Reserve cooling towers recently installed at the Finnish nuclear power plant Loviisa on the island of Hästholmen complement the main cooling system for the two 496 MW reactors. The cooling towers were built by GEA EGI Contracting/Engineering Co. Ltd., a member of the GEA Heat Exchangers Group, and were erected under the supervision of Fortum, the customer and plant operator.
The standby cooling towers serve as backups to the main plant cooling. If the seawater cooling systems become unavailable — for example, if an oil slick occurs in the plant vicinity — the standby towers will remove the residual heat from the plant into the air and allow the plant to be shut down safely. While plant operator Fortum had already prepared plans for a standby cooling system, the company implemented the standby cooling tower following post-Fukushima stress tests.
Installations started in the fall of 2014. The new cooling towers were installed on buildings such as a reserve residual heat removal system and tank areas. They were integrated into the cooling circuits during the following winter months. Some supplementary work outside the towers was performed in the spring. During the next regularly scheduled shutdown of the power plant, planned for this fall, performance testing of the standby cooling system will take place.
Two cooling towers were provided for each unit of the power plant. The towers were designed to withstand earthquakes and are protected from the weather by panels when not in use. An electric heating system prevents tower freezing.
One tower in each of the units serves to remove the residual heat from the reactor, and the other tower provides cooling of safety-related systems such as the spent-fuel-pool cooling, emergency-core cooling and containment heat-removal systems. The coolers, consisting of integrated finned-tube heat exchangers installed in “A” form, allow for a small footprint and fast dissipation of heat. The cooling effect is forced by fans powered from the normal grid or by an emergency standby diesel generator. The output of the new cooling towers is dimensioned to bring the reactor to hot shutdown state within a few days and later on to cold shutdown state. Fuel pools can be kept in normal operational parameters.
GEA EGI supported the construction work on site, which was performed locally by companies contracted by Fortum.