strong material such as stainless steel or the like and the ni based alloy then used to clad or line the interior surface of the stainless steel vessel in addition a ni based alloy of the aspect c of the present invention displays excellent resistance to stress corrosion cracking in supercritical water environments containing either sulfuric acid and phosphoric acid or phosphoric acid and hydrofluoric acid and can be used in such environments for extended periods meaning the alloy has excellent environmental and industrial potential in areas such as the detoxification of vx gas and gb gas and the like a ni based alloy of this aspect c is most effective when used in supercritical water environments containing non chlorine based inorganic acids such as sulfuric acid phosphoric acid and hydrofluoric acid although potential uses of the alloy are not restricted to this type of environment and the alloy can also be used in supercritical water environments containing hydrochloric acid or nitric acid supercritical water environments containing chloride salts such as sodium chloride magnesium chloride and calcium chloride or supercritical water environments containing ammonia accordingly the ni based alloy can also be used as the material for supercritical water devices used for treating space related waste products atomic waste products power production waste products as well as general industrial waste furthermore if a ni based alloy of this aspect c is used in the production of the reaction chamber in a treatment system then the outside.