Nuclear fuel re-processing plant

To present invention concerns welded portions in nuclear fuel re-processing plants and it particularly relates to a plant having austenite steel welded portions with less nitric acid corrosion sensitivity. Layers comprising at least one of elements selected from the group consisting of Ti, Zr, Hf, V, Nb and Ta or at least one of oxides thereof are formed to the surface of the austenite steel welded portions. This can reduce the possibility of nitric acid corrosion damage, particularly, at the welded portion under intense γ-ray irradiation in the nuclear fuel re-processing plant. (K.Y.)