protection of special nuclear material or (2) security measures for the physical protection and location of certain plant equipment vital to the safety of production or utilization facilities (10 CFR 73.2). The U.S. Nuclear Regulatory Commission has the authority to determine whether information is “safeguards information.”


In the context of spent fuel storage, measures to protect storage facilities against sabotage, attacks, or theft.

Shaped charge:

A demolition and wall penetration or perforation device that uses high explosive to create a high-velocity jet of material.

Single-purpose cask:

See Cask,

Special nuclear material:

Fissile elements such as uranium and plutonium.

Spent fuel:

See Spent nuclear fuel.

Spent fuel pool:

A water-filled pool that is used at all commercial nuclear reactors for storage of spent (used) fuel elements after their removal from a nuclear reactor Spent fuel pools are constructed of reinforced concrete and lined with stainless steel. The inside of the pool has storage racks to hold the spent fuel assemblies and may contain a gated compartment to hold a spent fuel cask while it is being loaded and sealed.

Spent (or used or irradiated fuel) nuclear fuel:

Fuel that has been “burned” in the core of a nuclear reactor and is no longer efficient for producing electricity. After discharge from a reactor, spent fuel is stored in water-filled pools (see Wet storage) for shielding and cooling.

Storage-only cask:

See Cask.

Thermal power:

Total heat output from the core of a nuclear reactor.


A fissile isotope of uranium that contains 92 protons and 143 neutrons. It is the principal nuclear fuel in nuclear power reactors.


An isotope of uranium that contains 92 protons and 146 neutrons.

Vital area:

A zone located within the protected area of a commercial nuclear power plant site that contains the reactor control room, the reactor core, support buildings, and the spent fuel pool. It is the most carefully controlled and guarded part of the plant site.


Unit of power.


Energy unit of measure equal to one watt of power supplied for one hour

Wet storage:

Storage of spent nuclear fuel in spent fuel pools.

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