Development of Closed-Circuit Television Inspection System for Steam Generators in Nuclear Power Plants

Author(s):  
Chao-Rong Wu ◽  
Bo-Wen Lu
2020 ◽  
Vol 12 (12) ◽  
pp. 5149
Author(s):  
Ga Hyun Chun ◽  
Jin-ho Park ◽  
Jae Hak Cheong

Although the generation of large components from nuclear power plants is expected to gradually increase in the future, comprehensive studies on the radiological risks of the predisposal management of large components have been rarely reported in open literature. With a view to generalizing the assessment framework for the radiological risks of the processing and transport of a representative large component—a steam generator—12 scenarios were modeled in this study based on past experiences and practices. In addition, the general pathway dose factors normalized to the unit activity concentration of radionuclides for processing and transportation were derived. Using the general pathway dose factors, as derived using the approach established in this study, a specific assessment was conducted for steam generators from a pressurized water reactor (PWR) or a pressurized heavy water reactor (PHWR) in Korea. In order to demonstrate the applicability of the developed approach, radiation doses reported from actual experiences and studies are compared to the calculated values in this study. The applicability of special arrangement transportation of steam generators assumed in this study is evaluated in accordance with international guidance. The generalized approach to assessing the radiation doses can be used to support optimizing the predisposal management of large components in terms of radiological risk.


2021 ◽  
Vol 131 ◽  
pp. 103580
Author(s):  
Luca Pinciroli ◽  
Piero Baraldi ◽  
Ahmed Shokry ◽  
Enrico Zio ◽  
Redouane Seraoui ◽  
...  

Author(s):  
Masaki Yoda ◽  
Naruhiko Mukai ◽  
Makoto Ochiai ◽  
Masataka Tamura ◽  
Satoshi Okada ◽  
...  

Stress corrosion cracking (SCC) is the major factor to reduce the reliability of aged reactor components. Toshiba has developed various laser-based maintenance and repair technologies and applied them to existing nuclear power plants. Laser-based technology is considered to be the best tool for remote processing in nuclear power plants, and particularly so for the maintenance and repair of reactor core components. Accessibility could be drastically improved by a simple handling system owing to the absence of reactive force against laser irradiation and the flexible optical fiber. For the preventive maintenance, laser peening (LP) technology was developed and applied to reactor components in operating BWR plants. LP is a novel process to improve residual stress from tensile to compressive on material surface layer by irradiating focused high-power laser pulses in water. We have developed a fiber-delivered LP system as a preventive maintenance measure against SCC. Laser ultrasonic testing (LUT) has a great potential to be applied to the remote inspection of reactor components. Laser-induced surface acoustic wave (SAW) inspection system was developed using a compact probe with a multi-mode optical fiber and an interferometer. The developed system successfully detected a micro slit of 0.5mm depth on weld metal and heat-affected zone (HAZ). An artificial SCC was also detected by the system. We are developing a new LP system combined with LUT to treat the inner surface of bottom-mounted instruments (BMI) of PWR plants. Underwater laser seal welding (LSW) technology was also developed to apply surface crack. LSW is expected to isolate the crack tip from corrosive water environment and to stop the propagation of the crack. Rapid heating and cooling of the process minimize the heat effect, which extends the applicability to neutron-irradiated material. This paper describes recent advances in the development and application of such laser-based technologies.


Author(s):  
Murat Bakirov ◽  
Sergei Chubarov ◽  
Nikolay Trunov

The basic method of the operational inspection of metal of heat exchanging tubes (HET) of steam generators (SG) is eddy-current multifrequency method all over the world. The greatest distribution was received variant with eddy-current testing (ECT) by use of a bobbing probe on the Russian nuclear power plants (NPP). Tubes with the defects which a subject to plugging are defined by results of lead operational ECT over the certain algorithm. SG resource is settled and replacement is required at achievement of a limit on number of the plugged tubes [1].


Atomic Energy ◽  
2008 ◽  
Vol 105 (3) ◽  
pp. 165-174 ◽  
Author(s):  
N. B. Trunov ◽  
B. I. Lukasevich ◽  
D. O. Veselov ◽  
Yu. G. Dragunov

Sign in / Sign up

Export Citation Format

Share Document