Accumulation of radiation damage in metastable β-phase plutonium

An increase with time in resistivity occurs in plutonium at low temperatures as a result of radioactive self damage. The effect has been studied in experiments at liquid helium temperature lasting over 8000h and has been found to exist in the α , β and δ phases of the metal. In all cases the resistivity approaches saturation, the rates of increase depending on the crystal structure and isotropic content of the sample. In spite of wide differences in these rates the functional increase is roughly the same. The temperature dependence of the accumulated resistivities in all three modifications deviates very strongly from a simple additive resistance obeying Matthiesen’s rule. The resistivity of fully damaged α plutonium is almost temperature independent, becoming smaller than that of the undamaged specimen above about 50 °K. Measurements on neptunium and uranium 233 have also shown resistivity increases with time at helium temperatures, but the effect is too small to decide whether Matthiesen’s rule is obeyed in these metals. The observed effects have been discussed under the assumption that in plutonium scattering of electrons at low temperatures is mainly due to a co-operative phenomenon.

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Self-Irradiation Damage in Actinide Metals and Alloys

Mortimer¹,

Marples²,

Lee³

1975

International Metallurgical Reviews

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This review covers the effects of self-irradiation damage on the physical properties of the α-emitting actinide metals Th, Pa, U, Np, and Pu and some of their alloys: compounds are not considered. The damage to the lattice caused by the α-particles and recoiling nuclei anneals out below room temperature so that the experiments have to be carried out at cryogenic temperatures, mainly in liquid helium. The properties that have been studied include resistivity, length, lattice parameters, thermal conductivity, and specific heat. Most work has been done on the resistivities. These increase with time, showing an exponential approach to saturation after some thousands of hours. In addition to the main exponential law, smaller exponential terms can be separated in some cases, indicating that more than one damage mechanism occurs. The lengths and lattice parameters also saturate exponentially. For most materials these increase but the metastable phases β- and δ-plutonium contract with time. Because the α-particle and, particularly, the recoiling nucleus have only short ranges in these metals, large numbers of atoms are displaced from the lattice in a small volume. The defects are thus not independent of each other, and this, combined with the complex electronic and crystal structures of the actinides, makes calculations on the detailed structure of the defects very difficult. The subject has therefore been approached from a phenomenological standpoint.

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Accumulation of radiation damage in metastable β-phase plutonium

Cited by 3 publications

References 10 publications

Failure of Matthiessen’s Rule in Plutonium

Failure of Matthiessen’s Rule in Plutonium

Resistivity of plutonium, neptunium and uranium due to the accumulation of radioactive self damage

Self-Irradiation Damage in Actinide Metals and Alloys

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