Actions in a radiation hazard situation
Instructions for members of the public in the event of a radiation hazard situation
Finland has never had a radiation hazard situation in which there was a need to, for example, protect oneself indoors or take iodine tablets. However, the authorities are prepared for a radiation hazard, and the operations are regularly practised. In the event of a radiation hazard situation, the protective measures taken by the authorities aim to prevent and limit the public's exposure to radiation. The objective is to minimize the stochastic effects of radiation (cancer) to the extent possible, as well as to prevent the direct health hazards caused by radiation (e.g. radiation injuries, radiation sicknesses).
Read more about the different operators and their duties on the Authorities cooperate in the event of a radiation hazard situation page.
Radiation hazard situation and protective measures
A radiation hazard situation refers to a situation in which the consequences of an event may require special measures to limit or reduce the radiation exposure of members of the public or of persons participating in emergency work and protective measures.
Protective measures are measures that aim to keep the radiation exposure of the population as low as possible in the event of a radiation hazard situation, to keep other harmful effects caused by the situation as low as possible, and to restore the living conditions of people and the functioning of society to as normal as possible after the radiation hazard situation.
STUK’s duties in a radiation hazard situation
The duties of the Radiation and Nuclear Safety Authority include preparedness and expert tasks in the radiation hazard situation. STUK forms a situational picture of the event and determines the danger zone. STUK also assesses the adverse effects of the situation on the population and the environment and makes recommendations on the necessary protective measures. In addition, STUK advises, for example, the industry, trade and transport and customs authorities in reducing the harmful effects and investigates the need for restrictions on the use of foodstuffs.
Radiation hazard situations are divided according to their temporal phase into the early phase, intermediate phase and recovery phase.
Laki Säteilyturvakeskuksesta (Act on the Radiation and Nuclear Safety Authority) (finlex.fi)
Protective measures in the early phases of a radiation hazard situation
In radiation hazard situations in which there is a risk of radioactive substances being released or in which they have been released into the air, protective measures are taken even before the radioactive substances arrive in the area. The key protective measures are staying indoors, access restrictions, and evacuation from the immediate surroundings of the incident. Taking iodine tablets is a supplementary protection measure to staying indoors in accidents in which radioactive iodine is released. These measures are used to limit the immediate radiation exposure of humans. Furthermore, agricultural production, other production and various premises must be protected to reduce contamination.
In a local radiation hazard situation, the area is isolated and evacuated. An example of such a situation is a hazard caused by an unshielded radiation source with effects limited to the immediate vicinity of the incident or indoors. A local radiation hazard situation may be caused by an accident in the use or transport of radioactive substances or by intentional unlawful use of radioactive substances.
Employee safety
In the event of an accident, employees involved in rescue and protection operations may be exposed to radiation to a greater extent than the rest of the population. Protective measures to avoid direct damage to health concern first and foremost those rescue workers who have to work in the immediate vicinity of strong radiation sources.
The employer is responsible for the radiation protection of employees engaged in radiation practices. Protective measures must be taken so that the employees will not be exposed to radiation unnecessarily. The goal is that the employee's dose does not exceed 20 millisieverts (mSv) per year. Before starting a task, the extent of exposure is assessed and monitoring of the accumulation of the dose during the work is planned. If no personal dosemeters are used, the radiation dose is assessed by measuring the dose rate of external radiation.
Rescue and protective personnel must wear protective clothing and respiratory filters. If it is possible that there is radioactive iodine in the air in the contaminated area, preparations are also made to take iodine tablets.
Further information
- Occupational radiation exposure and health surveillance (For the user of radiation -pages)
- Exceptional situations related to environmental health. A handbook for environmental health care staff and co-operation partners. Chapter 16. Radiological emergency handbook (the Ministry of Social Affairs and Health publication, 2014) (pdf)
Protective measures in the intermediate phase of a radiation hazard situation
In the later stages of the radiation hazard situation, the radiation level in the living environment no longer rises and no new releases of radioactive substances are expected. In the later stages, it will be decided whether the protective measures implemented in the early stages can be lifted, eased or changed. Furthermore, new protective measures to reduce radiation exposure and the amount of radioactive substances in the living environment are launched, if necessary. These measures aim to ensure the radiation safety of people and the continuation of society’s critical operations.
Depending on the environmental radiation level in the later stages, it will be decided whether people should stay indoors or if the recommendation could be lifted. A prerequisite for lifting the recommendation to stay indoors is that the environmental radiation level is sufficiently low. Even in this case, it might be necessary to avoid unnecessary time outdoors and doing dusty work outside, for example.
People are evacuated from areas where the environment is heavily contaminated. Evacuation is carried out in a systematic and controlled manner to keep the radiation exposure of people minimal.
The aim is to keep the evacuation period as short as possible by cleaning and making the evacuated areas habitable quickly. The contamination level of the areas is also quickly reduced at the early stages due to the decay of radioactive substances. A short-term evacuation must become a long-term evacuation if, even with cleaning, the radiation level in the area does not decrease sufficiently.
Access restrictions are used to prevent people from accessing contaminated areas. They are necessary in areas where staying indoors or evacuation is required. Restrictions are used to prevent unnecessary exposure as well as the spread of radioactive substances carried by humans, objects and means of transport. Access restrictions may concern road and rail traffic as well as harbours and airports.
In the access restricted areas, essential tasks can be carried out. Such tasks are those related to rescue services, food supply and other vital operations, evacuations and urgent cleaning operations. Instructions will be provided to limit radiation exposure in the area and to set up cleaning stations.
When staying indoors is no longer required, access restrictions are lifted.
Cleaning indoor areas from radioactive substances
- Clean the surfaces, textiles and any uncovered items on the floor and shelves. Replace or wash the air filters.
- Clean up more often than usual.
- Throw away the cleaning cloths and vacuum cleaner bag that were used in the cleaning.
- Food that has been stored in the refrigerator or in sealed packages is safe to eat. Throw away all other food.
Once the radioactive plume has left the area, ventilation and cleaning indoors begins as soon as possible. Ventilation and cleaning are important, as radioactive substances seep in while the radioactive plume is passing. If indoor areas are not cleaned, radioactive substances may find their way from the contaminated surfaces into your body.
The radiation dose can be reduced considerably through simple cleaning measures, such as wiping with a damp cloth, washing surfaces and vacuum cleaning. Dusty work methods should be avoided. Premises to be cleaned first are those where people spend long periods of time, such as apartments, day care centres, schools and hospitals, or where there are a lot of people, such as workplaces and shopping centres. The premises should be re-cleaned regularly, since people carry radioactive substances indoors.
Air filters should be changed or washed as quickly as possible in premises where the ventilation was on while the radioactive plume passed. This prevents the detachment and migration of radioactive substances from the filters indoors.
The contaminated areas of the living environment must be cleaned, as people moving around in uncleaned areas will be exposed and radioactive substances can travel indoors and to other areas.
The cleaning must begin from people’s immediate living environment, such as passageways, outer surfaces of buildings, yards, playgrounds and parks. Cleaning methods include washing with water, brushing machine cleaning, removal of vegetation, removal of topsoil and removal of snow in the winter.
In contaminated areas, the means of transport, work machines, tools and objects outdoors should also be cleaned. The means of transport, work machines and tools used in the area should always be re-cleaned after use.
The aim is to clean the living environment so that there will be no need to restrict its use. In other contaminated areas, exposure is reduced by restricting their use. The restrictions concern activities that are not absolute necessary, such as movement during leisure time or other recreational use. It may be necessary to restrict recreational activities for the first couple of months.
Ensuring food safety is a long-term need. Foodstuffs cannot be used or supplied for sale if the activity concentration limits set for them are exceeded. A temporary ban on the sales and use of foodstuffs may be needed before their safety is confirmed with measurements. Productions restrictions are also set if the activity concentration limits of the products may be exceeded.
Instructions will be provided concerning restrictions on the use of self-produced foodstuffs and natural produce originating from the forest and lakes. Radioactive substances remain in nature for a long time. Instructions concerning fish, mushrooms and berries may be needed for years, even decades in the most severely contaminated areas.
Agricultural producers and production plants will receive instructions on how to ensure the cleanliness of raw materials and final products by acquiring clean feed from outside the fallout area.
Guidance on preparing for radiation or radiological emergencies and ensuring food safety can be found on the Finnish Food Authority's Preparedness for Radiation Hazards page (ruokavirasto.fi).
Contamination of the area disturbs business activities, such as the operations of industry, farm and forestry work, and peat or biofuel production, and operations of central storage, trade, tourism and leisure services.
In contaminated areas, there must be measures ensuring radiation safety of raw materials and products and the continuation of business activities. The radiation safety of employees and customers must also be ensured.
All production, trade and logistics facilities and production equipment must be cleaned. Objects and unprotected raw materials and products are to be cleaned, if possible. The plants’ outdoor areas must also be cleaned to avoid contamination of processed raw materials and products and the migration of radioactive substances into cleaned areas. Cleaning must be repeated if there is reason to suspect that radioactive substances may find their way back to the area or production facilities while transporting people or goods.
It is important to ensure the radiation safety of products for sale. A temporary sales ban may be needed at the early stages until the safety of the products is confirmed.
It is not necessary to clean natural areas. Instead, it can be recommended to avoid those areas.
Waste containing radioactive substances is generated when the environment is cleaned and products are discarded. The cleaning waste consists of topsoil, vegetation and snow that has been removed, waste from roads and yards as well as air filters and sludge from waterworks. Discarded products are unsold foodstuffs and products. Waste volumes may be extremely large.
Waste management must already be considered when cleaning the living environment so that the cleaning waste from the more contaminated areas is kept separate from that of less contaminated areas. The aim is also that different waste types, such as soil and removed vegetation, are kept separate. This facilitates the placement of waste. Most waste is only slightly radioactive and can be placed in a dumping area or landfill.
Work carried out in contaminated areas, such as cleaning the living environments and maintaining essential operations of the society, must be planned and implemented so that the employees will not be exposed to radiation unnecessarily. The employees should use protective equipment to reduce radiation exposure if necessary. The authorities will provide information about the contamination level of the areas and safety equipment required in the work. Radiation exposure is constantly monitored.