In-depth element analysis of weld no. 4 of RPV of unit no. 1 of KzNPP (atomic emission spectroscopy)

Two micro boat samples cut from weld no. 4 of RPV of unit 1 of Kozloduy Nuclear Power Plant (NNP) were studied by atomic emission spectroscopy for the content of phosphorus. The analysis was performed at several depths on flat surfaces, machined by a cutter. Special procedures were developed for the accounting of the dark current generated by the radioactivity of the samples. The final results for phosphorus for 0.1 mm depth is 0.0485–0.0515 wt%, for depths 2.4–6.2 mm the content is 0.0449±0.0022 wt% and for 6.6 mm the content is 0.0423±0.0022 wt%. The results are in good agreement with independent analysis performed at the Institute I.V. Kurchatov in Moscow and also with the results from wet chemical analysis performed at the Institute of Metal Science in Sofia.