National Academies Press: OpenBook

Effects of Nuclear Earth-Penetrator and Other Weapons (2005)

Chapter: 2 Hard and Deeply Buried Targets

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Suggested Citation:"2 Hard and Deeply Buried Targets." National Research Council. 2005. Effects of Nuclear Earth-Penetrator and Other Weapons. Washington, DC: The National Academies Press. doi: 10.17226/11282.
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2
Hard and Deeply Buried Targets

Potential U.S. adversaries worldwide are using intentionally hardened facilities to conceal and protect their leaders, military and industrial personnel, weapons, equipment, and other assets and activities. Such facilities, called hard and deeply buried targets (HDBTs), are a serious challenge to U.S. national security objectives of maintaining the capability to hold such adversary assets at risk. Ranging from hardened, surface bunker complexes to tunnel facilities deep underground, HDBTs are typically large, complex, and well concealed, incorporating strong physical security, modern air defenses, protective siting, multifaceted communications, and other important features that make many of them able to survive attack by conventional weapons. Potential adversaries are increasingly locating HDBTs in basements of multistory buildings located in urban settings, complicating attack planning and increasing the risk of serious collateral effects. This situation places a premium on achieving accurate target characterization so as to obtain the required lethality from precisely delivered weapons during a strike.

Many HDBTs are of a shallow “cut and cover” design, with an equivalent concrete structural overburden of less than 3 meters’ thickness. This type of facility typically has a tactical function, such as providing support for artillery or missile launchers. Many such facilities can be held at risk by current weapons, or weapons under development if deployed, if the numbers of U.S. weapons are adequate, accurate target location coordinates are known, and adversaries’ defenses are overcome. The missile operations tunnels and armament bunkers in some theaters are particularly troublesome because of their sheer numbers, protective berms, and the strategic positioning of their entrances and exits away from direct routes of attack.

Hundreds of much harder facilities (with a concrete overburden equivalent of 20 to 100 meters) protect strategic capabilities (e.g., leadership, command and control, weapons of mass destruction [WMD]) and were built using either conventional drill-and-blast tunneling techniques or more modern mining equipment. These are typically equipped with redundant ventilation, power, and communications systems. U.S. capabilities to place these types of facilities at risk are challenged not only by the depths of burial and redundancies in critical functional systems, but also by sophisticated techniques for camouflage, concealment, and deception, and some collocation of HDBTs in civilian areas. Such facilities, which conceal and protect an adversary’s most valued strategic capabilities, are described in more detail in this chapter.

Suggested Citation:"2 Hard and Deeply Buried Targets." National Research Council. 2005. Effects of Nuclear Earth-Penetrator and Other Weapons. Washington, DC: The National Academies Press. doi: 10.17226/11282.
×

BASIC DEFINITIONS

Hard and Deeply Buried Targets

The generic term “hard and deeply buried targets” refers to all types of intentionally hardened targets, either aboveground or belowground, that are designed to withstand or minimize the effects of kinetic weapons.

Underground Facility

The generic term “underground facility” refers to all types of underground hardened structures and facilities regardless of their depth.

Hardened Structure

The generic term “hardened structure” refers to a structure that is intentionally strengthened to provide protection from the effects of kinetic weapons. All hardened structures can be further grouped into one of three types, defined by the location of the roof of the structure’s functional workspace:

  • Aboveground hardened structure. The roof of the functional workspace is above the ground surface. Included in this category are earth-bermed structures that are not exposed directly to weapons effects and for which air blast effects are reduced owing to the aerodynamic shape of the berm.

  • Shallow underground structure. The roof of the functional workspace is between the ground surface level and 20 meters deep.

  • Deep underground hardened structure. The roof of the functional workspace is covered by 20 or more meters of soil and/or rock.

Strategic Hard and Deeply Buried Target

The term “strategic hard and deeply buried target” refers to those HDBTs that perform a strategic function, such as command and control of military forces, protection of national leadership, WMD production or storage, and ballistic missile production, storage, or launch. The proposed nuclear earth-penetrator weapon (EPW) is being designed to defeat this target class.

BASIC FACTS AND ESTIMATES

Following is a concise list of background facts and estimates relating to HDBTs:

  • Potential U.S. adversaries worldwide are using underground facilities to conceal and protect their leadership, military and industrial personnel, weapons, equipment, and other assets and activities. These facilities include hardened surface bunkers and tunnel facilities deep underground.

  • Many underground command, control, and communications (C3) complexes and missile tunnels are between 100 and 400 meters deep, with the majority less than 250 meters deep. A few are as deep as 500 meters or even 700 meters, in competent granite or limestone rock.

  • As identified by the Defense Intelligence Agency, there are about 10,000 HDBTs in the territory of potential U.S. adversaries worldwide.

Suggested Citation:"2 Hard and Deeply Buried Targets." National Research Council. 2005. Effects of Nuclear Earth-Penetrator and Other Weapons. Washington, DC: The National Academies Press. doi: 10.17226/11282.
×
  • Of the 10,000 HDBTs identified, about 20 percent are estimated to have a major strategic function.

  • Over half of these strategic HDBTs are located near or in urban areas.

  • The number of known strategic HDBTs is increasing at a rate of about 10 percent per year. This increase is attributable mostly to discovery by the U.S. intelligence community and to a lesser extent to construction in countries seeking protection from U.S. military capabilities.

  • With the current U.S. nuclear arsenal, a number of the more important strategic HDBTs cannot be held at risk of physical destruction of the functional area.

    A few hundred of the strategic HDBTs could be candidates for targeting with the robust nuclear earth penetrator (RNEP) weapon currently under study.

EXAMPLES OF STRATEGIC HARD AND DEEPLY BURIED TARGETS

Examples of strategic HDBTs are shown in Figure 2.1 and detailed in this section. Representative actual overburdens, not their reinforced concrete equivalents, are described in the following examples.

Missile Tunnel

Hard Target Type: Deep underground tunnel

Function: Deployment area for short-range ballistic missiles (SRBMs) that have a chemical weapon warhead; warhead mating performed in maintenance area

Site Location: Remote valley; nearest civilian population center is 30 kilometers away

FIGURE 2.1 Examples of strategic hard and deeply buried targets. (See text for details. Acronyms are defined in Appendix D.)

Suggested Citation:"2 Hard and Deeply Buried Targets." National Research Council. 2005. Effects of Nuclear Earth-Penetrator and Other Weapons. Washington, DC: The National Academies Press. doi: 10.17226/11282.
×

Number of Stories or Levels: One

Number of Entrances: Two

Overburden: 120 meters at working area

Geology: Varying layer depths of residual soil, weathered rock, and limestone

Berms: Tunnel adits constructed to form a berm

Tunnels: Tunnel lining is 1 meter of reinforced concrete from entrance to blast doors, then 0.5 meter reinforced concrete throughout internal cavities

Blast Doors: 1 meter of steel-lined reinforced concrete

Reinforced Concrete: Compression strength of all concrete is estimated at 4,000 pounds per square inch

Deep Underground C3 Complex

Hard Target Type: Bunkered facility deep underground

Function: Reserve post for providing command, control, and communications support to strategic nuclear forces as well as wartime protection for senior military authorities

Site Location: Mountainous region in country’s interior, more than 200 kilometers away from a city of 50,000 and 6 kilometers from a village of 150

Number of Stories or Levels: Multilevel facility connected by elevators, shafts, and tunnels

Number of Entrances: Two horizontals entrances and one vertical shaft entrance

Overburden: 400 to 700 meters overburden at working area

Geology: Single monolithic upthrust of quartzite sandstone

Berms: None

Tunnels: Tunnel lining reinforced concrete

Blast Doors: Sliding double blast doors exist in excess of 0.7 meter thick at each entrance; main entrance is 7 meters wide, and auxiliary entrance is 9 meters wide

Reinforced Concrete: Reinforced concrete facing walls installed at both entrances, and a slab of reinforced concrete covering the vertical shaft

CW/BW Aboveground Bunker

Hard Target Type: Hardened aboveground bunker

Function: Chemical weapons (CW) munitions filling (artillery and bombs) and CW munitions storage

Site Location: Remote desert area, within a large chemical weapons production and R&D complex; no civilian facilities within a 10 kilometer range; nearest populated area is 40 kilometers northwest of the complex

Number of Stories or Levels: One

Number of Entrances: One

Overburden: 8 meters thick, including two 1 meter burster slabs separated by a 3 meter layer of 8 inch rocks, covered by soil

Ceiling: 1 meter of reinforced concrete

Walls: 1 meter of reinforced concrete

Floor: 2 meters of reinforced concrete

Roof: 0.5 meter of steel-lined concrete

Blast Doors: 0.5 meter of steel-lined concrete

Suggested Citation:"2 Hard and Deeply Buried Targets." National Research Council. 2005. Effects of Nuclear Earth-Penetrator and Other Weapons. Washington, DC: The National Academies Press. doi: 10.17226/11282.
×

C3I Shallow Underground Bunker

Hard Target Type: Shallow underground bunker

Function: National-level military command-and-control facility

Site Location: Within a large military complex on the outskirts of a large city (population 250,000)

Number of Stories or Levels: One

Number of Entrances: Four

Overburden: Five layers above roof:

3 meters of compacted soil

1 meter of reinforced concrete burster slab

3 meters of crushed/compacted rock

1 meter of reinforced concrete burster slab

3 meters of compacted soil

Thickness of:

Walls: 1 meter of reinforced concrete

Floor: 1 meter of reinforced concrete

Roof: 2 meters of reinforced concrete

Blast Doors: 0.5 meter of steel-lined concrete

C3I Basement Bunker

Hard Target Type: Basement bunker

Function: National-level command-and-control facility

Site Location: Within a military headquarters complex under a six-story Army Headquarters building in a heavily populated (750,000) urban area; civilian structures (hospitals, schools, embassies) all located within a 1 kilometer radius of the facility

Number of Stories or Levels: Two-level bunker underneath six-story building

Number of Entrances: Two

Thickness of:

Walls: Exterior, 2 meters; interior, 0.5 to 1 meter of reinforced concrete

Floor: 1 meter of reinforced concrete

Roof: 4.1 meters of reinforced concrete equivalent above upper bunker level

Blast Doors: 4 blast doors, sliding, steel-lined concrete

Shallow Accessible Bunker/Silo

Hard Target Type: Shallow buried “cut and cover” bunker

Function: Biological weapons (BW) agent storage and production

Site Location: Collocated within aboveground civilian bioproducts R&D and production complex; hilly terrain, vegetation; large civilian population within a 0.5 kilometer radius of the facility

Number of Stories or Levels: One

Number of Entrances: One

Overburden: 7 meters of compacted soil

Walls: 1 meter of reinforced concrete

Floor: 1 meter of reinforced concrete

Roof: 2 meters of reinforced concrete

Blast Doors: 0.5 meter overall; steel-lined concrete

Suggested Citation:"2 Hard and Deeply Buried Targets." National Research Council. 2005. Effects of Nuclear Earth-Penetrator and Other Weapons. Washington, DC: The National Academies Press. doi: 10.17226/11282.
×
Page 13
Suggested Citation:"2 Hard and Deeply Buried Targets." National Research Council. 2005. Effects of Nuclear Earth-Penetrator and Other Weapons. Washington, DC: The National Academies Press. doi: 10.17226/11282.
×
Page 14
Suggested Citation:"2 Hard and Deeply Buried Targets." National Research Council. 2005. Effects of Nuclear Earth-Penetrator and Other Weapons. Washington, DC: The National Academies Press. doi: 10.17226/11282.
×
Page 15
Suggested Citation:"2 Hard and Deeply Buried Targets." National Research Council. 2005. Effects of Nuclear Earth-Penetrator and Other Weapons. Washington, DC: The National Academies Press. doi: 10.17226/11282.
×
Page 16
Suggested Citation:"2 Hard and Deeply Buried Targets." National Research Council. 2005. Effects of Nuclear Earth-Penetrator and Other Weapons. Washington, DC: The National Academies Press. doi: 10.17226/11282.
×
Page 17
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Underground facilities are used extensively by many nations to conceal and protect strategic military functions and weapons' stockpiles. Because of their depth and hardened status, however, many of these strategic hard and deeply buried targets could only be put at risk by conventional or nuclear earth penetrating weapons (EPW). Recently, an engineering feasibility study, the robust nuclear earth penetrator program, was started by DOE and DOD to determine if a more effective EPW could be designed using major components of existing nuclear weapons. This activity has created some controversy about, among other things, the level of collateral damage that would ensue if such a weapon were used. To help clarify this issue, the Congress, in P.L. 107-314, directed the Secretary of Defense to request from the NRC a study of the anticipated health and environmental effects of nuclear earth-penetrators and other weapons and the effect of both conventional and nuclear weapons against the storage of biological and chemical weapons. This report provides the results of those analyses. Based on detailed numerical calculations, the report presents a series of findings comparing the effectiveness and expected collateral damage of nuclear EPW and surface nuclear weapons under a variety of conditions.

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