Wear Scar Progression of Impact-Fretting at Elevated Temperature for Steam Generator Tubes in Nuclear Power Plants

Fretting wear generated by flow induced vibration is one of the important degradation mechanisms of steam generator tubes in the nuclear power plants. Understanding of tube wear characteristics is very important to keep the integrity of the steam generator tubes to secure the safety of the nuclear power plants. Experimental examination has been performed for the purpose of investigating the impact fretting. Test material is alloy 690 tube and 409 stainless steel tube supports. From the results of experiments, wear scar progression is investigated in the case of impact-fretting wear test of steam generator tubes under plant operating conditions such as pressure of 15MPa, high temperature of 290C and low dissolved oxygen. Hammer imprint that is actual damaged wear pattern, has been observed on the worn surface. From investigation of wear scar pattern, wear mechanism was initially the delamination wear due to cracking the hard oxide film and finally transferred to the stable impact-fretting pattern.

Download Full-text

Crack Initiation Factor by Impact Fretting Wear at INCONEL Alloy for Steam Generator Tube in Nuclear Power Plants

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.26-28.1269 ◽

2007 ◽

Vol 26-28 ◽

pp. 1269-1272

Author(s):

Chi Yong Park ◽

Jeong Kun Kim ◽

Tae Ryong Kim ◽

Sun Young Cho ◽

Hyun Ik Jeon

Keyword(s):

Steam Generator ◽

Wear Mechanism ◽

Nuclear Power ◽

Power Plants ◽

Nuclear Power Plants ◽

Operating Conditions ◽

Fretting Wear ◽

Steam Generator Tube ◽

Inconel Alloy ◽

The Impact

Inconel alloy such as alloy 600 and alloy 690 is widely used as the steam generator tube materials in the nuclear power plants. The impact fretting wear tests were performed to investigate wear mechanism between tube alloy and 409 stainless steel tube support plates in the simulated steam generator operating conditions, pressure of 15MPa, high temperature water of 290°C and low dissolved oxygen(<10 ppb). From investigation of wear test specimens by the SEM and EDS analysis, hammer imprint, which is known to be an actual damaged wear pattern, has been observed on the worn surface, and fretting wear mechanism was investigated. Wear progression of impact-fretting wear also has been examined. It was observed that titanium rich phase contributes to the formation of voids and cracks in sub-layer of fretting wear damage by impact fretting wear.

Download Full-text

Development of Wear Test System for Steam Generator Tubes in Nuclear Power Plants

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.297-300.1418 ◽

2005 ◽

Vol 297-300 ◽

pp. 1418-1423 ◽

Cited By ~ 1

Author(s):

Chi Yong Park ◽

Yong Sung Lee ◽

Myung Hwan Boo

Keyword(s):

Steam Generator ◽

Nuclear Power ◽

Power Plants ◽

Nuclear Power Plants ◽

Wear Test ◽

Test System ◽

Fretting Wear ◽

Stable Operation ◽

Test Results ◽

Steam Generator Tubes

In steam generators of nuclear power plants, flow-induced vibration (FIV) can lead to tube damage by fretting-wear occurred due to impact and sliding movement between the tubes and their supports. There have been many studies and test results on wear damage of steam generator tubes but they were not reflected the mechanical and chemical conditions accurately. KEPRI nuclear power laboratory developed a wear test system, which is able to control the motion of impact and sliding simultaneously in the pressurized high temperature water-chemistry conditions. Some wear tests were performed to verify the stable operation for the wear test. This wear test system with new concepts was described briefly, and some data for verifying its performance have been shown in the cases of the selected some test results. In the test, Alloy 690 was used for tube materials and 409 stainless steel for support plates. A little data deviation was obtained and stability of system operation was investigated.

Download Full-text