Environmental impact

In nuclear power plants, nuclear energy is converted into heat energy to make water boil into steam, which in turn drives a turbine. The kinetic energy from the turbine is converted into electrical energy in the generator. The radioactive emissions that occur are reported in millisievert, mSv, as this unit of measurement shows the consequences of the release for people in the plant's surroundings. The emissions may not exceed one tenth of the normal background radiation, ie a radiation dose of 0.1 mSv per year.

Radioactive gaseous fission products are formed in the fuel. These can come out in the steam. When the steam is condensed in the turbine condenser, the fission products are sucked away and transferred to an exhaust system where the activity can subside. In addition, small airborne particles accompany the steam and reach the turbine's delay system. When these are released through the chimney, their activity is measured in the unit Bequerel, Bq. The same applies to the amounts of water that are released. Since process plants cannot be completely tight, they have a leakage collection system for water that comes from the process. The water collects in tanks. When the radioactivity has become low enough, by decay or purification via a filter, the tanks are emptied into the sea after the activity has been measured.

Since you know which fission products have been released and its activity and also know what impact they have on the environment, you can calculate the radiation dose. To find out how the emissions affect the environment, any radiation doses to the people who can be most affected are calculated. These imaginary people are called critical group. They are an imaginary group around the power plant that mainly feeds on what they can get there from farming, animal husbandry, hunting and fishing. It would then receive the maximum permissible radiation dose, ie a maximum of 0.1 mSv per year. At OKG, we work to reduce emissions to as low levels as reasonably possible.

Waste in the form of rubbish, scrap, ion exchange masses and spent fuel is sorted into different groups according to the activity content. How the radioactive waste is handled depends on what form it is in and how large the activity content is. At Simpevarp, there is a landfill for low-level waste built according to the latest landfill technology.

Low-level waste: The vast majority of radioactive waste has a small activity content and gives off a very small amount of radiation. This can be, for example, rags, worn-out overalls, scrap metal, used paper towels, packaging materials, plastic and stationery. Oil, mainly turbine oil from controlled areas, can also contain radioactive particles. This oil is purified in a centrifuge, measured and if limit values ​​are kept, the oil can be reused for energy recovery in an approved incineration plant.

All waste from controlled areas is measured and sorted. Scrap metal is often so inactive after cleaning that it can be classified for free use and, for example, recycled in the metal industry.

Intermediate-level waste: The majority of the intermediate-level waste consists of filter masses, which have been used to purify the water in reactor systems, condensate systems and fuel basins. Used pipes, replaced machine parts and used protective clothing are also classified as intermediate-level. When working with such waste, some radiation shielding is needed. However, no special cooling of the material is needed. In a special rock chamber on the Simpevarp Peninsula, the concrete containers are stored with intermediate-level operational waste. The containers are then transported by special vehicle to the port of Simpevarp for loading on the vessel M/S Sigrid. The transport goes to SFR, the final repository for radioactive waste, outside the nuclear power plant at Forsmark.

A small part of the intermediate-level waste consists of spent core components that are either transported to Clab in the same way as the high-level waste or alternatively stored in steel tanks that are temporarily stored in a rock chamber at OKG pending final disposal in SFL (final disposal for long-lived low- and intermediate-level waste).

High-level waste: The high-level waste consists of the spent fuel. The fuel used is highly radioactive and generates large amounts of heat. In total, approximately 80 tonnes of highly active waste are received per year at OKG.

Management of highly active waste: During the annual audit shutdown, approximately 20 percent of the fuel used in the reactor core is replaced with new fuel. The spent fuel is first stored for about a year in a fuel pool, so-called cooling pool. From there, it is transported in beam-shielded transport containers with special vehicles for intermediate storage in Clab (central intermediate storage for spent nuclear fuel) pending final disposal.

Interim storage will take place for about 40 years. During that time, activity and heat dissipation have decreased by about 90 percent. The responsibility for this entire process lies with SKB, Svensk Kärnbränslehantering AB.

Hot water discharge: The cooling water is heated to about 10 ° C in the turbine condenser. The cooling water is taken in through large tunnels, passes through the facility, before it is discharged into Hamnefjärden on the north side of the peninsula. The amount of heat is actually so large that it makes up about two thirds of the total energy produced.

Biological checks: To find out what consequences this large amount of heat has on animal and plant life in the sea, extensive biological checks have been made since 1962. They show that the cooling water from OKG heats up about 15 km² along the coastline by one degree or more. Measurements and checks of temperatures, the physical and chemical properties of the water, the size of the fish stock, composition and health, and benthic fauna and algae are carried out on an ongoing basis.

Impact on the marine environment and wildlife: In the vast majority of cases, the effects are positive. The nutrient supply is good in the heated water as well as the oxygen supply. This has meant that both plants and animals have a faster growth here than in other parts of the Baltic Sea.

Energy consumption: The plants are heated mainly with water-borne heat generated from electricity, domestic steam from turbines and waste heat from the reactor water. Electricity is mainly used for machines and lighting.

How does the heated cooling water affect the sea?

Cooling water is a necessary condition for being able to operate a nuclear power plant. The cooling water from O3 is discharged into the nearby Hamnefjärden. The temperature rises by about 10 ° C from the time the seawater is led into the plant until OKG releases it. The seawater is used to cool the process water in a heat exchange system but has no contact with the process water.

The temperature increase affects the marine plant and animal life closest to Simpevarp. A control program compares the environmental effects in Simpevarp with a reference area near Valdemarsvik, approximately 120 km north of Simpevarp. The inspections are performed by SLU (Swedish University of Agricultural Sciences).

Impact on the fish

For fish species that benefit from the warmer water, such as perch, roach and birch, there is a strong positive growth effect. Some reproductive disorders in some fish species have been found, but at the same time there are more and larger fish in the area. Fish have the ability to search for the temperature zones that suit them best. Fish follow into the sieving stations at the cooling water intakes, the survivors are returned to the sea.

Impact on the birds

The good fish supply, but also the fact that Hamnefjärden is ice-free in the winter, makes it an important place for seabirds. The environmentally sensitive sea eagle also thrives in the Simpevarp area.

Impact on benthic fauna and algae

In Hamnefjärden, benthic fauna and algae are strongly affected by the cooling water, for example there is overgrowth of the bay and periodically there is a lack of oxygen for the benthic fauna. Outside Simpevarp, however, the algae and seaweed communities are species-rich. The area's seaweed belts are among the richest in Kalmar County. The distribution of cooling water at the bottoms in the Simpevarp archipelago will not change significantly with an increase in power. Thus, benthic animals and benthic vegetation will not be affected compared with the current situation.

LCA and LCC are two modern concepts that are increasing in demand today with regard to environmental impact. This with regard to the fact that consumers today demand more basic information regarding the products purchased in connection with an environmental impact. At the same time as the labeling of goods and products is developing and increasing, legislation is also being tightened, especially within the EU.

LCA - Life Cycle Analysis is a method for being able to present an overall picture of how large the total environmental impact is for a product's entire life cycle. This means from raw material extraction, via manufacturing, use until the product becomes waste, in these different steps transport and energy consumption in the intermediate stage are also included.

LCC - Life cycle cost analysis The analysis is performed based on an economic aspect such as costs and revenues over a lifespan of the product.

LCA and LCC are two concepts that are handled in parallel. From an environmental perspective, it usually becomes an economic issue and vice versa.