nozzle partially or entirely with a replacement nozzle that offers a sufficiently large id for weld tooling insertion after welding the new nozzle to the reactor bottom material a small diameter nozzle sleeve is inserted therein and then welded to the new nozzle to restore the operability of the small diameter nozzle the sleeve is welded to the replacement nozzle from below by either a socket or fillet weld the original nozzle remnant in a partial nozzle repair is welded to the sleeve also by a socket or fillet weld in the case of a heater penetration the sleeve of the heater could be overlaid to increase the od for welding into the increased id of the penetration the described method may involve a full replacement of the tube 12 as shown in fig2 or a partial replacement of the tube 12 as shown in fig3 referring to fig3 it will be seen that the bottom section of tube 12 has been cut out to form a diameter d d in the section 14 originally holding that part of the tube 12 that is now significantly larger than that of original tube 12 this was done by machining out the bottom half section of the tube as well as the reactor vessel bottom material by known means leaving the top half section of tube 12 intact and located partially within the section 14 a replacement nozzle section 19 having an inside diameter equal to the outside diameter of tube 12 is now inserted into the machined diameter d d of section 14 and is welded to the reactor vessel base material of section 14 with an idtb weld since the id of the replacement nozzle 19 is now sufficient to provide access for idtb weld tooling a safe end 20.