The Robust Nuclear Earth Penetrator (RNEP)

The Bush Administration requested funding from Congress to research a new type of nuclear bomb. The Robust Nuclear Earth Penetrator (RNEP) is a nuclear weapon that would burrow a few meters into rock or concrete before exploding and thus generating a powerful underground shock wave. Its hypothetical targets are deeply buried command bunkers or underground storage sites containing chemical or biological agents.

The RNEP budget: RNEP is not just a feasibility study: the Department of Energy's 2005 budget included a five-year projection—totaling $484.7 million—for the weapons laboratories to produce a completed warhead design and begin production engineering by 2009.[1] Last year, David L. Hobson, the Republican chairman of the House Appropriations Energy and Water Development Subcommittee, zeroed out FY05 funding for the program, stating, "we cannot advocate for nuclear nonproliferation around the globe, while pursuing more usable nuclear weapons options here at home." However, the FY06 budget request includes $4 million for RNEP and an additional $4.5 million to modify the B-2 bomber to carry the weapon.

The RNEP design: Weapons designers at Lawrence Livermore National Laboratory intend to use an existing high-yield nuclear warhead—the 1.2-megaton B83 nuclear bomb—in a longer, stronger and heavier bomb casing. The B83 is the largest nuclear weapon in the U.S. arsenal, and nearly 100 times more powerful than the nuclear bomb used on Hiroshima.[1]

Technical realities:
According to several recent scientific studies, RNEP would not be effective at destroying many underground targets, and its use could result in the death of millions of people.[2]

  • RNEP would produce tremendous radioactive fallout: A nuclear earth penetrator cannot penetrate deep enough to contain the nuclear fallout. Even the strongest casing will crush itself by the time it penetrates 10-30 feet into rock or concrete. For comparison, even a one-kiloton nuclear warhead (less than 1/10th as powerful as the Hiroshima bomb) must be buried at least 200-300 feet to contain its radioactive fallout.[3] The high yield RNEP will produce tremendous fallout that will drift for more than a thousand miles downwind. As, Linton Brooks, the head of the National Nuclear Security Administration told Congress in April, "the laws of physics will [never allow a bomb to penetrate] far enough to trap all fallout. This is a nuclear weapon that is going to be hugely destructive over a large area" if it goes off underground.
  • RNEP could kill millions of people: A simulation of RNEP used against the Esfahan nuclear facility in Iran, using the software developed for the Pentagon, showed that 3 million people would be killed by radiation within 2 weeks of the explosion, and 35 million people in Afghanistan, Pakistan and India would be exposed to increased levels of cancer-causing radiation (see Figure 1).[4]


Figure 1: Fallout from the use of RNEP against the Esfahan nuclear facility in Iran would spread for thousands of miles across Afghanistan, Pakistan and India. It would kill 3 million people within 2 weeks of the explosion and expose 35 million to cancer causing radiation.

  • RNEP would not be effective at destroying chemical or biological agents: Unless the weapon detonates nearly in the same room with the agents, it will not destroy them. 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 would more likely spread those agents into the environment, along with the radioactive fallout (See Figure 2). [56]


Figure 2: Only a small region around a nuclear explosion reaches temperatures high enough to sterilize chemical or biological agents. But the seismic shock or blast wave propagates much further, ejecting a large crater of dirt and debris. Agents stored within the crater volume, but outside the small sterilization zone, would be dispersed into the environment.

  • RNEP would not be effective at destroying the deepest or widely separated bunkers. The seismic shock produced by the RNEP would only be able to destroy bunkers to a depth of about a thousand feet. Modern bunkers can be deeper than that, with a widely separated complex of connected rooms and tunnels.
  • There are more effective conventional alternatives to RNEP: Current precision-guided conventional weapons can be used to cut off a bunker's communications, power, and air, effectively keeping the enemy weapons underground and unusable until U.S. forces secure them. Sealing chemical or biological agents underground is far more sensible than trying to blow them up.

References:
1. Medalia, J., Robust Nuclear Earth Penetrator Budget Request and Plan, FY2005-FY2009. March 24, 2004, Congressional Research Service: Washington, D.C. Available at: http://www.fas.org/spp/starwars/crs/RS21762.pdf, accessed May 2005.

2. National Research Council, Effects of Nuclear Earth-Penetrator and Other Weapons. 2005. Available at: http://books.nap.edu/catalog/11282.html, accessed May 2005.

3. Nelson, R.W., Low-Yield Earth-Penetrating Nuclear Weapons. Science & Global Security, 2002. 10(1): p. 1-20. Available at: http://www.princeton.edu/%7Eglobsec/publications
/pdf/10_1Nelson.pdf
, accessed May 2005.

4. Peter Wilk MD, et al., Projected Casualties Among U.S. Military Personnel and Civilian Populations from the Use of Nuclear Weapons Against Hard and Deeply Buried Targets. 2005, Physicians for Social Responsibility. Available at: http://www.psr.org/documents/psr_doc_0/
program_4/RNEP_Report_Final.pdf
, accessed May 2005.

5. Nelson, R.W., Nuclear "Bunker Busters" Would More Likely Disperse than Destroy Buried Stockpiles of Biological and Chemical Agents. Science & Global Security, 2004. 12(1-2): p. 69-89. Available at: http://www.princeton.edu/~rnelson/papers/agent_defeat.pdf, accessed May 2005.

6. May, M., Haldeman, Z., Effectiveness of Nuclear Weapons Against Buried Biological Agents. Science & Global Security, 2004. 12(1-2): p. 91-114.

Last Revised: May 31, 2005

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