Safe and reliable production

Safe operation, plant safety and reliability are maintained and continuously developed through "defence in depth" principle. Defence in depth is based on the idea of several barriers in order to avoid accidents. If the first barrier fails there are additional barriers securing that no accidents with radioactive releases happen.

Based on a full scope risk analysis, the probability of reactor core damage of Loviisa’s unit one is 4.6 x 10-5 per year, i.e. less frequent than once every 20,000 years. Fortum engages in continuous research and development work to lower the risk level further.

All design, constructions and decisions are made with conservative assumptions and high safety margins. Continuous improvement in all aspects of safe operation, including the know-how of the personnel and safety culture, are a high priority at the Loviisa power plant. The performance, work quality and documentation of all operations, both technical and organizational, are constantly monitored internally by Quality Assurance (QA) and the Nuclear Safety Assurance as well as the Finnish Radiation and Nuclear Safety Authority (STUK) and international organizations such as IAEA and WANO.
Defence in depth in nuclear safety: functional barriers


Defence in depth in nuclear safety: structural barriers


Five levels of the defense in depth
1. Prevention of abnormal operation and failures
First-level actions are good design, high quality of components and materials, high expertise in operation, maintenance and quality control. Quality assurance is also focused on.
2. Control of abnormal operation and detection of failures
The second level consists of systems that detect deviations as early as possible, allowing the plant to return to normal operation as fast as possible.
3. Control of accidents within design basis
The third level consists of the safety systems that prevent incidents leading towards severe accidents, mainly core damage, and limit radioactive materials within the containment system.
4. Control of severe conditions, including prevention of accident progression and mitigation of the consequences of a severe accident
The fourth level includes the Severe Accident Management (SAM) system and other actions that prevent and mitigate releases of radioactive material to the environment.
5. Mitigation of the consequences of significant external releases of radioactive materials
Loviisa power plant's emergency preparedness plan also covers emergencies involving a severe release of radioactive material into the environment. Emergency preparedness is constantly being improved and regularly rehearsed.

5/18/2015