The Burrowing Nuke – Its Pros and the Con

Writing in DefenseWatch, I have often made the point that there is little to fear from a potential terrorist nuclear strike because their only viable source for nuclear weapons is the old Soviet stockpile, and these weapons are old, the tritium probably has leaked away long ago, and they are highly vulnerable to transportation damage resulting in their probably not detonating.

There is, however, one kind of nuclear weapon that can withstand significant physical shock and still detonate: the burrowing nuke. It has a strong potential role to play in our fight against terrorists and the regimes that support them.

In the 1960s, the United States developed a thermonuclear device called the B61, a bomber-delivered nuke. This weapon had two interesting characteristics. It had a variable yield that could be adjusted before dropping, so that it could be tailored to a particular situation, and it had an adjustable delay that gave the delivering bomber time to retreat to a safe distance before detonation.

Over the years, the B61 went through several iterations. In August 1997, version 11 entered the U.S. nuclear arsenal. B61-11 had a significant additional characteristic: its case was hardened and its internal mechanisms were beefed up so that it could withstand a significant impact jolt. It is dropped from a great height so that it hits the ground at terminal velocity, and can penetrate up to 300 feet into compacted soil and rock.

The burrowing nuke was a reality.

Currently, the United States is continuing development of the B61, and is also working on a modification of the B83, an 18-inch thick, 12-foot long, variable-yield, delayed detonation nuke originally developed for the B-1 bomber force.

There is no evidence that the Soviets developed a parallel burrowing bomb of their own, so there is little danger that terrorists will get one of these devices in their hands.

These developments have gone almost unnoticed on the world stage. Current nuclear treaties allow for modification of existing warheads, but prohibit developing new ones. Technically, both of these devices are modifications of earlier designs. This classification has been vigorously protested by the anti-nuclear left, particularly the Tri-Valley Communities Against a Radioactive Environment and The Federation of American Scientists, with able assistance from Greenpeace and the Natural Resources Defense Council.

While these groups unequivocally oppose any development of nuclear weapons and any use of nuclear power with mindless determination, they do make a valid point. Early tests on underground nuclear explosions have indicated that such explosions are not normally contained. The explosion invariably blows a great crater in the ground, simultaneously spewing a significant amount of dirt into the air. At least in the earlier tests, this material was radioactive. The opposing groups contend that using these devices would inevitably cause significant civilian casualties.

They also maintain that penetration tests using non-explosive devices have demonstrated the limited ability for such devices to penetrate to genuinely useful levels. According to these opposing groups, typical penetrations into rock have been several dozen feet.

As is usual with these groups, their spokespeople inevitably distort the data they receive from freedom of information sources and occasional individuals from within the nuclear establishment.

Dr. Robert W. Nelson from the Federation of American Scientists is typical of these people. His bona fides include his position as a research physicist at Princeton University, but the simple fact is that he spends his time “consulting” to the Federation of American Scientists and in other anti-nuclear agitation. His “credentials” lend him credibility when he writes and appears before groups. Even the name, the Federation of American Scientists, sounds official and important. In fact, this group consists of a small number of radical anti-nuclear professional scientists, and a large number of anti-nuclear attorneys and lay people.

Unlike genuine scientists and honest political opposition groups, the anti-nuclear left always uses deception and misrepresentation to put its point across, probably because in the harsh light of reality, most of its arguments fall apart.

The manner in which Nelson and the others depict the action of the burrowing nuke is to display those test results that fall on one end of the spectrum. Some tests have demonstrated a disappointing depth of penetration. If a burrowing nuke were to explode at only several feet below the surface, of course the results would be dramatically different from what is desired.

Actual drop tests, however, confirm that the device functions very well, and typically penetrates 200 to 300 feet. So long as the yield of the device is sufficiently low, these explosions will produce very little surrounding damage. Furthermore, ongoing tests are developing a rocket boost capability that will significantly enhance penetration.

Furthermore, a new approach is also in development. Our guided bomb capability gives us the ability to deliver several small conventional bombs sequentially into the same hole. Each successive bomb burrows deeper, so that the final bomb in the sequence, the burrowing nuke, can detonate well below 1,000 feet.

Developing this

is fairly trivial, since all the technology is “off-the-shelf,” in terms of current weapon capabilities. All this development really requires is modification of currently existing smart bombs so they can penetrate before exploding. The only additional development is sequencing the explosions.

The other major objection of the opponents is the collateral contamination they suspect will result from employing such devices. Their projections, once again, result from applying the worst-case scenario without consideration for current developments in low residual radioactivity devices.

Modern nuclear bombs normally do not produce anywhere near the level of contamination resulting from the thermonuclear behemoths of the 1960s. They are designed for explosive effect, not radioactive contamination. Furthermore, in a typical scenario, we would use a relatively small nuclear device in the low kiloton range to take out, say Saddam’s bunker, not a megaton thermonuclear giant.

In a recent article (“How to Take Out Saddam’s Bunker,” DefenseWatch, July 10, 2002), I discussed using man-portable SADMs delivered in person by Special Forces personnel to accomplish this task. If you shift the job to the Air Force, there still is no need to increase the yield significantly of the devices you employ. Because even smart bomb technology is still less precise than hand emplacement, a ten-fold increase in yield may be warranted, but this still puts the yield below that of the bombs dropped during World War II.

The burrowing nuke is an excellent option for taking out deeply buried, heavily armored enemy bunkers. I urge the U.S. government to move ahead full speed with the continuing development and deployment of these devices. We will all be safer when the Saddams and Ghadafis of the world have been completely eliminated.

Robert G. Williscroft is DefenseWatch Navy Editor