Civil defense measure Criterion: the measure will be performed when required
to avoid the radiation dose to an individual listed below Taking shelter indoors (for two days) 10 mSv*
Ingestion of iodine tablets For persons under 18 years of age or pregnant: 10 mGy**, for adults: 100 mGy (thyroid dose)
Evacuation (for one week) 20 mSv
Table 4-1. The planning criteria for key civil defense measures used in emergency preparedness planning.
* The unit of radiation dose is the sievert (Sv)
** When referring to the effects of radiation on a single organ, the unit of radiation dose is the gray (Gy)
In addition to the sensitive sites listed in Section 7.10, all sites that may be simultaneously occupied by a considera- ble number of people are important from the point of view of rescue planning. Such sites include significant commer- cial districts, libraries, hotels, and various meeting facilities. Other sites with special implications for rescue operations include sites with fire and explosion hazards, such as gas sta- tions and certain industrial sites, and large production and storage facilities.
During the normal operation of the nuclear power plant, the protective zone and the emergency planning zone will have no effect on the everyday life of the population living within them. Iodine tablets will be distributed to the population living within the protective zone for use in acci- dent situations.
4.5.3.3 Civil defense measures
In the case of a nuclear accident, the need for civil defense measures is determined by the stages of the acci- dent and the current weather conditions. In an accident situation, the nuclear power plant emergency prepared- ness organization and the Radiation and Nuclear Safety Authority (STUK) will give recommendations con- cerning civil defense measures. The authorities will be responsible for the implementation of those measures. In the case of a radiation hazard caused by a severe nuclear accident, the key civil defense measures include taking shelter indoors, ingestion of iodine tablets, evacuation, access restrictions, the protection of domestic animal production, and restrictions on the use of foodstuffs. Measures will be performed according to pre-defined cri- teria (Table 4-1). The authorities will broadcast informa- tion on the performance of the civil defense measures on the radio and television.
Even in the case of most severe nuclear power plant acci- dents, taking shelter indoors and ingestion of iodine tab- lets are adequate measures in all areas located farther than 20–30 kilometers from the plant (STUK 2002). The purpose of taking shelter indoors while the radioactive plume passes over is to avoid breathing the radioactive outdoor air and to reduce exposure to the direct radiation from the plume. A milder measure would be to advise people to avoid going outdoors unless necessary. People will be advised to take
iodine tablets if the breathing air is expected to contain high levels of radioactive iodine (I-131) due to the accident. Respiration will carry the radioactive iodine to the lungs, and it is finally retained in the thyroid gland. Due to this, the radiation dose for the thyroid gland will be significantly high. As the iodine contained in the iodine tablets is also retained in the thyroid gland, it prevents the accumulation of radioactive iodine.
In Finland, the population living in the protective zone will be evacuated in the case of an impending significant release of radioactive substances into the environment. If there is enough time, the evacuation will be carried out before the radioactive plume reaches the area. If there is not enough time, people will take shelter inside, and the evacuation will be carried out after the plume has passed the area. As the nuclear power plant will be designed so that the probability of a release occurring in the early stages of an accident and causing a need for civil protec- tion measures is very small, there will be enough time for the performance of civil defense measures. In addition, access to areas which are contaminated or under the risk of contamination may be restricted for a specified time.
After the passing of the emission plume, no significant amounts of radioactive substances will remain in the out- door air. All rooms shall be carefully ventilated and surfaces wiped clean. Radioactive particles from the emission plume will still be present on land, building surfaces, and in water. While the natural elimination of radioactive substances remaining in the environment may take a long time, their concentration decreases significantly during the first year. If necessary, the environment may be cleaned, for example, by washing the walls and roofs of buildings located in the most contaminated areas.
The radiation dose from food products may be decreased by preventing them from being contaminated with radio- active substances. Protective measures are of particular importance in primary production. The effects of a nuclear accident on the food supply chain are determined by the season, crop cycle, the circumstances and practices of local food production, and the production structure. The risk of elevated activity levels in food products is significantly higher during the growth period than during other sea- sons. Radioactive substances are easily transferred into milk and meat. Therefore, farmers will be advised to move their
96 4 Nuclear safety
domestic animals indoors and, if possible, to cover their feed even when there is only a threat of an accident. Other possible measures include covering cowsheds, restriction of ventilation or filtering the air, and storage of clean water. Reasonably sized areas of vegetable, berry, and fruit crops may also be covered before the onset of radioactive fallout. Following the accident, tilling of the soil and fertilization will effectively decrease the amount of radioactive sub- stances ending up in farm products (Rantavaara 2005). The concentration of radioactive substances in affected food products may be decreased during processing by, for exam- ple, conversion of production. An example of this would be making cheese out of the milk so that most of the radioac- tive substances will be left in the whey.
The use of at least some food products will be restricted in the aftermath of a severe accident. If necessary, the pre-es- tablished limit values for food products to be placed in the market in the European Union (Council Regulation 87/3954), shown in table 4-2, may be quickly applied on the radioactivity concentration of food products.
Products sold in grocery shops shall be clean enough to meet the safety requirements set by the authorities. STUK and the pertinent ministries will provide through the media instructions and recommendations for the users of raw materials that are self-produced or harvested from the for- ests and lakes.
4.5.3.4 Liability in accident situations
Nuclear liability means the liability of the licensee of a nuclear facility for damage to third parties. According to the Nuclear Liability Act (484/1972), the licensees of nuclear facilities are liable for nuclear damage caused by nuclear incidents in their nuclear facility, regardless of whether the licensees are responsible for the cause of the damage. Compensable damage includes per- sonal injuries, damage to property, financial loss, and the costs of environmental restoration measures and counter-measures.
The licensees of nuclear facilities located in Finland have unlimited liability for nuclear damage caused by a single
nuclear event in Finland. The liability of the licensees of nuclear power plants located in Finland for nuclear damage caused outside Finland is limited to 600 million Special Drawing Rights of the International Monetary Fund, corre- sponding to approximately EUR 676 million. The licensee of the nuclear power plant shall have insurance covering this liability.
As per international treaties, the Finnish Radiation and Nuclear Safety Authority shall notify the International Atomic Energy Agency (IAEA) of an accident situation. All events classified INES 2 or higher must be notified to the IAEA, which will then convey the information to other gov- ernments. The EU has its own notification and information exchange system for events at nuclear power plants and radiation hazards.
4.6 Radiation and its health
impacts
Radiation is either ionizing or non-ionizing depending on how it affects the substance it encounters. Ionizing radia- tion originates from radioactive substances or equipment generating radiation, such as X-ray equipment.
The health impacts of ionizing radiation can be divided into two categories: direct and long-term effects. Direct impacts are inevitable adverse impacts caused by extensive cellular damage. Long-term impacts are statistically observ- able adverse impacts caused by genotype changes in a sin- gle cell.
The unit of radiation dose is the sievert (Sv), which is used to measure the health impacts of radiation. Since one sievert is a large amount of radiation, sub-units, such as one-thousandth of one sievert (millisievert, mSv) or one-millionth of one sievert (microsievert, μSv), are commonly used. Dose rate indicates the intensity of the radiation, or how large a radiation dose a person receives over a certain time. The unit of dose rate is sieverts per hour (Sv/h).
Table 4-2. The pre-established maximum permitted levels of the concentration of radioactive substances in food products to be placed in the market in the European Union.
Radionuclides Activity concentration, becquerel/kg*
Baby food Dairy products and liquid food products
Other food products
Isotopes of strontium 75 125 750
Isotopes of iodine 150 500 2000
Isotopes of plutonium and transplutonium elements 1 20 80
Other radionuclides with a half-life longer than 10 days, for
example, 134Cs and 137Cs 400 1000 1250
*) Following an accident, the maximum permitted levels, as set out in the table, may be applied for food products to be sold within the European Union market by a Commission Decision (the permitted levels for rarely used food products are ten times higher than the permitted levels for basic food products listed in this table) Situation-specific permitted levels may be applied by Council Decision.
97