Development of a remote measurement system for the gap between RV and CSB for RVI-modularization

Abstract

This paper describes the development of a measuring system to measure gaps between the reactor vessel (RV) and the core support barrel (CSB) remotely with the aim of reactor vessel internals (RVI)-modularization. A remote measurement system was developed for use at actual construction sites of nuclear power plants using a measurement sensor, a threaded connection jig, and a zero-point adjustment device. With these, a reduced-scale model system was validated. With the remote measurement system, experiments and analyses were performed using mockups for both the RV and the CSB to verify the applicability of the proposed system in a construction project. From the data acquired by the remote measurement system, shims were separately made and adjusted. After installing the shims on RV core-stabilizing lugs, the gaps satisfied requirements within the permissible range of 0.381–0.508 mm. We evaluated the reliability and applicability of the remote measurement method and concluded that the remote measurement system enables RVI-modularization with a significantly reduced construction period.