Bunker-busting nukes could devastate civilians

Bunker-busting nukes could devastate civilians

• 12:10 28 April 2005
• NewScientist.com news service
• Jeff Hecht

Nuclear “bunker busters” could destroy enemy hideouts hundreds of metres underground but, if the target is in an urban area, a strike could lead to more than a million civilian deaths, warns a report from the US National Research Council (NRC) issued on Wednesday.

"Using an earth-penetrating weapon to destroy a target 250 meters deep - the typical depth for most underground facilities - potentially could kill a devastatingly large number of people," said John Ahearne, chair of the report committee.

The report is unlikely resolve the heated debate over the Bush administration’s plans to develop a new Robust Nuclear Earth Penetrator - a weapon hardened to penetrate deep into the ground.

Its conclusions echo the claims of administration officials who say the bombs are needed to destroy deeply buried military control centres, labs and stores. But it also supports the contentions of critics who warn they could cause heavy civilian deaths. And the report fails to address two crucial criticisms - that developing new nuclear bunker-busters would encourage the resumption of nuclear testing and lower the threshold for use of nuclear weapons.

The US nuclear arsenal already has one earth-penetrating weapon - the B61-11 bomb - but it cannot penetrate solid rock. Pentagon planners want a weapon that can penetrate several metres of rock. That would allow it to target the more than 100 potential-enemy complexes, identified by US intelligence, and built 100 to 400 metres underground. In 2003, Congress asked the NRC to study the potential health and environmental impact of the new weapon.

Destructive forces

Subsurface explosions transfers energy into the ground far more efficiently than surface blasts. The NRC panel concluded that detonating a nuclear bomb just a few metres below the surface increases its power to destroy underground targets by a factor of 15 to 25 over a surface explosion.

Most of that advantage comes from penetrating just 3 metres into the ground. Once this depth is obtained, a 300-kiloton earth penetrator could destroy a target buried 200 m deep, while a 1-megaton weapon would be needed for a target 300 m underground.

The problem is that earth penetrators cannot plunge deeply enough into the ground to fully contain the effects of a nuclear blast, so casualties would be "for all practical purposes, equal to [those] from a surface burst of the same weapon yield”, the report suggests. That means surface casualties could be high.

Urban areas

And half of the 2000 “strategic” hardened or buried targets identified by the Pentagon are in urban areas, where the panel estimate death tolls would range "from thousands to more than a million, depending primarily on the weapon yield".

Nor would nuclear weapons be able to destroy chemical or biological agents in buried labs - unless the bomb was detonated inside the buried chamber, the panel concluded. That being the case, a non-nuclear "thermobaric" bomb - using fuel-air explosives - might be just as effective at destroying the agents if detonated inside the chamber.

And a nuclear bomb would probably kill more people than any chemical agents released from a destroyed underground factory, says the report, though that might not be true for biological weapons. "Release of as little as 0.1 kilograms of anthrax spores" would kill as many people as a 3-kiloton nuclear earth penetrator, the panel concluded.