Distortion energy-electronic energy compensation determines the nature of solute interactions with irradiation induced vacancies in ferritic steel

2021 ◽  
Vol 23 (14) ◽  
pp. 8689-8704
Author(s):  
Sarita Ahlawat ◽  
K. Srinivasu ◽  
A. Biswas ◽  
Niharendu Choudhury
Keyword(s):  
Pressure Vessel ◽  
Ferritic Steel ◽  
Solute Atom ◽  
Electronic Energy ◽  
Fundamental Knowledge ◽  
Rpv Steel ◽  
Distortion Energy ◽  
Energy Compensation ◽  
Solute Interactions ◽  
Reactor Pressure

Fundamental knowledge of vacancy–solute atom (in particular, Cu and Ni) interactions at the electronic level is of utmost importance to understand experimentally observed Cu-precipitation in reactor pressure vessel (RPV) steel.

Effects of Neutron Irradiation on the Mechanical and Electromagnetic Properties of Reactor Pressure Vessel Steels

2017 ◽  
Author(s):  
Li Chengliang ◽  
Shu Guogang ◽  
Chen Jun ◽  
Liu Yi ◽  
Liu Wei ◽  
...  
Keyword(s):  
Neutron Irradiation ◽  
Pressure Vessel ◽  
Power Plants ◽  
Hysteresis Loops ◽  
Reactor Pressure Vessel ◽  
Electromagnetic Properties ◽  
Irradiation Damage ◽  
Indentation Hardness ◽  
Rpv Steel ◽  
Reactor Pressure

The effect of neutron irradiation damage of reactor pressure vessel (RPV) steels is a main failure mode. Accelerated neutron irradiation experiments at 292 °C were conducted on RPV steels, followed by testing of the mechanical, electrical and magnetic properties for both the unirradiated and irradiated steels in a hot laboratory. The results showed that a significant increase in the strength, an obvious decrease in toughness, a corresponding increase in resistivity, and the clockwise turn of the hysteresis loops, resulting in a slight decrease in saturation magnetization when the RPV steel irradiation damage reached 0.0409 dpa; at the same time, the variation rate of the resistivity between the irradiated and unirradiated RPV steels shows good agreement with the variation rates of the mechanical properties parameters, such as nano-indentation hardness, ultimate tensile strength, yield strength at 0.2% offset, upper shelf energy and reference nil ductility transition temperature. Thus, as a complement to destructive mechanical testing, the resistivity variation can be used as a potentially non-destructive evaluation technique for the monitoring of the RPV steel irradiation damage of operational nuclear power plants.

scholarly journals 3-D Atom Probe Observation of Solute Atom Clusters in Reactor Pressure Vessel Steels

Materia Japan ◽  
2008 ◽  
Vol 47 (12) ◽  
pp. 619-619
Author(s):  
Kenji Nishida ◽  
Kenji Dohi ◽  
Akiyoshi Nomoto ◽  
Naoki Soneda
Keyword(s):  
Pressure Vessel ◽  
Solute Atom ◽  
Atom Probe ◽  
Reactor Pressure Vessel ◽  
Atom Clusters ◽  
Pressure Vessel Steels ◽  
Reactor Pressure

Nondestructive SANS Study of Reactor Pressure Vessel Steel after Irradiation

2006 ◽  
Vol 321-323 ◽  
pp. 1667-1670
Author(s):  
Young Soo Han ◽  
Eun Joo Shin ◽  
Baek Seok Seong ◽  
Chang Hee Lee ◽  
Duck Gun Park
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Pressure Vessel ◽  
Small Angle Neutron Scattering ◽  
Reactor Pressure Vessel ◽  
Pressure Vessel Steel ◽  
Rpv Steel ◽  
Induced Defects ◽  
Irradiation Induced Defects ◽  
Reactor Pressure

The irradiation induced defects of irradiated reactor pressure vessel(RPV) steel were investigated by a small angle neutron scattering. The degradation of the mechanical properties of RPV steels during an irradiation in a nuclear power plant is closely related to the irradiation induced defects. The size of these defects is known to be a few nanometers, and the small angle neutron scattering technique is regarded as the best non destructive technique to characterize the nano sized inhomogeneities in bulk samples. The RPV steel was irradiated in the HANARO reactor in KAERI. The small angle neutron scattering experiments were performed at SANS instrument in the HANARO reactor. Both unirradiated and irradiated RPV steels were measured and the SANS data of both steels were compared. The nano sized irradiation induced defects were quantitatively analyzed by SANS. The type of defects was also analyzed based on the SANS results, and the effect of the chemical composition of the RPV steel on the irradiation induced defects was discussed.

Fracture Toughness in Postulated Crack Area of PTS Evaluation in Highly-Neutron Irradiated RPV Steel

2021 ◽  
Author(s):  
Yoosung Ha ◽  
Masaki Shimodaira ◽  
Hisashi Takamizawa ◽  
Tohru Tobita ◽  
Jinya Katsuyama ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Vickers Hardness ◽  
Heat Affected Zone ◽  
Pressure Vessel ◽  
Structural Integrity ◽  
Rpv Steel ◽  
Pressurized Thermal Shock ◽  
Inner Surface ◽  
Surveillance Specimens ◽  
Reactor Pressure

Abstract The Japanese Electric Association Code 4206-2016 requires that the semi-elliptical crack sized 10 mm in depth × 60 mm in length shall be postulated near the inner surface of a reactor pressure vessel (RPV) in pressurized thermal shock events. The fracture toughness distribution was investigated in the postulated crack area under the PTS events of unirradiated and highly-neutron irradiated RPV steels. Vickers hardness in heat-affected zone (HAZ) due to stainless overlay cladding and 10 mm from the cladding were higher than that of a quarter thickness position, where the surveillance specimens are machined, for both unirradiated (E1) and irradiated (up to 1 × 1020 n/cm2, WIM) materials. Fracture toughness of HAZ and 10 mm from the cladding was higher for the above highly-neutron irradiated material. The same result was obtained in the unirradiated material. Therefore, it was confirmed that fracture toughness obtained from surveillance specimens can provide conservative assessment of structural integrity of RPV.

scholarly journals Reactor Pressure Vessel Steel Smart Behavior as Cause of Instability in Kinetics of Radiation Embrittlement

2019 ◽  
Vol 4 (2) ◽  
Keyword(s):  
Fast Neutron ◽  
Radiation Damage ◽  
Pressure Vessel ◽  
Radiation Stability ◽  
The Self ◽  
Radiation Embrittlement ◽  
Neutron Intensity ◽  
Rpv Steel ◽  
Kinetics Of ◽  
Reactor Pressure

Fast neutron intensity influence on reactor materials radiation damage is a critically important question in the problem of the correct use of the accelerated irradiation tests data for substantiation of the materials workability in real irradiation conditions that is low neutron intensity. Investigations of the fast neutron intensity (flux) influence on radiation damage and experimental data scattering reveal the existence of non-monotonous sections in kinetics of the reactor pressure vessels (RPV) steel damage. Discovery of the oscillations as indicator of the self-organization processes presence give reasons for new ways searching on reactor pressure vessel (RPV) steel radiation stability increasing and attempt of the self-restoring metal elaboration. Revealing of the wavelike process in the form of non monotonous parts of the kinetics of radiation embrittlement testifies that periodic transformation of the structure take place. This fact actualizes the problem of more precise definition of the RPV materials radiation embrittlement mechanisms and gives reasons for search of the ways to manage the radiation stability (nanostructuring and so on to stimulate the radiation defects annihilation), development of the means for creating of more stableness self recovering smart materials.

State of Advancement of the International REVE Project: Computational Modelling of Irradiation-Induced Hardening in Reactor Pressure Vessel Steels and Relevant Experimental Validation Programme

2002 ◽  
Author(s):  
Lorenzo Malerba ◽  
Eric van Walle ◽  
Christophe Domain ◽  
Stephanie Jumel ◽  
Jean-Claude Van Duysen
Keyword(s):  
Pressure Vessel ◽  
Large Scale ◽  
Methodological Approach ◽  
Computational Modelling ◽  
Ternary Systems ◽  
Reactor Pressure Vessel ◽  
Dislocation Loops ◽  
Simulation Tools ◽  
Rpv Steel ◽  
Reactor Pressure

The REVE (REactor for Virtual Experiments) project is an international joint effort aimed at developing multiscale modelling computational toolboxes capable of simulating the behaviour of materials under irradiation at different time and length scales. Well grounded numerical techniques such as molecular dynamics (MD) and Monte Carlo (MC) algorithms, as well as rate equation (RE) and dislocation-defect interaction theory, form the basis on which the project is built. The goal is to put together a suite of integrated codes capable of deducing the changes in macroscopic properties starting from a detailed simulation of the microstructural changes produced by irradiation in materials. To achieve this objective, several European laboratories are closely collaborating, while exchanging data with American and Japanese laboratories currently pursuing similar approaches. The material chosen for the first phase of this project is reactor pressure vessel (RPV) steel, the target macrosocopic magnitude to be predicted being the yield strenght increase (Δσy) due, essentially, to irradiation-enhanced formation of intragranular solute atom precipitates or clouds, as well as irradiation induced defects in the matrix, such as point defect clusters and dislocation loops. A description of the methodological approach used in the project and its current state is given in the paper. The development of the simulation tools requires a continuous feedback from ad hoc experimental data. In the framework of the REVE project SCK·CEN has therefore performed a neutron irradiation campaign of model alloys of growing complexity (from pure Fe to binary and ternary systems and a real RPV steel) in the Belgian test reactor BR2 and is currently carrying on the subsequent materials characterisation using its hot cell facilities. The paper gives the details of this experimental programme — probably the first large-scale one devoted to the validation of numerical simulation tools — and presents and discusses the first available results, with a view to their use as feedback for the improvement of the computational modelling.

Study on Irradiation Damage of RPV Steels Based on Coupling Cluster Dynamics and Crystal Plasticity Finite Element Method

2020 ◽  
Author(s):  
Xiaotong Wang ◽  
Ying Luo ◽  
Yuanyuan Dong ◽  
Weihua Yao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crystal Plasticity ◽  
Pressure Vessel ◽  
Irradiation Damage ◽  
Irradiation Hardening ◽  
Crystal Plasticity Finite Element ◽  
Rpv Steel ◽  
Reactor Pressure ◽  
Element Method

Abstract Irradiation hardening is one of the most important aging effects of reactor pressure vessel (RPV) steel in long-term service. A number of studies have indicated that irradiation hardening is mainly caused by irradiation induced defects, such as dislocation loops and precipitates. In this paper, we have simulated the irradiation damage of low-copper reactor pressure vessel (RPV) steel. The generation of Mn-Ni-Si precipitates is simulated by the cluster dynamics model based on rate theory. On this basis, the crystal plasticity finite element method based on modified crystal plasticity model is used to simulate the effect of Mn-Ni-Si precipitates on the mechanical properties of RPV steels. The simulated results has been compared with the experimental results from the literature. By coupling the cluster dynamics and the crystal plastic finite element method, we suggest a multi-scale simulation method to simulate and predict irradiation damage of RPV steel.

scholarly journals The Cause of Intergranular (IG) Fracture by Thermal Embrittlement in SA508 of Reactor Pressure Vessel (RPV) Steel

2021 ◽  
Vol 59 (9) ◽  
pp. 589-601
Author(s):  
Sung Soo Kim ◽  
Jung Jong Yeob ◽  
Young Suk Kim
Keyword(s):  
Thermal Treatment ◽  
Pressure Vessel ◽  
Boundary Segregation ◽  
Entropy Change ◽  
Reactor Pressure Vessel ◽  
Atomic Diffusion ◽  
New Paradigm ◽  
Lattice Contraction ◽  
Rpv Steel ◽  
Reactor Pressure

Intergranular(IG) fracture due to thermal treatment has been reported in a reactor pressure vessel(RPV) steel of Russian light water reactor in last decade. This is attributed to grain boundary segregation of phosphorus (P) or precipitation of carbide, etc.. This is a finding a difference in microstructure before and after IG cracking; this cannot explain the cause of the IG embrittlement. This old paradigm follows only correlation. Recently, a mechanism in which IG embrittlement occurs due to a decrease in entropy of a material has been reported at a temperature where atomic diffusion is possible. It is anticipated that new paradigm can explain the IG embrittlement of RPV based on a causal relationship. Thus, the thermal treatment at 350-420 oC was applied to RPV steel of SA508 and IG cracking was confirmed. DSC analysis was applied to confirm whether a decrease in entropy due to a short range ordering reaction occurs in SA508. It was possible to quantify the entropy change(⊿S= Q/T) through DSC measurement. A lattice changes due to thermal treatment were confirmed using XRD analysis in aged specimens. The results showed that lattice contraction by aging causes a reduction of fracture toughness. The internal stress formed inside the material due to entropy reduction can be calculated by multiplying the exothermic energy per unit mass by the density. This relationship is expressed by a equation of stress(σ) = exothermic heat(⊿Q) x density(ρ).

Fracture Toughness Evaluation of Neutron-Irradiated Reactor Pressure Vessel Steel Using Miniature-C(T) Specimens

2017 ◽  
Author(s):  
Yoosung Ha ◽  
Tohru Tobita ◽  
Hisashi Takamizawa ◽  
Yutaka Nishiyama
Keyword(s):  
Fracture Toughness ◽  
Pressure Vessel ◽  
Reactor Pressure Vessel ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Reactor Pressure Vessel Steel ◽  
Rpv Steel ◽  
Toughness Evaluation ◽  
Fracture Toughness Evaluation ◽  
Reactor Pressure

The applicability of miniature-C(T) (Mini-C(T)) specimens to fracture toughness evaluation was investigated for neutron-irradiated reactor pressure vessel (RPV) steel. By carefully selecting the test temperature, valid fracture toughness and reference temperature (To) were determined successfully with a relatively small number of specimens. The value of To determined using irradiated Mini-C(T) specimens was in good agreement with that determined using irradiated pre-cracked Charpy-type (PCCv) specimens. In addition, the scatter of the 1T-equivalent fracture toughness values obtained using the irradiated Mini-C(T) specimens was not significantly different from that obtained using the irradiated PCCv and other larger unirradiated specimens. The To values determined using Mini-C(T) specimens agree very well with the correlation between the Charpy 41J transition temperature and the To of commercially manufactured RPV steels reported in the past.

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