Development strategy of the improved standard technical specification for Wolsong CANDU-6 nuclear power plants

The Wolsong CANDU-6 can be differently treated to a certain extent in terms of operation and safety due to the wide span of commissioning dates between, namely, Unit 1 and Units 2,3,4. This fact resulted in the use of non-unified technical specification (OP and P style in Unit 1 and US standard technical specification style in Units 2,3,4). Thus, it became necessary to improve Limiting Condition for Operations (LCOs) that have been based upon insufficient selection criteria in context of safety standards in the past. The newly developed ISTS for Wolsong CANDU-6 is aimed to achieve the following points, (1) Elimination of unnecessary LCOs that are irrelevant to plant safety, (2) Unification of similar LCOs and relocating them, (3) Application of any improvements gained from operational experiences and/or research works, (4) Reinforcement of technical bases and also placing greater emphasis on human factor principles in order to make technical specification clearer and easier to understand. The goal of Wolsong CANDU-6 ISTS development is to improve plant safety practically by selecting safety significant LCOs, optimise surveillance requirements and reinforce technical bases, in order that the development of the first one for Pressurized Heavy Water Reactor (PHWR) nuclear power plants could be accomplished in the world. Furthermore, it can be utilized as the standard technical specification to prepare Wolsong-1 Improved Technical Specification (ITS) for the continuing operation after the major refurbishment. (author)