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The brittle–ductile transition temperature (BDTT) and fracture toughness are useful indicators of the brittleness of reactor pressure vessel materials. However, current methods to analyze these parameters are expensive and time-consuming; moreover, the relevant mechanism is not very clear. Thus, in this study, a body-centered cubic crystal plasticity finite element model (CPFEM) based on the densities of dislocation and irradiation defects, which are full- and partial-absorption dislocation loops, was numerically implemented on A508-3 steel. Irradiation embrittlement was investigated in the CPFEM framework. The cleavage failure model for a representative volume element was proposed to calculate the BDTT, the results of which agreed well with experimental results in the literature for both unirradiated and irradiated samples. The risk for brittle failure is higher for irradiated samples at constant temperature. Furthermore, the proposed model combined with the Beremin cleavage fracture local approach, could estimate the fracture toughness of A508-3 steel at different temperatures before and after irradiation. The results obtained were consistent with reported experimental data, indicating that irradiation exacerbates the embrittlement. This work is beneficial to the calculation and evaluation of irradiation effect of RPV steel, providing reference for the research of reactor life extension. [ABSTRACT FROM AUTHOR]

The study of irradiation hardening and embrittlement is critically important for the development of next-generation structural materials tolerant to neutron irradiation, and could dramatically affect the approach to the design of components for advanced nuclear reactors. In addition, a growing interest is observed in the field of research and development of irradiation-resistant materials. This review aims to provide an overview of the theoretical development related to irradiation hardening and embrittlement at moderate irradiation conditions achieved in recent years, which can help extend our fundamental knowledge on nuclear structural materials. After a general introduction to the irradiation effects on metallic materials, recent research progress covering theoretical modelling is summarized for different types of structural materials. The fundamental mechanisms are elucidated within a wide range of temporal and spatial scales. This review closes with the current understanding of irradiation hardening and embrittlement, and puts some perspectives deserving further study. [ABSTRACT FROM AUTHOR]

Basing on the analysis of the radiation embrittlement of RPV materials, the paper proposes a model and dependencies for description of WWER-1000 vessel material embrittlement with copper content above 0.10%. Standard dose-time trend curves have been modernized. The dose-time trend curves have been modernized. [ABSTRACT FROM AUTHOR]

In fractographic study of steels of nuclear reactor vessels after tests for crack resistance, two major sources of brittle destruction are detected: nonmetallic impurities and intergranular or subgranular boundaries. X-ray spectral microanalysis reveals that these are manganese sulfides and silicon oxides. The probable size of nonmetallic impurities (∼1 μm) which can initiate brittle destruction is detected. The interrelation between critical stress intensity coefficient K and distance from 'leader' to fatigue crack point CID (cleavage initiation distance) is considered. The influence of irradiation conditions on crack resistance of steels is demonstrated. [ABSTRACT FROM AUTHOR]

Reactor internals are subjected to three principal operation effects: neutron and gamma irradiation, static and dynamic mechanical stresses and coolant chemistry. In this study, we investigate the effect of these mechanisms on WWER 440 reactor vessel internals and present lifetime analysis, in order to extend the operational lifetime of reactor vessel internals. [ABSTRACT FROM AUTHOR]

We discuss irradiation tests performed at the Budapest research reactor operating with 10 MW using a new irradiation rig. Some examples of the use of the irradiation rigs are presented: results of reactor pressure vessel cladding, 9% Cr steels (Euroferr), application of Master Curve to irradiated reactor pressure vessel steels, as well as irradiation tests of Ti-alloys and tungsten. [ABSTRACT FROM AUTHOR]

Mechanical properties of WWER-440 RPV weld joints have been studied with account of different states of the material: baseline (unirradiated), irradiated up to the average fast neutron fluence of $\backslash 6.5\; cdot\; 10^19$ n/$\backslash cm^2$, irradiated and eventually annealed, re-irradiated with the accumulated fast neutron fluence $\backslash 1.3\; cdot\; 10^20$ n/$\backslash cm^2$. Tensile, impact fracture, and fracture toughness tests were performed for each state of the material with the use of Charpy specimens (standard, reconstituted, and pre-cracked). [ABSTRACT FROM AUTHOR]

Radiation embrittlement and aging mechanisms for NPP reactor pressure vessels and vessel internals have been studied within NPP Plant Life Management activities for the evaluation, prediction, and monitoring of the critical components' service life. The main achievements of the SAFELIFE project, integrating various networks on PLIM issues, are given. Results of neutron embrittlement of model alloys are presented, and surveillance and research data on WWER reactor pressure vessel and other steels are analyzed. Projects for the development of destructive and non-destructive testing of irradiated materials are outlined. [ABSTRACT FROM AUTHOR]

EUROATOM research programs aimed at studying aging mechanisms and remedial procedures for structural materials of nuclear reactor components have been analyzed. Within this framework, projects are carried out focusing on the development of non-destructive techniques applied to thermal aging, neutron embrittlement monitoring, improved surveillance for WWER-440 reactors, dosimetry, and the use of various fracture mechanisms for NPP integrity assessment. Among major achievements are the ATHENA project activities on re-embrittlement model validation after annealing and the effect of chemical composition on the embrittlement rate in RPV steels. A brief description is given of the main results of current EUROATOM projects, as well as the goals of the next stage of research within the SAFELIFE network on the NPP Plant Life Management. [ABSTRACT FROM AUTHOR]