Multi-barrier safety systems
Nuclear power plants are equipped with several protective barriers with two basic functions: shielding the staff from radiation and preventing the spread of radioactivity to the environment.
The first barrier is the crystal lattice of the fuel (1), in which most of the radioactive fission products remain embedded. The next barrier consists of the gas-tight fuel rod tubes (2).
These in turn, are surrounded by the reactor pressure vessel and the pipework around it (3), made of high-quality steel. The reactor pressure vessel is encircled by a one metre concrete shield, called the biological shield, which protects plant personnel against direct radiation.
A containment (4) provides a gas- and pressure-tight enclosure around the reactor pressure vessel. The thick reinforced-concrete walls serve at the same time to protect equipment against effects of natural phenomena and external man-made hazards.
In addition, a safety filter (5) ensures that radioactivity does not leak out into the surroundings, even if all other safety systems should fail out and the barriers become ineffective.
In the event of malfunction, a number of safety systems would be activated to shut down the reactor and supply emergency cooling to the core.
All safety features together ensure that the plants operate safely and reliably. The constant use of fail-safe equipment and system configurations is one of the most important safeguards. Continuous investments are made to improve safeguard equipment operability and to ensure that Vattenfall's plants are always in good condition, regardless of their age and service life.
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