Effective safety features

Safety comes first

The safety features of OL3 are based on existing solutions and technology which have been developed further. The focus of the development has been on safety systems and the management of abnormal situations.

There are four separate safety sub-systems, each capable of performing its safety functions independently. Each of the four systems is physically separated from the others into different facilities and buildings, which ensures that a sufficient amount of systems is operational at any time.

The reactor building, with its double-shelled reinforced concrete structure, is proof of the development of safety features. The inner shell is gas-proof and pressure resistant, designed to retain its integrity even in the case of a very severe accident. The outer shell provides physical protection against external hazards, and is strong enough to sustain even a direct crash by a large passenger aircraft.

These demanding safety features are required for managing severe reactor accidents leading to reactor core meltdown. 

In the extremely unlikely case of a reactor core meltdown, the core melt flowing from the reactor pressure vessel is conveyed to the core catcher at the base of the reactor building (white area pictured), where cooling is provided until the core melt solidifies. This ensures stable core melt control.

Strict safety requirements
The design requirements specified for OL3 represent the very latest knowledge in the field of reactor safety. The plant unit fulfils Finnish and European nuclear power plant safety requirements, and in many aspects the requirement level exceeds the international level.

In Finland, the general principles of nuclear safety are decided by the government. Detailed instructions are prepared by the Finnish Radiation and Nuclear Safety Authority (STUK), which also controls compliance with them.

The most important and latest international safety recommendations and requirements have also been taken into account in designing the new power plant unit, e.g. the Europen utility reguirements (EUR) defined by European power companies and the safety and quality recommendations of the International Atomic Energy Agency ( IAEA).