NAS Committee Reviews "Bunker Buster" Weapons

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Publication date: 
3 June 2005

One of the more contentious issues in the Energy and Water Development Appropriations bill last year was the funding of a program to study nuclear earth-penetrator weapons. Also known as RNEP (Robust Nuclear Earth Penetrator) or a nuclear "bunker buster," the proposed weapon is designed to hold-at-risk deeply buried targets beyond the range of conventional weapons. Last year, Congress voted to deny funding for the study of this weapon. The House of Representatives recently passed its version of the FY 2006 Energy and Water Development Appropriations bill which did not include funding for such a nuclear weapon study (see The House-passed version of the FY 2006 Defense Authorization bill worked around this controversy by removing the nuclear component from a study of earth penetrator weapons systems (see and by shifting the proposed work from the Department of Energy to the Department of Defense.

The Defense Authorization Act for FY 2003 mandated that a study be performed on the health and environmental impacts of an RNEP weapon. A National Research Council "Committee on the Effects of Nuclear Earth-Penetrator and Other Weapons" conducted this study. Fifteen experts from the university, private, and national laboratory communities served on this committee, chaired by John F. Ahearne of Sigma Xi. The committee released its study in a prepublication format in late April.

The study cites an estimate by the Defense Intelligence Agency that there are approximately 10,000 hard and deeply buried targets in the potential U.S. adversaries. Of these, about 20% "have a major strategic function," of which more than a hundred could be targeted by an RNEP weapon. These facilities are used to protect leaders, key personnel, weapons, equipment, and other assets and activities. Some of the facilities are located in the basements of multistory buildings in cities.

Much of the study is fairly technical. The committee summarized their findings in nine "most important conclusions," which are available at this NAS site: Among them are the following:

"Many of the more important strategic hard and deeply buried targets (HDBTs) are beyond the research of conventional explosive penetrating weapons and can be held at risk of destruction only with nuclear weapons. Many - but not all - known and/or identified hard and deeply buried targets can be held at risk of destruction by one or a few nuclear weapons."

"Current experience and empirical predictions indicate that earth-penetrator weapons cannot penetrate to depths required for total containment of the effects of a nuclear explosion."

"For attacks near or in densely populated urban areas using nuclear earth-penetrator weapons on hard and deeply buried targets (HDBTs), the number of casualties can range from thousands to more than a million, depending primarily on weapon yield. For attacks on HDBTs in remote, lightly populated areas, casualties can range from as few as hundreds at low weapon yields to hundreds of thousands at high yields and with unfavorable winds."

"For urban targets, civilian casualties from a nuclear earth-penetrator weapon are reduced by a factor of 2 to 10 compared with those from a surface burst having 25 times the yield."