[en] Results from a novel method for in-situ analysis of the reactor pressure vessel (RPV) metal, developed by a joint team of Bulgarian researches and NPP staff, are reported. The elemental content of the weld 4 of WWER-440/230 reactor has been determined. The method consists in excitation of emission lines in the visible and the near and far UV region by spark and arc. The light is analyzed by high resolution diffraction grids and is detected by photomultipliers. During the analyses the SPECTROPPORT apparatus was used and placed in the Universal Maintenance Cabin (URK-3) fixed inside the RPV. Detailed description is given of basic requirements for the analyzer, effect of the contact between the spectrometer head and the analyzed surface on the element analysis, effect of gamma radiation, the system and equipment for spectral analyses and scrap sampling, the spectrometer calibration. The most important finding of the analysis is the reduction of the phosphorus concentration in the first 1-1.5 mm of the weld (from 0.100 til 0.052%). The measured values up to 2 mm depth are consistent with chemical analysis performed in two institutes. The data for the elemental composition of the weld and for the base metal practically coincide with the corresponding data for Unit 1 in Greifswald-1 reactor. Results from ultrasonic and strength analysis are also reported. All available data and calculations show that the Unit 1 can be operated within the safe margins

[en] The paper deals with reactor pressure vessel (RPV) boat sampling performed at Kozloduy Nuclear Power Plant, Unit 1, from August to November 1996. Kozloduy NPP, Unit 1 has no reactor vessel material surveillance program. Changes in the material fracture toughness resulting from the fast neutron irradiation which cannot be monitored without removal of the vessel material. Therefore, the main objective of the project was to cut samples from the RPV wall in order to obtain samples of the RPV material for further structural analyses. The most critical area, i.e. weld No. 4 was determined as a location for boat sampling. Replication technique was applied in order to obtain precise determination of the weld geometry necessary for positioning of the cutting tool prior to boat sampling, and determination of divot depth left after boat sampling and grinding of sample sites. Boat sampling was performed by electrical discharge machining (EDM). Grinding of sample sites was implemented to minimize stress concentration effects on sample sites, to eliminate surface irregularities resulting from EDM process, and to eliminate recast layer on the surface of the EDM cut. Ultrasonic, liquid penetrant, magnetic particles, and visual examinations were performed after grinding to establish baseline data in the boat sampling area. The project preparation activities, apart from EDM process, and the site organization lead was entrusted to INETEC. The activities were funded by the PHARE program of the European Commission. (orig.)