•The influence of a very high neutron fluence, up to 3.2 × 1025 m−2, E>0.5 MeV, on the properties of VVER-440 weld was studied.•The effectiveness of recovery annealing at two different temperatures of the highly irradiated weld was investigated.•Long-term irradiation causes severe hardening and embrittlement and the formation of ultra-fine “black-dot “damage.•Recovery annealing at 475 °C results in significant recovery of mechanical properties, disappearance of the radiation-induced “black-dot” damage. Mechanical testing and microstructural investigation on VVER-440 15Cr2MoV welds were carried out after irradiation and after recovery annealing treatment at two different temperatures (340 °C and 475 °C) for 100 h. The welds are part of the last surveillance chain of an Armenian nuclear power plant and have been irradiated for ~200,000 h at 270 °C, receiving extreme high fluence values (3.2 × 1025 m−2, E>0.5 MeV). Prolonged irradiation caused severe hardening and embrittlement. The increase of the yield strength and corresponding decrease in the uniform elongation are, 606 MPa and 10.2% respectively, when compared to the as-received state. Annealing at 340 °C did not show noteworthy recovery of the tensile properties. The recovery annealing treatment for 100 h at 475 °C resulted a significant recovery of the yield strength and relative uniform elongation (82% and 97% respectively) in conjunction with the disappearance of the irradiation-induced black-dot damage. The contribution of the observed irradiation-induced microstructural features to the total measured hardening was modelled using the Russel-Brown dispersion hardening model to qualitatively explain the observed hardening and recovery of the tensile properties after irradiation and annealing treatment respectively.