Method of assuring nuclear fuel rod pressurization during manufacture

A method of determining and assuring that the pressure charged in a fuel rod is retained therein after the rod is sealed by welding a hole closed in the fuel rod end plug are described. The fuel rod end having the open end plug is sealed in a plenum chamber of known volume. A helium source then charges a first chamber to a predetermined pressure, and after isolating the helium source, the first chamber is discharged into the plenum chamber and the fuel rod. If a pressure sensor in the system indicates a relatively high reading, the end plug has not permitted gas to pass into the fuel rod. A relatively low reading indicates that the fuel rod has been pressurized and the hole in the end plug is then welded shut. To verify that the end plug is properly sealed, the plenum chamber is vented to a third chamber of known volume and the system pressure is then determined. If such pressure reaches a predetermined high value, the end plug weld is defective. A relativel low reading indicates that the integrity o the seal weld is sound