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Time For Some Debunking

From the South China Morning Post, attributed to Twitter

Looks like nuclear misinformation is flaring up again in the news stream. I can’t debunk it all – much of it contains too little fact for that. But I can say why I think some of these things are improbable.

The big story is in the South China Morning Post: Chinese scientists plan ‘disposable’ nuclear reactor for long-range torpedo.

Let me say that the idea of a disposable nuclear reactor, even with quote marks, strikes me as improbable.

The Chinese researchers are proposing a mini version of the Russian Poseidon unmanned submarine – the world’s first known underwater drone powered by nuclear energy.

Ah, okay! Vaporware!

We have not yet seen a prototype of the fearsome Poseidon, touted by Vladimir Putin as being able to cause a radioactive tidal wave along the entire US East Coast. Nor any signs of its development. I have long been dubious of this and the nuclear-powered Burevestnik cruise missile, which was at least tested and killed a number of its developers.

To build a new nuclear power system with “mature and simple technology that is easy to use and maintain, inexpensive and suitable for mass production, we need to think out of the box,” Guo said.

And this is far out of the box.

For their design the project team stripped most shielding materials from their reactor, protecting only some critical components from radiation. They also replaced expensive coatings made with rare earth elements inside the reactor core with cheap materials such as graphite.

Mmmn, yes. Here’s what a graphite reactor looks like.

7576-1 file #65 Graphite Reactor Reactor East Loading Face 1-2-1952 ORNL

Ah, okay, that’s not quite fair. Here’s a more modern graphite reactor. Both are admittedly higher-power and therefore larger than this out of the box torpedo propellant.

The trouble with giving numbers for this sort of thing is that they can be analyzed. Putin has stuck to much vaguer descriptions, largely of the ranges and destruction that these miracle weapons could cause if they existed.

The reactor, as heavy as two average Chinese adult males, would generate more than 1.4 megawatts of heat with less than 4kg (8.8lbs) of low-concentration uranium fuel.

“Low-concentration uranium fuel” usually means 3-4% uranium, but it could be up to 20%. Certainly reporters and scientists often express percentages confusingly, but a straightforward reading is that the amount of uranium is 0.8 kg or less. How one produces the nuclear reactions characteristic of a reactor with that much uranium, even with an infinite water reflector, should be explained. It would indeed be a remarkable and out of the box achievement.

The way reactors generate heat couples poorly with propulsion. They produce a uniform heat, and what is needed for propulsion is a sudden whack, like the chemical reactions we are accustomed to seeing for rockets and such. That’s a continuing issue for these nuclear-powered whatsits.

A chain reaction would start as soon as the torpedo left the launching platform and take about half an hour – 20 times faster than a typical reactor on a nuclear submarine – to reach a working temperature of 300 degrees Celsius (572 Fahrenheit) and accelerate the torpedo to a cruising speed of around 60km/h (37mph).

Zero to sixty in half an hour! That illustrates what I just said. Depending on the miraculous feat of producing a chain reaction with just 0.8 kg of uranium.

This one isn’t nuclear, but look at those operative words: “Restarted development.” This is not a weapon we need to worry about next week or probably next year. This is a conventional weapon and thus might actually be developed.

All these miracle weapons are “in development.” My sense of them, having seen the sale by Edward Teller of Star Wars to Ronald Reagan, is that Russia, and now China, has such an entrepreneur who has convinced the leadership that these are the miracle weapons that will give them an unassailable edge over the United States.

More cynically, it’s chum in the water to waste our time debunking them.

I’ll believe the Russians are moving military equipment into the Zaporizhzhia Nuclear Power Plant, but the only “highly flammable substances” there would be diesel fuel for the backup generators. An engineered safety feature of nuclear power plants is to avoid any danger of fire, so the presence of anything flammable is minimized. I suspect that someone is saying that to try to scare the Russians off or to make them sound irresponsible. The Ukrainians have done this kind of hazard inflation before.

As usual, don’t retweet this stuff indiscriminately, and don’t let it keep you awake at night. It would be nice if reporters could get more educated on scientific possibilities and impossibilities, but obviously that isn’t going to happen soon.

Cross-posted to Nuclear Diner

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