Figure 2.3 Neutron Energy Spectra of Plutonium-Beryllium and Plutonium-Boron Neutron Sources Compared

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

Figure 2.3

Neutron Energy Spectra of Plutonium-Beryllium and Plutonium-Boron Neutron Sources

Compared with a Fission Source

plutonium exists in the " phase, which has a triclinic structure with a theoretical density

of about 19.86 g/cm3. The dimensional stability of this phase is aggravated by its high

linear thermal expansion coefficient and its low " 6 $ transition temperature. This

transformation takes place at approximately 115C, resulting in a 10% volume change.

The combination of a high specific activity and low thermal conductivity can result in

significant dimensional distortion during metal-forming operations. For this reason, a *-

stabilized dilute gallium alloy, which has a density of about 15.75 g/cm3, is used when a

more dimensionally stable plutonium is desired (Merz, 1971).

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