Prior Information to the Public

This page is the doorway to the REPPIR prior information in the order the regulations suggest


“Prior information is intended to give the local population a clear understanding of the action that they may be asked to take in a radiation emergency. If an event was to occur this would allow the necessary protective action to be implemented smoothly and speedily. Information should be drafted and presented with absolute clarity, so it creates understanding and awareness, and avoids causing alarm” (REPPIR Guidance P. 824)

The local authority which has an area covered by an off-site plan with a detailed emergency planning zone has duties to provide prior information under REPPIR Regulation 21.

What is slightly worrying about the ambition of this regulation is that you would want several hours, if not a full working day, to present the amount of material asked for to graduate recruits to the nuclear industry assuming you had their full attention. To attempt to inform the heterogeneous community in a random area of the UK, whether or not they were at all interested, is ambitious. Meanwhile remember that guidance 824 requires "absolute clarity".

Prior Information

If there was to be a radiation accident the authorities would try to reduce the dose to members of the public affected by predicting where the resulting radiation doses might be above the thresholds for advising protective actions and, in those areas, asking them to shelter, asking them to evacuate (in severe or prolonged events), asking them to take stable iodine (reactor accidents only), asking them to avoid contaminated food and asking them not to spent too long in contaminated areas.

Regulation requires local authorities to give prior information to people who live or work near licensed sites where the operator's risk assessments conclude that these actions may be required quickly in response to an alert. The intent of this information to help the public make the protective actions work well.

Basic facts about ionising radiation and its effects

The important thing to learn from this section is that the amount of radiation your body is exposed to is called your radiation dose and is measured in a unit called a millisievert (often written as mSv). The rate at which your radiation dose is increasing with time is called the “radiation dose rate” (sometimes “dose rate” for short) and is measured in millisievert per hour (mSv/hr or

It may be helpful to understand that we are exposed to variable rates of background radiation from the rocks and sky around us and manmade radiation in medical scans and treatments. [[#BG | A "scale" of sources and harm can be found below]].

Large doses (i.e. greater than 5,000 mSv) in a short period of time can cause rapid on-set illness and death. Low doses (i.e. doses below about 2,000 mSv) are far less likely to produce noticeable effects in the short term but can lead to additional cancers in the years that follow.


“Radioactivity” is a natural phenomenon.

A largely unwanted by product of the fission chain reaction that powers nuclear reactors is radioactive material in the form of used fuel, contaminated and activated plant, stored wastes and authorised discharges. This material is carefully managed to minimise the amount released in normal operation and to minimise both the probability and potential consequences of accidental releases.

Radioactive material emits fast moving sub-atomic particles (Alpha particles and beta particles) and packets of energy called gamma rays.

These were compared to “little bullets” by the scientist in the TV series Chernobyl. These bullets, properly called “ionising radiation” (sometimes just “radiation”), can cause chemical changes in any material they pass through. In your body these chemical changes can lead to tissue damage (injury) resulting in the possibility of illness or even death. Therefore, we use radioactivity carefully and work hard to reduce radiation doses. (See other explanations).


Neutrons are another form of ionising radiation. They are also produced by radioactive decay but this is relatively uncommon. They are mainly produced by the fission chain reaction in operating nuclear reactors.

The four important types of radiation alpha particles (α), beta particles (β), gamma rays (γ) and Neutrons (ν or n) have very different properties. Because of the different ways they interact with the material they are passing through they have different ranges (the maximum distance they can travel) and different effects on human tissue (see here for further information on radiation properties).

It is important to distinguish between radioactive materials and radiation. Remember that radioactive materials emit radiation.

Radiation dose, quantities and units

The effects of radioactivity on the health of an individual result from a complex chain of events. If you consider someone standing in the cloud of radioactive material leaking from a damaged nuclear reactor you realise that they will be exposed to a mix of alpha, beta and gamma radiation all with a range of energies coming towards them from all directions. Estimating the dose to a particular internal organ is complex as is then predicting the impact of that dose.

When a radioactive particle or photon of energy passes through anything, including human tissue, it can "ionise" it (See Wikipedia, Ionization ). This means that it knocks electrons out of the orbit of the atoms they are associated with.

We measure the tissues exposure to radiation by measuring the charge of the electrons liberated by the same radiation field in dry air. This is measured in coulomb/kilogram (C/kg). An older unit was the roentgen (See Wikipedia, Roentgen (unit)).

Alternatively we could measure the energy absorbed by the tissue per unit mass of tissue. This is the "absorbed dose" with the unit gray (1 joule per kilogramme (J/kg)).

But the harm done to the tissue is not always proportional to the absorbed dose. The different types of radiation deposit their energy in different ways. Some, such as the alpha particle, lose all their energy over a very short, relatively straight, pathway; others such as beta radiations bounce around more depositing their energy over a larger volume. These patterns of energy deposition affect the amount of harm done to the individual cells that human tissue is composed of. We adjust the absorbed dose by a factor depending on the radiation and its energy to give "Effective dose" which gives a measure of the harm done to the tissue. (Unit sievert (Sv)).

Effective dose gives a measure of the likely harm done to a volume of tissue with no mention of how much tissue or which ones are affected. Obviously a person will be less affected by a radiation dose of a given number of sieverts that effects just one part of the body (such as a hand or a foot) than a person who is given a "whole body dose" meaning that every part of them receives the dose.

(An important thing to realise is that if one person gets a 1 Sv dose to their left foot and another gets a 1 Sv whole body dose then their left feet have had the same dose. In the first case the person has to cope with a potentially damaged foot. In the second case the person has an equally damaged foot but also has harm spread over the rest of their body).

"Dose equivalent" is another accounting trick which assigns each part of the body with a weighting factor and is calculated by multiplying a part of the body's effective dose with its weighting factor and summing over the whole body to produce a single number which can be used to indicate the likely level of harm to the individual.

Figure. Scale of radiation sources and effects (Note: Log scale, each box is 10 times the dose of the one below it)

Natural/Background radiation.Radiation is not only produced by industry. Natural background radiation is all around us (What is background radiation?). Many rocks, notably granite, are naturally radioactive and give off both radiation and radioactive gases such as radon. Some foods are naturally radioactive. For example, bananas are a good source of potassium which is an essential nutrient (our bodies need it to work properly) but potassium is naturally slightly radioactive so our bananas are also slightly radioactive and each give a very small radiation dose. (See Infographic: What to know before you go bananas about radiation. We are also exposed to radiation from space “cosmic radiation”, which decreases the deeper you get into the atmosphere. People in high flying aircraft are exposed to a higher dose rate than those at sea level.

We have always lived with background radiation and don’t notice any effects it might have. Small increases in radiation dose for X-rays and even large doses in cancer therapy are accepted because of the benefits they offer.

The average annual dose from all sources or radiation to the UK population was 2.7 mSv in 2010 (See Ionising Radiation Exposure of the UK Population: 2010 Review ). The average annual background radiation dose in Cornwall is 6.9 mSv while in Madras and Kerala (India) it is 30 mSv.

A nuclear accident could increase radiation rates for those nearby during the accident and, to a much lesser extent, to those near the scene of the accident in the following years.

The ICRP claim that for doses below 100 mSv there are no detectable effects (see Fukushima Nuclear Power Plant Accident, ICRP ref: 4847-5603-4313).

500 mSv is the limit advised for people to be submitted to when saving lives.

1000 mSv (1 Sv) see the onset of vomiting within 24 hours while 5000 mSv kills half the people exposed to it. For more information on the short and long term effects of exposure see [[effects of exposure]].

Internal and external radiation

The difference between internal exposure and external exposure lies in whether the source that emits radiation is inside or outside the body.

"External radiation exposure" is the term we use when radiations from a source external to the body hit the body resulting in ionisation of body tissues.

In a nuclear accident you may be exposed to external radiation if you are standing near or in a plume of radioactive material as it drifts by or from radioactive material deposited on the ground or other surfaces as the plume goes by.

The defence against external radiations is summarised by the term "time, distance and shielding"

  • The more time you spend within the radiation field of the source the more radiation you will be exposed to. Only stay in areas with high radiation levels for the briefest time possible.
  • The nearer you stand to the radiation source the higher the radiation dose-rate is likely to be. Try to stay as far away from the source as possible as much as possible. For physically small sources the inverse square law applies, the dose rate drops as 1/r2 so if you double your distance from a source, you reduce the dose rate by a factor of 4 (i.e 22), increase the distance by a factor of three reduces the doserate by a factor of nine (i.e. 32).
  • If you can put a material that absorbs radiation between you and the radioactive source, then it will absorb the radiation dose and you will not (shielding).

"Internal radiation exposure" is the term we use when radiations from a source internal to the body hit the body resulting in ionisation of body tissues.

In a nuclear accident you may be exposed to internal radiation if you inhale any radioactivity while a plume of radioactive material drifts by or from eating food contaminated with radioactive material either after harvest or before.

The defence against internal radiation exposure is to reduce your intake of radioactivity. For inhalation dose this entails getting away from the plume (evacuation), reducing your exposure to the plume (shelter) and, less often used for the public in the UK, respiratory protection (wearing a mask to filter out at least some of the particulate radioactive material).

After the plume has passed the reduction of internal radiation dose becomes a matter of avoiding the consumption of contaminated food and drink. Your local authority, along with government departments, will be provide you with advice and taking steps to prevent unacceptable food and drink being available to buy. "Exposure pathways"

There are several ways in which you could be exposed to radiation following a release of radioactive dust or gas to the air.


If the cloud of radioactive gas or dust passes near enough to you for the radiation from it to reach you then you will receive a radiation dose we call “cloud shine”. Radioactivity that has deposited on surfaces such as the ground, walls, roofs or trees can continue to decay giving off radiations resulting in a radiation dose due to “ground shine”. These are examples of external radiation.

If you are inside the cloud of radioactive gas and dust, then you will breathe in some of the radioactivity and some of it will stay in your body and later decay giving you a “inhalation dose”.

Radioactivity may land on food crops such as vegetables or fruit or may land on the grass eaten by cows and other animals leading to food becoming radioactive. If that contaminated food were to be eaten the radioactivity would get into body and provide an “ingestion dose”.

Inhalation dose and ingestion dose are both the result of “internal radiation”. Cloud and ground shine are “external radiations”.

The protective actions we advise you to take seek to minimise your radiation dose by:

  • reducing the amount of radioactivity that you breathe in by:
    • sheltering in a building that helps to keep the radioactive dusts and gases out or
    • by evacuating the area to prevent all inhalation.
  • Reducing the amount of radioactivity that you eat by preventing contaminated food being sold and advising against eating food from local gardens, allotments and hedgerows.

For nuclear reactor faults you may also be advised to take stable iodine tablets (otherwise called potassium iodide tablets, PITs or SITs). These reduce the dose to the thyroid from radioiodine, a radioactive material found only in operating reactors.

"Short term and long term effects of radiation"

Two main types of radiation harm are known.

Deterministic effects. These have a rapid impact with both the rapidity of the symptom showing and the severity of the effect increasing as the dose increases. These can be compared to sunburn; the stronger the sun the sooner you burn and the longer to stay out in it the worse the burning gets. We reduce these doses by reducing exposure (sun screen, going indoors, moving to the north of Scotland) and reducing the exposure time (limiting our time outdoors).

stochastic effects. These might take months to decades to be noticeable and only some of those exposed will suffer from them. It is the probability of seeing the effect that rises with dose not the severity. These can be compared to the risks of repeatedly crossing a busy road in a careless manner. The more often you cross the more likely you are to be hit by a vehicle. But the number of times you cross does not affect the consequences if you are finally hit by a vehicle. We reduce these effects by reducing the dose to which we are exposed (not crossing the road or crossing it carefully).

In the short term, large doses of radiation ("acute radiation exposure") can lead to tissue damage which causes effects that can develop almost immediately, in the case of very large doses, or in the following days, weeks and months for lower doses. See [[Effects of exposure#deterministic | determinist effects]] for more details.

Very large doses (> 2.5 Sv) in a short time can lead to [[Effects of exposure#ARS | Acute Radiation Syndrome]] , a very unpleasant set of symptoms, and death within hours to days of exposure. People exposed to smaller doses of radiation will not exhibit short term effects but will have a elevated chance of getting a cancer in the following year. Since cancer is common it may not be obvious that any particular cancer was a result of a particular exposure. Evidence for this type of effect depends on finding increased incidence of rare cancers after large groups have been exposed. See [[Effects of exposure#Stochastic |stochastic effects]] for more details.

Types of radiation emergency

The type of radiation accident that may occur in your area depends on the type of nuclear establishment you live near.

Gas Cooled reactors

The emergency plans for gas cooled reactors are based on depressurisation events with coincident failed fuel. This is because that class of accidents is capable of releasing the most radioactivity over the shortest period of time for any fault type that is considered to be reasonably foreseeable (although that term is not used in the revised REPPIR regulations).

The AGR safety cases recognise a number of faults including:

  • Coolant leak
  • Failure to post-trip cool
  • Reactor trip with failure to shut-down
  • Water ingress fault
  • Untripped gag fault

Some of these faults will give little or no warning before a release to atmosphere of radioactive material begins. Other faults will develop over many hours before a release occurs, in which time the operators will probably be able to prevent it but the authorities should consider putting in place precautionary protective actions in case the repair does not succeed.

For many fault types the operator should be able to give a reasonably accurate assessment of the duration of the release. This is likely to be in the order of a few hours as it depends on the time taken to depressurise the reactor and seal any breach.

For the “no-notice” faults leading to a release of up to a few hours or so, shelter and, for reactor faults only, taking of pre-distributed stable iodine are the most practical protective actions for most members of the public.

The operator will know if a fault is likely to last for more than the few hours. In this case consideration should be given to how best to protect and reassure the public. More extensive protective actions, such as sheltering for longer or further out from the incident site, a wider distribution of stable iodine and evacuation of the inner downwind areas, could all be considered. All of these raise communication and organisation issues and will lead to more people seeking support from the local authorities and health authorities.

The 2011 HIREs for the AGR fleet (For example the Torness HIRE) reported that “systematic analysis has identified that various internal and external events could result in a radiation accident leading to releases of radioactivity and potential radiation emergencies. These initiating events include failed fuel, failure in containment, fires and fuel movement operations”. Faults could run for a few seconds or for several days depending on the circumstances. The big releases are likely to take several hours. They went on to say that the lower ERLs could be exceeded out to < 800m (shelter, whole body), < 1000 m (shelter, organ), < 200 m evacuation (whole body and organ) and < 1000 m stable iodine. At that stage EDF would have recommended a 1 km DEPZ but some sites, particularly those next to a Magnox site have larger DEPZs.

In 2017 the AGR HIREs were revised giving more details of the types of faults considered and slightly changing the dose model used. However, the reports concluded that the previous reference accident source term remained fit for purpose.

They concluded that the 5 mSv dose contour was at 870 m, the sheltering ERL was potentially exceeded out to 680 m under best estimate dispersion and 1,600 m under pessimistic dispersion estimates; the lower ERL for evacuation could be exceeded to 180 m. Food controls (based on 500 Bq/kg Council Food Intervention Level in milk) might extend 43 km downwind in average conditions.

The 2020 consequence report for Hunterston B (for example) states that “The assessments required under REPPIR indicate detailed planning is justified for the urgent protective actions of administration of stable iodine and implementation of sheltering within a distance of ~ 2 km from the site for protection of the public. The protective actions should be capable of being enacted as soon as is practical after the declaration of a Radiation Emergency has occurred or before a release starts to maximise the averting of dose. Stable iodine can be administered up to 5-8 hours following exposure as averting iodine inhalation dose of ~ 50% is still possible”. The increase in distance compared to the previous assessments seems to be due to a switch in the weather assumption from average weather to pessimistic weather (in the sense that it is a weather pattern that does not encourage the plume to spread upwards and outwards as it travels downwind).

The iodine prophylaxis distance is estimated at about 2,000 m; the shelter distance as about 950 m and evacuation at 300 m. EDF then recommend shelter and stable iodine to 2,000 m and that this be the minimum radius of the DEPZ.

Commercial Pressurised Water Reactors

Sizewell B is Britain’s only currently operating commercial pressurised water reactor. It is situated on the east coast, near Sizewell in Suffolk, around 35 km north-east of Ipswich. It is a four-loop reactor rated at 1188 MWe (meaning that at full power it can generate 1188 MW of electricity). Hot, pressurised water from the reactor is pumped via four pipe loops to four steam generators (only one loop is shown in the diagram). The steam generators transfer the heat in the water they receive to a separate water/ steam circuit (the secondary circuit). This steam is then used to drive the turbogenerators which produce electricity.

A detailed discussion of potential faults for PWRs included:

  • Criticality Control Faults
    • Control rod ejection/withdrawal/malfunction;
    • Incorrect connection of an inactive reactor coolant system loop (by adding cold water you make the reactor more reactive);
    • Boron dilution issues;
    • Inadvertent loading of a fuel assembly into an improper position;
  • Coolant flow issues
    • Single or multiple main coolant pump trip;
    • Inadvertent closure of a main isolation valve in a reactor coolant system loop;
    • Seizure of one main circulation pump or shaft break of one main circulation pump;
    • Coolant flow blockage in a fuel assembly;
    • Primary to secondary leakage;
  • Heat removal perturbations
    • Steam line breaks;
    • Inadvertent opening of steam relief valves;
    • Secondary pressure control malfunction with an increase of steam flow;
    • Feedwater system malfunction/line break/pump trip;
    • Reduction of steam flow from steam generator for various reasons;
  • Loss of Coolant Accidents (LOCA)

In addition consideration has been given to the potential accidents arising in used fuel stores and in the reactor refuelling process.

The 2020 consequence report for Sizewell B states that “EDF Energy has considered a wide range of accident scenarios in the hazard evaluation process and selected a candidate release as the basis of the consequences assessment. The candidate release assumes the most pessimistic attributes from a number of fault sequences in terms of time to release and quantity of activity released it, therefore, does not correspond to the release from a specific individual fault”.

The nuclear submarine programme

The Royal Navy operate a number of nuclear powered submarines and it is possible that UK waters will be visited by nuclear powered vessels from other countries. British submarines use small Pressurised Water Reactors (PWR).

Detailed safety cases exist for the submarines but, for obvious reasons, these are highly confidential. Local authorities have been given outline descriptions of the faults that are possible and a “representative Accident”, which assumes several concurrent failures of the safety barriers NEAG Paper No 2 which is described thus:

1. A number of cautious assumptions are made about the radioactive material inventory and other characteristics of the reactor;
2. A leak occurs in the primary cooling circuit of the reactor which cannot be isolated and which is beyond the capacity of the coolant make up systems;
3. A series of extremely unlikely engineering and other failures also occur;
4. The primary coolant leak coupled with the engineering and other failures lead to damage to the fuel within the reactor after > 3 hours, resulting in elevated gamma radiation levels around the reactor;
5. The fuel damage in turn releases some radioactive material from the reactor. This is largely contained within the submarine but a small proportion may be released to the environment over the following 1 to 2 days;
6. The radioactive material would be carried downwind and would therefore present a hazard in the downwind sector only. This hazard would arise principally via inhalation initially.

The Representative Accident analysis determines a period of approximately 3.5 hours from the onset of the initial event (a 15mm non-isolable leak) to the onset of radiological hazard. Other, less likely, fault sequences could reduce the warning time dramatically.

In addition:

nuclear core production takes place near Derby. For emergency planning purposes it is assumed that a critical accident could occur with the 2020 consequence reporting an estimated a distance of 360 m to “protect against the direct neutron and gamma radiation hazards from the [criticality] incident, in accordance with the lower ERL for shelter of 3 mSv” with an OPZ of 1 km being set by the Secretary of State for Defence.

Submarine construction and initial testing takes place in Barrow. The planning assumptions upon the emergency plans are based assume a release of radioactive material to the atmosphere or waters Devonshire Dock Complex Consequences Report .

Nuclear Dockyards a use a similar risk analysis for the operational submarine and have additional risk estimates for their own processes and radioactive waste holdings.

The consequence reports for the production and maintenance of warheads near Reading consider accidents that would spread material by explosive distribution, these are non-fission incidents, where the material that would dominate in this type of release will be plutonium (which is an alpha emitting actinide) in an inhalable particulate form and criticality excursions.

Nuclear fuel storage and reprocessing (Sellafield)

The work at Sellafield can be considered under a number of headings:

  • Retrievals of nuclear waste, fuel and sludge that are stored inside legacy ponds and silos, the highest risks and hazards at Sellafield;
  • Remediation. As well as the legacy ponds and silos, the site has hundreds of nuclear and non-nuclear facilities that need to be cleaned-up;
  • Spent nuclear fuel management. The site used to reprocess spent nuclear fuel. That means taking the fuel that has been used inside a nuclear power station and extracting the individual component parts of plutonium (1%), uranium (96%) and waste (3%). Although the process has stopped the building are still there.

The 2019 REPPIR-19 Consequence Report for Sellafield Limited reports the analysis of 10 different atmospheric release scenarios. It concludes that shelter would be appropriate out to 2.7 km in average weather conditions and 5.3 km in pessimistic weather conditions based on damage that might be sustained in a 1 in 1000 year earthquake. For evacuation the distances are 0.8 km and 1.8 km, with the recommendation that plans are capable of completing evacuation within 2 hours of the alert.

Food controls may be needed out to 72.5 km for milk and 137.5 km for green vegetables.

Environmental impact

For an airborne release, radioactive material will be dispersed downwind. Some of this material will deposit to the ground and other surfaces and will be available for uptake into the terrestrial food chain via ingestion of contaminated foodstuffs. There is also the possibility of external radiation doses from deposited radioactivity.

For airborne releases the weather conditions during the release and shortly afterwards are very important. Radioactive materials in the form of dusts and gases will be blown with the wind, moving downwind and spreading out as they go. This is a fast process; 2 m/s is a slow wind speed but even at this speed a plume will be 1 km downwind in less than 9 minutes and 5 km downwind in 42 minutes. At average windspeeds of about 5 m/s the plume is 1 km long in just over three minutes and 5 km in less than 17 minutes. The weather also affects the rate of spreading out. On a hot sunny day the plume will spread horizontally and vertically more than it would on a cold winter night. This means higher airborne concentrations further downwind on a cold night but fewer people exposed to them due to lack of spread.

Rain can also be important. Some gases and dusts would be washed out of the air by rain leaving less in the atmosphere (reducing inhalation doses to those further downwind) but more on the ground (increasing ground gamma doses to those in the area after plume transit).

Because the concentrations, and therefore doses, are higher downwind the authorities may focus their resources in these areas providing help to those downwind as their priority.

For a marine release, radioactive material will be deposited in the area surrounding the release - this may affect the marine food chain and pose a hazard via ingestion of contaminated seafoods. It could also cause an external hazard to people walking on or near contaminated shore lines. Radioactivity in the environment may be moved by resuspension into the air, following flows of water during and after rainfall and by hitching a lift (contaminating) on passing animals, people and vehicles. Experience shows that radioactivity will be widely but unevenly distributed after a major accident and estimating the doses to people living in contaminated areas is complex. Decontaminating the environment i.e. reducing the levels of contamination is far from easy and is a slow, expensive and usually ineffective process.

Protective actions

This section describes the protective actions envisaged to alert, protect and assist the general public in the event of a radiation emergency.

If you live near a nuclear site with a DEPZ and an off-site pland it is important that you understand how you will be alerted to a radiation emergency.

You can find this information from the local authority's prior information leaflet or from their web-site.

The tools used to alert you are likely to include some or all of:

  • Sirens (if your site has these make sure you know when they are tested and check you can hear them)
  • Alerts on local radio and television (be sure you know how to tune to these if needed)
  • Alerts on telephone systems or social media pages (ensure that you register of some or all of the options if you can)
  • Vans with loud hailers

The protective actions you may be asked to take include:

  • Shelter (Go in, Stay in, Tune in) - the most likely and most cost effective protective action for quick acting events
  • Take stable iodine - used for releases from operating nuclear reactors only otherwise ineffective
  • Evacuation - only used for very severe or long lasting events

The advice given to you will be determined in the local Strategic Coordination Centre (SCC) where the emergency services, local authority, operator, public health bodies, national health and others will be meeting to exchange information and pool expertise and resources to manage the event.

They will be following the [[off-site plan | local authority's off-site plan]].

The local authority and the health bodies, in particular, will be concerned about the needs of people asked to shelter at short notice and will be comparing intelligence about potentially vulnerable people and working out how to ensure their safety and comfort.

There may also be advice issued to avoid the consumption of food and water that may have become contaminated with radioactive material as a result of the accident. This will initially be based on rough over-estimates of potential contamination levels and be quite widespread. Within days this advice will be turned into compulsion by the issuing of emergency orders preventing the sale of potentially contaminated food using the Food and Environmental Protection Act 1985 . In the days and weeks after the event, careful measurements and modelling will take place to reduce the area affected but some food controls could last for several years.

Advice about protective actions

This section discusses the appropriate information on protective action to be taken by the general public in the event of a radiation emergency Sheltering and associated action

If you are advised to shelter the key is to "Go in, Stay in, Tune in". The intention of shelter is to reduce the levels of contamination you and your family are breathing in. Just like you close the doors and windows of your house if there is a bad smell outside, such as a neighbour with a garden fire, you are generally asked to close your windows and doors and in addition turn off heating systems and fans that might draw in air from outside.

By reducing the levels of airborne radioactive dust and gas inside your house compared to outside you can reduce the amount of radioactive material you inhale by a useful amount.

For more information on sheltering reread the prior information from your local authority or on this site go to [[Shelter | Shelter]] (for what to do and what not to do) or [[Shelter science | Shelter science]] for more information on how it works.

Distribution and taking of stable iodine tablets

If you live within the Detailed Emergency Planning Zone (DEPZ) of an operating nuclear power station you may have had stable iodine tablets (otherwise called potassium iodide tablets, PITs or SITs) pre-distributed to you. You should keep these safe and dry and only take them when advised to do so.

If you live near a nuclear submarine berth there may plans to distribute stable iodine tablets to you if and when needed rather than pre-distribute.

The tablets should come with clear instructions about how to take them.


Evacuation is not expected to be needed for reasonably foreseeable faults at most UK nuclear sites (a severe earthquake on the Sellafield site is an exception - they recommend evacuation of the population within between 0.8 km and 1.8 km downwind depending on the weather ( REPPIR Consequence Report

If the release is likely to be at a high rate for a long period of time or with an adequate warning, evacuation may be the best option. The evacuation zone would depend on several factors such as the weather conditions (the evacuation zone will be downwind of the accident scene with allowances made for forecast wind direction changes), time of day and population distribution.

It is implicitly assumed that evacuation is a short term affair and that you will be allowed back to your within hours or days when the plant is made safe and the levels of contamination in and near your home determined to be safe. In really severe accidents (Chernobyl and Fukushima scale events) it may be necessary to relocate you (move you out of your home on a semi-permanent or permanent basis).

The US Ready web-site "Plan to Evacuate" has some very good general advice for preparing and responding to evacuation advice.

In their prior information Emergency information for local residents (Hinkley for example) | EDF advice that you:

  • get together the people in your household (excluding children at school) and pets
  • pack a supply of warm clothes
  • pack any special food that anyone in your family needs
  • pack any medicines that anyone in your family needs
  • take personal documents and valuables
  • pack some books and toys for children
  • complete the registration card in the calendar and take both with you
  • make sure fires are out and that cookers, ventilation fans, TVs etc. are turned off and unplugged
  • lock up your property - leave using your own transport, keeping windows and ventilation closed. If this is not possible you will be told where transport will be provided from one or more of the following assembly points
  • go to the reception centre (see map) or any other centre designated, unless you wish to take your pets with you
  • or, go to a friend or relative's home if it is outside the evacuation area - but please inform the police of your location with the registration card.''

Arrangements for particular groups such as children at school, the sick and elderly [[File:care establishment.png | thumb | frame | Example Action Card]]

Where there are care homes, schools or hospitals within a DEPZ they will have been asked to prepare emergency plans and given advice by the local authority. They are charged with the duty of keeping your loved ones safe until you can be reunited.

For example, the Sellafield prior information has:

"If your children are at school during an emergency then naturally you will want to collect them as soon as possible. However, it may not be safe to do so. They will be looked after as a priority group by the school or they will be evacuated to a safe place where they will be looked after by school staff and emergency responders.

Listen to local radio for advice or arrangements which have been made."

longer-term advice on the consumption of contaminated food and drink

Food Standards Agency (FSA) is responsible for providing advice to the affected public concerning any implications for the food chain. This covers the handling and consumption of food and restrictions and the movement of crops and animals into the food chain of affected areas.

Farmers and consumers will be advised (in some cases compelled) on how to change their behaviour to reduce their ingestion dose to acceptable levels if radioactive contamination is found in the food chains.

As a consumer you might be advised not to eat food grown in your allotment, garden or in the wild. Food with radiation contamination levels above accepted values will be prevented from coming to market.

Responsibility for implementing the protective action.

You can learn which local authorities have off-site planning and response duties on the ONR website

Your local prior information should make clear who is responsible for providing you with advice and support during the response to a radiation emergency.

The extent of the detailed emergency planning zone.

The extent of each DEPZ should be noted in Your local authority's website and prior information.