A nuclear reactor exploding like a bomb is an element of many stories ("Pacific Rim", etc). From some of these stories it looks like at least some reactors can be blasted just by sending a command through the user friendly interface. How much of this is true?

A nuclear reactor is a complex device, not designed to be a bomb, and a bomb is also a complex device built for the different purpose. The known reactor accidents (Chernobyl, Fukushima, SL-1) resulted in dangerous contamination but all explosions were just "steam explosions" or at least much weaker than could be achieved with the dedicated nuclear bomb.

Is there a fundamental reason why nuclear reactors do not explode as true bombs or is this simply because the design is focused to make them safer and not to behave so? Can we build a useful nuclear reactor capable of the true nuclear explosion if required?

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    $\begingroup$ This question is not about world building. It belongs on physics or engineering. $\endgroup$ – Travis Christian Jan 14 '16 at 21:10
  • $\begingroup$ I'm voting to close this question as off-topic because it displays a lack of research effort. The principles here certainly aren't elementary or easy to understand, but the answer can be found pretty quickly on the internet. $\endgroup$ – HDE 226868 Jan 14 '16 at 21:44
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    $\begingroup$ Certainly--but not in the sense you think. Chernobyl was a true nuclear explosion--but a fizzle by bomb standards. The key to getting a big boom is that you must assemble the bomb very, very quickly so that it produces a lot of energy before that energy has time to destroy it. A reactor is inherently built with a lot of extra stuff in it, even if you used explosives to crush it you couldn't get much of a boom. $\endgroup$ – Loren Pechtel Jan 15 '16 at 0:56

Can we build a useful nuclear reactor capable of the true nuclear explosion if required?

This is a really interesting question. As a designer who is designing this system with the intent of turning it into a bomb with the flick of a switch, the simplest system to think of would be one that relies on an experimental fuel rather than the traditional fuels. A metal alloy works best. A bit of hand waving about superior properties and the lack of organic binders would work wonders. Then, have that wonderful user-friendly interface drain the coolant by pressure filling the reactor with a reactive solvent. The metal filler remains solid while the uranium liquefies and drains out to the bottom until it reached critical mass - nuclear bomb out of a reactor.

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  • $\begingroup$ "Gipsy danger" reactor could easily be designed along these lines (we do not know much about its technical details). This is somewhat the answer. Thanks. $\endgroup$ – eigenvalue Jan 15 '16 at 14:28
  • $\begingroup$ Looking over the critical mass tables, I'd recommend Plutonium in retrospect v. Uranium. You can get a much smaller mass of Plutonium to go critical than the Uranium. However, I'm not sure what Solvent can be used. I had a specific solvent/metal filler in mind with the Uranium (though - didn't want to just mention them on this site and wind up with a call from the CIA.) $\endgroup$ – Mark Jan 15 '16 at 16:39


If you're asking whether a currently running (or designed) nuclear reactor could explode like a nuclear bomb, the answer is "no." In fact, reactor fuel is much too lean on the fissionables ($U_{235}$) to explode.

It would be difficult to cause them to explode at any level of force (e.g. a steam explosion) since they're designed for safety.

Probably Yes

If you're asking whether it would be possible to make a reactor that could double as a bomb when necessary, the answer is "probably yes."

The problem is that it wouldn't be a very good bomb or reactor.

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The biggest difference is that a nuclear reactor is designed for a controlled energy release at a relatively slow rate. This is to allow the energy to be collected and used. It is still a lot of energy production, but there are safety measures in place. Also the reactors are designed to catch and collect the energy.

A nuclear bomb on the other hand is designed to maximize yield and energy output in a short amount of time as possible. The bomb is designed with explosives to compress all the material at once causing fusion generating energy to cause the fission reaction.

So most likely the best your are going to get from a power plant is energy build up that the system can't handle, and with all the water in it, a steam explosion, of relatively conventional explosions. However, it will be mixed with radioactive material. like sprinkling uranium in a stick of dynamite, it makes it much more dangerous but because of the radioactivity, not the nuclear power.

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