773 Technical project description

Decommissioning waste is waste generated in conjunc- tion with the closing down and dismantling of the nuclear power plant. When the operation of the nuclear power plant is discontinued, radioactive substances originating from the migration of radioactive contamination or the activation of the materials of components located in the immediate vicinity of the nuclear reactor will remain in the plant’s structures, systems, and equipment.

The goal of the decommissioning of the plant is to dis- mantle the radioactive systems, completely decontaminate the nuclear power plant of radioactivity, and free the build- ings and areas from authority supervision. However, some of the buildings can be left undismantled and, after decon- tamination, recommissioned for use as part of a new power plant or entirely other purposes.

The waste generated in conjunction with decommission- ing could be processed using current technology. As the decommissioning of the power plant and the processing of the decommissioning waste will take place several dozens of years in the future, the process will be eventually imple- mented utilizing the best technology available at that time.

According to the Nuclear Energy Act, the nuclear power plant licensee shall be responsible for the planning and implementation of the decommissioning of the plant. The plant decommissioning plan and the associated costs shall be first established in the power plant construction license application. The decommissioning plan and the cost esti- mate will be further specified for the power plant operating license application. After this, the plan shall be updated every six years. The Radiation and Nuclear Safety Authority (STUK) shall approve the plan and any revisions. No other field of industry is using a similar statutory procedure to ensure that no adverse effects or liabilities will be caused to outside parties after the end of the operations.

The plan will discuss the decommissioning methods and schedule, the storage of decommissioning-related radi- oactive waste before disposal, and the final disposal. The purpose of the plan is to ensure that the radioactive parts of the plant to be dismantled will not present any danger to the environment.

The funds required for the decommissioning of the nuclear power plant will be deposited in advance to the National Nuclear Waste Management Fund in the form of annual nuclear waste management fees as prescribed in the Nuclear Energy Act. While the environmental impacts of the decommissioning of the new nuclear power plant will be assessed later in a separate EIA procedure, this section describes the decommissioning process in order to provide a general view of the nuclear power plant project’s lifespan.

3.14.1 Decommissioning strategy

According to Fennovoima’s preliminary plan, the delayed dismantling strategy will applied in the decommission- ing of the nuclear power plant. Delayed dismantling takes advantage of the decay of the radionuclides over time, which facilitates dismantling work as the radiation levels decrease. The method can be divided into four phases: 1. The spent nuclear fuel is removed from the reactor and

the fuel pools and transferred to safe storage, where it awaits final disposal.

2. The nuclear power plant is brought into the state of monitored conservation, or a state in which the risks affecting the environment and the people working at the plant are within acceptable limits and which can be safely maintained until the final dismantling of the nuclear power plant.

3. For the duration of the monitored conservation, con- tinuous monitoring and guarding of the nuclear power plant is arranged to ensure that the plant remains in a safe state.

4. The dismantling is implemented.

Since the dismantling of the nuclear power plant will com- mence only after a long period of conservation, particular attention must be paid to maintaining familiarity with the plant until the time of dismantling even in the eventual case that the persons responsible for the design and opera- tion of the nuclear power plant are not be available at the time of dismantling. This can be ensured by starting the dis- mantling work with the dismantling of non-radioactive and slightly radioactive systems already during the monitored conservation period.

3.14.2 Waste and the processing thereof

During the monitored conservation period, low and inter- mediate level waste will still be generated from the clean- ing of buildings and the servicing and maintenance of the systems required during the conservation. As the properties of this waste correspond to those of waste generated during operation, the principles applied to the classification and packing of low and intermediate operating waste may be applied to it as well.

However, large amounts of waste with less common properties of operating waste will also be generated in the course of the decommissioning process. The total amount of this waste will be 10,000–15,000 m3 _{, and it can be classi-}

fied as follows:

• activated steel

• activated concrete

• contaminated ferritic steel

• other contaminated steel

• contaminated concrete

• contaminated insulation.

As much of the decommissioning waste as possible will be decontaminated (cleansed of radioactive substances) in order to enable its clearance and processing in the same manner as ordinary waste. A part of the waste will be low and intermediate level waste. It will be processed, packed, and disposed of in the operating waste repository in the same manner as operating waste generated during the operation of the plant.

Once the decommissioning of the plant has been com- pleted, the plant area has been cleaned in accordance with the radiation safety requirements, and all waste has been appropriately disposed of or transported out of the area,

78 3 Technical project description

an application concerning the future purpose of the former plant area will be submitted to the Radiation and Nuclear Safety Authority (STUK) for approval. In accordance with the Nuclear Energy Act, the Ministry of Employment and the Economy will make a decision on the termination of the management obligation concerning nuclear waste and the decommissioning of the nuclear power plant on the basis of the application prepared by the party under the waste management obligation.

3.15 Transportation and

commuter traffic

3.15.1 Construction phase traffic

During the construction phase, the amount of commuter traffic to and from the plant will be considerably higher in comparison with the present situation. The number of work- ers will be at its highest in the fourth year of the construc- tion of the power plant, with a total of some 3,500 workers.

A temporary accommodation area for the workers, with access to the work site by foot or by bus, will be built in the vicinity of the plant area. About one-third of the workforce employed during the construction phase will be accommo- dated in these quarters. As regards the calculation of traffic volumes, these workers are assumed to travel to the nearest city or municipal center two and a half times a week on pri- vate business. It is further assumed that two-thirds of them will be using a car.

About two-thirds of the workforce employed during the construction phase will live near the plant, and they are assumed to commute from home. Of these workers, two- thirds are assumed to use a car, and they are assumed to drive to and from the plant once per working day.

In addition to commuter traffic, a maximum of 50 heavy transport vehicles will visit the plant every day. Items trans- ported by road will include construction materials, equip- ment, and components.

In all, during the construction phase, the volume of pas- senger traffic from Monday to Friday will be approximately 4,000 private vehicles per day, and the volume of heavy traf- fic will be approximately 100 heavy vehicles per day.

Table 3-6 shows a summary of the traffic volumes.

3.15.2 Operation phase traffic

Approximately 400 people will be working at the plant during the operation phase. It is assumed that three- fourths of the workers will commute by car. The volume of commuter traffic will therefore be approximately 600 vehicles per day. If required, regular bus transportation will be arranged between the surrounding municipali- ties with plant worker populations and the plant site. In addition, there will be maintenance and goods transports to the plant, resulting in a traffic volume of about 30 vehi- cles per day.

The amount of transportation of goods and passenger traffic within the plant area is usually small.

Number of vehicles per day Construction phase Passenger traffic 4,000 Heavy traffic 100 Operation phase Normal operation Passenger traffic 600 Heavy traffic 30 Annual maintenance Passenger traffic 1,150

Maintenance and goods transport traffic 10

Table 3-6. Estimated traffic volumes at the nuclear power plant during the construction and opening phases.

During annual maintenance, the number of workers visiting the plant increases by about 500, of whom three- fourths are assumed to be staying in the accommodation area built during the construction phase. Of these workers, two-thirds are assumed to be using a car, arrive at the area at the beginning of the week, and travel back for the weekend. These workers are assumed to travel to the city or municipal center two and a half times a week on private business. The other annual maintenance workers will commute from the surrounding areas.

Table 3-6 shows a summary of the traffic volumes in the construction and operation phases.

3.16 Radioactive emissions and

the limitation thereof

During the normal operation of the nuclear power plant, small amounts of radioactive substances, such as noble gases (xenon and krypton), gaseous activation products (carbon-14), halogens (iodine), and active substances in aerosol form, will be released in a controlled manner in the atmosphere and in the sea water.

These radioactive substances are generated in the nuclear reactor during operation. The majority of the radioactive substances will be contained inside the fuel rods. Furthermore, the reaction of neutrons released as the result of the splitting of nuclei with impurities present in the reactor coolant will generate activation products. Therefore, some radioactive substances will also be con- tained in the primary circuit water and the associated cleaning and waste water systems. Small amounts of gase- ous radioactive substances will be generated in the atmos- phere immediately surrounding the pressure vessel due to the effect of neutrons.

The waters and gases containing radioactive substances will be decontaminated and delayed for low activity con- centration. The decontaminated gases will be led to the plant’s vent stack, and the waters will be led to the sea with the cooling water. The emissions will be measured in

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