Streetwise Professor

Note: I wrote this Saturday, but was unable to post because of a technical problem at the site. No doubt those damned Russkies were trying to silence me 😛 I’ve only made slight edits, and added the part about Norwegian detection of iodine. Some of what is posted here anticipated discussions in the comments on Sunday and Monday.

In my original post on the Severodvinsk explosion I expressed puzzlement at the Russian explanation that they were testing an “isotope power source for a liquid-fueled rocket engine.”  I did some research to address my ignorance, and found, indeed, that radioisotope rocket engines are a thing.  The problem is that this thing is inconsistent with the closure of nearby waters due to the presence of toxic rocket fuel (allegedly from the explosion) and the mention of “liquid rocket fuel” in the explanation.

Radioisotope rocket engines work by using the energy released from the decay of radioactive isotopes to heat a solid material (the “capacitor”).*  When the capacitor is sufficiently hot, fuel is passed over it.  The capacitor heats the fuel.  The hot gas is vented out through a shaped nozzle, which accelerates it (exploiting the Venturi Effect), creating thrust.

The motor generates a greater pulse (the thrust produced with respect to the amount of propellant exhausted per unit time) than the Space Shuttle Main Engines.  But it generates far less power.  Further, it is fuel limited, and thus does require fuel which limits its utility as a source of continuous propulsion.  Thus, its main application is as rocket thrusters in space, not launching projectiles or powering aircraft or missiles in the atmosphere.  All of the applications of this source of power that I have seen relate to space in some way.

But here’s the thing: whereas conventional rocket engines operate by combustion (i.e., stored chemical energy is released as the result of the burning of the rocket fuel) radioisotope rockets do not.  The fuel is not burned, just heated. Hydrogen has advantages and disadvantages as a fuel for such rockets, but crucially there is no need for conventional rocket fuel, which is nasty stuff—toxic when it isn’t blowing up.

Which is why I call bullshit on the Russian story that specifically mentions “a liquid-fueled rocket engine.”  Conventional liquid rocket fuel combusts—big time.  Even if the Russians were to say that the liquid fuel was liquid hydrogen, that would not explain the alleged release of toxic rocket fuel in quantities sufficient to require the closure of beaches and fishing areas.  And why wouldn’t the Russians say it was a hydrogen explosion? The huge explosion also suggests highly explosive rocket fuel. 

Put simply: a radioisotope propulsion system cannot explain a release of radiation and toxic, combustible liquid rocket fuel. An explosion of a Petrel, or something like it can. The Petrel needs a rocket booster, and hence rocket fuel. The missile’s ramjet is powered by a nuclear reactor.

The Norwegians also reported they detected a release of radioactive iodine. This is consistent with the destruction of a reactor with a fissile fuel source, but not with the explosion of a radioisotope propelled vehicle.

One last thing cements my suspicions.  In their move along, nothing to see here explanation, the Russians said that NASA has developed an isotope power source (“Kilopower”).  Yes, Kilopower is a low power (1kW, with plans to go to 10kW) engine intended to generate electricity for spacecraft. (No rocket fuel, or any fuel for that matter, required!)  So it is almost impossible to imagine it, or anything remotely like it, blowing up, or even being around anything that would blow up, as happened in Severodvinsk. 

But “the Americans do it!” is an excuse right out of the old Soviet playbook. It is a convenient cover story, and one used repeatedly in the past.  Which suggests that they have something the Americans are not doing to cover up.  When this is added to the glaring inconsistency involving rocket fuel and radioisotope rocket engines, the circumstantial case that a Petrel/Skyfall accident is to blame for Severodvinsk becomes very strong indeed.

*It is sickly amusing to note that although the most commonly mentioned power source is Plutonium, Polonium (of Litvinenko infamy) has also been suggested.