Neutron bomb

The neutron release generated by a nuclear fusion reaction is intentionally allowed to escape the weapon, rather than being absorbed by its other components.

The case traps the energy from the fission bomb for a brief period, allowing it to heat and compress the main thermonuclear fuel.

The burst of neutrons created in the thermonuclear reaction is then free to escape the bomb, outpacing the physical explosion.

Since the neutrons are absorbed or decay rapidly, such a burst over an enemy column would kill the crews but leave the area able to be quickly reoccupied.

[15][16] Development of two production designs for the Army's MGM-52 Lance short-range missile began in July 1964, the W63 at Livermore and the W64 at Los Alamos.

[15] Development was subsequently postponed by President Jimmy Carter in 1978 following protests against his administration's plans to deploy neutron warheads to ground forces in Europe.

[27] In May 1998, Senior Pakistani Scientist, Dr. N. M. Butt, stated that "PAEC built a sufficient number of neutron bombs—a battlefield weapon that is essentially a low yield device".

[29] Although no country is currently known to deploy them in an offensive manner, all thermonuclear dial-a-yield warheads that have about 10 kiloton and lower as one dial option, with a considerable fraction of that yield derived from fusion reactions, can be considered able to be neutron bombs in use, if not in name.

[30] Considerable controversy arose in the US and Western Europe following a June 1977 Washington Post exposé describing US government plans to equip US Armed Forces with neutron bombs.

[33][34][need quotation to verify] Neutron bombs are purposely designed with explosive yields lower than other nuclear weapons.

"[37]Although neutron bombs are commonly believed to "leave the infrastructure intact", with current designs that have explosive yields in the low kiloton range,[38] detonation in (or above) a built-up area would still cause a sizable degree of building destruction, through blast and heat effects out to a moderate radius, albeit considerably less destruction, than when compared to a standard nuclear bomb of the exact same total energy release or "yield".

[39] The Warsaw Pact tank strength was over twice that of NATO, and Soviet deep battle doctrine was likely to be to use this numerical advantage to rapidly sweep across continental Europe if the Cold War ever turned hot.

[4] Rather than making extensive preparations for battlefield nuclear combat in Central Europe, the Soviet military leadership believed that conventional superiority provided the Warsaw Pact with the means to approximate the effects of nuclear weapons and achieve victory in Europe without resort to those weapons.

The blast would create pressures of at least 4.6 psi (32 kPa) out to a radius of 600 meters, which would severely damage all non-reinforced concrete structures.

At the conventional effective combat range against modern main battle tanks and armored personnel carriers (< 690–900 m), the blast from a 1 kt neutron bomb would destroy or damage to the point of nonusability almost all un-reinforced civilian buildings.

[44][45] Neutron activation from the explosions could make many building materials in the city radioactive, such as galvanized steel (see area denial use below).

[46] The pulse of neutron radiation would cause immediate and permanent incapacitation to unprotected outdoor humans in the open out to 900 meters,[9] with death occurring in one or two days.

The median lethal dose (LD50) of 6 Gray would extend to between 1350 and 1400 meters for those unprotected and outdoors,[44] where approximately half of those exposed would die of radiation sickness after several weeks.

Despite this, Ducrete—which has an elemental composition similar (but not identical) to the ceramic second-generation heavy metal Chobham armor of the Abrams tank—is an effective radiation shield, to both fission neutrons and gamma rays due to it being a graded-Z material.

A problem faced by Sprint and similar ABMs was that the blast effects of their warheads change greatly as they climb and the atmosphere thins out.

At higher altitudes, starting around 60,000 feet (18,000 m) and above, the blast effects begin to drop off rapidly as the air density becomes very low.

The burst of neutrons released by an ER weapon can induce fission in the fissile materials of primary in the target warhead.

The energy released by these reactions may be enough to melt the warhead, but even at lower fission rates, the "burning up" of some of the fuel in the primary can cause it to fail to explode properly, or "fizzle".

The use of neutron-based attacks was discussed as early as the 1950s, with the US Atomic Energy Commission mentioning weapons with a "clean, enhanced neutron output" for use as "antimissile defensive warheads.

[61] Some sources claim that the neutron flux attack was also the main design goal of the various nuclear-tipped anti-aircraft weapons like the AIM-26 Falcon and CIM-10 Bomarc.

Ionization greater than 50 Gray in silicon chips delivered over seconds to minutes will degrade the function of semiconductors for long periods.

[63] However, while such attacks might be useful against guidance systems, which used relatively advanced electronics, in the ABM role, these components have long ago separated from the warheads by the time they come within range of the interceptors.

[61] Lithium-6 hydride (Li6H) is cited as being used as a countermeasure to reduce the vulnerability and "harden" nuclear warheads from the effects of externally generated neutrons.

At lower altitudes, the X-rays generated by the bomb are absorbed by the air and have mean free paths on the order of meters.

[68] In November 2012, British Labour peer Lord Gilbert suggested that multiple enhanced radiation reduced blast (ERRB) warheads could be detonated in the mountain region of the Afghanistan-Pakistan border to prevent infiltration.

The 1979 Soviet/Warsaw Pact invasion plan, " Seven Days to the River Rhine " to seize West Germany in the event of a nuclear attack on Poland by NATO forces. Soviet analysts had correctly assumed that the NATO response would be to use regular tactical nuclear weapons to stop such a massive Warsaw Pact invasion. [ 35 ] According to proponents, neutron bombs would blunt an invasion by Soviet tanks and armored vehicles without causing as much damage or civilian deaths as the older nuclear weapons would. [ 4 ] Neutron bombs would have been used if the REFORGER conventional response of NATO to the invasion was too slow or ineffective. [ 4 ] [ 36 ]
U.S. Army M110 howitzers in a 1984 REFORGER staging area before transport. This dual capable system could fire nuclear artillery shells. [ 40 ] [ 41 ]
A wooden framed house photographed during a 1953 nuclear test, 5 pounds per square inch (34 kPa) overpressure, full collapse.
The neutron cross section and absorption probability in barns of the two natural boron isotopes found in nature (top curve is for 10 B and bottom curve for 11 B. As neutron energy increases to 14 MeV, the absorption effectiveness, in general, decreases. Thus, for boron-containing armor to be effective, fast neutrons must first be slowed by another element by neutron scattering .
The radiation weighting factor for neutrons of various energy has been revised over time and certain agencies have different weighting factors; however, despite the variation amongst the agencies, from the graph, for a given energy, a fusion neutron (14.1 MeV) although more energetic, is less biologically harmful as rated in Sieverts , than a fission-generated thermal neutron or a fusion neutron slowed to that energy, c. 0.8 MeV.
The easiest to achieve fusion reaction, of deuterium ("D) with tritium (T") creating helium-4 , freeing a neutron , and releasing only 3.5 MeV in the form of kinetic energy as the charged alpha particle that will inherently generate heat (which manifests as blast and thermal effects), while the majority of the energy of the reaction (14.1 MeV) is carried away by the uncharged fast neutron . [ 71 ] Devices with a higher proportion of yield derived from this reaction would be more efficient in the stand-off asteroid impact avoidance role, due to the penetrative depth of fast-neutrons and the resulting higher momentum transfer that is produced in this "scabbing" of a much larger mass of material free from the main body, as opposed to the shallower surface penetration and ablation of regolith , that is produced by thermal/soft X-rays.