Retention of deuterium in damaged low-activation steel Rusfer (EK-181) after gas and plasma exposure

Abstract

Reduced-activation ferritic–martensitic steels (RAFMS) are advanced structural materials for the construction of future fusion reactors with high fluxes of neutrons, such as DEMO or a Fusion Neutron Source (FNS).In the present work the influence of different damages on deuterium retention in the RAFM Rusfer (Chernov et al., 2007) was investigated. Three different types of damage were applied:(i)irradiation by 20MeV W6+ ions to a damage fluence of 0.89dpa (1.4×1018ions/m2). Tungsten ion irradiation was used as proxy for displacement damage created by neutrons;(ii)heat loads in the QSPA-T facility with 10 pulses of 0.5MJ/m2 with a duration of 0.5ms;(iii)low-temperature hydrogen plasma irradiation in the LENTA facility at 320 and 600K to a fluence of 1025H/m2.The hydrogen isotope retention properties of the damaged and undamaged material were investigated by exposure to deuterium gas several weeks after damaging. The deuterium retention was investigated in the temperature range of RT–773K at pressure 104Pa. Deuterium depth profiles were measured a month after gas exposure by nuclear reaction analysis (NRA) using the D(3He,p)α nuclear reaction. Deuterium retention in damaged and undamaged Rusfer in the temperature range of 300–600K has a maximum at 500K for all types of damage investigated. The typical value of deuterium concentration in the bulk is 10−3at.%. Peculiarities of D retention in damaged samples are discussed.