Damage to Macor glass-ceramic from high-dose 14 MeV neutrons

Macor machinable glass-ceramic was irradiated to fluences up to 1x1023 14 MeV n/m2 at room temperature. Post-irradiation measurements were carried out to determine changes in high-frequency electrical conductivity, hardness, and density. it was found that neutron damage caused slight increases in conductivity and hardness. The major change noted was in density, where a fluence of 4x1022 n/m2 caused swelling of 1.55 vol% while a dose of 1x1023 n/m2 resulted in a lower swelling value (0.82 vol%). This unusual behavior is explained by a model involving expansion of the mica phase of Macor and contraction of the glassy phase. Implications of the present results for engineering performance of Macor at these and higher fluences are discussed. (orig.)