Localized Corrosion of Stainless Steel in a Nuclear Waste Cooling Water System—Part 5: Inhibition Studies Using “All-Metal” Artificial Pits

CORROSION ◽  
10.5006/0416 ◽  
2012 ◽  
Vol 68 (12) ◽  
pp. 1076-1084 ◽  
Author(s):  
C.J. Donohoe ◽  
G.O.H. Whillock
Keyword(s):  
Stainless Steel ◽  
Nuclear Waste ◽  
Water System ◽  
Cooling Water ◽  
Localized Corrosion ◽  
Cooling Water System ◽  
System Part ◽  
Inhibition Studies

Localized Corrosion of Stainless Steel in a Nuclear Waste Cooling Water System—Part 2: Plant Inspection Findings

CORROSION ◽  
10.5006/0413 ◽  
2012 ◽  
Vol 68 (9) ◽  
pp. 844-852 ◽  
Author(s):  
C.J. Donohoe ◽  
G.O.H. Whillock ◽  
P.J. Apps
Keyword(s):  
Stainless Steel ◽  
Nuclear Waste ◽  
Water System ◽  
Cooling Water ◽  
Chloride Ions ◽  
Localized Corrosion ◽  
Water Radiolysis ◽  
Cooling Water System ◽  
System Part ◽  
Plant Inspection

Parts of a nuclear waste cooling water system, constructed from an austenitic stainless steel, are known to be susceptible to localized corrosion. This is attributed to the presence of chloride ions in the water, albeit only at low concentration (<10 mg/L), and oxidants produced by water radiolysis. Plate samples were cut and taken for examination from downstream tanks located in man-access areas out of the radiation field. Large pits were found. The largest were highly elongated but had failed to form through-wall penetrations. Smaller pits that were spheroidal in shape were found that had formed through-wall penetrations. The pits were sectioned and their internal morphologies examined by scanning electron microscopy. The elongated pits were found to have a crystalline internal morphology associated with the mechanism of etch-type pitting. The spheroidal pits had a smoother interior morphology but it was not bright or distinctive-like classic pits formed by a salt-filming mechanism. Formation of the spheroidal pits is attributed to corrosion by a quasi-salt-filming mechanism.

Localized Corrosion of Stainless Steel in a Nuclear Waste Cooling Water System—Part 4: Artificial Pit Investigation of Nitrate Inhibition

CORROSION ◽  
10.5006/0415 ◽  
2012 ◽  
Vol 68 (11) ◽  
pp. 967-981 ◽  
Author(s):  
G.O.H. Whillock ◽  
T.J. Binks ◽  
C.J. Donohoe
Keyword(s):  
Stainless Steel ◽  
Nuclear Waste ◽  
Water System ◽  
Cooling Water ◽  
Bulk Water ◽  
Localized Corrosion ◽  
Water Radiolysis ◽  
Wire Electrode ◽  
Cooling Water System ◽  
The Wire

A nuclear waste cooling water system, constructed from an austenitic stainless steel, is known to be susceptible to localized corrosion because of the combined presence of low concentrations of chloride (Cl−) ions in the water (<10 mg/L) and oxidants produced by water radiolysis. Corrosion propagates in the system as pitting corrosion, and inspections of accessible components indicated that large pit cavities could form. To investigate possible inhibition options, an artificial pit, termed the wire-electrode artificial pit, was developed and shown to be capable of sustaining corrosion under representative conditions. Tests carried out using this artificial pit to investigate the effect of sodium nitrate (NaNO3) added to the bulk water are reported here. The results showed that nitrate (NO3−) was capable of affecting inhibition at 60°C, although large concentrations and long times were required, e.g., inhibition took up to 20 days at 60,000 mg/L NO3−. Complimentary polarization tests were also carried out in a range of artificial pit solutions as a function of nitrate concentration to aid interpretation of the wire-electrode tests. The existence of a threshold molar NO3−/Cl− ratio for passivation to occur was identified but not clearly defined.

Localized Corrosion of Stainless Steel in a Nuclear Waste Cooling Water System— Part 1: Crevice Corrosion Studies

CORROSION ◽  
10.5006/0412 ◽  
2012 ◽  
Vol 68 (8) ◽  
pp. 677-687 ◽  
Author(s):  
G.O.H. Whillock ◽  
S.E. Worthington ◽  
C.J. Donohoe
Keyword(s):  
Stainless Steel ◽  
Nuclear Waste ◽  
Crevice Corrosion ◽  
Water System ◽  
Cooling Water ◽  
Chloride Ions ◽  
Localized Corrosion ◽  
Stainless Steel Surface ◽  
Water Radiolysis ◽  
Cooling Water System

Parts of a nuclear waste cooling water system, constructed from an austenitic stainless steel, are known to be susceptible to localized corrosion. This is attributed to the presence of chloride ions in the water, albeit only at low concentrations (<10 mg/L), and oxidants produced by water radiolysis. Experiments were carried out using an engineered crevice connected to a large passive stainless steel surface to demonstrate the viability of crevice corrosion. Similar tests were undertaken to investigate the efficacy of nitrate as an inhibitor. In irradiated water containing up to 300 mg/L Cl− and at temperatures of up to 60°C, crevice corrosion of UNS 30403 and 18Cr-13Ni 1Nb was inhibited by nitrate added at molar ratios of approximately 2.9 to 5.7 with respect to chloride. Once corrosion is inhibited, the nitrate/chloride ratio can be reduced to maintain passivity, but a nitrate:chloride ratio of approximately 0.6 or lower is unlikely to be effective.

Corrosion Inhibitor on Copper and Stainless Steel for Component Cooling Water System of NPP

2013 ◽  
Author(s):  
Jin-hua Liu ◽  
Bin Gong ◽  
E Jang ◽  
Wei-gang Ma ◽  
Ju-hua Wen ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Corrosion Inhibition ◽  
Nuclear Power ◽  
Pure Water ◽  
Water System ◽  
Cooling Water ◽  
Immersion Test ◽  
Pitting Potential ◽  
Protection Mechanism ◽  
Cooling Water System

Based on the corrosion issues of component cooling water system (CCWs) in nuclear power plant (NPP), the corrosion inhibition properties and protection mechanism on copper and stainless steel was studied by using tests such as electrochemical method, immersion test and dynamic water simulation. Results show that the optimum inhibitor is the compound of tolyltriazole (TTA) and phosphate, which has an excellent corrosion inhibition efficiency on copper in either pure water or abnormal water. The inhibitor also elevated the pitting potential of stainless steel and contributed to the corrosion resistance.

scholarly journals Effects of Polymer-Polymer Complexes on the Corrosion of Mild Steel in Cooling Water System (Part 2)

2001 ◽  
Vol 50 (3) ◽  
pp. 106-114 ◽  
Author(s):  
Masahiro Morooka ◽  
Isao Sekine ◽  
Toshiyuki Tanaki ◽  
Norimitsu Hirose ◽  
Makoto Yuasa
Keyword(s):  
Mild Steel ◽  
Water System ◽  
Cooling Water ◽  
Polymer Complexes ◽  
Cooling Water System ◽  
System Part
Sign in / Sign up

Export Citation Format

Share Document