Secondary side corrosion in steam generator tubes: lessons learned in France from the in-service inspection results

1997 ◽  
Vol 168 (1-3) ◽  
pp. 255-259 ◽  
Author(s):  
Robert Comby
Keyword(s):  
Steam Generator ◽  
Lessons Learned ◽  
Steam Generator Tubes ◽  
Secondary Side ◽  
Service Inspection

Numerical Study of the Deposition of Radioactive Nucleoids (Aerosol) in PWR Steam Generator

2021 ◽  
Author(s):  
Muhammad Aadil ◽  
Rab Nawaz ◽  
Ajmal Shah ◽  
Kamran Rasheed Qureshi
Keyword(s):  
Steam Generator ◽  
Numerical Study ◽  
Deposition Efficiency ◽  
Decontamination Factor ◽  
Radioactive Nuclide ◽  
Discrete Phase Model ◽  
Velocity Magnitude ◽  
Discrete Phase ◽  
Steam Generator Tubes ◽  
Secondary Side

Abstract This research presents numerical study of deposition efficiency and decontamination factor of radioactive nuclide in steam generator tubes of a typical 325 MWe PWR. To find out the deposition of aerosol, the discrete phase model (DPM) has been used. The flow has been characterized as compressible, adiabatic, turbulent and wall bounded. When steam generator tube gets ruptured, the radioactive nuclides can escape from primary side and create a radioactive field in the secondary side. This can be harmful for the personnel working at the plant. Therefore, in order to ensure the safety of the plant and personnel, it is important to study the particles deposition on the wall of steam generator tubes. In the present study, a CFD methodology has been first developed and validated with the published results. After methodology validation, it has been applied to the U-tube of a typical PWR steam generator. It has been observed that due to the action of centrifugal force near the bent, the velocity magnitude is high towards the inner wall and the flow separates at the bent entrance. Furthermore, the flow inside the tube is rotational with vortices throughout the domain due to the presence of the bent. Finally, the deposition efficiency and decontamination factor have been calculated and it has been observed that both increase with the increase in particle size due to inertial effects.

Probability of Burst in Steam Generator Tubes Using Monte Carlo Method

2006 ◽  
Author(s):  
Jae Bong Lee ◽  
Jai Hak Park ◽  
Hong-Deok Kim ◽  
Han-Sub Chung ◽  
Tae Ryong Kim
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Steam Generator ◽  
Flaw Size ◽  
Assessment Model ◽  
Statistical Approaches ◽  
Inspection Data ◽  
Steam Generator Tubes ◽  
Non Destructive ◽  
Service Inspection

A statistical assessment model for structural integrity of steam generator tubes was proposed using Monte Carlo method. The growth of flaws in steam generator tubes was predicted using statistical approaches. The statistical parameters that represent the characteristics of flaw growth and initiation were derived from in-service inspection (ISI) non-destructive evaluation (NDE) data. Based on the statistical approaches, flaw growth models were proposed and applied to predict distribution of flaw size at the end of cycle (EOC). Because NDE measurement results differ from that of real ones in steam generator tubes, a simple method for predicting the physical number of flaws from periodic in-service inspection data was proposed. The probabilistic flaw growth rate was calculated from the in-service non-destructive inspection data. And the statistical growth of flaw was simulated using the Monte Carlo method. Probabilistic distributions of the flaw size and the probability of burst were obtained from numerously repeated simulations using the proposed assessment model.

Optimisation of helical geometry of inspection probe for steam generator tubes of the PFBR

2021 ◽  
Vol 63 (10) ◽  
pp. 585-591
Author(s):  
G Perumalsamy ◽  
P Visweswaran ◽  
D Jagadishan ◽  
S Joseph Winston ◽  
S Murugan
Keyword(s):  
Steam Generator ◽  
Structural Design ◽  
Smooth Transition ◽  
Fast Breeder Reactor ◽  
Groove Design ◽  
Helical Groove ◽  
Helical Geometry ◽  
Steam Generator Tubes ◽  
Helical Grooves ◽  
Service Inspection

The steam generator (SG) tubes of the prototype fast breeder reactor (PFBR) located in Kalpakkam, India, need to be periodically inspected using the remote field eddy current (RFEC) technique. During the pre-service inspection of the SG tubes, it was found that the RFEC probes experienced frequent mechanical breakages. To avoid these failures, changes in the existing structural design of the RFEC probe were required. A helical groove design was proposed to obtain a smooth transition in the variation of stress across the probe during the inspection. It was difficult to calculate the flexural stiffness of the proposed helical geometry probe due to the varying cross-section along its length. In this paper, the smearing approach adopted to calculate the stiffness of the RFEC probe and the sensitivity analysis carried out to determine the optimal design of the probe are discussed. A probe was fabricated based on the helical groove design and tested to qualify its suitability for the SG inspection. The RFEC probe with helical grooves was employed for the pre-service inspection of the SG tubes of the PFBR. More than 200 tubes have been inspected using the proposed design and no mechanical failure of the probe has been observed.

OXIPROBE: A Non Destructive Tool for Determining Steam Generator Oxide Characteristics

2009 ◽  
Author(s):  
John P. Krasznai
Keyword(s):  
Heat Transfer ◽  
Carbon Steel ◽  
Steam Generator ◽  
Transfer Efficiency ◽  
Steam Generators ◽  
Heat Transfer Efficiency ◽  
Tube Removal ◽  
Steam Generator Tubes ◽  
Non Destructive ◽  
Secondary Side

CANDU Stations are designed with significant amounts of carbon steel piping in the primary circuit. Although the primary coolant chemistry is such that carbon steel corrosion is minimized, nevertheless magnetite transport from the carbon steel surfaces to the steam generators is a significant issue leading to potential reduction in heat transfer efficiency in the steam generator. There are other contributors to the reduction of heat transfer efficiency such as divider plate leakage whereby some of the coolant short circuits the steam generator tubes and secondary side steam generator tube fouling. CANDU station operators have utilized a number of mitigating measures such as primary and secondary side mechanical and chemical tube cleaning, and divider plate refurbishment to counter these problems but these are all expensive and dose intensive, It is therefore very important to establish the relative contribution of each source to the overall heat transfer degradation problem so the most effective results are obtained. Tube removal and laboratory assessment of the oxide loading is possible and has been utilized but at best it provides an incomplete picture since typically only short lengths of tubes are removed — most often from the hot leg and the tube removal process adversely impacts the primary side oxide integrity. Kinectrics Inc. has developed, qualified and deployed Oxiprobe, a highly mobile non destructive technology able to remove and quantify the deposited oxide loading on the primary surfaces of steam generator tubes. The technology is deployed during shutdown and provides valuable, direct information on: • Primary oxide distribution within the steam generator; • Oxide loading (thickness of oxide) on the primary surfaces of steam generator tubes; • Oxide composition and radiochemical characterization. The End Effector probe can reach either side of the straight section of the steam generator U tube but as currently designed it is unable to be deployed in the U-tube region. The current technology is able to visit 4 tubes simultaneously. The technology is Code classified as a Class 6 fitting by the Canadian Nuclear Safety Commission and registered by the Ontario Technical Standards and Safety Authority as a pressure boundary retaining system. Although the application of the technology to date has been applied to steam generator tubes, in principle it can be applied to any heat exchanger tube, vertical or horizontal. This paper will describe the system, the qualification program for its deployment as well as some actual field results. The applicability of the technology for PWR steam generators is also addressed.

Parametric Study of External Pressure on Steam Generator Tube Bends

2012 ◽  
Author(s):  
Mitch Hokazono ◽  
Clayton T. Smith
Keyword(s):  
Steam Generator ◽  
Parametric Study ◽  
External Pressure ◽  
Light Water Reactor ◽  
Material Strength ◽  
Steam Generators ◽  
Elliptical Cross ◽  
Light Water ◽  
Water Reactor ◽  
Steam Generator Tubes

Integral light-water reactor designs propose the use of steam generators located within the reactor vessel. Steam generator tubes in these designs must withstand external pressure loadings to prevent buckling, which is affected by material strength, fabrication techniques, chemical environment and tube geometry. Experience with fired tube boilers has shown that buckling in boiler tubes is greatly alleviated by controlling ovality in bends when the tubes are fabricated. Light water reactor steam generator pressures will not cause a buckling problem in steam generators with reasonable fabrication limits on tube ovality and wall thinning. Utilizing existing Code rules, there is a significant design margin, even for the maximum differential pressure case. With reasonable bend design and fabrication limits the helical steam generator thermodynamic advantages can be realized without a buckling concern. This paper describes a theoretical methodology for determining allowable external pressure for steam generator tubes subject to tube ovality based on ASME Section III Code Case N-759-2 rules. A parametric study of the results of this methodology applied to an elliptical cross section with varying wall thicknesses, tube diameters, and ovality values is also presented.

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