Investigation of Pb–Li compatibility issues for the dual coolant blanket concept

One proposed blanket concept uses advanced ferritic alloys and a SiC/SiC composite flow channel insert with both Pb–17 at.%Li and He coolants. As the first step in determining the long-term compatibility of SiC/SiC in Pb–Li, specimens of high-purity, chemical vapor deposited (CVD) SiC were exposed in capsules for up to 5000 h at 800 °C and 1000 h at 1200 °C. Dissolved Si was detected in the Pb–Li after the highest temperature exposures suggesting that SiC may be limited to <1100 °C in Pb–Li. Aluminide coatings are being considered for corrosion resistant coatings for the tubing between the first wall and the heat exchanger. Initial results indicate that, in Pb–Li at 700 °C, FeCrAl, Fe3Al and NiAl form a protective alumina layer which reduces dissolution compared to type 316 stainless steel.