Filtered Containment Venting System
Filtered Containment Venting System (FCVS) is a system to retain fission products in case of a nuclear accident.
In the event of a nuclear power plant accident the pressure within the nuclear reactors containment building can increase. A FCVS allows for the release of the over-pressure through a scrubber normally containing water, stones and chemicals, where most of the fission products are contained. This reduces the radioactive release to the environment with up to 99%.
Fukushima nuclear disaster
The plant involved in the Fukushima Daiichi nuclear disaster did not contain FCVS.
Many countries require FCVS: for example, Sweden, Germany and France.