The report describes the state-of-the-arts for the reconstitution of Charpy impact specimens in order to increase the reliability of fracture toughness results of the irradiated specimen in the view of life extension program of power reactor to be carried out in the future. The reconstituted Charpy specimen can increase the number of specimens by three times since each half of Charpy specimen can be recovered to a full impact specimen by proper welding process. The reliability of test results with irradiated specimen can be enhanced by the reconstituted Charpy impact specimens, so these specimens can be used to get another data in the life extension research program to investigate the variation of fracture toughness of irradiated materials as a function of neutron fluence. These specimens can also be used to get additional test results for thermal annealing study when in-situ annealing of the reactor vessel is needed. This report reviews the method to make two full Charpy specimen (reconstituted Charpy) specimen from two halves of tested specimen and the applicability of this method to life extension program, and compares the characteristics of various welding methods. (Author).