What Makes a Nuclear Reactor ‘Fail-Safe?’

Incidents like Chernobyl and Fukushima nuclear disasters are great proponents of the dangers of nuclear reactors going terribly wrong. But the fact is, 30 countries around the world are operating 449 nuclear reactors, and a couple of incidents, no matter how terribly catastrophic, are not enough to discredit the almost fail-safe set up that make any nuclear power plant extremely safe.

So what are some of the ways this immunity against a possible disaster is achieved? The video by YouTuber Randy Dobson explains this as he tries to demystify the word “fail-safe” when applied to nuclear reactors.

The video dwells on how the nuclear reactor works, explaining the “fission” reaction behind making both nuclear weapons and nuclear reactors roll forward. But harnessing the extremely volatile and potentially destructive technology into electricity creating mechanism requires carefully designed system with a slower and more arduous process.

As the video narrates, a key mechanism behind making nuclear power is the control rod assembly. The rods are made out of elements like boron and absorb neutrons to control the fission process. The rods can be lowered and raised into the reactor to control the rate of fission, and electromagnets are used to control the height of rods and hold them in place. In case the power goes out, the electromagnets stop working, leading to the rods falling under the effect of gravity and completely halting the fission process.

It is also important to point out what the term “fail-safe” even means. Many people mistakenly believe it means that a system cannot fail, or that it is very unlikely to fail. That is not the case.

What fail-safe means is that the system is designed so that when it does fail, that failure will most likely result in a safe outcome.

A good example is the air brakes on large trucks. They rely on air pressure to work, but the air pressure doesn’t apply the brakes, it releases them. If the air system fails, strong springs within the brake assembly apply the brakes. If anything goes wrong, the truck stops.

The brakes in your car are a good example of a fail-unsafe system. Your hydraulic system applies the brakes. If the hydraulic system fails, you have no brakes. Because car brakes are fail-unsafe, they have two backup systems. First, there are two separate hydraulic circuits in the normal brakes. If one fails, you will still have working brakes. If both hydraulic circuits fail, you still have the cable-operated emergency brake.

You can learn more about making a nuclear reactor fail-safe by watching the video below.


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