The greatest attention is given to operational safety. This applies to normal operation as well as in case of extraordinary occurrences such as unforeseen defects on plant parts. For this reason, the most important components, such as controllers and alarm releases are present in double or multiple form and are situated in separate locations. If any of the controllers or alarm releases fail, there is still a second or a third one available which can perform the same function.

Facts & figures

Barriers
Multiple barriers ensure that the high level of radioactivity which is emitted during nuclear fission and the fission products cannot escape into the surrounding atmosphere.

Fuel pellet
The fission products can practically not leave the structure of the pellet.

Cladding tubes
The cladding tubes, which are welded gas-tight, prevent fission products from escaping into the primary loop.

Reactor pressure vessel
The fuel elements are enclosed in the reactor pressure vessel. They are cooled by the cyclical flow of water from the enclosed primary loop.

Biological shield
The reactor pressure vessel is screened by a so-called biological shield, made from concrete measuring three meters in thickness.

Steel lining of the concrete containment building
The entire reactor loop system is encased in a 35 mm thick, steel-pressure shell, welded gas-tight.

Concrete containment
The concrete reactor containment building has a wall thickness of 90 cm. A further steel shell on the inside of the containment concrete is also welded gas-tight. There is an intermediate space containing a vacuum between the outer enclosure and the 35 mm inner steel shell. This provides additional protection against gases or particles escaping.

More info about nuclear energy:

www.kernenergie.ch
www.atomenergie.ch
www.ensi.ch
www.nuklearforum.ch