Precipitation phenomena during corrosion testing in forced-convection Pb-15.7Li loop PICOLO

•Precipitates are formed to reduce oversaturation in the cold leg of PICOLO loop.•Precipitates were collected by the magnetic trap but not completely.•The electro-magnetic pump was plugged by precipitates and highlights the risk.•Precipitates are migrating with breeder flow and can growth up to some 100 μm.•The Fe/Cr precipitates exhibit a Cr amount of 9% similar to the Eurofer composition.