Irradiation effects on tungsten stabilized martensitic steels

Tungsten stabilized martensitic stainless steels are being developed for fusion reactor first wall application in order to lower retained radioactivity so as to permit shallow land burial after reactor decommissioning. Two such alloys have been designed, fabricated, fast neutron irradiation in FFTF and examined by transmission electron microscopy. The two compositions were Fe-7.5Cr-2.OW-.17C and Fe-10.2Cr-1.7W-.3V-.-2C. Conditions examined included irradiation temperatures of 365, 420, 520 and 600 C to doses as high as 34 dpa. Small amounts of void swelling are found at the two lowest temperatures. It is demonstrated that levels of tungsten on the order of 2 wt% do not result in excessive intermetallic precipitation under these irradiation conditions. 11 refs., 8 figs., 4 tabs.