Korea Electric Power Research Institute (KEPRI) had worked a comprehensive Plant Lifetime Management (PLiM) project for a CANDU plant Wolsong Unit 1 in corporation with Korea Hydro and Nuclear Power (KHNP). The project has been performed to understand the ageing status of major components screened from the plant and to address provisions for the continued operation beyond its design life. A feasibility of the continued operation was reviewed in the aspects of technology, economics, and regulatory environments. And detail life evaluation and development of ageing management programme for continued operation are on-going. This section introduces general approach of ageing assessment in Korea, screening of critical structures and components, and an experience of ageing assessment for an example of fuel channel that is the most critical component in CANDU plant.

A. II.1.1. INTRODUCTION

A CANDU6 nuclear power plant in the Republic of Korea has been operating about 22 years since 1983, which is more than two-thirds of design life. As time passed, systems, structures, and components (SSCs) can be degraded by various modes of ageing phenomena although good operation and maintenance practices have been implemented to the field. Korea Electric Power Research Institute (KEPRI) has worked a comprehensive Plant Lifetime Management (PLiM) project for a CANDU plant Wolsong -1 in corporation with Korea Hydro and Nuclear Power (KHNP). The project had been performed to understand the ageing status of major components screened from the plant and to address provisions for the continued operation over its design life. A feasibility of the continued operation was reviewed in the aspects of technology, economics, and regulatory environments. And detail life evaluation and development of ageing management programme for continued operation as of the second phase of PLiM programme are carried out until 2007. This article introduces general approach of ageing assessment, screening of critical components and an experience of ageing assessment for an example of fuel channel that is the most critical component in CANDU plant.

Figure A. II.1 shows a schematic diagram of the PLiM feasibility study. On and off-shore licensing requirements and current practice for continued operation of CANDU plants beyond design life are reviewed and used for a reference of ageing assessments. Prior to assessing ageing and life of the SSCs, KEPRI screened the critical SSCs that are passive and long-life components and can limit the continued plant operation. An example of the screened major critical components and groups are listed in the centered box of Figure 1. Collected data of design, manufacturing, test and inspection, maintenance, replacement, drawings, material, and operation history are used as technical fundamental of the assessment. And they are stored into the PLiM database with the results of technical ageing and life evaluations. Including PLiM recommendations from assessing ageing of each SSC, PLiM cost and investment strategy can be established. Based on the cost and strategy economic evaluation is performed in the way of various economic parameters, like comparison of continued operation cost, generation cost change, and income per kW with alternative power sources that will used instead of the PLiM plant. In this study 1000MWe Korean standard nuclear power plant was assumed as an alternative power source based on the national policy of electricity power resources.