INCLUSION OF MOBILE HELIUM IN A RATE THEORY MODEL OF VOID SWELLING

The effect of mobile helium on swelling has been studied by using a rate theory model of void growth. The partitioning of mobile helium to various internal sinks and the trapping of interstitial helium atoms by vacancies were included in the model. Helium gas generated during neutron irradiation increases swelling at temperatures above the peak void swelling temperature. Two temperature regimes of enhanced swelling are related to gas-assisted void growth and gas-driven bubble growth. Swelling due to void and bubble growth in a fusion reactor first wall is predicted using nickel as an example, and the effects of dislocation density and grain size on swelling are discussed. It is found that, as compared to simultaneous helium injection during heavy-ion bombardment, the method of helium preinjection is inadequate in simulating a fusion reactor condition. © 1979.