Assessment of the WWER-440/V-213 reactor condition

Radiation stability of WWER RPV cladding materials

“…From the open literature typical un-irradiated values of the DBTT of WWER cladding are estimated, using the criterion of 40 J/cm 2 , to be in the range of À40 to À20 1C [19]; with small variations between different layers. The effect of irradiation, for WWER-440 end-of-life fluence, in terms of DBTT shift (DDBTT) is reported to be in the range of 60-90 1C, with small differences between layers (approximately 20 1C); with 100 1C considered as the maximum value of the shift [1].…”

“…To neutralise dilution with the base metal, prevent hot cracking and induce resistance to intergranular corrosion, a highly overalloyed material is used for welding the first pass of the austenitic cladding. The following welding materials are used for WWER RPV cladding: first layer (one bead) welding strip of the type Sv-07Cr25Ni13 and OF-10 flux; second layer (two beads) welding strip of the type Sv-8Cr19Ni10Mn2Nb and OF-10 flux, their original requirements are summarised in Table 1 [1]. After the cladding application, tempering of the clad metal is made in order to relieve residual welding stresses.…”

“…The structure of the cladding material is then similar to a weld structure, with a typical content of 3-10% of d-ferrite (preventing hot cracking). If we look into more detail the cladding structure can be sub-divided into a few individual layers (typically three) reflecting the cladding welding technology designed to optimise adherence to the base metal [1]. The grain size of the material is large, as can be observed in Fig.…”

“…To protect the reactor pressure vessel (RPV), made of ferritic low-alloy steel, from primary water corrosion the inner surface of the vessel of Russian-design WWERs, just as in western-designed reactors, is coated with a thin layer of anticorrosive material [1]. To be noted is that the first generation of WWER pressure vessels were designed and made without any anticorrosive protection material [2].…”

Probabilistic Assessment of Crack Failure of Reactor Pressure Vessel (RPV) Cladding Material

“…Russian designed VVER-1200 reactor pressure vessels are made of ferritic low-alloy steels. The inner surface of these RPV is coated with anti-corrosive material to protect it from corrosion environment that was not considered in case of first generation VVER reactors (Timofeev and Karzov, 2006). Austenitic steel is used for RPV cladding material because of its special characteristics like ductility, corrosion resistance, cryogenic toughness, strength and hardness (Timofeev and Ulin, 1992).…”