Evaluación y cartografía de servicios de los ecosistemas

The impact of the new unit on the landscape can be mitigated by choosing surface materials and colours similar to the existing units. The vicinity of the new unit can be landscaped.

13.2.2 Discharges of radioactive substances and nuclear safety

Even though the discharges of radioactive substances during the operation of a nuclear power plant are minor, power plants are continuously involved in development and reforms aimed to further reduce the discharges. For example, radioactive discharges from the Olkiluoto 1 and 2 plant units into water have been reduced through technical and procedural reforms.

Safety aspects attributable to nuclear power plants are described in Section 10.

13.2.3 Mitigating the impacts of waste water

Waste water generated at the power plant shall be treated by mechanical, chemical or biological means or combinations of these depending on the quality of the waste water. The volume of waste water generated shall be minimised through water use planning and recycling.

13.2.4 Cooling water intake

Cooling water intake structures shall be designed so that the water flow rate outside the structure is as low as possible. This ensures that the intake of water will not cause danger to water traffic. A low flow rate will also reduce the amount of fishes and aquatic vegetation coming to the power plant, which will decrease contamination of the screens and travelling band screens within the cooling water cleaning system. Nets fitted at the mouth of intake channels will prevent fish from being carried by cooling water. The nets are kept in place from May through to June and also during other times if it is found that substantial amounts of fish are entering the system.

13.2.5 Remote cooling water intake and discharge The cooling water flow model has not examined options for remote cooling water intake and discharge because they would be located within the Rauma archipelago Natura area off Olkiluoto.

Remote intake

A remote cooling water intake could be located deeper than a local intake, which would provide slightly cooler water in the summer and correspondingly reduce the temperature of the OL4 discharge. However, the

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Envir onmental Impact Assessment

difference would be smaller than the cooling water warm-up at OL4. The difference in sea water temperature in the Natura area due to the difference between remote and local intakes would be fractional. The energy required for the pumping of cooling water will increase in proportion to the length of the tunnel. The pumping energy is converted into waste heat going into the sea. Shells and of Olkiluoto, between the Natura areas of the Rauma northern archipelago and the Luvia archipelago.

The discharge opening of the tunnel could be behind the shallows approximately four kilometres away at Kallio-Hyörtti-Lännenkivet-Iso Pyrekari. This solution would not significantly improve the situation in the Natura areas. During unfavourable wind conditions, warm water will affect the Natura area. Furthermore, this would create a new area with the sea bed in an unnatural state.

Impacts of the construction of a remote intake and discharge require more reinforcements as its length increases. A longer tunnel will also require a larger surge basin.

Regardless of the reinforcement actions required, the quality of the rock plays an important role in tunnel construction with regard to the permanence of tunnel structures and the operation of the cooling water tunnels.

The geology to the north of Olkiluoto island suggests the presence of a weak area in the northwest-southeast direction along the route of the potential discharge tunnel, the penetration of which would impose difficulties on the implementation.

13.2.6 Tower cooling

An alternative to direct water system cooling is the use of cooling towers that will discharge the excess thermal load primarily directly into the atmosphere. The thermal load on the water system is small. Cooling towers are quite a common solution in Central Europe, for example, where

the water resources of plants located inland are often quite limited (rivers, groundwater), and the combined production of power and heat is not as common as in Finland.

Winter conditions, for example, can cause problems to an indirect cooling system. Because approximately one per cent of the cooled water flow is evaporated into the cooled air flow, fog will be formed in connection with the air exhaust particularly at low outdoor temperatures.

Depending on the conditions, the phenomenon can be quite intense and cause icing in nearby areas as the fog lands on surfaces. The blowers in the cooling towers will also generate some noise, while water system cooling does not cause any noise carried outside the plant. Cooling towers operating without blowers are substantially higher than power plant buildings and thus have a substantial landscape impact.

The amount of electrical output produced depends on factors such as the temperature of cooling water used for condensing the steam conducted to the turbine. The colder the cooling water, the higher the power obtained from the turbine. The most substantial disadvantage of indirect cooling is that it is not as efficient as direct cooling. This hampers the efficiency of the power plant, which causes a financial loss and increases the quantity of nuclear waste per unit of electricity produced. The power requirement of the cooling tower pumps and optional blowers will also reduce the amount of electrical energy obtained from the plant.

In summary, it can be stated that there are no techno-economically feasible or environmentally justifiable alternatives for direct water system cooling.

13.2.7 Utilisation of cooling water

The cooling water from the existing nuclear power plant units, totalling approximately 60 m³/s, is conducted directly to the sea through a discharge channel. The commissioning of OL3 currently under construction will double the need for cooling water. The fourth power plant unit will increase the total cooling water requirement to approximately 180 m³/s.

The cooling water is taken from the sea and warms up in the condensers by approximately 12 °C. Thus the temperature of the discharge water varies roughly between 15 and 30 °C depending on the season. The total

The existing power plant units and the third unit under construction have a single-stage turbine condensing system. It would be theoretically possible to design a dual-stage condensing system for the fourth

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power plant unit. In this case, the condensing water from the first stage would be at a high temperature, allowing the utilisation of the condensing heat. However, this alternative is not realistic for OL4 because there is no suitable thermal load in the vicinity. The existing district heating load can be supplied by existing thermal plants, and there is no industry in the area that would require plenty of new heat production. The district heating load in the area is not expected to increase substantially in the near future as this would require the construction of a large and densely populated residential area.

Because the cooling water is sea water, it is not suitable for the irrigation of agricultural areas due to its salt content. However, low-temperature cooling water could be used for heating greenhouses, for example; in such a solution, the water is conducted to greenhouses and releases heat and humidity when flowing through.

The cooled water is conducted back to the sea through a discharge channel. However, to be profitable, such a solution would require large greenhouses, and there are no such facilities near the power plant.

Fish or crayfish farms would be a potential application for salty warm water. However, no large-scale fish farming is carried out near the power plant at present.

All in all, the heat consumption of these operations is so minor in relation to the available thermal load that the resulting reduction would not be significant to the thermal load conducted to the water system.

Furthermore, the water impacts of some of these forms of heat utilisation, such as large-scale fish farming, could be more harmful than the impacts of the heat that would not need to be conducted to the water system. In addition to minor environmental advantages or even disadvantages, the fact that it is uneconomical is a problem with the small-scale utilisation of heat.

The disadvantages of cooling water discharged into the sea include that the warm discharge water will keep the vicinity of the discharge point unfrozen in winter. If there was a water area in the vicinity that would benefit from the lack of ice, it would be reasonable to examine the possibilities of discharging at least some of the water into such an area. An example of such a water area could be a harbour. However, there are no large harbours near Olkiluoto. The nearest large harbour is located in Rauma, more than 20 km from the power plant.

There are currently no other feasible possibilities for utilising the heat contained in the cooling water that would improve the condition of the sea outside Olkiluoto.

TVO is open to any proposals regarding extensive utilisation of the cooling water heat.

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Envir onmental Impact Assessment

13.2.8 Nuclear waste management

Nuclear waste generated at the plant is handled appropriately. Spent fuel is kept in intermediate storage at the plant until disposal in Finnish bedrock begins.

Liquid low- and intermediate-level waste is either dried or solidified. The disposal of low- and intermediate-level waste is implemented through an extension to the disposal facility located at the power plant site.

13.2.9 Waste management

Foul smells from the landfill shall be prevented through compacting and covering the waste. Harm caused by particles and microbes in the landfill area shall be mitigated through covering the waste. Dust formation shall be prevented through covering the waste and sprinkling or salting the roads as necessary. Harm caused by a closed landfill shall be mitigated through measures such as using a gas collection system to prevent the discharge of landfill gas directly into the atmosphere, a tight surface structure in the fill area and bio-filters.

13.2.10 Noise impacts

Noise during the operation of the power plant can be mitigated to a level compliant with official guidelines concerning occupational safety and environmental noise levels.

The construction technology and materials used in the plant building will efficiently attenuate noise from machinery and equipment. Furthermore, noise sources can be isolated by protective housings or fitting them with mufflers as necessary. Vibration can be attenuated by placing vibrating equipment on flexible platforms.

13.2.11 Impact of the transport, use and storage of chemicals and oils

Precautions have been taken for disturbances and accidents associated with the handling and storage of chemicals through sewerage, shielding pools and automatic alarms, as well as operating plans and instructions. Applicable safety guidelines and regulations are observed in the transportation of chemicals. The risk of discharges of harmful amounts of these substances into the water or soil during operation or an accident is minor.

Comprehensive safety instructions shall be prepared for the plant, addressing the control and prevention of chemical accidents. Plant personnel will be trained on the safe use of chemicals. Accidents associated with the storage and with handling of chemicals are improbable.

Any leaks will be stopped and minimised by structural means, eliminating the discharge of any significant amounts of harmful chemicals into the environment.

Any leaks can be caught in shielding pools, sludge or oil trap wells or a neutralising tank. Training provided to personnel working on the power plant site shall pay special attention to minimising the occupational safety and environmental risks of chemicals.