Waste water generated at the power plant and on the site includes water from the raw water treatment and demineralisation plant, water from the liquid waste treatment plant, water used for flushing the travelling band screens, sanitary waste water and laundry waste water. The waste water is processed appropriately before being conducted to the sea.
Process waste water
The new plant unit has a designated treatment plant for liquid waste that processes all water coming from the so-called controlled area that may contain radioactive substances. The waters are treated mostly by filtration and evaporation to reduce radioactivity.
Process waste water that will be discharged into the water system after treatment (such as filtration, ion exchange, separation and evaporation) mainly includes filter rinsing and decantation water, floor cleaning water, sewage from the laboratory, neutralised waste water originating from decontamination, as well as laundry waste water. The radioactivity of water is measured before it is conducted to the cooling water discharge tunnel. Furthermore, the radiation level of the water in the discharge pipe is monitored by instruments that will automatically close the valves in the discharge pipe if there is excess radioactivity in the water. A collection sample is taken during outward pumping, and the concentrations and releases of radionuclides and total phosphorus are measured and determined.
The existing units (OL1 and OL2) generate approximately 70 m3 of process waste water daily, the
nuclear power plant unit under construction (OL3) is estimated to generate approximately 200 m3 daily, and
the new nuclear power plant unit is estimated to generate between 70 and 400 m3 daily.
Waste water originating from the production of process water
The filter sludge liquor originating from the filtration of raw water at Korvensuo is conducted to an earth basin of 10,000 m3 in which the sludge will be sedimented.
The overflow from the basin is conducted through a secondary settlement basin of 0.6 hectares to an open 11
ditch and further to the sea in the Eurajoensalmi inlet to the east of Marikarinnokka (to the west of Kornamaa). The quality of the overflow water is similar to the raw water taken from the Eurajoki river, and it does not contain any significant amounts of residue from water treatment chemicals.
The settling section of the water treatment plant located at the power plant site produces sludge liquor and filter rinsing waters. Sludge liquor and rinsing waters having a pH of 5.5 to 6.5 are conducted to the cooling water discharge channel. Water that might contain oil is conducted through oil traps fitted with alarms. Table 9-12 presents an estimate of the volumes of waste water generated in the treatment of process waters at different stages of plant operation.
Waste water originating from the demineralisation plant
The ion exchangers of the demineralisation plant are revitalised using water with added sodium hydroxide or sulphuric acid. The acidic and alkaline waste water from revitalisation are conducted to a neutralisation pool. The waste water is neutralised to a pH range of 7 to 10 before being conducted into the cooling water discharge channel. The reject from the reverse osmosis device at the demineralisation plant is also conducted to the neutralisation pool. The waste water mainly contains salts generated in neutralisation.
The total volume of water is presently approximately 100 m3 weekly or an average of 15 m3 daily. The total
daily volume of water will be 35 m3 once the unit
under construction (OL3) is completed and 45 to 80 m3
once the new unit (OL4) is completed. The existing demineralisation plant will also serve the extension to the power plant (OL3) but the construction of OL4 will require a new demineralisation plant or an extension to the existing one.
Laundry waste water
Each power plant unit has a laundry of its own for laundering protective clothing such as overalls and shoe protectors used in the controlled area (area in which radioactive substances may be present). The laundries use low-phosphate detergents. The waste water from laundering, which is slightly radioactive, is mechanically decontaminated using nap collectors and centrifuges. The decontaminated waste water is conducted to the cooling water discharge tunnel together with cleaned process waste water. The new plant unit will have a laundry of its own for laundering protective clothing used in the controlled area. The total volume of water from the existing units (OL1 and OL2) is approximately 1,000 m3 annually or an average of 3 m3 daily. The volume of waste water from the unit under construction (OL3) is estimated at 500 m3 annually. The new unit (OL4) will also generate approximately 500 m3 of laundry waste water annually. The laundry waste water is treated at the plant unit’s liquid waste treatment plant. The waste water contains detergents used for laundering and contaminants discharged from the laundry. The phosphorus concentration in the waste water is low. Water used for rinsing the screens and filters in cooling water systems
The matter collected in the fine screens and travelling band screens used for the treatment of cooling water (screenings) is rinsed off the screens using sea water. The screenings mainly consist of debris, algae, mussels and fish carried with the cooling water. Solid matter is separated from the rinsing water and treated as required under the power plant’s environmental permit. The rinsing water is conducted to the cooling water discharge system. The combined volume of rinsing water at the existing plant units (OL1 and OL2) is 160 m3 per hour at maximum and 80 m3 per hour on average (22 l/s). The amount of screenings for the two plant units (OL1 and OL2) is estimated to be 7 to 15 tonnes annually, approximately half of which is fishes.
The predicted cooling water flow for the plant unit under construction (OL3) and the new plant unit (OL4) is approximately 60 m3/s per unit at maximum - that is, in the same order as the combined flow of the existing units. It can thus be estimated that the volume of rinsing water for the fine screens and travelling band screens will be approximately equal to the total of the existing units – that is, approximately 160 m3 per hour at maximum
and 80 m3 per hour on average.
The matter collected in the sieves of the cooling water system at the spent fuel storage is rinsed with sea water to the cooling water discharge pipe.
Waste water from the waste water treatment plant Waste water from sanitary facilities and water from the washing and rinsing of floors on non-radioactive industrial premises is conducted to a biological-chemical waste water treatment plant located at the Olkiluoto plant site. The capacity of the treatment plant is approximately 100 m3 per hour, which is sufficient also for the treatment
Operating condition of the nuclear power plant units
Sludge liquor from the filtration of raw water [m3/h]
Sludge liquor from settlement at water treatment plant [m3/h]
Water used for rinsing filters at water treatment plant [m3/day]
OL1/OL2 5 1 4
OL1/OL2/OL3 construction time 15 - 20 3 - 4 12 - 16
OL1/OL2/OL3 operation 8 - 13 2 - 3 6 - 10
OL1/OL2/OL3/OL4 construction time 25 - 35 5 - 7 20 - 28
OL1/OL2/OL3/OL4 operation 11 - 21 3 - 5 8 - 16
Table 9-12 Estimate of the volumes of waste water generated in the treatment of process waters at different stages of plant operation.
Envir
onmental
Impact
Assessment
of sanitary waste water generated at the new unit during the operating stage. A pumping station will be constructed in connection with the new unit for pumping waste water into the existing system.The introduction of the new unit will increase the volume of sanitary waste water by approximately 40 m3 daily. During the operation of the new unit (OL4),
the four units combined will generate a total of 180 m3
of sanitary waste water daily. Table 9-13 illustrates the volumes of sanitary waste water at the different stages of operating the units.
The load caused by waste water with regard to organic matter (BHK7ATU) will amount to a total of 500 kg annually, phosphorus approximately 40 kg annually and nitrogen approximately 3,000 kg annually. The treated waste water is conducted through volume measurement to the cooling water discharge channel. The sludge generated in waste water treatment is pumped from the settlement basins through condensation basins to sludge basins and transported to the Rauma town waste water treatment plant for treatment.
Table 9-14 presents the waste water flows of the two existing power plant units in 2006 and an estimate of the waste water flows of the power plant unit under construction and the new power plant unit.
traps before being conducted to the drainage network. The underdrains in the foundations of power plant buildings are conducted to the rain water drains through foundation water wells fitted with no-return valves.
The levels within the area are balanced so that not even in an exceptional flood situation will rain water flow to the floors or foundations of buildings but will be allowed to flow directly to the sea without causing any damage or harm.