scholarly journals Long-term effects of a chemical decontamination procedure on the corrosion state of the heat exchanger tubes of steam generators

2022 ◽  
Vol 7 (1) ◽  
pp. 77-83
Author(s):  
Andrea Szabó Nagy ◽  
Kálmán Varga ◽  
Bernadett Baja ◽  
Zoltán Németh ◽  
Desző Oravetz ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Heat Exchanger ◽  
Oxide Layer ◽  
In Situ Monitoring ◽  
Ex Situ ◽  
General Corrosion ◽  
Long Term Effects ◽  
Steam Generators ◽  
Corrosion State

Our previous studies have revealed that a ”hybrid” structure of the amorphous and crystalline phases is formed in the outermost surface region of the austenitic stainless steel tubes of steam generators (SGs) as an undesired consequence of the industrial application of the AP-CITROX (AP: alkaline permanganate; CITROX: citric and oxalic acid) decontamination technology. The formation of this mobile oxide-layer increased the amount of the corrosion products in the primary circuit significantly, resulting in magnetite deposition on fuel assemblies. Owing to the fact that there is no investigation method available for the in-situ monitoring of the inner surfaces of heat exchanger tubes, a research project based on sampling as well as on ex-situ electrochemical and surface analytical measurements was elaborated. Within the frame of this project, comprehensive investigation of the general corrosion state and metallographic features of 36 stainless steel specimens, cut out from various locations of the 21 steam generators of the Paks NPP in the time period of 2000-2007 has been performed. The present work gives a brief overview on the general corrosion state of the heat exchanger tubes of SGs, concerning the long-term effects of the AP-CITROX procedure on the chemical composition and structure of the protective oxide-layer.

scholarly journals Comprehensive investigation of the corrosion state and surface properties of the stainless steel tubes of steam generators

2021 ◽  
Vol 9 (3) ◽  
Author(s):  
Andrea Szabó Nagy ◽  
Kálmán Varga ◽  
Bernadett Baja ◽  
Zoltán Németh ◽  
Deszo Oravetz ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Heat Exchanger ◽  
Chemical Composition ◽  
Oxide Layer ◽  
General Corrosion ◽  
Steam Generators ◽  
Protective Oxide ◽  
Comprehensive Investigation ◽  
Protective Oxide Layer ◽  
Corrosion State

Evaluating the water chemistry in the primary circuit and the effect of chemical econtamination of the heat exchanger tubes performed by the AP-CITROX (AP: alkaline permanganate; CITROX: citric and oxalic acid) procedure at Paks NPP (Hungary), a project dealing with the comprehensive investigation of the general corrosion state of the steam generators (SGs) has been initiated. Owing to the fact that there is no investigation method available for the in-situ monitoring of the inner surfaces of heat exchanger tubes, a research program based on sampling as well as on ex-situ electrochemical (voltammetric) and surface analytical measurements (SEM-EDX, CEMS, XRD, XPS) was developed and elaborated. In the time period of 2000-2008 - within the frame of the above project - 45 stainless steel specimens, cut out from various locations of the steam generators of the Paks NPP were investigated. Based on the measured corrosion characteristics (corrosion rate, thickness and chemical composition of the protective oxide-layer) it was found that these parameters are strongly dependent on the decontamination history of steam generators. The present work gives a brief overview on the general corrosion state of the heat exchanger tubes of SGs, concerning the long-term effects of the AP-CITROX procedure on the chemical composition and structure of the protective oxide-layer.

Effect of a chemical decontamination procedure on the corrosion state of the heat exchanger tubes of steam generators

2006 ◽  
Vol 48 (9) ◽  
pp. 2727-2749 ◽  
Author(s):  
A. Szabó ◽  
K. Varga ◽  
Z. Németh ◽  
K. Radó ◽  
D. Oravetz ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Steam Generators ◽  
Chemical Decontamination ◽  
Corrosion State

Age-Related Degradation of Steam Generator Internals Based on Industry Responses to Generic Letter 97-06

2002 ◽  
Author(s):  
M. Subudhi ◽  
E. J. Sullivan
Keyword(s):  
Steam Generator ◽  
Nuclear Power ◽  
Power Plants ◽  
Pressurized Water Reactor ◽  
Long Term Effects ◽  
Steam Generators ◽  
Pressurized Water ◽  
Age Related ◽  
The U.S

This paper presents the results of an aging assessment of the nuclear power industry’s responses to NRC Generic Letter 97-06 on the degradation of steam generator internals experienced at Electricite de France (EdF) plants in France and at a United States pressurized water reactor (PWR). Westinghouse (W), Combustion Engineering (CE), and Babcock & Wilcox (B & W) steam generator models, currently in service at U.S. nuclear power plants, potentially could experience degradation similar to that found at EdF plants and the U.S. plant. The steam generators in many of the U.S. PWRs have been replaced with steam generators with improved designs and materials. These replacement steam generators have been manufactured in the U.S. and abroad. During this assessment, each of the three owners groups (W, CE, and B&W) identified for its steam generator models all the potential internal components that are vulnerable to degradation while in service. Each owners group developed inspection and monitoring guidance and recommendations for its particular steam generator models. The Nuclear Energy Institute incorporated in NEI 97-06, “Steam Generator Program Guidelines,” a requirement to monitor secondary side steam generator components if their failure could prevent the steam generator from fulfilling its intended safety-related function. Licensees indicated that they implemented or planned to implement, as appropriate for their steam generators, their owners group recommendations to address the long-term effects of the potential degradation mechanisms associated with the steam generator internals.

Long-Term Effects of Humidity on Stainless Steel Pitting in Sea Salt Exposures

2021 ◽  
Vol 168 (2) ◽  
pp. 021501
Author(s):  
J. Srinivasan ◽  
T. D. Weirich ◽  
G. A. Marino ◽  
A. R. Annerino ◽  
J. M. Taylor ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Sea Salt ◽  
Long Term Effects

Long-Term Effects of Temperature Exposure on SLM 304L Stainless Steel

JOM ◽  
2017 ◽  
Vol 70 (3) ◽  
pp. 384-389 ◽  
Author(s):  
Tarak Amine ◽  
Caitlin S. Kriewall ◽  
Joseph W. Newkirk
Keyword(s):  
Stainless Steel ◽  
304L Stainless Steel ◽  
Long Term Effects ◽  
Effects Of Temperature ◽  
Temperature Exposure

Long-Term Corrosion Resistance of Biomedical Grade Stainless Steel ISO 5832-1 ("316LVM") under External Anodic Electrical Pulsing Conditions

2010 ◽  
Vol 89-91 ◽  
pp. 455-460
Author(s):  
Ronald Rebentisch ◽  
Regina Lange ◽  
Ulrich Beck
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Surrounding Tissue ◽  
Second Step ◽  
Minor Effect ◽  
General Corrosion ◽  
Current Signal ◽  
Electrochemical Passivation ◽  
Phosphate Buffered Saline

For medical implant application of metals or alloys, one major prerequisite is the absence of release of metal ions to the surrounding tissue. In the case of stainless steel, this prerequisite can be achieved by modifying the surface by chemical and electrochemical passivation pre-treatments so that the general corrosion-rate will be reduced and pitting corrosion will not occur. In a first step, the surface of the test specimens (10 mm diam.) were chemically pre-treated with nitric acid using different concentrations and duration. In the second step, the passivation effect was tested by applying voltage-scans reaching from hydrogen to oxygen evolution in a 3-electrode CV-measurement using phosphate buffered saline (PBS) (pH7.4) as electrolyte. It turned out that after the 2nd of a total of five scans all CV-diagrams looked almost the same and the chemical passiva-tion treatment was of minor effect; none of the CV-diagrams showed effects of pitting corrosion. The third step was to apply external electrical anodic pulses (n=5.3x106) on the surface of the specimen (+4.5V, 0.5ms, 740Hz). In the forth step, the passive behaviour again was tested using the same CV-measurement setup. Again, no effect of pitting corrosion was seen and in parts of the CV-diagrams the measured current signal was less than before.

scholarly journals The long-term effects and detection ranges of passive integrated transponders in white-clawed crayfish Austropotamobius pallipes

2018 ◽  
pp. 20
Author(s):  
Jen Nightingale ◽  
Paul Stebbing ◽  
Nick Taylor ◽  
Gráinne McCabe ◽  
Gareth Jones
Keyword(s):  
Ex Situ ◽  
Individual Identification ◽  
Long Term Effects ◽  
Term Survival ◽  
Detection Range ◽  
Pit Tags ◽  
Austropotamobius Pallipes ◽  
Significant Difference ◽  
Passive Integrated Transponders

Individual identification of the endangered white-clawed crayfish (Austropotamobius pallipes) can provide valuable information when assessing long-term survival of animals released into the wild; currently the most effective method is the use of passive integrated transponders (PIT) tags. A 360 days ex situ experiment was undertaken on 20-month, captive-born A. pallipes of carapace length (CL): 22–31 mm, to assess growth and survival after PIT-tagging. Thirty crayfish, matched for sex and size, were PIT-tagged, with 30 untagged crayfish as a control. All crayfish survived for the first 60-day post-tagging, indicating that there was no short-term survival effect of the procedure, in controlled conditions. There was no significant difference in survival or growth over the year between tagged and untagged crayfish, indicating that A. pallipes (≥22 mm CL) can be PIT-tagged safely. A second ex situ experiment investigated the detection range of adult, wild-caught, PIT-tagged A. pallipes. Eighteen A. pallipes were tagged with either 8 mm or 12 mm tags and added to different treatments (bare tank, tank with substrate, brick refuge, pipe refuge, pipe refuge plus slate), and the distance to detection was measured. Throughout all treatments the A. pallipes tagged with 12 mm PIT tags were detected significantly further away (35.6 ± 3.8 mm) than the 8 mm PIT-tagged crayfish.

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