Materials Korea A comprehensive. Materials research institute leading in materials technology.

Materials Testing & Reliability Division

Materials Testing & Reliability Division

Head of Department
Song, Sang-u

Department Introduction

Joining technology department is performing the development of repair welding technologies and its suitability assessment for power plants to guarantee the safety and reliability of weld. Our major research area is as follows; 1) finite element analysis, 2) mechanical tests, 3) consulting and technical support

+82-55-280-3414

Major Activities

Development of standard welding procedure specification and equivalent P-No. table of unassigned material
Development of welds integrity verification equipment for the small bore piping
Development of seal welding technique for the repair of reactor vessel head penetration
Verification of post welding heat treatment requirements in nuclear industry Code
Development of KEPIC MI Code Cases and Addenda

Major Research Area

Development of repair welding technologies and its suitability assessment for power plants
Prediction of residual stresses, distortions and microstructure changes for weld using FE analysis
Analysis of failure mechanism for weld
Technical support and training for small and medium sized welding company

Future Research Plan

  • Online repair(mechanical clamping, socket overlay) of small-diameter pipe weldment
  • Development of repair/replacement items for nulcear power plant using 3D printing method
  • Computational analysis and verification about residual stress of joint
  • Development of manufacturing and welding technology of hign Mn steel cast valve for cryogenic application
  • Development of regulatory technology for weld integrity and repair weld safety in reactor component

Major R&D Activities

Development of standard welding procedure specification and equivalent P-No. table of unassigned material

  • Standard welding procedure specification(SWPS) refers to the Welding procedure specification (WPS) which can be used for production weld without any specific procedure qualification (PQ) test performed by manufacturers. In other words about conventional WPS, qualification tests of WPS should be performed by each manufacturer. However SWPS, developed by one designed reponsible organization, refers to the pretested SWPS which should satisfy adequate test results and the technical requirements of construction codes. Hence the SWPS can be used without performing qualification test directly by manufacturers.
  • Since the material to be used are important essential variables on welding, for the WPS and the PQR, the unassigned materials shall be qualified by the same unassigned materials. When the repair & replacement activities are performed in these NPPs, there are some difficulties to obtain the unassigned materials and to increase the number of welding procedure qualification tests because procedure qualification test shall be carried out for each one of the unassigned materials.
  • Development of Material Equivalent Table through making a comparative analysis between the assigned material specifications in KEPIC/ASME and the unassigned material specifications
  • Conducting a comparative experiment of weldability (Implant & Varestraint Test)
  • Reducing the overall cost of qualifying welding procedures
  • Development of KEPIC Code Case applicable to repair & replacement activities in operating NPPs.
Development of standard welding procedure specification
Development of equivalent P-No. table of unassigned material

Development of welds integrity verification equipment for the small bore piping

  • Not only foreign NPPs but also domestic NPPs, the failure and leakage of socket type joints were reported consistently. Also, due to the deterioration of NPPs, the frequency of failure and leakage of socket type joints will be rise. We are developing the non-contact monitoring system and welds integrity verification equipment to predict the failure of pipes. Furthermore we are developing the socket weld overlay and mechanical clamping device for on-line repair to contribute to reliability of NPPs.
  • Development of the non-contact monitoring system of safety class small bore piping
  • Development of welds integrity verification equipment for the small bore piping
  • Development of socket weld overlay technology
  • Development of mechanical clamping device for safety class 2, 3 pressure boundary
  • Verification test of overlayed and clamped joint and development of certificate system for KEPIC Code.
Welds integrity verification equipment
3D modeling of prototype clamping device