Assumed Process of Piping Failure in Nuclear Power Plants Under Destructive Earthquake Conditions

1991 ◽  
Vol 113 (2) ◽  
pp. 268-272
Author(s):  
H. Shibata
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Piping System ◽  
Safety Problem ◽  
Type Of Failure

This paper deals with an assumed process of piping failure in nuclear power plants which may cause a catastrophic accident during a destructive earthquake condition. The type of failure discussed is the so-called double-ended guillotine break, DEGB. As a safety problem, we are going to eliminate this type of failure by LBB, and we have assumed that this would then not occur by an earthquake. The author tries to clarify the possibility of failure during earthquakes. He reviews his related papers since 1973, and discusses zipping failure of snubbers and supporting devices. He shows a procedure to simulate the zipping failure of a piping system supported by snubbers.

A Multi-Dimensional Approach to Design and Execution of Modifications, Refurbishments, and Beyond for Existing Nuclear Power Plants

2020 ◽  
Author(s):  
Omid Malekzadeh ◽  
Matthew Monid ◽  
Michael Huang
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Three Dimensional ◽  
Spatial Models ◽  
Technical Information ◽  
Lessons Learned ◽  
Piping System ◽  
Full Potential ◽  
Cad Models

Abstract Three-Dimensional (3D) CAD models are utilized by many designers; however, they are rarely utilized to their full potential. The current mainstream method of design process and communication is through design documentation. They are limited in depth of information, compartmentalized by discipline, fragmented into various segments, communicated through numerous layers, and finally, printed onto an undersized paper by the stakeholders and end-users. Large nuclear projects, such as refurbishments and decommissioning, suffer from spatial, interface, and interreference challenges, unintentional cost and schedule overruns, and quality concerns that can be rooted to the misalignments between designed and in-situ or previously as-built conditions that tend to stem from inaccessibility and lack of adequate data resolution during the transfer of technical information. This paper will identify the technologies and the methodology used during several piping system modifications of existing nuclear power plants, and shares the lessons learned with respect to the benefits and shortcomings of the approach. Overall, it is beneficial to leverage available multi-dimensional technologies to enhance various engineering and execution phases. The utilization and superposition of various spatial models into 3D and 4D formats, enabled the modification projects to significantly reduce in-person plant walkdown efforts, provide highly accurate as-found data, and enable stakeholders of all disciplines and trades to review the as-found, as-designed, and simulated as-installed modification; including the steps in between without requiring significant plant visits. This approach will therefore reduce the field-initiated changes that tend to result in design/field variations; resulting in less reliance on Appendix T of ASME BPVC Section III, reduction in the design registration reconciliations efforts, and it aligns with the overarching goal of EPRI guideline NCIG-05. Beyond the benefits to design and execution, the multidimensional approach will provide highly accurate inputs to some of the nuclear safety’s Beyond Design Basis Assessments (BDBA) and allowed for the incorporation of actual design values as input and hence removing the unnecessary over-conservatisms within some of the inputs.

Development of Elastic-Plastic Constitutive Models for the Evaluation of Nuclear Piping Systems Under Severe Cyclic Loading

2012 ◽  
Author(s):  
Yukio Takahashi ◽  
Yoshihiko Tanaka
Keyword(s):  
Cyclic Loading ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Kinematic Hardening ◽  
Constitutive Models ◽  
Seismic Loading ◽  
Piping System ◽  
Elastic Plastic ◽  
Piping Systems

It is essential to predict the behavior of nuclear piping system under seismic loading to evaluate the structural integrity of nuclear power plants. Relatively large stress cycles may be applied to the piping systems under severe seismic loading and plastic deformation may occur cyclically in some portion of the systems. Accurate description of inelastic deformation under cyclic loading is indispensable for the precise estimation of strain cycles and accumulation potentially leading to the failure due to fatigue-ratcheting interaction. Elastic-plastic constitutive models based on the nonlinear kinematic hardening rule proposed by Ohno and Wang were developed for type 316 austenitic stainless steel and carbon steel JIS STPT410 (similar to ASTM A106 Gr.B), both of which are used in piping systems in nuclear power plants. Different deformation characteristics under cyclic loading in terms of memory of prior hardening were observed on these two materials and they were reflected in the modeling. Results of simulations under various loading conditions were compared with the test data to demonstrate the high capability of the constitutive models.

Noncontact Measurement Method of Vibration Stress Using Optical Displacement Sensors for Piping Systems in Nuclear Power Plants

2015 ◽  
Vol 1 (3) ◽  
Author(s):  
Akira Maekawa ◽  
Tsuneo Takahashi ◽  
Takashi Tsuji ◽  
Michiyasu Noda
Keyword(s):  
Nuclear Power ◽  
Measurement Method ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Vibration Measurement ◽  
Piping System ◽  
Noncontact Measurement ◽  
Displacement Sensors ◽  
Optical Displacement ◽  
Vibration Stress

In nuclear power plants, vibration stress of piping is frequently measured to prevent the occurrence of fatigue failure. A simpler and more efficient measurement method is desired for rapid integrity evaluation of piping. In this study, a method to measure vibration stress in a noncontact manner using optical displacement sensors is presented and validated. The proposed method estimates vibration-induced stress of small-bore piping directly using noncontact sensors based on a light-emission diode. First, the noncontact measurement method was proposed, and the measurement instrument based on the proposed method was developed for the validation. Next, vibration measurement experiments using the instrument were conducted for a mock-up piping system and an actual piping system. The measurement results were compared with the values measured by the conventional method of known accuracy using strain gauges. From this comparison, the proposed noncontact measurement method was demonstrated to be able to provide sufficient accuracy for practical use.

scholarly journals Review of Recent Aging-Related Degradation Occurrences of Structures and Passive Components in U.S. Nuclear Power Plants

2009 ◽  
Author(s):  
Jinsuo Nie ◽  
Joseph I. Braverman ◽  
Charles H. Hofmayer ◽  
Young-Sun Choun ◽  
Min Kyu Kim ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Research Effort ◽  
National Laboratory ◽  
Brookhaven National Laboratory ◽  
Piping System ◽  
Passive Components ◽  
The Status ◽  
Capability Evaluation

The Korea Atomic Energy Research Institute (KAERI) and Brookhaven National Laboratory (BNL) are collaborating to develop seismic capability evaluation technology for degraded structures and passive components (SPCs) under a multi-year research agreement. To better understand the status and characteristics of degradation of SPCs in nuclear power plants (NPPs), the first step in this multi-year research effort was to identify and evaluate degradation occurrences of SPCs in U.S. NPPs. This was performed by reviewing recent publicly available information sources to identify and evaluate the characteristics of degradation occurrences and then comparing the information to the observations in the past. Ten categories of SPCs that are applicable to Korean NPPs were identified, comprising of anchorage, concrete, containment, exchanger, filter, piping system, reactor pressure vessel, structural steel, tank, and vessel. Software tools were developed to expedite the review process. Results from this review effort were compared to previous data in the literature to characterize the overall degradation trends.

Simplified Approach to Design of Crushable Material due to Dynamic Load

2012 ◽  
Author(s):  
Sivadol Vongmongkol ◽  
Asgar Faal-Amiri ◽  
Hari M. Srivastava
Keyword(s):  
Closed Form ◽  
Energy Absorption ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Closed Form Solution ◽  
High Energy ◽  
Form Solution ◽  
Piping System ◽  
The Impact

Crushable material has widely been used as an engineering solution for energy absorption devices among many industries. Abnormal and severe accident loads in the design of nuclear power plants are required to be addressed in order to comply with Nuclear Regulatory Commission (NRC) requirements which makes the crushable material more suitable in its highly dynamic application. One of the severe loads is from a postulated high energy piping system rupture. Its effects are required to be mitigated so that the proper operation of safety related systems, structures and components (SSC) of these facilities is assured. The postulated pipe rupture loads are among the highest loads that need to be addressed in the design process of nuclear power plants. The impact forces produced by the postulated pipe rupture are typically being absorbed by energy absorption devices called “Pipe Whip Restraints” in which the restraints can minimize the loads affecting the SSCs to within an acceptable limit. This paper provides a simplified closed-form solution to determine the energy absorbing characteristic that will help to design these devices. This paper will also provide a comparison between results of the proposed simplified closed-form solution equations to the experimental test results and the calculated results using finite element analysis.

Seismic fragility analysis of seismically isolated nuclear power plants piping system

2015 ◽  
Vol 284 ◽  
pp. 264-279 ◽  
Author(s):  
Ehsan Salimi Firoozabad ◽  
Bub-Gyu Jeon ◽  
Hyoung-Suk Choi ◽  
Nam-Sik Kim
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Piping System ◽  
Seismically Isolated

Work structure in nuclear power plants

1983 ◽  
Author(s):  
Marjorie B. Bauman ◽  
Richard F. Pain ◽  
Harold P. Van Cott ◽  
Margery K. Davidson
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Work Structure
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