Physical and Chemical Properties - doe-std-1128-98

DOE-STD-1128-98

Figure 2.2.

Atom Ratio of 241Am to 241Pu (t=0) Produced by the Beta Decay of 241Pu as a

Function of Time Since Chemical Separation

2.3

PHYSICAL AND CHEMICAL PROPERTIES

This discussion of plutonium's physical and chemical properties begins with

plutonium metal, followed by its alloys and compounds. Knowledge of the physical

properties of these classes of materials and how the plutonium was produced is the

key to understanding and predicting the hazards of working with this challenging

element. According to Healy (1993), "Nature does not decide what happens to any

material based on its radioactivity but rather on its form and mass." Form and mass

are determined by the engineering application and the kinds of processes needed to

achieve both intermediate and final products. Thus, to prevent nature from taking its

course, there can be no shortcuts in good practices for plutonium facilities.

2.3.1 Plutonium Metal

The metallic state of plutonium is undoubtedly the most complicated of all the

elements. Plutonium is a silvery-white metal, much like nickel in appearance. It

has a low melting point (640C) and an unusually high boiling point (3327C).

The metal exists in six allotropic forms, as indicated in Table 2.5. Two of the

allotropic forms, σ and σ ', contract upon heating; the other forms expand

upon heating. At room temperature, pure

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