A neutron bomb was a type of tactical nuclear weapon built mainly by the U.S. specifically to release a relatively large portion of its energy as energetic neutron radiation. This contrasts with standard thermo-nuclear weapons, which are designed to capture the intense neutron radiation inside the bomb to increase its overall yield. The technical term for the neutron bomb was "enhanced radiation weapon" (ERW). In terms of explosive yield, ERWs were about one-tenth that of a conventional fission type weapon. While significantly less in explosive power, they were still much more potent than any conventional bomb, so damage to material was reduced and not eliminated.

History

The neutron bomb is generally credited to Samuel Cohen of the Lawrence Livermore National Laboratory, who developed the concept in 1958. Although initially opposed by President John F. Kennedy, its testing was authorized and carried out in 1963 at an underground Nevada test facility. Development was subsequently postponed by President Jimmy Carter in 1978 following protests against his administration's plans to deploy neutron warheads in Europe. President Ronald Reagan restarted production in 1981.

Three types were built by the United States. The W66 warhead for the anti-ICBM Sprint missile system was produced and deployed in the mid 1970s and retired soon thereafter along with the missile system. The W70 Mod 3 warhead was developed for the short-range, tactical Lance missile, and the W79 Mod 0 was developed for artillery shells. The latter two types were retired by President George Bush in 1992 due to the end of the Cold War. The last W70 Mod 3 warhead was dismantled in 1996, and the last remaining neutron bomb (W79 Mod 0) was dismantled by 2003 when the dismantling of all W79 variants was completed.

France tested a neutron bomb at the Mururoa Atoll on June 24, 1980. Enhanced radiation weapons were also produced by France in the early 1980s, though they have since destroyed these weapons. The 1999 "Cox Report" indicates that China is able to produce neutron bombs, although no country is known to currently deploy them.

Technical Overview

A neutron bomb, or enhanced radiation bomb (ER weapon), is a fission-fusion thermonuclear weapon in which the burst of neutrons generated by the fusion reaction is intentionally not absorbed inside the weapon, but allowed to escape. The X-ray mirrors and shell of the weapon are made of chromium or nickel so that the neutrons are permitted to escape. Contrast this with cobalt bombs, also known as salted bombs.

Neutron bombs have low yields compared with other nuclear weapons. This is because neutrons are absorbed by air, so a high yielding neutron bomb would not be able to radiate neutrons beyond its blast range and so would have no destructive advantage over a normal hydrogen bomb. Note that using the explosive yield of a neutron weapon to measure its destructive power can be deceptive: most of the injuries caused by a neutron weapon come from ionizing radiation, not from heat and blast.

This intense burst of high-energy neutrons is intended as the principal mechanism of killing, although a large amount of heat and blast is also produced. A common idea is that a neutron bomb "leaves the infrastructure intact"; however, current designs have yields in the kiloton range, the detonation of which could cause heavy destruction through blast and heat effects. A yield of one kiloton is not much for a nuclear weapon but it is nearly two orders of magnitude (100x) bigger than the most powerful conventional bombs. The blast from a neutron bomb may be enough to level almost any civilian structures inside the lethal radiation range.[6]

One of the uses for which this weapon was conceived is large-scale anti-tank weaponry. Armoured vehicles offer a relatively high degree of protection against heat and blast, the primary destructive effects released by "normal" nuclear weapons. This means that inside a tank, military personnel can be expected to survive a nuclear explosion at a much closer range, while the vehicles' NBC protection systems ensure a high degree of operability even in a nuclear fallout environment. ER weapons are meant to kill a much higher percentage of enemy personnel inside their tanks by releasing a much higher percentage of the total yield in the form of neutron radiation, against which even tank armour does not protect very well.

The term "enhanced radiation" refers only to the burst of neutron radiation released at the moment of detonation, not to any enhancement of residual radiation in fallout.

A neutron bomb requires considerable amounts of tritium, which has a half-life of 12.3 years, compounding the difficulties of extended storage. The tritium would have to be replaced periodically, and the old tritium processed to remove decay products.

Neutron Bomb Tactics

Neutron bombs could be used as strategic anti-ballistic missile weapons or as tactical weapons intended for use against armored forces; in fact, the neutron bomb was originally conceived as a weapon that could stop Soviet armored divisions from overrunning Western Europe without destroying Western Europe in the process.

As an anti-ballistic missile weapon, an ER warhead was developed for the Sprint missile system as part of the Safeguard Program to protect United States cities and missile silos from incoming Soviet warheads by damaging their electronic components with the intense neutron flux.

Tactical neutron bombs are primarily intended to kill soldiers who are protected by armor. Armored vehicles are extremely resistant to blast and heat produced by nuclear weapons, so the effective range of a nuclear weapon against tanks is determined by the lethal range of the radiation, although this is also reduced by the armor. By emitting large amounts of lethal radiation of the most penetrating kind, ER warheads maximize the lethal range of a given yield of nuclear warhead against armored targets.

One problem with using radiation as a tactical anti-personnel weapon is that to bring about rapid death of the individuals targeted, a radiation dose that is many times the lethal level must be administered. A radiation dose of 6 Gy is normally considered lethal. It will kill at least half of those who are exposed to it, but no effect is noticeable for several hours. Neutron bombs were intended to deliver a dose of 80 Gy to quickly kill targets. A 1 kt ER warhead can do this to a T-72 tank crew at a range of 690 m, compared to 360 m for a pure fission bomb. For a 6 Gy dose, the distances are 1100 m and 700 m respectively, and for unprotected soldiers 6 Gy exposures occur at 1350 m and 900 m. The lethal range for tactical neutron bombs exceeds the lethal range for blast and heat even for unprotected troops, which is likely the reasoning for the idea that a neutron bomb destroys life and not infrastructure. If a neutron bomb were detonated at the correct altitude, deadly levels of radiation would blanket a wide area with minimal heat and blast effects when compared to a pure bomb.

The neutron flux can induce significant amounts of short-lived secondary radioactivity in the environment in the high flux region near the burst point. The alloys used in steel armor can develop radioactivity that is dangerous for 24-48 hours. If a tank exposed to a 1 kt neutron bomb at 690 m (the effective range for immediate crew incapacitation) is immediately occupied by a new crew, they will receive a lethal dose of radiation within 24 hours.

One significant drawback of the weapon is that not all targeted troops will die or be incapacitated immediately. After a brief bout of nausea, many of those hit with about 5-50 Sv of radiation will experience a temporary recovery (the latent or "walking ghost phase" lasting days to weeks.

SOURCE: Wikipedia