050429  米国で深地中貫通型核爆弾(「バンカーバスター」)の開発を巡って賛否両論が対立

 
来週から核不拡散条約(NPT)再検討会議が開幕しますが、米国ではこのところ、9.11後のテロ戦争対策として新型核兵器(ミニ核爆弾等)の開発の重要性を訴える声がブッシュ政権内部で盛り上がっています。とくに深地中貫通型核爆弾(いわゆる「バンカーバスター」)は、地下深くに構築された敵陣地や兵器工場・貯蔵所等を破壊するために有効であるとして、議会でも研究予算(開発は含まず)を認めておりますが、一方で、いかに小型化しても、また、いかに地中に潜っても、やはり大量の放射性物質が地上に飛散するから安全ではない、使用する場所によっては数千人から百万人以上の戦闘員、非戦闘員を殺傷する危険性がある、という意見が、連邦議会や政府の科学技術政策に影響力を持つ全米科学アカデミー(NAS)傘下の国家調査評議会(NRC)の「地中貫通型核兵器等の影響に関する委員会」(Committee on the Effects of Nuclear Earth-Penetrator and Other Weapons) の報告書で明らかにされ、注目されているようです。
 
昨日議会上院でこの問題が議論された際、ハト派の民主党議員の反対論に対して、Rumsfeld国防長官は「現在約70カ国で約1万箇所の地下軍事施設が構築されており、強固な岩盤をくりぬいて一日にバスケットボール・コート1つ分を掘るだけの技術もある。それに対抗する手段を米国は持っていない。持っているのは非常に巨大な破壊力を持つ(在来型の)核兵器だけだが、これは破壊力が巨大すぎ放射能の影響も大きい、もっと小型でクリーンな核爆弾を開発する必要がある」と述べた由。なお、上記の報告書によれば、「バンカーバスター」は、通常の核爆弾を地表付近で爆発した場合に比べて1/15〜1/25の爆発力で、しかも数百メートル下の地下施設を破壊するだけの衝撃力を持つだろうとのことです。ご参考まで。
--KK
 
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'Bunker Buster' Casualty Risk Cited

By Ann Scott Tyson
Washington Post Staff Writer
Thursday, April 28, 2005; Page A07

Earth-penetrating nuclear bombs would be capable of destroying military targets deep underground, but not without inflicting "massive casualties at ground level," according to a congressionally mandated study released yesterday.

The study's findings reflect a growing scientific consensus that even relatively small nuclear "bunker-buster" weapons -- under study by the Bush administration but strongly opposed by some members of Congress and arms-control advocates -- could not be used without a high cost in human life. Such a bomb could cause more than a million deaths, depending on the yield, the report said.

"You can use a much smaller weapon if you use an earth penetrator, maybe 20 times smaller, but you will kill a lot of people, because it puts out a huge amount of radioactive debris," said John F. Ahearne, chairman of the Committee on the Effects of Nuclear Earth-Penetrator and Other Weapons of the National Research Council, which produced the report. The council, a branch of the National Academy of Sciences, advises the federal government on science and technology.

The study represents an authoritative finding amid a long-standing conflict over whether it is possible to design an earth-penetrating nuclear bomb that would destroy deeply buried targets without killing people aboveground.

The report found that casualties from an earth-penetrator weapon "would be equal to that from a surface burst of the same weapon yield," causing from thousands to more than a million deaths in an urban area, and hundreds to hundreds of thousands in lightly populated areas with unfavorable winds.

In its fiscal 2003 Defense Authorization Act, Congress directed the Pentagon to request the study to examine the health and environmental effects of the bombs.

The Bush administration this spring renewed its push for $8.5 million in funding to resume Pentagon and Energy Department studies of bunker-buster nuclear warheads. Congress killed funding for the study last year, and lawmakers indicated this year they will again question the request.

On Capitol Hill yesterday, Defense Secretary Donald H. Rumsfeld faced incredulity from at least one senator on why the administration is pursuing the weapons.

"It is beyond me as to why you're proceeding with this program when the laws of physics won't allow a missile to be driven deeply enough to retain the fallout, which will spew in hundreds of millions of cubic feet if it's at 100 kilotons," Sen. Dianne Feinstein (D-Calif.) said in a subcommittee hearing of the Appropriations Committee.

Rumsfeld replied that 70 countries are pursuing "activities underground" using technology that allows them to burrow into solid rock the length of a basketball court in a single day.

"At the present time, we don't have a capability of dealing with that. We can't go in there and get at things in solid rock underground," he said. "The only thing we have is very large, very dirty, big nuclear weapons. So . . . do we want to have nothing and only a large, dirty nuclear weapon, or would we rather have something in between?"

The Pentagon estimates there are 10,000 hardened targets -- above and below ground -- in the territory of potential adversaries. About 20 percent have a "major strategic function" such as housing command-and-control systems or weapons stockpiles, and of that 20 percent, half are near or in urban areas.

The study found that nuclear weapons, if aimed accurately, would be more effective than conventional bombs in destroying hard and deeply buried targets. Such nuclear weapons could work with a yield one-fifteenth to one-twenty-fifth as large if they are detonated a few yards below the earth's surface, causing a shock wave that could destroy bunkers hundreds of yards below.