Development of a measurement system of gap between CSB and RV to shorten a nuclear reactor installation period

To decrease the timescale for the installation of a nuclear reactor, a reduced-scale model system is proposed for Korea's third generation nuclear reactor, the APR1400 (advanced power reactor 1400). The construction period of a nuclear power plant is one of the most important factors to make a company competitive in international nuclear energy markets. Our study is related to the modularization of reactor internals to reduce the construction period of nuclear power plants. Generally, reactor internals comprise three components: the core support barrel (CSB), the lower support structure (LSS)/core shroud (CS), and the upper guide structure (UGS). The existing method of assembly is very complicated and requires approximately 8–10 months to complete. The installation of the reactor vessel (RV) is a critical process during the construction period. The proposed method for the modularization of reactor internals can shorten the construction period by a minimum of 2 months compared to the existing method. In order to modularize the reactor internals, gaps between the CSB snubber lug and RV core-stabilizing lug must be measured using a remote method from outside the RV. Therefore, the development of a remote measurement system was necessary. In this paper, we select a suitable sensor and develop a reduced-scale model system for the physical simulation of gap measurement.