Surveillance specimens, for example Charpy specimens, are used to monitor the effect of irradiation embrittlement on Reactor Pressure Vessel (RPV) steels. Reconstitution technology is an advanced method that can be used to avoid possible shortages of surveillance specimens in case of long-term operation beyond design life. The validation of the reconstitution technology for surveillance specimens of RPV steels down to an insert length of 10 mm requires investigating the eventual annealing effect during reconstitution. The optimum irradiation conditions for reconstitution studies of irradiated specimens were investigated based on the basic data obtained on un-irradiated specimens. The irradiation fluence of 1 × 10¹⁹ n/cm² was found most appropriate to assess the influence of annealing during reconstitution.