Mechanical Analysis of Underclad Cracks in Reactor Pressure Vessel Nozzles

2003 ◽  
Author(s):  
Nicolas Verdiere ◽  
Henriette Churier-Bossennec ◽  
Franc¸ois Champigny
Keyword(s):  
Mechanical Analysis ◽  
Reactor Vessel ◽  
Core Shell ◽  
Straight Section ◽  
The Core ◽  
Inner Radius ◽  
Service Inspection ◽  
Reactor Pressure ◽  
Circular Cracks ◽  
Fast Fracture

During the in-service inspection in 1999 in Tricastin 1 Nuclear Plant, underclad cracks had been discovered in the core shell. Following specific justification of these defects, other parts of the reactor vessel also sensitive to this kind of defects have been re-examined, and particularly RPV nozzles, which are classified as “concerned by fast fracture”. Recent assessments with large defects, superior to maximum realistic ones, have been conducted in different sections in the reactor vessel inlet and outlet nozzles: circular cracks of 10 mm in the inner radius, and 20 mm depth in the straight section. Theses assessments highlighted the verification of acceptance criteria in various, normal and emergency conditions with large margins. Fatigue analysis has also been conducted. For underclad cracks located in the inner radius of RPV inlet nozzles, a small propagation in the austenitic cladding is demonstrated but would not lead to any cladding perforation within 40 years.

Life Assessment of Components With Underclad Cracks in PWR

2004 ◽  
Author(s):  
Nicolas Verdiere ◽  
Pierre Cambefort ◽  
Karim Zamoum ◽  
Karl Payraudeau ◽  
Se´bastien Royer
Keyword(s):  
Maximum Size ◽  
Mechanical Analysis ◽  
Life Assessment ◽  
Core Shell ◽  
Mechanism Of Formation ◽  
The Core ◽  
Large Size ◽  
Service Inspection ◽  
Reactor Pressure ◽  
Selection Of

During the in-service inspection in 1999 in Tricastin 1 Nuclear Plant, underclad cracks had been discovered in the core shell. Following the specific demonstration of the acceptability of these defects, other components also sensitive to this kind of defects have been re-examined. The life assessment includes a review of the mechanism of formation of theses underclad flaws by cold cracking and the selection of the components sensitive to theses cracks. This includes various shells of the reactor pressure vessel, the steam generator and the pressurizer. A second part consists in mechanical analysis of theses selected components, with an underclad flaw of very large size. This is compared with the maximum size of a realistic crack, which depends of the size of the heat affected zone during the cladding process. The third part has to do with the In Service Inspection. This concerns only the reactor pressure nozzles — both inlet and outlet — which are examined during the inspection of the core shell of the reactor vessel.

Improved Reactor Vessel and Bottom Nozzle UT Inspection Experience

2005 ◽  
Author(s):  
S. W. Glass ◽  
A. Richmond ◽  
G. Alexander
Keyword(s):  
Pressure Vessel ◽  
Field Experience ◽  
Reactor Vessel ◽  
Reactor Pressure Vessel ◽  
Inspection Period ◽  
New Techniques ◽  
Nuclear Station ◽  
Service Inspection ◽  
Reactor Pressure

Framatome ANP, an AREVA and Siemens company, recently completed a combined ten-year reactor pressure vessel (RPV) in-service inspection (ISI) and a volumetric ultrasonic (UT) examination of all bottom-mounted nozzles (BMNs) at Florida Power & Light’s (FPL) Turkey Point-3 nuclear station. Both the 10-year RPV robot and the BMN tool had undergone significant improvements since their last deployment. The enhancements focused primarily on reducing inspection times. The new tools were also designed to minimize the in-containment lay-down area and utility support during the inspection period. This latter aspect was particularly critical for FPL during this outage because of the busy refuel floor schedule that included both vessel examination and head replacement tasks. It was logical to combine these two examinations since they are both performed with the internals completely removed. The vessel examination required approximately 4 days (95.5 hours) and the BMN examination required 1.5 days (36 hours). Total “hook-to-hook” time was 5.75 days (138 hours) — more than 1 day ahead of schedule. The dose savings over alternate inspection approaches for the BMN examination was also very significant. This paper discusses the tool improvements and new techniques used for the examinations of the RPV and the BMNs as well as the field experience during the FPL examination.

Reactor Pressure Vessel Life Management at French PWR Plants

2002 ◽  
Author(s):  
Anne Mermillod ◽  
Georges Bezdikian ◽  
Serge Rostain
Keyword(s):  
Electricity Generation ◽  
Safety Margin ◽  
Ductile Failure ◽  
Mechanical Analysis ◽  
Reactor Vessel ◽  
Experimental Program ◽  
Surveillance Programme ◽  
Input Parameters ◽  
Reactor Pressure

The capability of nuclear electricity generation by French Utility’s EDF (Electricite´ de France) is 75% of global generation, 58 PWR units are in operation, 34 units three-loop, 20 units four-loop (1300MWe) and 4 units four-loop (1450MWe). The French Utility methodology to justified reactor vessel assessment on specific plants is to verify, for a known defect (real or hypothetic), safety margin to non ductile failure for each transient and for case of loading. The demonstration must be done for each instant of the reactor vessel life, and must include material embrittlement caused by irradiation degradation. This paper will describe EDF methodology aging assessment for at least 40 years, comparing: • The boundary RTNDT (Reference Nil Ductility Transition Temperature) support by reactor vessel. • The estimated RTNDT at 40 years. Estimated RTNDT for 40 years is determined with a prediction formula that needs following input parameters: • The initial RTNDT during the construction. • Fluence assessment received by reactor vessel during 40 years in operation. • Chemistry material composition. The Boundary RTNDT supported by reactor vessel is determined with a mechanical analysis that needs the following input parameters: • Defect characteristics. • Transient definition. The determination of each parameter will be described, and an experimental program to verify the conservatism of methodology will be presented (Irradiation Surveillance Programme).

Magnetic Properties of Fe3O4/CoFe2O4 Composite Nanoparticles with Core/Shell Architecture

2020 ◽  
Vol 65 (10) ◽  
pp. 904
Author(s):  
V. O. Zamorskyi ◽  
Ya. M. Lytvynenko ◽  
A. M. Pogorily ◽  
A. I. Tovstolytkin ◽  
S. O. Solopan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Spinel Ferrite ◽  
Composite Nanoparticles ◽  
Core Shell ◽  
Cofe2o4 Nanoparticles ◽  
Core Diameter ◽  
The Core ◽  
Shell Particles ◽  
Interface Parameters ◽  
Shell Composite

Magnetic properties of the sets of Fe3O4(core)/CoFe2O4(shell) composite nanoparticles with a core diameter of about 6.3 nm and various shell thicknesses (0, 1.0, and 2.5 nm), as well as the mixtures of Fe3O4 and CoFe2O4 nanoparticles taken in the ratios corresponding to the core/shell material contents in the former case, have been studied. The results of magnetic research showed that the coating of magnetic nanoparticles with a shell gives rise to the appearance of two simultaneous effects: the modification of the core/shell interface parameters and the parameter change in both the nanoparticle’s core and shell themselves. As a result, the core/shell particles acquire new characteristics that are inherent neither to Fe3O4 nor to CoFe2O4. The obtained results open the way to the optimization and adaptation of the parameters of the core/shell spinel-ferrite-based nanoparticles for their application in various technological and biomedical domains.

scholarly journals Iron Based Core-Shell Structures as Versatile Materials: Magnetic Support and Solid Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 72
Author(s):  
Christian Zambrzycki ◽  
Runbang Shao ◽  
Archismita Misra ◽  
Carsten Streb ◽  
Ulrich Herr ◽  
...  
Keyword(s):  
Water Purification ◽  
Functional Materials ◽  
Core Material ◽  
Solid Catalyst ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
The Core ◽  
Shell Nanostructures ◽  
Sio2 Shell ◽  
Iron Based

Core-shell materials are promising functional materials for fundamental research and industrial application, as their properties can be adapted for specific applications. In particular, particles featuring iron or iron oxide as core material are relevant since they combine magnetic and catalytic properties. The addition of an SiO2 shell around the core particles introduces additional design aspects, such as a pore structure and surface functionalization. Herein, we describe the synthesis and application of iron-based core-shell nanoparticles for two different fields of research that is heterogeneous catalysis and water purification. The iron-based core shell materials were characterized by transmission electron microscopy, as well as N2-physisorption, X-ray diffraction, and vibrating-sample magnetometer measurements in order to correlate their properties with the performance in the target applications. Investigations of these materials in CO2 hydrogenation and water purification show their versatility and applicability in different fields of research and application, after suitable individual functionalization of the core-shell precursor. For design and application of magnetically separable particles, the SiO2 shell is surface-functionalized with an ionic liquid in order to bind water pollutants selectively. The core requires no functionalization, as it provides suitable magnetic properties in the as-made state. For catalytic application in synthesis gas reactions, the SiO2-stabilized core nanoparticles are reductively functionalized to provide the catalytically active metallic iron sites. Therefore, Fe@SiO2 core-shell nanostructures are shown to provide platform materials for various fields of application, after a specific functionalization.

scholarly journals Light-Scattering Simulations from Spherical Bimetallic Core–Shell Nanoparticles

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 359
Author(s):  
Francesco Ruffino
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Bimetallic Nanoparticles ◽  
Dominant Role ◽  
Scattered Light ◽  
Specific Interaction ◽  
Surface Enhanced Raman Spectroscopy ◽  
Localized Surface Plasmon ◽  
Core Shell ◽  
The Core

Bimetallic nanoparticles show novel electronic, optical, catalytic or photocatalytic properties different from those of monometallic nanoparticles and arising from the combination of the properties related to the presence of two individual metals but also from the synergy between the two metals. In this regard, bimetallic nanoparticles find applications in several technological areas ranging from energy production and storage to sensing. Often, these applications are based on optical properties of the bimetallic nanoparticles, for example, in plasmonic solar cells or in surface-enhanced Raman spectroscopy-based sensors. Hence, in these applications, the specific interaction between the bimetallic nanoparticles and the electromagnetic radiation plays the dominant role: properties as localized surface plasmon resonances and light-scattering efficiency are determined by the structure and shape of the bimetallic nanoparticles. In particular, for example, concerning core-shell bimetallic nanoparticles, the optical properties are strongly affected by the core/shell sizes ratio. On the basis of these considerations, in the present work, the Mie theory is used to analyze the light-scattering properties of bimetallic core–shell spherical nanoparticles (Au/Ag, AuPd, AuPt, CuAg, PdPt). By changing the core and shell sizes, calculations of the intensity of scattered light from these nanoparticles are reported in polar diagrams, and a comparison between the resulting scattering efficiencies is carried out so as to set a general framework useful to design light-scattering-based devices for desired applications.

Tuning and understanding the electronic effect of Co-Mo-O sties in bifunctional electrocatalysts for ultralong-lasting rechargable zinc-air battery

2021 ◽  
Author(s):  
Yi Guan ◽  
Nan Li ◽  
Jiao He ◽  
Yongliang Li ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Electronic Effect ◽  
Metal Organic Frameworks ◽  
Core Shell ◽  
Zeolitic Imidazolate Frameworks ◽  
Assembly Strategy ◽  
The Core ◽  
Bifunctional Electrocatalysts ◽  
Metal Organic ◽  
Air Battery

Herein, we report a post-assembly strategy by growing the bimetallic Co/Zn zeolitic imidazolate frameworks (BIMZIF) on the surface of the customized Mo metal-organic frameworks (MOFs) (Mo-MOF) to prepare the core-shell...

scholarly journals Solubilization of Charged Porphyrins in Interpolyelectrolyte Complexes: A Computer Study

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 502
Author(s):  
Karel Šindelka ◽  
Zuzana Limpouchová ◽  
Karel Procházka
Keyword(s):  
Dissipative Particle Dynamics ◽  
Water Soluble ◽  
Coarse Grained ◽  
Core Shell ◽  
Computer Study ◽  
Interpolyelectrolyte Complex ◽  
The Core ◽  
Porphyrin Derivatives ◽  
Oppositely Charged ◽  
Positively Charged

Using coarse-grained dissipative particle dynamics (DPD) with explicit electrostatics, we performed (i) an extensive series of simulations of the electrostatic co-assembly of asymmetric oppositely charged copolymers composed of one (either positively or negatively charged) polyelectrolyte (PE) block A and one water-soluble block B and (ii) studied the solubilization of positively charged porphyrin derivatives (P+) in the interpolyelectrolyte complex (IPEC) cores of co-assembled nanoparticles. We studied the stoichiometric mixtures of 137 A10+B25 and 137 A10−B25 chains with moderately hydrophobic A blocks (DPD interaction parameter aAS=35) and hydrophilic B blocks (aBS=25) with 10 to 120 P+ added (aPS=39). The P+ interactions with other components were set to match literature information on their limited solubility and aggregation behavior. The study shows that the moderately soluble P+ molecules easily solubilize in IPEC cores, where they partly replace PE+ and electrostatically crosslink PE− blocks. As the large P+ rings are apt to aggregate, P+ molecules aggregate in IPEC cores. The aggregation, which starts at very low loadings, is promoted by increasing the number of P+ in the mixture. The positively charged copolymers repelled from the central part of IPEC core partially concentrate at the core-shell interface and partially escape into bulk solvent depending on the amount of P+ in the mixture and on their association number, AS. If AS is lower than the ensemble average ⟨AS⟩n, the copolymer chains released from IPEC preferentially concentrate at the core-shell interface, thus increasing AS, which approaches ⟨AS⟩n. If AS>⟨AS⟩n, they escape into the bulk solvent.

scholarly journals Correction: Topology of transition metal dichalcogenides: the case of the core–shell architecture

Nanoscale ◽  
2021 ◽  
Author(s):  
Jennifer G. DiStefano ◽  
Akshay A. Murthy ◽  
Shiqiang Hao ◽  
Roberto dos Reis ◽  
Chris Wolverton ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Core Shell ◽  
The Core ◽  
Metal Dichalcogenides

Correction for ‘Topology of transition metal dichalcogenides: the case of the core–shell architecture’ by Jennifer G. DiStefano et al., Nanoscale, 2020, 12, 23897–23919, DOI: 10.1039/D0NR06660E.

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