Project Pluto

Project Pluto was a United States government program to develop <a href="/facts/Nuclear-powered/jzSyvxSn">nuclear-powered</a> <a href="/facts/Ramjet/wFschau9">ramjet</a> engines for use in <a href="/facts/Cruise_missile/Frego9PF">cruise missiles</a>. Two experimental engines were tested at the <a href="/facts/Nevada_Test_Site/eWg04MIr">Nevada Test Site</a> (NTS) in 1961 and 1964 respectively.
On 1 January 1957, the <a href="/facts/U.S._Air_Force/7MxWBYlc">U.S. Air Force</a> and the <a href="/facts/U.S._Atomic_Energy_Commission/7VXrvVJ9">U.S. Atomic Energy Commission</a> selected the <a href="/facts/Lawrence_Radiation_Laboratory/tvjPSwC9">Lawrence Radiation Laboratory</a> to study the feasibility of applying heat from a <a href="/facts/Nuclear_reactor/8xqjIbge">nuclear reactor</a> to power a <a href="/facts/Ramjet_engine/wFschau9">ramjet engine</a> for a <a href="/facts/Supersonic_Low_Altitude_Missile/heNuNVBK">Supersonic Low Altitude Missile</a>. This would have many advantages over other contemporary nuclear weapons delivery systems: operating at <a href="/facts/Mach_number/Ee01MIgw">Mach</a> 3, or around 3,700 kilometers per hour (2,300 mph), and flying as low as 150 meters (500 ft), it would be invulnerable to interception by contemporary air defenses, carry more nuclear warheads with greater <a href="/facts/Nuclear_weapon_yield/53of1vqQ">nuclear weapon yield</a>, deliver them with greater accuracy than was possible with intercontinental ballistic missile (ICBMs) at the time and, unlike them, could be recalled.
This research became known as Project Pluto, and was directed by Theodore Charles (Ted) Merkle, leader of the laboratory's R Division. Originally carried out at <a href="/facts/Livermore,_California/PKRFAQXw">Livermore, California</a>, testing was moved to new facilities constructed for $1.2 million (equivalent to $9 million in 2023) on 21 square kilometers (8 sq mi) at NTS Site 401, also known as <a href="/facts/Jackass_Flats/Q63Y4pp8">Jackass Flats</a>. The test reactors were moved about on a railroad car that could be controlled remotely. The need to maintain supersonic speed at low altitude and in all kinds of weather meant that the reactor had to survive high temperatures and intense radiation. Ceramic <a href="/facts/Nuclear_fuel/8RhAomlJ">nuclear fuel</a> elements were used that contained <a href="/facts/Highly_enriched_uranium/vSb2Tcsb">highly enriched</a> <a href="/facts/Uranium_oxide/Re5lMJbS">uranium oxide</a> fuel and <a href="/facts/Beryllium_oxide/o3VnG96d">beryllium oxide</a> <a href="/facts/Neutron_moderator/1qa6YvDD">neutron moderator</a>.
After a series of preliminary tests to verify the integrity of the components under conditions of strain and vibration, Tory II-A, the world's first nuclear ramjet engine, was run at full power (46 MW) on 14 May 1961. A larger, fully-functional ramjet engine was then developed called Tory II-C. This was run at full power (461 MW) on 20 May 1964, thereby demonstrating the feasibility of a nuclear-powered ramjet engine. Despite these and other successful tests, ICBM technology developed quicker than expected, and this reduced the need for cruise missiles. By the early 1960s, there was greater sensitivity about the dangers of radioactive emissions in the atmosphere, and devising an appropriate test plan for the necessary flight tests was difficult. On 1 July 1964, seven years and six months after it was started, Project Pluto was canceled.

Project Pluto open-in-new

Project Pluto