attributable primarily to the reduction in yield made possible by the greater ground shock produced by buried bursts.

Conclusion 5. The yield required of a nuclear weapon to destroy a hard and deeply buried target is reduced by a factor of 15 to 25 by enhanced ground-shock coupling if the weapon is detonated a few meters below the surface.

Conclusion 6. 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.

Conclusion 7. 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.

Conclusion 8. In an attack on a chemical or biological weapons facility, the explosive power of conventional weapons is not likely to be effective in destroying the agent. However, the BLU-118B thermobaric bomb, if detonated within the chamber, may be able to destroy the agent. An attack by a nuclear weapon would be effective in destroying the agent only if detonated in the chamber where agents are stored.

Conclusion 9. In an attack with a nuclear weapon on a chemical weapons facility, civilian deaths from the effects of the nuclear weapon itself are likely to be much greater than civilian deaths from dispersal of the chemical agents. In contrast, if the target is a biological weapons facility, release of as little as 0.1 kilogram of anthrax spores will result in a calculated number of fatalities that is comparable on average to the number calculated for a 3 kiloton nuclear earth-penetrator weapon.


Hard and Deeply Buried Targets and Nuclear Earth-Penetrator Weapons

In potential adversary nations, there is a large (2,000) and growing number of identified, strategically important facilities that are sheltered in underground bunkers.

Weapon Effects

Because of the limitations on the penetration depth of penetrating weapons in the stockpile today, as well as those of the robust nuclear earth penetrator (RNEP) weapon currently under study, effects of their use would not be contained.1 Depending on many variables, including weapon yield, proximity of the target to urban areas, distribution of the civilian population and warning time available for sheltering or evacuation, ambient wind profile, and other weather conditions, this study’s calculations of numbers of deaths and serious injuries resulting from attacks on representative targets near or in urban areas range from less than 103 to greater than 106.

Nuclear EPWs (300 kilotons to 1 megaton) can hold at risk HDBTs of interest (1 kilobar hard) at up to ~100 meters to 300 meters depth of burst in granite with high probability of damage (PD greater than 0.95) if delivered with high precision.

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