RPV material investigations of the former VVER-440 Greifswald NPP

The Greifswald NPP was operated between 1973 and 1990. The units are of Russian WWER-440-230 type. Now trepans from the RPV were gained to investigate the post mortem properties of the material.
The paper describes the results of weld metal originating from the critical weld of the RPV of unit 1. The RPV of this unit was annealed after 14 years of operation, followed by two additional years of operation.
The neutron dosimetry was based on fluence calculations as well as retrospective Nb dosimetry. Both approaches are shortly described. A decrease of 60% through the thickness of the RPV was found by both methods.
The material test results comprise Charpy-V, tensile and fracture toughness parameters. The main interest is focussed on the comparison of assessment codes applied in Russia and other European countries where WWER-440 reactors are operated. An additional aspect is the comparison of results determined on sub-size Charpy specimens immediately after the annealing procedure.
The first results show, that the material properties are near the predicted values.