Pressurized water reactor plant steam generator upper internals have been monitored in accordance with accepted industry practice and on schedules based on the history of good inspection results with isolated cases of failures in a small percentage of plants worldwide. The current practice is, in general, to perform a small sample qualitative visual inspection. The causal factors for the historical events are indicators but, in general, not directly applicable to the current rationale for increased quantitative surveillance. There is an emerging trend toward increased indications of degradation with identifiable causal factors similar to but distinct from the traditional failure mechanisms. Primary and secondary moisture separation components and feedwater ring degradation is increasing as calculated by traditional models and according to qualitative and quantitative inspection results. Two established objective criteria for the performance functions for the steam drum components under consideration are: moisture carryover < 0.25% and material loss of 62.5 mils from nominal component thickness of 0.25 inches. These traditional acceptance criteria can be re-established based on an engineering evaluation of failure modes and effects. Two changes that have increased the concern for unacceptable degradation of steam drum components in recent years are 1) the chemistry improvements to reduce flow assisted corrosion (FAC) in the feed train piping with the concomitant reduction in entrained iron transport into steam generators, and 2) the increase in water-steam flow velocities that result from power uprates. The reduction of entrained particulate into the steam generators is positive with respect to fewer corrodents introduced but may have an unintended and previously under-analyzed effect of the transport of entrained particulate into the upper regions of the tube bundle and into the moisture separation components. The first indications of degraded moisture separator components have begun to emerge and warrant consideration of an increased surveillance program for selected plants. This paper discusses how recent changes in the operating parameters and secondary water chemistry control have created conditions for concern for exceeding the traditional moisture carryover criteria and erosion-corrosion of upper steam drum components, especially in light of extended life operation. Examples of recent developments in inspection results and considerations for improved materials, increased and improved surveillance techniques, and replacement strategies will be presented.
Skip Nav Destination
16th International Conference on Nuclear Engineering
May 11–15, 2008
Orlando, Florida, USA
Conference Sponsors:
- Nuclear Engineering Division
ISBN:
0-7918-4814-0
PROCEEDINGS PAPER
Increased Concern for Degradation of Upper Steam Drum Internals Leading to Monitoring and Modifications Considerations Available to Purchase
David P. Popovich,
David P. Popovich
Westinghouse Electric Company, LLC, Madison, PA
Search for other works by this author on:
M. H. Hu,
M. H. Hu
Westinghouse Electric Company, LLC, Madison, PA
Search for other works by this author on:
Jonathan L. Barkich,
Jonathan L. Barkich
Westinghouse Electric Company, LLC, Madison, PA
Search for other works by this author on:
Peter R. Nelson
Peter R. Nelson
Westinghouse Electric Company, LLC, Madison, PA
Search for other works by this author on:
David P. Popovich
Westinghouse Electric Company, LLC, Madison, PA
M. H. Hu
Westinghouse Electric Company, LLC, Madison, PA
Jonathan L. Barkich
Westinghouse Electric Company, LLC, Madison, PA
Peter R. Nelson
Westinghouse Electric Company, LLC, Madison, PA
Paper No:
ICONE16-48938, pp. 351-359; 9 pages
Published Online:
June 24, 2009
Citation
Popovich, DP, Hu, MH, Barkich, JL, & Nelson, PR. "Increased Concern for Degradation of Upper Steam Drum Internals Leading to Monitoring and Modifications Considerations." Proceedings of the 16th International Conference on Nuclear Engineering. Volume 1: Plant Operations, Maintenance, Installations and Life Cycle; Component Reliability and Materials Issues; Advanced Applications of Nuclear Technology; Codes, Standards, Licensing and Regulatory Issues. Orlando, Florida, USA. May 11–15, 2008. pp. 351-359. ASME. https://doi.org/10.1115/ICONE16-48938
Download citation file:
11
Views
Related Proceedings Papers
Related Articles
The Effect of Water Chemistry on the Reliability of Modern Large Steam Turbines
J. Eng. Power (July,1979)
Failure Investigation on Reheater Pendent Tubes Due to External Scale Exfoliation and Internal Scale Formation
J. Pressure Vessel Technol (December,2011)
Velocity Guidelines for Avoiding Erosion-Corrosion Damage in Sweet Production With Sand
J. Energy Resour. Technol (March,1998)
Related Chapters
Introduction
Consensus on Operating Practices for the Sampling and Monitoring of Feedwater and Boiler Water Chemistry in Modern Industrial Boilers (CRTD-81)
Introduction
Consensus on Operating Practices for the Control of Feedwater and Boiler Water Chemistry in Modern Industrial Boilers (CRTD 34)
Section 1. Introduction
Consensus on Operating Practices for the Control of Feedwater and Boiler Water Chemistry in Industrial and Institutional Boilers