Plutonium Alloys - STD-1128-98master0038

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

2.3.2

Plutonium Alloys

Alloying plutonium gives rise to a host of materials with a wide range of physical,

chemical, and nuclear properties.1 The search for and development of new alloys has

been focused mainly on the manufacture of atomic weapons, reactor fuels, heat sources,

and neutron sources. The challenge of alloy development is how to maximize the desired

properties without adding undesired ones. Unfortunately, some properties mutually

exclude others (e.g., a gain in hardness usually results in a loss of ductility), so users may

be forced to rethink their needs.

The radiological hazards of a plutonium alloy taken through its product life cycle differ

from those of the pure metal isotope by virtue of the alloy's properties, which affect its

form (i.e., its chemical composition, density, and geometric shape). Because form can be

radically changed by external conditions (e.g., heat, pressure, and chemical atmosphere),

a knowledge of the following properties will aid in evaluating the radioactive hazard:

melting point

diffusivity

viscosity

strength

vapor pressure

pyrophoricity.

In nuclear fuel applications, the neutron absorption cross-section of the alloying elements

and impurities must also be considered for its effect on radiation exposure.

2.3.3

Plutonium Compounds

Much of what was said in Section 2.3.2 about the properties of plutonium alloys also

applies to plutonium compounds because both are mixtures of plutonium and other

elements.

Plutonium is the fifth element in the actinide series, which consists of elements with

properties that stem from partial vacancies in the 5th electron shell. These elements form

the seventh row in the periodic table. In general, there are four oxidation states: III, IV,

V, and VI. In aqueous solutions, plutonium (III) is oxidized into plutonium (IV), which

is the most stable state. The compounds PuF4, Pu(I03)4, Pu(OH)4, and Pu(C2O4)2 6H2O

See Volume 1 (Section 2) and Volume 2 (Section 5) of the Plutonium Handbook: A Guide to the Technology (Wick, 1967); Plutonium

(Taube, 1964); and Chapter 11 of the "Reactor Handbook" in Materials, vol. 1 (Tipton, 1960). Beginning in 1957, a series of international

conferences were held whose proceedings contain a wealth of information on plutonium alloys. From 1960 through 1975, the conferences were

held every five years and produced a proceedings for each conference: Refer to The Metal Plutonium (Coffinberry and Miner, 1961); Plutonium

1960 (Grison et al., 1961); "Plutonium 1965" (Kay and Waldron, 1966); "Plutonium 1970 and Other Actinides," Parts I and II (Miner, 1971); and

"Plutonium 1975 and Other Actinides" (Blank and Lindner, 1976).

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