Corrosion Cause Analysis of Electric Feedwater Pump Motor Shaft in Nuclear Power Plants and Relevant Corrective Actions

2017 ◽  
Author(s):  
Che Yinhui ◽  
Guan Jianjun ◽  
Zu Shuai ◽  
Chen Qiang
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Economic Benefits ◽  
Motor Shaft ◽  
Cause Analysis ◽  
Root Cause ◽  
Feedwater Pump ◽  
Corrective Actions

Electric feedwater pump is an important feedwater equipment of nuclear power plants, and its reliability is directly related to the safe and steady operation of nuclear power plants and also economic benefits. In fact, corrosion of electric feedwater pump motor shaft occurs repeatedly, and even bearing shell in the motor can be burned out happen sometimes. This text sets out to analyze the cause of corrosion of electric feedwater pump motor shaft, identify the root cause, and further work out pertinent corrective actions based on the structure of the feedwater pump.

Semiconductor Wear Out at Nuclear Power Plants

2000 ◽  
Author(s):  
James B. Riddle
Keyword(s):  
Failure Analysis ◽  
Case Studies ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Light Output ◽  
Analysis Techniques ◽  
Root Cause ◽  
Corrective Actions ◽  
Control Circuits

Abstract This paper will examine semiconductor wear out at San Onofre Nuclear Generation Station (SONGS). The topics will include case studies, failure mechanisms, diagnostic techniques, failure analysis techniques and root cause corrective actions. Nuclear power plants are unique in that instrumentation and control circuits are continuously energized, are periodically tested, and have been in operation for greater than 25 years. Root cause evaluations at SONGS have identified numerous semiconductor failures due to wear out. Case studies include light output deterioration in opto-isolators, junction alloying failures of transistors and integrated circuits and parametric shifts in operational amplifiers. In most cases the devices do not fail catastrophically but degraded to the point of circuit level functional failure. Failure analysis techniques include circuit analysis, board level troubleshooting to identify the degraded components. Intermittent failures require power cycling, thermal cycling, and long term monitoring to identify the responsible components. Corrective actions for semiconductor wear out at SONGS include enhanced monitoring and proactive change out of identified part types.

Root Cause Analysis of Pipeline Rupture in the Condensate Extraction System of Nuclear Power Plant

2017 ◽  
Author(s):  
Chen Qiang ◽  
Han Ning ◽  
Chen Weihan ◽  
Che Yinhui
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Root Cause Analysis ◽  
Extraction System ◽  
Stable Operation ◽  
Pressurized Water ◽  
High Oxygen Content ◽  
Cause Analysis ◽  
Root Cause

Pipe rupture in the Condensate Extraction system (CEX) of nuclear power plants will lead to high oxygen content in the secondary circuit and therefore exacerbates equipment and pipeline corrosion. At the same time, there is a risk of loss of vacuum in the system, which has a direct impact on the safe and stable operation of nuclear power plants and will affect the economic benefits. In this paper, Equipment Failure Root Cause Analysis (ERCA) methodology is employed combined with metallography analysis (SEM analysis, XRD) and finite element simulation analysis, to investigate the root cause for drainage pipeline rupture in CEX System of Pressurized Water Reactor (PWR). Detailed analysis process of ERCA was introduced including RCA project establishment, data collection, failure modes analysis and so on. The most probable failure mode is pointed out through the investigation and evidence analyzed. It suggests that the improper design and the installation of limiting orifice plate should be the root cause. And corresponding corrective actions are put forward in details to prevent the recurrence.

A New Eddy Current 3-D Profilometry for a Quantitative Measurement of Geometric Anomaly in Steam Generator Tubes of Nuclear Power Plants

2006 ◽  
Vol 321-323 ◽  
pp. 426-429
Author(s):  
Deok Hyun Lee ◽  
Myung Sik Choi ◽  
Do Haeng Hur ◽  
Jung Ho Han ◽  
Myung Ho Song ◽  
...  
Keyword(s):  
Steam Generator ◽  
Eddy Current ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Three Dimensional ◽  
Accurate Information ◽  
Profile Measurement ◽  
Root Cause ◽  
Steam Generator Tubes

Most of the corrosive degradations in steam generator tubes of nuclear power plants are closely related to the residual stress existing in the local region of a geometric change, that is, an expansion transition, u-bend, ding, dent, bulge, etc. Therefore, accurate information on a geometric anomaly in a tube is a prerequisite to the activity of a non destructive inspection for a precise and earlier detection of a defect in order to prevent a failure during an operation, and also for a root cause analysis of a failure. In this paper, a newly developed eddy current technique of a three-dimensional profilometry is introduced and the proof for the applicability of the technique to a plant inspection is provided. The quantitative profile measurement using a new eddy current probe was performed on steam generator expansion mock-up tubes with various geometric anomalies typically observed in the operating power plants, and the accuracy of the measured data was compared with those from the laser profilometry.

Root Cause Analysis of the Unexpected Behaviour of a Flaked Material Under Irradiation and Transferability to the Doel 3/Tihange 2 Reactor Pressure Vessels

2016 ◽  
Author(s):  
Evy De Bruycker ◽  
Séverine De Vroey ◽  
Xavier Hallet ◽  
Jacqueline Stubbe ◽  
Steve Nardone
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Root Cause Analysis ◽  
Pressure Vessels ◽  
Operating Cycle ◽  
Cause Analysis ◽  
Root Cause ◽  
History Of ◽  
Manufacturing History ◽  
Reactor Pressure

During the 2012 outage at Doel 3 (D3) and Tihange 2 (T2) Nuclear Power Plants (NPP), a large number of nearly-laminar indications were detected mainly in the lower and upper core shells. The D3/T2 shells are made from solid casts that were pierced and forged. Restart authorization in 2013 was accompanied by a number of “mid-term” requirements, to be completed during the first operating cycle after the restart. One of these requirements was the mechanical testing of irradiated specimens containing hydrogen flakes. These tests showed unexpected results regarding the shift in the Reference Temperature for Nil Ductility Transition (RTNDT) of the flaked material VB395 (Steam Generator shell rejected because of flakes) after irradiation. This paper presents the root cause analysis of this unexpected behaviour and its transferability (or not) to the D3/T2 Reactor Pressure Vessels (RPVs). A mechanistic and a manufacturing based approach were used, aiming at identifying the microstructural mechanisms responsible for the atypical embrittlement of VB395 and evaluating the plausibility of these mechanisms in the D3/T2 RPVs. This work was based on expert’s opinions, literature data and test results. Both flaked and unflaked samples have been investigated in irradiated and non-irradiated condition. All hydrogen-related mechanisms were excluded as root cause of the unexpected behaviour of VB395. Two possible mechanisms at the basis of the atypical embrittlement of VB395 were identified, but are still open to discussion. These mechanisms could be linked to the specific manufacturing history of the rejected VB395 shell. Since the larger than predicted shift in transition temperature after irradiation of VB395 is not linked with the hydrogen flaking and since none of the specific manufacturing history features that are possible root causes are reported for the D3/T2 RPVs, the D3/T2 shells should not show the unexpected behaviour observed in VB395.

The Problems of Nuclear Power are Much Too Serious to Leave to Nuclear Experts

1998 ◽  
Vol 42 (10) ◽  
pp. 737-739 ◽  
Author(s):  
Vladimir Munipov
Keyword(s):  
Operating Procedure ◽  
Chernobyl Accident ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Protection System ◽  
Root Cause ◽  
Nuclear Age ◽  
Plant Personnel ◽  
Machine Interaction

The full story of the Chernobyl disaster is yet to be disclosed. The initial cause of the accident was a very unlikely violation of the operating procedure and conditions by the plant personnel which showed the design faults of the reactor and the control and protection system rods. The main or root cause of the accident was the inadequate design of the user-machine interaction. Many people involved with the reliability and safety of Nuclear Power Plants now believe that even if the operators had acted correctly their actions would have resulted in the explosion. The main lesson from the Chernobyl accident is that the Nuclear Age calls for a new culture and and can certainly not tolerate ignorance. Chernobyl is a severe warning of what can happen if people disregard the necessity of including ergonomics in the process of designing and operating complex technical facilities.

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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