Numerical implementation and validation of a porous approach for fluid–structure interaction applied to pressurized water reactors fuel assemblies under axial water flow and dynamic excitation

2021 ◽  
Author(s):  
Vincent Faucher ◽  
Guilllaume Ricciardi ◽  
Romain Boccaccio ◽  
Kevin Cruz ◽  
Thibaud Lohez ◽  
...  
Keyword(s):  
Water Flow ◽  
Fluid Structure Interaction ◽  
Pressurized Water Reactors ◽  
Numerical Implementation ◽  
Pressurized Water ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Dynamic Excitation ◽  
Fuel Assemblies ◽  
Water Reactors

Integrity of a Curved Divider Plate in Steam Generators of Pressurized Water Reactors Due to Dynamic Pressure Loading Considering Fluid Structure Interaction

2002 ◽  
Author(s):  
Konrad Schramm
Keyword(s):  
Fluid Structure Interaction ◽  
Differential Pressure ◽  
Pressurized Water Reactors ◽  
Plastic Behavior ◽  
Pressure Loading ◽  
Steam Generators ◽  
Pressurized Water ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Water Reactors

A non-linear analysis procedure has been developed to investigate the plastic behavior of the divider (or partition) plate in Steam Generators (SG) of Pressurized Water Reactors (PWRs). The integrity of the divider plate in the primary channel head of a Steam Generator of a Pressurized Water Reactor has to be verified for a postulated loss of coolant accident (LOCA). Primary stresses due to differential pressure Δp have to be analyzed for faulted conditions. A static elastic-plastic finite element analysis for the divider plate was performed showing unrealistically high plastic deformation due to the high differential pressure loading resulting from the assumption of rigid walls in the fluid analysis. Therefore the LOCA is analyzed in a Fluid Structure Interaction Analysis (FSIA), representing the divider plate as a single degree of freedom system (SDOFS) acting like a piston. The present paper explains how the Δp across the plate was correlated with an equivalent displacement ve and how the mass of the plate is considered. In the FSIA a realistic dynamic response of the divider plate is considered now, with a significant reduction of differential pressure Δp. The analysis results proved the resistance of the divider plate with sufficient margin.

Situation of the Baffle-Former Bolts in Belgian Units

2009 ◽  
Author(s):  
Robert Ge´rard ◽  
Fre´de´ric Somville
Keyword(s):  
Stress Corrosion ◽  
Water Flow ◽  
Stress Corrosion Cracking ◽  
Structural Integrity ◽  
Operating Time ◽  
Reactor Vessel ◽  
Pressurized Water Reactors ◽  
Pressurized Water ◽  
Fuel Assemblies ◽  
Water Reactors

The baffle to former bolts are used in Pressurized Water Reactors to attach the baffle plates to the former plates in the reactor vessel lower internals. The resulting structure forms a boundary for the flow of coolant and provides lateral support to the fuel assemblies. Some edge bolts are also present, assembling together the baffle plates. After an operating time of the order of 120 000 hours, some bolts exhibit cracking at the junction of the head and the shaft of the bolt. Examinations of failed bolts have made it possible to identify the cause of cracking as irradiation assisted stress corrosion cracking (IASCC). Up to now, baffle bolt cracking has been detected in units older than 15 years, where the baffle bolts are not cooled (no holes in the former to allow a water flow on the bolt shaft). In Belgium the concerned unit are Tihange 1 and Doel 1–2. The paper summarizes the experience with baffle bolts cracking in Belgian units and the strategy implemented to mitigate this problem, consisting of structural integrity analyses, baffle bolts inspections and replacement, and research programs in the field of IASCC, including examinations of highly irradiated replaced bolts.

Identification of Non-Linear Damping of Nuclear Reactor Components in Case of One-to-One Internal Resonance

2016 ◽  
Author(s):  
Joachim Delannoy ◽  
Marco Amabili ◽  
Brett Matthews ◽  
Brian Painter ◽  
Kostas Karazis
Keyword(s):  
Fuel Assembly ◽  
Internal Resonance ◽  
Fluid Structure Interaction ◽  
Fundamental Parameter ◽  
Pressurized Water ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Safety Margins ◽  
Non Linear ◽  
One To One

In Pressurized Water Reactors (PWR) assemblies are exposed to challenging thermal, mechanical, and irradiation loads during operation. Global core and local fuel assembly flow fields coupled with seismic excitation result in fuel assembly and fuel rod vibrations. The fact that vibrations may become excessive in certain conditions has consequences on operational safety margins in fuel assemblies designs. In order to understand how the fuel assembly responds dynamically to an external excitation, it is important to identify the main characteristics of the structures. Among them, the fuel assembly system damping is a fundamental parameter that is usually identified by a number of experiments involving fluid-structure interaction. Recent studies have shown that the damping ratio increases with the excitation force when the structure is entering large-amplitude vibrations, in which case the geometric non-linearities have to be taken into account. The present paper presents an advanced identification procedure developed to identify the system characteristics from experimental non-linear response curves obtained from forced vibration tests, accounting for fluid-structure interaction, at different excitation levels. Furthermore, the numerical tool developed in this analysis is capable of working with systems presenting one-to-one internal resonance, i.e. systems with symmetry such as circular tubes and circular cylindrical shells. The method relies on a harmonic decomposition of the displacement to cope with the data usually available by vibration measurements.

scholarly journals Burnable Poison Selection and Neutronics Analysis of Plate Fuel Assemblies

2021 ◽  
Vol 9 ◽  
Author(s):  
Shikun Xu ◽  
Tao Yu ◽  
Jinsen Xie ◽  
Lei Yao ◽  
Zhulun Li
Keyword(s):  
Fuel Assembly ◽  
Critical Role ◽  
Pressurized Water Reactors ◽  
Effective Control ◽  
Pressurized Water ◽  
Burnable Poison ◽  
Fuel Assemblies ◽  
Long Life ◽  
Water Reactors ◽  
Selection Of

Burnable poisons play a critical role in long-life pressurized water reactors. Plate fuel elements have good application prospects in long-life pressurized water reactors. In long-life pressurized water reactors with large initial residual reactivity in the core, a reasonable selection of burnable poisons can suppress the large residual reactivity at beginning of lifetime and can achieve a long burnup depth at end of lifetime. Therefore, the selection of burnable poisons is a crucial factor to be considered in the design of long-life pressurized water reactors. In this study, the selection of burnable poisons and neutronics characteristics of long-life PWR plate fuel assembly were studied. The transport-burnup calculations of different burnable poison fuel assemblies were carried out. Some candidate BPs are selected to realize the effective control of reactivity. The results show that when the enriched isotopes 157Gd, 167Er and B4C are used as burnable poisons, there is almost no reactivity penalty; when PACS-J and 231Pa are used as burnable poisons, due to their own characteristics, not only does not cause reactivity penalty at end of lifetime, but also the fuel assembly life is extended, the fuel utilization rate is improved. The combination of PACS-J and the slow-burnup burnable poisons can obtain a better reactivity curve. The results of this article show that the plate fuel assemblies can be selected with enriched isotope 157Gd, enriched isotope 167Er, B4C, 231Pa and PACS-J as burnable poisons, and the combinations of burnable poisons can be selected with two combination schemes, PACS-Er and PACS-Pa.

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