SEDL / STP / STP956-EB / STP25662S

Investigation of Neutron Irradiated Reactor Pressure Vessel Steel by Positron Annihilation and Electron Microscopy

Sastry Viswanathan, B
Scientific officers, Materials Science Laboratory, Indira Gandhi Centre for Atomic Research, Tamil Nadu,

Pachur, D
Research physicist, Kernforschungsanlage Jülich, Jülich,

Nandedkar, RV
Scientific officers, Materials Science Laboratory, Indira Gandhi Centre for Atomic Research, Tamil Nadu,

Pages: 10    Published: Jan 1987

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Abstract

Positron lifetime, annihilation line shape, and electron microscopic measurements have been carried out on neutron irradiated pressure vessel steel (HSST Plate 03) meeting ASTM A533-B (Unified Numbering System [UNS] K12539). The positron annihilation parameters for specimens irradiated at 423 K to a dose of 1.5 × 10¹⁸ n/cm² are found to decrease sharply during the post-irradiation annealing interval, 473 to 623 K. This correlates well with the stage seen in the recovery of Vickers hardness. On the basis of known evidence for carbon migration in α-iron and the interpretation of present results, enhancement and recovery of radiation hardening have been qualitatively understood in terms of formation and dissolution of carbon decorated vacancy complexes.