• Home
  • FAQ
  • Is human intervention required to shut down the reactor in the event of an earthquake?
print

Is human intervention required to shut down the reactor in the event of an earthquake?

Is human intervention required to shut down the reactor in the event of an earthquake?

No

The reactor has three sensors (3-axis accelerometers) which permanently monitor ground movements. If two of these three sensors detect an acceleration greater than 0.01 g, the safety rods automatically fall, shutting down the reactor. This acceleration corresponds to a weak earthquake with a magnitude of less than 3 close to the reactor.

Of course, this automatic shutdown takes place under the supervision and control of the reactor operator teams.

The reactor has five independent safety rods. During reactor operation, these safety rods are always in the raised position. They are held suspended in this position by means of electromagnets. The rod drop is therefore a “failsafe” mechanism: any failure, loss of power supply, cable break, etc… causes the safety rods to fall by the force of gravity due to the loss of current to the electromagnets. This automatic shutdown does not therefore require any external energy source.

To speed up the rod drop time, the safety rods are driven downwards by compressed air at a pressure of 10 bar, which is permanently available in small reservoirs located above the safety rods. Any fall in the pressure of the compressed air in these reservoirs also automatically triggers a safety rod drop.