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ICMST-Kobe 2014
Nov 2(Sun) - 5(Wed), 2014
Kobe, Japan
Nuclear Regulation Authority Outline of the New Safety Standards for Light Water Reactors for Electric Power Generation
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EJAM5-3NT58 "Development of Future Prediction of Animation by coupling of Principle Component Analysis and Singular Spectrum Analysis"
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EJAM5-3NT59 Remote Controlled Robot with expandable features

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GA 1 - 2 - 3 - 4 - AP 1 - 2 - 3 - 4 - 5 - NT 1 - 2 - 3 - 4 - 5 - 6Vol.1No.2
Vol.1, No.1, NT5 EJAM(1-1-NT5) - Internal Polishing Preventive Maintenance Technique for Primary Loop Recirculation Piping

Internal Polishing
Preventive Maintenance Technique for Primary Loop Recirculation Piping

 
TOSHIBA CORPORATION
 

KEYWORDS:
SCC, PLR piping, austenitic stainless steel, sensitized zone, stress improvement, polishing, whetstone

 
1. Technical summary
 
Classification
(I: Inspection, II: Repair, III: Replacement, IV: Preventive Maintenance, V: Others)
 
In this technique, inner surface of a pipe is polished in order to improve residual stress. Through the process, residual stress just near the inner surface removes to compression and SCC crack initiation is prevented.
Figure1(1) Figure1(2)

(1)

(2)

Fig. 1 Improvement of Surface Residual Stress and SCC Prevention by Internal Polishing

Figure2

Fig. 2 Sample of whetstone

 
2. Scope

(1) Components
Stainless steel piping/components such as BWR PLR (Primary Loop Recirculation) piping
(2) Objective Location
SCC Sensitized zone of the pipe base metal near the weld
(3) Materials
Austenitic stainless steel

 
3. Features

(1) Prevent initiation of SCC crack at the sensitized zone.
(2) This technique is applied under the air condition.
(2) This technique is adopted at the installation of piping/components (construction or replacement).

Figure3

Fig. 3 Improvement of Surface Residual Stress and SCC Prevention

 
4. Examples of Application
(1) This technique was applied to BWR PLR piping.
(2) Same process has been applied to other components such as nozzle safe-end and Reactor Internals made of stainless steel.
 
5. Reference
(1) Teruaki Sato, Kazuyoshi Yonekura, Satoshi Hongo, Shoji Hayashi and Hideyo Saito, ” Introduction of Repair/ Maintenance Techniques for SCC in Primary Loop Recirculation System Piping”, Maintenology,Vol.3,No.3(2004)
( in Japanese). (in English)
(2) Kaneo Takamori et al, ”SCC Crack Initiation and Propagation of Low Carbonized Stainless Steel in High Temperature Pure Water”, Maintenology, Vol.3,No2(2004),( in Japanese).
 
6. Contact
Japan Society of Maintenology (ejam@jsm.or.jp)