A turbine rotor blade , comprising: an airfoil body including a concave pressure side outer wall and a convex suction side outer wall that connect along a leading edge and a trailing edge , the concave pressure side outer wall and the convex suction side outer wall having an airfoil inner surface defining a radially extending chamber for receiving a coolant flow; a tip end at a radial outer end of the airfoil body ; a shank at a radial inner end of the airfoil body , the radially extending chamber extending at least partially into the shank to define a shank inner surface ; and an impingement cooling structure within the radially extending chamber , the impingement cooling structure including: a hollow body including a first end , a second end , an interior surface and an exterior surface , a plurality of cooling passages through the hollow body and in fluid communication with the radially extending chamber to allow the coolant flow to pass from the interior surface of the hollow body to impinge on at least the airfoil inner surface , wherein the first end of the hollow body is integrally formed to the shank inner surface , wherein the second end of the hollow body is integrally formed to an inner surface of the tip end , and wherein the exterior surface of the hollow body is uniformly spaced from the airfoil inner surface between the first end and the second end of the hollow body . an airfoil body including a concave pressure side outer wall and a convex suction side outer wall that connect along a leading edge and a trailing edge , the concave pressure side outer wall and the convex suction side outer wall having an airfoil inner surface defining a radially extending chamber for receiving a coolant flow; a tip end at a radial outer end of the airfoil body ; a shank at a radial inner end of the airfoil body , the radially extending chamber extending at least partially into the shank to define a shank inner surface ; and an impingement cooling structure within the radially extending chamber , the impingement cooling structure including: a hollow body including a first end , a second end , an interior surface and an exterior surface , a plurality of cooling passages through the hollow body and in fluid communication with the radially extending chamber to allow the coolant flow to pass from the interior surface of the hollow body to impinge on at least the airfoil inner surface , wherein the first end of the hollow body is integrally formed to the shank inner surface , wherein the second end of the hollow body is integrally formed to an inner surface of the tip end , and wherein the exterior surface of the hollow body is uniformly spaced from the airfoil inner surface between the first end and the second end of the hollow body . a hollow body including a first end , a second end , an interior surface and an exterior surface , a plurality of cooling passages through the hollow body and in fluid communication with the radially extending chamber to allow the coolant flow to pass from the interior surface of the hollow body to impinge on at least the airfoil inner surface , wherein the first end of the hollow body is integrally formed to the shank inner surface , wherein the second end of the hollow body is integrally formed to an inner surface of the tip end , and wherein the exterior surface of the hollow body is uniformly spaced from the airfoil inner surface between the first end and the second end of the hollow body . <EOS>