Chapter 2. DEFINITIONS

TM 55-315

CHAPTER 2

DEFINITIONS

Unless otherwise specified, the following definitions will be used throughout this manual (49 CFR 173. 403).

2-1. A1

The A1 quantity is the maximum activity of special-form radioactive material permitted in a Type A package.

2-2. A2

The A2 quantity is the maximum activity of radioactive material other than special-form or low specific activity (LSA)

radioactive material permitted in a Type A package.

2-3. Atomic Number

The atomic number is the number of protons in the nucleus of an atom; also, the number of orbital electrons surrounding

the nucleus of a neutral atom (symbol: Z).

2-4. Bequerel (Bq)

A unit, in the international system of units (si), of measurement of radioactivity equal to one transformation per second.

It is expressed in terms of disintegrations per second.

2-5. Closed Transport Vehicle

A closed transport vehicle is a vehicle equipped with a securely attached exterior enclosure that, during normal transport,

restricts the access of unauthorized persons to the cargo space containing the radioactive materials. The enclosure may

be temporary or permanent, and in the case of packaged materials, may be of the see-through type, and must limit

access from the top, sides, and ends.

2-6. Consignee

The consignee is the person or company that receives the shipment.

2-7. Consignor

The consignor is the person or company that makes the shipment.

2-8. Containment System

The containment system is the packaging components intended to retain the radioactive contents during transport.

2-9. Conveyance

Conveyance means:

a. Transport by public highway or rail; any transport vehicle or large freight container.

b. Transport by any vessel, or any hold compartment, or defined deck area of a vessel.

c. Transport by any aircraft.

2-10. Critical Mass

Critical mass is that amount or mass of active material that will just support a sustaining chain reaction.

2-11. Criticality

Criticality is the condition of being critical. A reactor is described as having reached criticality when the chain reaction

starts.

2-12. Curie (Ci)

Curie is a measurement unit of radioactivity. One curie equals 3.7 x 1010 nuclear disintegrations per second. One

microcurie (u Ci) = (10 -6) (3.7 x 1010) disintegrations per second (dps) = 3.7 x 104 dps.

2-13. Depleted Uranium

Depleted uranium is uranium that contains less uranium-235 than the naturally occurring distribution of uranium isotopes.

2-14. Design

Design is the description of a special-form material, a package, or a packaging that enables those items to be fully

identified. The description may include specifications, engineering drawings, reports showing compliance with regulatory

requirements, and other relevant documentation.

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