written by Keith Pearce, owner and principle consultant of Katmal Limited. Please contact me to discuss any ideas you have to make this a better resource.

A note on navigation This wiki contains a lot of hyperlinks which take you to another place, usually to drill down into deeper information. They are not always within this wiki. These links are shown in a different colour and sometimes underlined. It is easy to get lost. Your browser's "back button" will work to take you back along your path and you can always find this page by clicking the "Main page" link in the Navigation pane to the left of the page or the Katmal Limited logo.


A “radiation emergency” is a non-routine situation or event arising from work with ionising radiation that necessitates prompt action to reduce the consequences. The consequences in question could be harm to human life or health, environmental harm, economic harm or harm to quality of life.

The "prompt action" referred to in this definition may include one or several Protective actions, "action or actions taken in order to prevent or reduce the exposure of emergency workers, members of the public, the environment or the contamination of property from ionising radiation in the event of a radiation emergency" (REPPIR Reg 2(1)).

From the public point of view a radiation emergency becomes of serious concern when they are near a nuclear site (or other source of radioactive material) that is releasing radioactive material in significantly larger amounts than is normal such that those members of the public are asked to take measures (shelter, stable iodine, evacuation, food controls) to reduce their dose.

What might be the effects of a radiation emergency?

There are three main types of radiation emergency related to the nuclear licensed sites to consider:

  • A release of radioactive dusts and gases to the atmosphere which spread out downwind and give additional radiation doses to people in or near their path and leave the ground and other surfaces contaminated with radioactive dust after they have passed leading to further radiation dose and contamination of food and water supplies. The potential for lasting environment and economic harm.
  • A release of radioactive material to water courses leading to additional radiation doses to people in, on or near the water and contamination of aquatic food chains. The potential for lasting environment and economic harm.
  • A criticality incident. This is an intense flash of neutron and gamma radiation which is potentially fatal to those close to the scene and dangerous out to maybe a few hundred metres. These can be "cyclic" i.e. repeat for a period of time up to several days. Can be followed by a release of fission products leading to an event similar to the previous two but generally of reduced consequence. Less lasting environmental harm.

In the first two events the public can take simple steps to reduce their radiation exposure and an important component of off-site plans is the generation and promulgation of advice to the public on these steps and then provision of support to affected members of the public. See Protective Actions for more details of these protective actions.

Beyond the nuclear licensed sites there is the remote possibility of:

The response, for those near the scene but not injured in the blast would be to seek shelter.

  • A Radiological Exposure Device is a radioactive source placed in a public area to cause radiation exposure among the public.
  • An Orphan Source is an amount of radioactive material that has escaped control. These can be very powerful sources, although the term does also apply to weak sources. There have been a number of cases where sources have been lost and gone on to cause significant harm. The IAEA have recorded 68 such incidents in total [1].

People exposed to high levels of radiation from an orphan source or a Radiological Exposure Device could develop symptoms of Acute Radiation Syndrome (ARS), or could develop radiation burns. These health effects may take hours, days, or weeks to appear and may range from mild to severe effects, such as death or cancer. Some people may not experience any lasting health effects. People experiencing symptoms should seek medical help.

  • Transport accident - Radioactive sources are frequently transported on our roads, rail system and in the air. Transport is in suitably robust containers appropriate for the source and, where appropriate, emergency plans are in place. Transport accidents do happen but tend to be minor[2].
  • Occupational Accident - many people work with strong radiation sources for medical purposes, non-destructive testing and research. Accidents can and do happen.

Public preparedness and response

It is obvious that any advice given to the public in the event of a radiation emergency will be more effective if the public can hear the advice, can understand the advice and can and do act upon it in an effective manner. This is the justification for REPPIR Regulation 22 Prior Information to the Public.

It is also widely believed, and highly credible, that the public will be better at hearing, understanding and responding to advice if they have been told in advance (with periodic reminders) about the situations in which advice might be given, how it would be given, what it might ask the public to do and what support is available to help them prepare and then to respond. This is the justification for REPPIR Regulation 21 Prior Information to the Public.

Someone caught in the areas affected by a radiation emergency will want to achieve a number of things, including:

  • To be sure that their family and friends are safe;
  • Be sure that their health and the health of their family and friends has not been affected;
  • To be allowed to get on with their life with as little disruption as possible.

The first of these is really about understanding the situation, about communication and about a little bit of preparation.

This Wiki is intended explain the risks involved in living or working near a nuclear site, the nature of Radiation Emergencies (the term the regulations use instead of nuclear accident), how some simple preparations could make your response more effective and how to respond on the day if you are alerted to a Radiation Emergency affecting you or your family and friends.

It works by giving a brief overview of the situation which assumes some knowledge but adds layers of understanding by using links to deeper information. These links are displayed as blue underlined words. Follow the links for a fuller explanation of the term underlined if you wish.

Concept of Operations

If there is a radiation emergency anywhere in the UK the response will follow the pattern given in the government Nuclear Emergency Planning and Response Guidance, Concept of Operations [3]. See Conops for more details.

The operator, aided by the emergency services as needed and monitored by the regulators, is responsible for actions on-site to bring the event to a safe end-point, protect the public by minimising the release, protect their personnel and provide information and advice to the off-site authorities.

The Off-site response will be co-ordinated in a facility called the Strategic Coordination Centre (SCC) (more details here) which is attended by the local authority, the emergency services, the regulators, the health service and various government departments and advisors. It is here that the advice to the public is agreed and promulgated.

The off-site response can reach upwards to central government for support if required.

UK Policies on radiological and civil nuclear safety

An outline of the UK's radiological and civil nuclear safety regime can be found on the BEIS website [4].

This includes:

  • Following international best-practice advice with regard to nuclear safety[5] as given by the International Atomic Energy Agency (IAEA).
  • Alignment with international safety standards (IAEA and International Commission on Radiological Protection (ICRP))
  • Providing a legal framework for safety
  • Effective coordination of the UK’s government departments, devolved administrations and regulators through the Radiological Safety Group chaired by the Department for Business, Energy and Industrial Strategy (BEIS)
  • International leadership through engagement and participation in the relevant international fora and organisations (e.g. IAEA, ICRP, OECD-NEA, UNSCEAR, OSPAR and the World Health Organisation (WHO)) that cover radiological and nuclear safety.
  • Commitment to research and development (see Funding for nuclear innovation)

Emergency preparedness and response arrangements are based on the central government’s Concept of Operations [3] (see here for further information). The Civil Contingencies Act 2004 (CCA) and the Radiation (Emergency Preparedness and Public Information) Regulations 2019 (REPPIR19) provide the regulatory framework.

The Civil Contingencies Act and accompanying non-legislative measures, delivers a single framework for civil protection in the UK. It identifies Category 1 responders, with requirements to assess risk, make plans and exercise response, and Category 2 responders expected to support the effort and with planning and response roles for particular events in their sector. (See the government web-site for more information)

The REPPIR Regulations (REPPIR-19) places duties on operators and Local Authorities to put in place proportionate plans onsite and offsite. The regulations require the operator to make a detailed evaluation of the hazards posed from their activities and the potential consequences, to provide sufficient information to the relevant Local Authority to allow a detailed emergency planning zone (DEPZ) to be determined.

For defence nuclear emergency response see JSP 471 [6].

Route map

Here you have a number of options:

Other key pages

Protective Actions



You can see a complete list of the pages on [| here]

Number of users: 122 06 July 2022

This page last edited by Keith Pearce (Katmal Limited) (talk) 11:21, 30 December 2021 (UTC)

  1. International Atomic Energy Agency, Lessons Learned from the Response to Radiation Emergencies (1945–2010), IAEA, Vienna (2012),\books/IAEABooks/8920/Lessons-Learned-from-the-Response-to-Radiation-Emergencies-1945-2010
  2. PHE-CRCE-014, Radiological Consequences Resulting from Accidents and Incidents Involving the Transport of Radioactive Materials in the UK – 2012 Review
  3. 3.0 3.1 Central government’s Concept of Operations
  4. How we regulate radiological and civil nuclear safety in the UK (webpage)
  5. IAEA Fundamental Safety Principles,
  6. MOD, JSP 471 Defence Nuclear Emergency Response Part 1: Directive