Dynamic Response Analysis of Control Rod Drive Mechanism Under the Stepping Impact Force for Nuclear Power Plants

2012 ◽  
Author(s):  
Xiaoyao Shen ◽  
Yongcheng Xie
Keyword(s):  
Dynamic Response ◽  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
Impact Force ◽  
Response Analysis ◽  
Control Rod ◽  
Drive Mechanism ◽  
Finite Element Software ◽  
The Impact

The control rod drive mechanism (CRDM) is an important safety-related component in the nuclear power plant (NPP). When CRDM steps upward or downward, the pressure-containing housing of CRDM is shocked axially by an impact force from the engagement of the magnetic pole and the armature. To ensure the structural integrity of the primary coolant loop and the functionality of CRDM, dynamic response of CRDM under the impact force should be studied. In this manuscript, the commercial finite element software ANSYS is chosen to analyze the nonlinear impact problem. A nonlinear model is setup in ANSYS, including main CRDM parts such as the control rod, poles and armatures, as well as nonlinear gaps. The transient analysis method is adopted to calculate CRDM dynamic response when it steps upward. The impact loads and displacements at typical CRDM locations are successfully obtained, which are essential for design and stress analysis of CRDM.

Proposal for Evaluation With Strain-Based Criterion of Impact Phenomena Between Steel Structure and Tornado Missile

2016 ◽  
Author(s):  
Yuko Sakamoto ◽  
Koji Shirai ◽  
Toshiko Udagawa ◽  
Shunsuke Kondo
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Impact Analysis ◽  
Structural Integrity ◽  
Steel Structures ◽  
Severe Accident ◽  
Numerical Code ◽  
Pressurized Water ◽  
Impact Phenomena ◽  
The Impact

In Japan, nuclear power plants must be protected from tornado missiles that are prescribed by Nuclear Regular Authority (NRA). When evaluating the structural integrity of steel structures in the plant with impact analysis by numerical code, strain-based criteria are appropriate because the tornado missiles have huge impact energy and may cause large deformation of the structures. As one of the strain-based criteria, the Japan Society of Mechanical Engineers (JSME) prescribes limiting triaxial strain for severe accident of Pressurized Water Reactor (PWR) steel containment. To confirm whether or not this criterion is appropriate to the evaluation of the impact phenomena between the steel structures and the tornado missiles, a free drop impact experiment to steel plates (carbon steel and austenitic stainless steel) was carried out with heavy weights imitated on one of the tornado missiles, followed by an impact analysis of the experiment with AUTODYN code and the JSME strain-based criterion. Consequently, it was confirmed that the strain-based criterion of JSME standard was for evaluating the fracture of steel structures caused by tornado missiles.

scholarly journals Dynamic Response Analysis of Retaining Dam under the Impact of Solid-Liquid Two-Phase Debris Flow Based on the Coupled SPH-DEM-FEM Method

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Bailong Li ◽  
Changming Wang ◽  
Yanying Li ◽  
Yiao Liu ◽  
Nan Jiang ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Debris Flow ◽  
Impact Force ◽  
Time History ◽  
Impact Behavior ◽  
Response Analysis ◽  
Two Phase ◽  
Fem Method ◽  
Solid Liquid ◽  
The Impact

Based on the coupled SPH-DEM-FEM numerical method, this paper analyzes the dynamic interaction of solid debris flow particle-liquid debris flow slurry-retaining dam in order to explore the dynamic response of retaining dam under the impact of the solid-liquid two-phase debris flow and delves into the process of the debris flow impact on the dam, the impact force of debris flow, and the elastic-plastic time-history characteristics of the dam under different slopes of trapezoidal grooves. The calculation results show that the coupled SPH-DEM-FEM method can vividly simulate the impact behavior of the solid-liquid two-phase debris flow on the dam, reproduce the impact, climbing, and siltation in the process of the debris flow impact; the dynamic time-history curve of the retaining dam is consistent with the law of the literature, and the result of the debris flow impact force obtained is close to that of the empirical formula. Moreover, this paper studies the impact force distribution of the debris flow impact process. The results have a certain reference value for the study of the dynamic response of the retaining dam under the impact of the solid-liquid two-phase debris flow and the engineering design of the debris flow-retaining dam.

Comparison of Analytical Methods to Study the Impact of a Postulated Closure Head Drop Accident on the Structural Integrity of the Bottom-Mounted Instrumentation System

2010 ◽  
Author(s):  
William C. Castillo ◽  
Geoffrey M. Loy ◽  
Joseph M. Remic ◽  
David P. Molitoris ◽  
George J. Demetri ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
The United States ◽  
Reactor Vessel ◽  
Primary Coolant ◽  
Heavy Load ◽  
Pressurized Water ◽  
System Pressure ◽  
The Impact

During typical nuclear power plant refueling activities for a pressurized water reactor (PWR), the reactor vessel closure head assembly must be removed from the reactor vessel (RV), transported for storage, and returned to the RV after refueling. This is categorized as a critical heavy load lift in NUREG-0612 [1] because a drop accident could result in damage to the components required to cool the fuel in the RV core. In order to mitigate the potentially severe consequences of a closure head drop, the United States Nuclear Regulatory Commission (USNRC) has mandated that nuclear power plants upgrade to a single failure-proof crane, show single failure-proof crane equivalence, or perform a head drop analysis to demonstrate that the core remains covered with coolant and sufficient cooling is available after the head drop accident. The primary coolant-retaining components associated with the RV are the inlet and outlet nozzles and the hot and cold leg main loop piping. Typical head drop analyses have considered these components to ensure that their structural integrity is maintained. One coolant-retaining component that has not been included in head drop evaluations on a consistent basis is the bottom-mounted instrumentation (BMI) system. In a typical Westinghouse PWR, 50 to 60 BMI nozzles are connected through the bottom hemisphere of the RV to one-inch diameter guide tubes which run under the vessel to a seal table above. Failure of the BMI system has the potential to adversely affect core coolability, especially if multiple failures are postulated within the system. A study was performed to compare static and dynamic methods of analyzing the effects of a head drop accident on the structural integrity of the BMI system. This paper presents the results of that study and assesses the adequacy of each method. Acceptability of the BMI system pressure boundary is based on the Nuclear Energy Institute Initiative (NEI 08–05 [2]) criteria for coolant-retaining components, which are based on Section III, Appendix F of the ASME Code [3].

Study on Change of Chromium Plating Thickness of Threads of Control Rod Drive Mechanism of Nuclear Power

2019 ◽  
Vol 956 ◽  
pp. 125-134
Author(s):  
Fang Wang ◽  
Song Xue ◽  
En Jiang
Keyword(s):  
Current Density ◽  
Nuclear Power ◽  
Power Plants ◽  
High Current Density ◽  
Root Diameter ◽  
Nuclear Radiation ◽  
Thickness Change ◽  
Control Rod ◽  
Drive Mechanism ◽  
Chromium Plating

Control rod drive mechanism is one of the key main components in nuclear power plants and serves in harsh environments such as high temperature, high pressure and nuclear radiation. In order to ensure the service life and to prevent biting when assembling, some of the threads of control rod drive mechanism need to be chromium plated. In view of the high demands of the same chromium plating thickness on all surfaces of the threads of control rod drive mechanism of nuclear power and non-uniformity in chromium plating thickness of threads due to poor throwing power of chromium plating solution, five representative kinds of threads of control rod drive mechanism were selected and the plating thickness change of the root diameter, pitch diameter and crest diameter of threads was studied in this paper by means of depositing different thickness chromium coating on the surface of threads. The experimental results show that thicker coating is deposited on the crest of thread because of high current density and thinner coating is deposited on the root of thread because of low current density, which can provide reference for specification of chromium plating thickness of thread products of control rod drive mechanism.

Impact Resistant Design for FLEX Building Equipment Door

2016 ◽  
Author(s):  
Shakir Y. Haider ◽  
David J. Calhoun
Keyword(s):  
Dynamic Response ◽  
Natural Disaster ◽  
Nuclear Power ◽  
Power Plants ◽  
Limit State ◽  
Time History ◽  
Nuclear Regulatory Commission ◽  
Integration Time ◽  
Limit States ◽  
Finite Element Software

After the 2011 Japan earthquake and tsunami caused significant damage at Fukushima Daiichi, the Nuclear Regulatory Commission required all US nuclear power plants to have a mitigation strategy for beyond design basis events. Industry-developed response plans, called “FLEX” strategies, deployed new, portable equipment such as diesel generators and cooling pumps. As this new equipment needs to be available after a natural disaster, storage in protected locations is required. Many nuclear plants have recently constructed new storage buildings, or FLEX buildings, as part of their post-Fukushima strategy. The equipment door is a critical component of a FLEX building. Large enough to drive a semi-trailer truck through, it is required to protect the equipment in case of an earthquake, flood, tornado and also may need to be capable of opening within a few minutes in order to respond during an emergency. The equipment door presented in this paper serves these purposes very effectively. The composite section of the door is capable of shielding the structure from penetration as well as overall dynamic response from tornado missile impact. The door travels on an overhead rail which, being indoors and above the opening, provides reliable door movement in case of snow or ice during winters or in case of debris from wind or tornado. Latches capable of withstanding tornado missile impact forces also restrain the door in case of wind or seismic forces. The door is opened by means of motorized trollies and is also equipped with a backup opening device by means of an air winch in case of a power loss. The door and the latches that restrain the door from impact are analyzed using ANSYS finite element software. A limit state analysis is performed that identifies the sequence of yield limit states for the components of the door and the door latch as the loading progresses. The analysis continues until the ductility limit state for the latch is reached. Redistribution of stresses within the components of the latch is observed during the analysis. A modal analysis and a direct integration time history analysis is also performed to capture the dynamic response due to impact loading. Overall, this paper presents a highly robust and reliable design for a FLEX building equipment door that is capable of protecting the contents of the building during a natural disaster and remaining operational during the response after an emergency.

Dynamic Response Analysis of the T-Shaped Steel Reinforced Concrete Column under Different Impact Conditions

2013 ◽  
Vol 351-352 ◽  
pp. 663-666
Author(s):  
Shou Yan Bai ◽  
Jing Jiang ◽  
Ya Feng Xu
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Response ◽  
Response Analysis ◽  
Concrete Column ◽  
Lateral Impact ◽  
Reinforced Concrete Column ◽  
Impact Site ◽  
Steel Reinforced Concrete ◽  
Finite Element Software ◽  
The Impact

This paper simulated the resistance to lateral impact properties of the T-shaped steel reinforced concrete column through the large finite element software ABAQUS. Extracting the time-displacement curves of different impact sites, by comparison we know: with the impact site is farther and farther from solid end, the maximum lateral displacement in the impact site of the member is bigger and bigger. The maximum displacements in the symmetrical place to the mid-span of the member are very similar. From time-displacement curves of seven models we can know, after reaching the ultimate bearing capacity, the curves leveled off gradually and changed slowly showing good stability and showing good ductility and deformation capacity. It can be concluded: the impact different parts of the dynamic response of lateral impact of the T-shaped steel reinforced concrete columns have a certain impact.

Weld Residual Stress Activities Within the ATLAS+ Project

2018 ◽  
Author(s):  
Mike C. Smith
Keyword(s):  
Residual Stress ◽  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
Integrity Assessment ◽  
Weld Residual Stress ◽  
Stress Profiles ◽  
Assessment Procedures ◽  
Design And Manufacture ◽  
The Impact

Weld residual stresses can have significant effects on the service performance and structural integrity of pressure-retaining components in nuclear power plants. Reliable prediction and measurement of residual stress in plant-representative components can be challenging. The impact of residual stress on structural integrity can also be difficult to predict reliably. This paper describes the residual stress activities taking place within ATLAS+, and covers welded mock-up design and manufacture, residual stress measurements and simulation, the development of residual stress profiles for structural integrity assessment, and their incorporation into assessment procedures.

Dynamic Analysis and Evaluation of Control Rod Device Mechanism Missile Impact on Shielding Plate

2018 ◽  
Author(s):  
Xianhui Ye ◽  
Furui Xiong ◽  
Bin Zheng ◽  
Naibin Jiang
Keyword(s):  
Maximum Stress ◽  
Structural Integrity ◽  
Strain Analysis ◽  
Response Analysis ◽  
Structural Failure ◽  
Control Rod ◽  
Analysis And Evaluation ◽  
New Type ◽  
Maximum Stress Intensity ◽  
The Impact

The flying of missile will severely jeopardize the structural integrity in control rod ejection accident. In order to analyze the strength of a new type of shielding plate under control rod drive mechanism (CRDM) missile impact, this article develops the simulation model and conducts the response analysis of the missile under 4 cases. In addition, the strain analysis and evaluation of protection shielding plate at the most dangerous case are performed. The motion analysis of CRDM missile indicates that the fracture at trapezoid thread place as well as the shielding plate rim under impact is most dangerous because the maximum kinetic energy of the impact can be obtained. So only this case should be examined when performing the evaluation of the shielding plate. Stress analysis shows the maximum stress intensity of the shielding plate will exceed the yielding stress and thereby local plasticity will occur. Strain analysis shows that compared with the extension ratio at structural failure, the computed strain still has margin to ensure the shielding plate will not be penetrated. Meanwhile the strain analysis of bolts which fix shielding plate are calculated. The strain level of two bolts are exceed limit and others is relatively low. The shield plate can be firmly fixed. Hence, this new type of the protection shielding plate is capable to prevent the damage of other components by the flying of CRDM missile.

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