A cruise missile with a nuclear reactor heated turbofan engine and a liquid fueled booster rocket is the most likely description of the Russian developmental weapons system that exploded while being tested on August 8. It’s likely that the explosion occurred during maintenance or fueling operations on a barge floating off shore and not during an actual flight test.
Like other operational cruise missiles, the developmental weapons system probably flies at a low altitude at a velocity of roughly 500 kts, well below the speed of sound. The payload is likely to be less than 1000 kilograms. The missile probably has a small radar cross-section and includes a sophisticated navigational, communications and maneuvering system that allows it to be redirected while in flight.
Its small (approximately 10-20 MWth) nuclear fission reactor heat source provides it with almost unlimited range and a flight duration that is likely to be measured in days or weeks instead of hours. While operating, the reactor heat source will create a moderate to high level of direct radiation. It is a “point source” of radiation with a dose rate that falls off rapidly in inverse proportion to the square of the distance from the reactor.
Since there are generally no living organisms close to a cruise missile in flight, that radiation field is not an operational impediment to using a nuclear fission-heated turbofan engine. Even after the missile hits its eventual target and explodes, the reactor is likely to remain just a local source of radiation without much spreading of radioactive material.
Aside: Basis for that surprising conclusion rests on what bomb damage assessment photos show of the remains of a conventional cruise missile. It’s common to be able to detect recognizable turbofan engine parts. If they can survive warhead detonation, so will a propulsion reactor. End Aside.
The above is my own pieced-together interpretation. It is not the official story released by any government agency or investigative news outlet.
What have other sources said?
On August 8, 2019, there was a powerful, deadly explosion on a barge floating near the Nenoksa military base on the White Sea’s southern shore. That base is well known to intelligence sources as a place where Russia tests military weapons systems.
Four Russian monitoring stations that are capable of detecting radiation and that routinely provide data into an international network set up to help monitor for nuclear weapons testing reported a brief-duration increase in background radiation levels.
Based on publicly available sources on the Internet, it’s not clear exactly how long the increased levels lasted. Even the most pessimistic articles indicate that the levels reported from Severodvinsk – about 40 km from the test site – were no more than 16 times normal background. No monitoring station outside of Russia measured any increased radiation levels.
On August 21, Vladimir Putin stated that the explosion happened during testing of a promising weapons system. He also described the people killed during the explosion as doing “extremely important work to ensure the security of our state.”
Official Russian news sources have described the explosion as one that involved “isotope power sources.” Several of the five killed or three injured people were described as experts in the nuclear energy or radiological fields and as employees of the Russian Federal Nuclear Center. In some reports, the word “fissile” has also been used along with isotope power sources.
President Trump has described the missile that exploded as a nuclear powered cruise missile. Quoted experts for major media outlets like the New York Times and CBS News have disputed that description.
CBS’s quoted expert, Pavel Luzin, stated the explosion could not have involved a nuclear powered cruise missile because “Its (characteristics are) simply against the laws of physics.”
Mr. Luzin expanded on his dismissal of the existence of a nuclear fission heated cruise missile in an article for the Moscow Times titled I Don’t Believe a Missile Is to Blame for Russia’s Deadly ‘Nuclear’ Explosion. That article concluded with a bold, but ill-informed and incorrect statement.
However, the bottom line is that the mysterious cruise missile doesn’t exist because it contradicts the laws of physics.“I Don’t Believe a Missile Is to Blame for Russia’s Deadly ‘Nuclear’ Explosion” Moscow Times, August 14, 2019
The New York Times quoted Ankit Panda, described as a nuclear expert at the Federation of American Scientists as follows.
“I’ve generally been of the belief that this attempt at developing an unlimited-range nuclear-powered cruise missile is folly. It’s unclear if someone in the Russian defense industrial bureaucracy may have managed to convince a less technically informed leadership that this is a good idea, but the United States tried this, quickly discovered the limitations and risks, and abandoned it with good reason.”“U.S. Officials Suspect New Nuclear Missile in Explosion That Killed 7 Russians”, NY Times, Aug 12, 2019
Truth about nuclear propulsion for aircraft
During the period from 1951-1961, the US invested more than $1 billion then-year dollars developing and testing a wide range of systems for aircraft nuclear propulsion. Though a number of “experts” have stated that the program was halted due to technical failures or insurmountable physical obstacles, the truth is that the program ended as a result of fairly typical budgeting and prioritization decisions.
Some decision makers, like Secretary of Defense Charles Wilson, weren’t impressed by the speed or altitude limitations in systems achievable with 1950s vintage materials and control system technologies. He called the proposed nuclear powered bomber a “shitepoke” a bird that flies low and slow when comparing it to supersonic, high-flying penetration bombers.
A major effort during the Aircraft Nuclear Propulsion program involved radiation shields for the crews of manned bombers with mission that lasted days or weeks. It is a big technical challenge to provide sufficient protection for long duration exposures.
The problem is made tougher by its circular nature. Big, heavy planes require high powered reactors. High powered reactors produced more intense radiation fields and require more shielding. More shielding requires larger, heavier airframes. And so on.
Those design challenges shrink rapidly when the airframe is a few thousand kilograms and the “pilot” is a lightweight, easily shielded piece of electronic equipment. Nuclear fission turbofans work just like those heated by chemical combustion, but their exhaust gas is heated air instead of a mixture of combustion products.
In contrast to the simple safety of a nuclear fission-heated turbofan motor, a liquid fueled rocket motor is a volatile, explosive component that has been known to suffer seriously damaging explosions.
Unlike the frequently directional explosions produced by cruise missile warheads, an exploding booster rocket can cause unidirectional harm and might even break enough barriers in the reactor to produce a moderate radioactive material release.
One final observation – creating mystery and refusing to openly answer simple questions is a terrific way to generate fear, uncertainty and doubt in a public that has been taught to distrust. Nations that depend on revenues from selling oil and gas to provide roughly 50% of their government budgets have numerous reasons to stoke fear of radiation and small nuclear powered systems.