The Truck Bomb Problem

Shortly after the 1983 bombing of a U.S. Marine barracks in Beirut Lebanon, the NRC commissioned "An Analysis of Truck Bombs Threats at Nuclear Facilities" which was performed by the Sandia National Laboratories. The study concluded:

"Unacceptable damage to vital reactor systems could occur from a relatively small charge at close setback distances, and from larger but still reasonable-sized charges at large setback distances, greater than the protected area for most plants."
Sandia National Laboratories 1984

This represented the NRC's most feared result. At some plants, a large bomb detonated from offsite can cause enough damage to lead to a deadly release of radiation or even a meltdown! Instead of taking steps for proper protection, the NRC hid the findings from the public and announced that the study was ongoing. Yet two years later in 1986, the NRC commissioners voted 3-2 to continue assuming that a terrorist would not deliver a bomb by vehicle; hence, no vehicle barriers to prevent the 1993 intrusion at Three Mile Island.

Current NRC regulations and interim NRC regulations do not adequately protect vital reactor systems to the “real world” bomb threats, but are limited to much smaller bombs. The 1996 bombing of the US military barracks at the Khobar Towers in Saudi Arabia was equal to 20,000lbs of TNT and is considered a large bomb by terrorism experts.


There are two shock waves produced by a truck bomb - the air wave and the ground wave. The earthquake-proofing measures of reactor coolant pipes can be overwhelmed by a large truck bomb resulting in a devastating failure. The lateral accelerations propagated through the ground from a truck bomb far exceed those produced during the peak magnitude of an earthquake. This shock wave can cause a large break Loss of Coolant Accident by virtue of the rapid jolt where pipes do not have time to flex and act in a forgiving manner as they were designed to do during an earthquake.

In the event of a large truck bomb attack detonated from several hundred feet away from the reactor, the reactor building will most likely continue standing, but the pipes inside can rupture. Any water pipe which breaks, also becomes a potential water jet which could produce the unwanted consequence of an electrical short circuit. Oil pipes used to cool reactor pumps canrupture and potentially start fires if they have in effect become a blowtorch as burning oil under pressure is sprayed from the fracture. There are other safety systems pipes which can rupture and cause explosions which I am not comfortable disclosing publicly. The Three Mile Island Nuclear Generating Station has tripled its setback distance for proper security checks of incoming vehicles following the September 11th attacks. The new setback distance is still not sufficient to protect against a large bomb.

The force of the Oklahoma City bomb blast
  • damaged 324 surrounding buildings
  • overturned automobiles and touched off car fires
  • blew out windows and doors in a 50-block area
  • the explosion was felt 55 miles from the site and registered 6.0 on the Richter Scale
  • foundations were cracked over a four block area
  • the Oklahoma City bomb is categorized as a medium-sized bomb by terrorist experts

TMI Alert's Recommendations
  1. extend the setback distances to 1100 feet
  2. keep vehicle barriers closed at the entrances at all times
  3. perform bomb checks before a vehicle comes within 1100 feet of vital systems (At TMI, vehicles should be checked before crossing the bridge to the island.)
  4. install blast deflection shields where needed

This page updated by Three Mile Island Alert January 2004