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When President Donald Trump heard that Russia\u2019s\u00a0<\/strong>experimental nuclear-powered cruise missile had\u00a0exploded, killing seven scientists and causing a major radiological incident less than 300 miles from the Finnish border, he fired off a boastfultweet. \u201cWe have similar, though more advanced, technology,\u201d he\u00a0said.<\/p>\nThis is\u2026not accurate. In the late 1950s and early 1960s, the United States pursued a less advanced version of a similar technology but abandoned the effort before ever launching an actual test vehicle. Nuclear-powered cruise missiles, the Pentagon concluded, are a bad\u00a0idea.<\/p>\n
But the concept still appeals to Vladimir Putin, who last year\u00a0revealed\u00a0his pursuit of an \u201cunlimited-range\u201d missile that Russia calls the\u00a09M730 Burevestnik\u00a0(Storm Petrel) and which\u00a0NATO<\/span>\u00a0has dubbed the\u00a0SSC<\/span>-X-9 Skyfall. A missile powered by a small nuclear reactor could cruise about its target for days, giving it a wide range of potential targets it could strike upon\u00a0command.<\/p>\n In 1957, the\u00a0U.S.<\/span>\u00a0Air Force and the Atomic Energy Commission launched Project Pluto to build the Supersonic Low-Altitude Missile. The work proceeded at the\u00a0Lawrence Radiation Laboratory\u00a0(today, Lawrence Livermore National Laboratory), in Berkeley, California, under the supervision of\u00a0Charles \u201cTed\u201d Merkle, a hard-driving physicist. In 1959, Merkle\u00a0reported\u00a0to the Air Force on the feasibility of the project, noting a number of enormous technical challenges but also \u201csome interesting and exciting possibilities to\u00a0discuss.\u201d<\/p>\n Like the makers of Skyfall, Merkle decided on a\u00a0ramjet\u00a0design. Powered into the sky atop a conventional rocket booster, the ramjet would compress incoming air in a uniquely shaped chamber, superheat it with a small nuclear reactor, and expel it as exhaust, propelling the missile almost three times faster than\u00a0sound.<\/p>\n The biggest challenge: nuclear reactors are fragile things. Putting one in a cruise missile would require a design that could withstand three types of stress that no previous reactor had needed to\u00a0endure.<\/p>\n \u201cThere are the stresses associated with the pressure drop through the \u2018reactor\u2019 and, as indicated earlier, this stress is of the order of hundreds of psi [pounds per square inch] when spread over the entire reactor,\u201d Merkle wrote. \u201cWhen concentrated at various support points, it contributes loads like thousands of psi. Next in order: to transfer heat from the fuel to the air stream, there must be a temperature drop in the fuel-bearing materials and, for typical ceramics and power densities that would be of interest for possible missile applications, stresses of many thousand psi result as a consequence of these temperature\u00a0differences.\u201d<\/p>\n Then there were the inertial stresses of flight. \u201cSince in principle such ramjet power plants can operate from sea level to quite high altitudes, rather large \u2018gust loadings\u2019 must be anticipated,\u201d he\u00a0wrote.<\/p>\n Undaunted, the lab went to work creating a 500-megawatt reactor that could operate at 2,500 degrees Fahrenheit. Four years later, after much experimentation with different materials and the careful assembly of 500,000 small fuel rods, they had an engine called\u00a0Tory-IIA<\/span>.<\/p>\n On May 14, 1961, they tested it at an 8-square-mile facility in a desolate area of Nevada called Jackass Flats. But they wouldn\u2019t be able to fly it, not yet, since it was potentially a nuclear bomb. Instead they used a flatbed rail\u00a0car.<\/p>\n In a 1990 article for\u00a0Air and Space Magazine<\/em>,<\/em>\u00a0Gregg Herken writes that \u201cthe Tory-IIA<\/span>\u00a0ran for only a few seconds, and at merely a fraction of its rated power. But the test was deemed a complete success. Most importantly, the reactor did not catch fire, as some nervous Atomic Energy Commission officials had worried it\u00a0would.\u201d<\/p>\n But as Herken tells it, Washington was already beginning to cool to the idea of a nuclear-powered cruise missile. The biggest reason: the missile\u2019s unshielded nuclear reactor would spew radiation along its flight path, potentially irradiating its own ground crew and everyone else between the launch pad and the\u00a0target.<\/p>\n Anticipating this, Merkle downplayed the danger in his initial 1959 report, using language that sounds ripped directly from\u00a0Dr. Strangelove.<\/em>\u00a0\u201cOne problem that bothers the design of reactors to be used near people is the necessity of confining all the fission products to the reactor fuel element,\u201d he wrote. \u201cA typical mission might produce some-what less than 100 grams of fission product. Of these it might be expected that some large percentage would naturally remain in fuel elements\u2026Consequently the fission activity introduced locally into the atmosphere is minute compared with even the most minute atomic weapon.\u201d\u00a0<\/em><\/p>\n Phew.<\/p>\n Edwin Lyman, senior scientist and acting director of the nuclear safety project at the Union of Concerned Scientists, offers some perspective. \u201cI suppose that at a time when the nuclear weapon states were still engaged in atmospheric testing, there wasn\u2019t a whole lot of concerns about releasing additional radioactivity into the environment. Merkle\u2019s cavalier attitude seems in tune with the era. But such a system should be considered completely unacceptable today,\u201d Lyman told\u00a0Defense One<\/em>\u00a0in an\u00a0email.<\/p>\n \u201cOne thing is that to characterize radiation releases in terms of \u2018grams\u2019 is misleading. Chernobyl released only a few hundred grams of iodine-131 yet it resulted in thousands of thyroid cancers among children.\u201d He noted that the Pluto tests ejected not only radioactive gases but far more dangerous radioactive\u00a0particle matter as\u00a0well.<\/p>\n The team tested a modified version of the engine once more in 1964 and the project was\u00a0canceled.<\/p>\n The high fallout, both politically and literally, mean that nuclear-powered cruise missiles remain a terrible idea, says Kingston Reif, the director for disarmament and threat reduction policy at the Arms Control Association. \u201cIf you think the current excessive\u00a0U.S.<\/span>\u00a0plans to replace the\u00a0U.S.<\/span>\u00a0nuclear arsenal\u00a0are controversial, imagine the negative domestic and international reaction to a\u00a0U.S.<\/span>\u00a0effort to renew R&D on nuclear cruise missile powered by an unshielded nuclear reactor,\u201d said Reif. \u201cRussia should abandon development of this grotesque, unnecessary and almost certainly unworkable weapon\u00a0immediately.\u201d<\/p>\n Added Lyman, \u201cif the missile was shot down, the fuel would overheat and you\u2019d have a 500-thermal-megawatt reactor meltdown \u2014 about one-sixth the size of a large power reactor \u2014 but without any containment. Also, the lack of radiation shielding would make it difficult, if not impossible, for emergency responders to approach\u00a0it.\u201d<\/p>\n That\u2019s similar to the problem Russia is grappling with right\u00a0now.<\/p>\n