If the United States is serious about preventing the proliferation of nuclear weapons, the last thing we should do is develop a new generation that might never work as advertised.
by Rob Nelson
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| Figure 1. Radioactive fallout from a “bunker buster” dropped on the Esfahan nuclear facility in Iran would spread across Afghanistan, Pakistan, and India within two days. Three million people would die within two weeks of the explosion and 35 million people would have a greater risk of developing cancer. See full-size image. |
During last year's presidential campaign, President Bush and Senator John Kerry agreed that the greatest security threat facing the United States is the proliferation of nuclear weapons. Having secured a second term, however, the Bush administration is seeking to expand the U.S. nuclear arsenal by asking Congress to fund research into new types of nuclear weapons.
The administration's fiscal 2006 budget request, for example, includes four million dollars for research on the Robust Nuclear Earth Penetrator (RNEP), also called the nuclear "bunker buster"—a powerful nuclear bomb that would burrow a few meters into the ground before exploding. Its hypothetical targets are underground command centers or buried storage sites containing chemical or biological agents.
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The RNEP only penetrates a few meters of rock or concrete—nowhere near the depth necessary to contain the nuclear explosion. |
An additional $4.5 million has been requested to modify the B-2 bomber that would carry the weapon. The Department of Energy has ambitious plans for this program: its 2005 budget included a five-year projection—totaling $484.7 million—that anticipates a completed warhead design and the start of production engineering by 2009. Though the House rejected the administration's request, the Senate voted to keep the funding in place. The weapon's fate will therefore be decided in conference by the end of the year.
UCS research has shown that the RNEP has little practical use from a military and technical perspective. In fact, not only would this weapon prove ineffective in destroying many of its intended targets, but its use could also result in the deaths of millions of civilians. If it is used against buried stockpiles of active chemical or biological (CB) agents, it could even release these agents into the environment without sterilizing them.
A Mission Doomed to Fail
Even by nuclear weapons standards, the RNEP would be a powerful bomb. Its designers intend to encase an existing 1.2-megaton B83 nuclear warhead—the largest in the U.S. arsenal—in a longer, stronger, and heavier outer shell. The B83 is almost 80 times more powerful than the bomb used on Hiroshima.
The RNEP is intended to generate a strong seismic shock wave capable of crushing hardened underground bunkers within about 1,000 feet of the explosion, but much deeper bunkers can be constructed using modern tunneling equipment. Very deep bunkers (or underground facilities spread out over a wide area) would be immune from such an attack.
Furthermore, because the RNEP would only penetrate a few meters of rock or concrete—nowhere near the hundreds of meters in depth necessary to contain the explosion—the weapon would produce tremendous nuclear fallout, potentially drifting more than 1,000 miles downwind. When Congress asked Linton Brooks, the head of the National Nuclear Security Administration, to confirm earlier suggestions that the fallout would be contained, he said, "I don't believe the laws of physics will ever let that be true. . . . This is a nuclear weapon that is going to be hugely destructive."
Simulation software developed for the Pentagon shows that an RNEP dropped on Iran's Esfahan nuclear facility would cause three million radiation-related deaths within two weeks of the explosion. Another 35 million people in Afghanistan, India, and Pakistan would be exposed to increased levels of cancer-causing radiation (see Figure 1).
The RNEP will also be unable to destroy chemical or biological agents unless it detonates nearly in the same room as the agents. Because the United States is unlikely to know the precise location, size, and geometry of underground bunkers, a nuclear attack on a storage bunker containing chemical or biological agents could release those agents into the environment along with radioactive fallout (see Figure 2).
Figure 2. Only a small area around the site where a nuclear bunker buster detonates will reach temperatures high enough to sterilize chemical or biological (CB) agents. Right: The blast wave extends much farther, creating a large crater. CB agents stored within the blast zone, but outside the small sterilization zone, would be released into the environment. |
Misguided Strategy
Safer and more effective alternatives to the RNEP already exist. Precision-guided conventional weapons, for example, can be used to cut off a bunker's communications, power, and air, effectively rendering the enemy's weapons unusable until U.S. forces can secure them.
Since it is hard to imagine any American president electing to use nuclear weapons when conventional alternatives are available, the RNEP program seems mainly designed to continue nuclear weapons research at the nation's weapons labs. Pursuing this course, however, will send the wrong signal to the rest of the world just as the international community is trying to convince Iran and North Korea to give up their nuclear weapons programs. Last year, Rep. David Hobson (R-OH), the subcommittee chairman responsible for eliminating RNEP funding, stated, "We cannot advocate for nuclear nonproliferation around the globe, while pursuing more usable nuclear weapons options here at home."
In other words, the United States would be foolish to pursue such weapons at a time when its own security depends on limiting the appeal of nuclear weapons to other countries.
Rob Nelson is a senior scientist in the Global Security Program and a visiting research scholar at the Princeton University Program on Science & Global Security.
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