Nuclear bunker buster
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215373197
2008-05-27T22:18:15Z
130.126.120.175
/* Development of bunker-busting weapons */
{{Morefootnotes}}
[[Image:Nevada Test Site craters.jpg|right|thumb|250px|[[Subsidence craters]] left over after underground nuclear (test) explosions]]
'''Bunker-busting nuclear weapons''', also known as '''earth-penetrating weapons (EPW)''', are a type of [[nuclear weapon]] designed to penetrate into [[soil]], [[Rock (geology)|rock]], or [[concrete]] to deliver a nuclear warhead to a target. These weapons would be used to destroy hardened, underground [[military]] [[bunker]]s buried deep in the ground. In theory, the amount of [[radioactive]] [[nuclear fallout]] would be reduced from that of a standard, air-burst nuclear detonation because they would have relatively low [[nuclear weapon yield|explosive yield]]. However because such weapons necessarily come into contact with large amounts of earth-based debris, they may, under certain circumstances, still generate fallout. [[Warhead]] yield and weapon design have changed periodically throughout the history of the design of such weapons.
== Methods of operation ==
=== Penetration by explosive force ===
[[Concrete]] design remains little changed since 60 years ago. The majority of protected concrete structures in the US military are derived from standards set forth in ''Fundamentals of Protective Design'', published in 1946 (US Army Corps of Engineers). Various augmentations, such as [[glass]], [[fiber]]s, and [[rebar]], have made concrete less vulnerable, but far from impenetrable. Raymond T. Moore was able to create a "human sized hole" in 18 inch (45 cm) thick reinforced concrete in less than 48 seconds with a mere 20 lb (9 kg) of explosive and a [[bolt cutter]].
When explosive force is applied to concrete, three major fracture regions are usually formed: the initial crater, a crushed aggregate surrounding the crater, and "scabbing" on the ''opposite'' side of the crater. Scabbing, also known as "[[spall]]ing," is the violent separation of a mass of material from the opposite face of a plate or slab subjected to an impact or impulsive loading (this does not necessarily mean that the barrier itself must have been penetrated at this point).
As the compressive wave propagates to the opposite side of the concrete and is reflected, the concrete fractures, and scabbing occurs on the interior wall. As such, an [[asymptotic]] relationship exists between the strength of the concrete and the damage that will be done between the crater, aggregate, and scabbing.
While soil is a less dense material, it also does not transmit [[shock wave]]s as well as concrete. So while a penetrator may actually travel further through soil, its effect may be lessened due to its inability to transmit shock to the target.
=== Penetration with a hardened penetrator ===
[[Image:Secant ogive.png|thumb|right|200px|A secant ogive]]
Further thinking on the subject envisions a penetrator, dropped from service height of a [[bomber]] aircraft, using kinetic energy to penetrate the shielding, and subsequently deliver a nuclear explosive to the buried target.
The problems with such a penetrator is the tremendous heat applied to the penetrator unit when striking the shielding (surface) at hundreds of meters per second. This has partially been solved by using metals such as [[tungsten]] (with a much higher melting point than steel), and altering the shape of the projectile (such as an [[ogive]]).
Altering the shape of the projectile, to incorporate an [[ogive]] shape has yielded substantial results. [[Rocket sled]] testing at [[Eglin Air Force Base]] has demonstrated penetrations of 100 to {{convert|150|ft|m}} in concrete {{Fact|date=March 2007}} when traveling at {{convert|4000|ft/s|m/s|abbr=on}}. The reason for this is [[liquefaction]] of the concrete in the target, which tends to flow over the projectile. Variation in the speed of the penetrator can either cause it to be vaporized on impact (in the case of traveling too fast), or to not penetrate far enough (in the case of traveling too slow). An approximation for the penetration depth is obtained with an [[Impact depth|impact depth formula]] derived by [[Sir Isaac Newton]].
=== Combination penetrator-explosive munitions ===
Another school of thought on nuclear bunker busters is using a light penetrator to travel 15 to 30 meters through shielding, and detonate a nuclear charge there. Such an explosion would generate powerful shock waves, which would be transmitted very effectively through the solid material comprising the shielding (see "scabbing" above).
== Criticism ==
{{POV-section|date=December 2007}}
The main criticism of nuclear bunker busters is [[nuclear fallout]] and nuclear proliferation. The purpose of an earth-penetrating nuclear "bunker buster" is to reduce the required yield needed to ensure the destruction of the target by coupling the explosion to the ground, yielding a shock wave similar to an earthquake. For example, the United States retired the [[B53 nuclear bomb|B-53 warhead]], with a yield of 9 [[megaton]]s, because the [[B61 nuclear bomb|B-61 Mod 11]] could attack similar targets with much lower yield (400 [[kiloton]]s){{Fact|date=September 2007}}, due to the latter's superior ground penetration. Thus the fallout of a B-61 Mod 11 would likely be less than that of a B-53. Supporters note that this is one of the reasons nuclear bunker busters should be developed. Critics claim that developing new nuclear weapons sends a proliferating message to non-nuclear powers, undermining non-proliferation efforts.
Critics also worry that the existence of lower-yield nuclear weapons for relatively limited tactical purposes will lower the threshold for their actual use, thus blurring the sharp line between conventional weapons intended for use and weapons of mass destruction intended only for hypothetical deterrence and increasing the risk of escalation to higher-yield nuclear weapons.<ref>{{cite web |url= http://www.hsfk.de/index.php?id=9&no_cache=1&detail=3124&no_cache=0&cHash=0991198fec|title=Intervention und Kernwaffen – Zur neuen Nukleardoktrin der USA |accessdate=2008-02-15 |first= Stephanie Sonius|last= Harald Müller |year= 2006 |language= German}}</ref>
Fallout from any nuclear detonation is increased with proximity to the ground. While a megaton-class yield will inevitably throw up many tons of (newly) radioactive debris, which falls back to the earth as fallout, critics contend that despite their relatively minuscule explosive yield, nuclear bunker busters create more fallout per kiloton yield.
The scientific group [[Union of Concerned Scientists]] points out that, at the [[Nevada Test Site]], the depth required to contain fallout from an average-yield [[nuclear testing|nuclear test]] was over 100 meters, depending upon the weapon's yield. They contend that it is improbable that penetrators could be made to burrow so deeply. With yields between 0.3 and 340 kilotons, they argue, it is unlikely the blast would be completely contained.
Another criticism is that bunkers can be built at greater depth to make them more difficult to reach. The target's vulnerability is then limited to openings like the ventilation system, which are susceptible to conventional explosives. Proponents of nuclear bunker busters respond that deeper bunkers entail higher costs, limiting the potential enemies who can withstand nuclear bunker busters.
Politically, as well, such nuclear bunker busters are unpopular. Most targets are near cities{{Fact|date=September 2007}}, critics argue, and even minimal fallout will inflict unacceptable levels of collateral damage. Furthermore, they state, the testing of new nuclear weapons would be prohibited by the proposed [[Comprehensive Test Ban Treaty]], although the United States has refused to agree to be bound by this treaty.{{Fact|date=September 2007}}
Finally, the need to use nuclear weapons in this role is questioned by critics{{Fact|date=September 2007}}. They argue that conventional ground-penetration weapons are able to destroy enough buried or strengthened sites to lessen or even remove the need to use nuclear technology. Other conventional weapons such as [[thermobaric weapon]]s have proven effective in defeating buried targets which have not been hardened.
== Development of bunker-busting weapons ==
[[Image:NukesGulf B-61.jpg|right|thumb|200px|[[B61 nuclear bomb]]]]
As early as 1944, the Wallis [[Tallboy bomb]] and subsequent [[Grand Slam bomb|Grand Slam]] weapons were designed to penetrate deeply fortified structures through sheer explosive power. These were not designed to directly penetrate defences, though they could do this (for example the [[Valentin submarine pens]] had [[ferrous concrete]] roofs 7 metres (23 ft) thick which were penetrated by two Grand Slams on [[27 March]] [[1945]]), but rather to penetrate under the target and explode leaving a [[camouflet]] (cavern) which would undermine foundations of structures above, causing it to collapse, thus negating any possible hardening. The destruction of targets such as the [[V-3 cannon|V3 guns]] at [[Mimoyecques]] or with the first operational use of the Tallboy. One bored through a hillside and exploded in the [[Saumur]] rail tunnel about 18 m (60 ft) below, completely blocking it; show that these weapons could destroy any hardened or deeply [[Earthworks (engineering)|excavated]] installation, and modern targeting techniques allied with multiple strikes could unquestionably perform a similar task.<ref>[http://www.raf.mod.uk/bombercommand/grandslam.html Grand Slam raids]</ref><ref>[http://www.raf.mod.uk/bombercommand/jul44.html RAF web site: RAF Bomber Command: July 1944] (See V-3 [[July 6]] The photograph shows clearly the camouflet effect)</ref><ref>[http://www.raf.mod.uk/bombercommand/saumur.html RAF web site: RAF Bomber Command: saumur]</ref>
Development continued, with weapons such as the nuclear [[B61 nuclear bomb|B61]], and conventional thermobaric weapons and [[GBU-28]]. One of the more effective housings, the GBU-28 used its large mass (2,130 kg / 4,700 lb) and casing (constructed from barrels of surplus 203 mm [[howitzer]]s) to penetrate 6 meters (20 ft) of concrete, and more than 30 meters (100 ft) of earth.<ref>[http://es.rice.edu/projects/Poli378/Gulf/gwtxt_ch6.html#GBU-28 Report to Congress on the Conduct of the Persian Gulf War]</ref> The B61 Mod 11, which first entered military service in January 1997, was specifically developed to allow for bunker penetration, and is speculated to have the ability to destroy hardened targets a few hundred feet beneath the earth.<ref>[http://nuclearweaponarchive.org/Usa/Weapons/B61.html The B61 (Mk-61) Bomb]</ref>
While penetrations of 20–{{convert|100|ft|m}} were sufficient for some shallow targets, both the [[Soviet Union]] and the United States were creating bunkers buried under huge volumes of soil or reinforced concrete in order to withstand the multi-megaton thermonuclear weapons developed in the 1950s and 1960s. Bunker penetration weapons were initially designed out of this [[Cold War]] context.
[[Image:Southern afghanistan.jpg|thumb|right|200px|Mountainous terrain in Afghanistan]]
The weapon was revisited in the post-Cold War during the 2001 [[War in Afghanistan (2001–present)|U.S. invasion of Afghanistan]], and again during the [[2003 invasion of Iraq]]. During the campaign in [[Tora Bora]] in particular, the [[United States]] believed that "vast underground complexes," deeply buried, were protecting opposing forces. Such complexes were not found. While a nuclear penetrator (the "Robust Nuclear Earth Penetrator", or "RNEP") was never built, the [[United States Department of Energy|DOE]] was allotted budget to develop it, and tests were conducted by the [[Air Force Research Laboratory]].
As well, it has been stated<ref>[http://www.guardian.co.uk/iran/story/0,,1724473,00.html US envoy hints at strike to stop Iran], The Guardian, [[March 6]], [[2006]].</ref> that [[Iran]] may have such deeply buried bunkers to guard its [[Nuclear program of Iran|nuclear program]].
The [[George W. Bush|Bush]] administration removed its request for funding<ref>[http://www.cnn.com/2005/US/10/25/bunker.buster.ap/index.html]{{Dead link|date=March 2008}}</ref> of the weapon in October 2005. Additionally, [[US Senator]] [[Pete Domenici]] announced funding for the nuclear bunker-buster has been dropped from the [[United States Department of Energy|Department of Energy]]'s fiscal 2006 budget at the department's request.<ref>[http://news.yahoo.com/s/ap/20051026/ap_on_go_pr_wh/bunker_buster]{{Dead link|date=March 2008}}</ref>
While the project for the RNEP seems to be in fact canceled, [[Jane's Information Group]] speculates<ref>[http://www.janes.com/defence/news/jid/jid051117_1_n.shtml US dumps bunker-buster - or not?], Jane's.</ref> work may continue under another name.
==Citations==
{{Reflist}}
== References ==
* ''Barrier Penetration Tests,'' Moore, R. T. National Bureau of Standards, [[ASIN]] B0006CHZT6
* ''Penetration Resistance of Concrete: A Review,'' James R. Clifton, The Physical Security and Stockpile Directorate, Defense Nuclear Agency, [[ASIN]] B0006E76U2
* ''U.S. Nuclear Weapons: Changes In Policy And Force Structure,'' Woolf, Amy F., ISBN 1-59454-234-1
* ''Nuclear Weapon Initiatives: Low-yield R&D, Advanced Concepts, Earth Penetrators, Test Readiness,'' Ernest, Jonathan V., et al., ISBN 1-59454-203-1
== See also ==
{{commons|Tactical nuclear weapons}}
* [[Bunker buster]] (conventional, non-nuclear)
* [[Fail-deadly]]
* [[No first use]]
* [[Nuclear strategy]]
* [[Thermobaric weapon]]
* [[Tsar Bomba]]
== External links ==
* [http://www.ucsusa.org/global_security/nuclear_weapons/page.cfm?pageID=777 Earth Penetrating Weapons], Lisbeth Gronlund, David Wright and Robert Nelson, Union of Concerned Scientists, May 2005
* [http://www.newscientist.com/article.ns?id=dn3016 Bunker-busters set to go nuclear], David Hambling, New Scientist, [[7 November]] [[2002]]
* [http://www.fas.org/faspir/2001/v54n1/weapons.htm Low-Yield Earth-Penetrating Nuclear Weapons], Robert W. Nelson, Federation of American Scientists, January/February 2001, Volume 54, Number 1
* [http://arxiv.org/abs/physics/0510052 The B61-based "Robust Nuclear Earth Penetrator:" Clever retrofit or headway towards fourth-generation nuclear weapons?], Andre Gsponer, Independent Scientific Research Institute, [[31 March]] [[2007]]
[[Category:Nuclear warfare]]
[[Category:Anti-fortification weapons]]
[[Category:Nuclear bombs]]
[[Category:Superbombs]]
[[Category:Bunkers]]
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