Risk Analysis on Holes Machining and Inspecting of RVI as One of the Main Equipments in Nuclear Island

Abstract

As one of the main equipments in nuclear island, Reactor Vessel Internal (abb: RVI) provides space for nuclear fuel assemblies installment and location, steers CRDM (Controlling Rod Drive Mechanism, one of the main equipments in nuclear island) to control the start-up, power adjustment, and shutdown of the reactor, leads a channel for coolant to the reactor core and dominates the rate of flow to assure the normal running of the first circle in the reactor, shields RPV (Reactor Pressure Vessel, another main equipment in nuclear island) from radiation, and supports the reactor both during normal and emergency conditions as well. There are series of screw holes and pinholes in the surface of RVI, ensuring the accurate positioning of baffles and formers (which points out the foundation of the functions RVI operates in the core mentioned above). These holes are with different dimensions and diverse types, which making machining them a tough task to accomplish. This essay focuses on the machining and dimension inspection processes of these holes, establishing a risk-prevention system to distinguish the technical risks, and formulating corresponding actions to control the final quality. Besides, the machining processes, dimensional testing technology and modularization management mentioned in this essay can be used as a beneficial feedback for technicians and quality surveillances involved in the nuclear power field as well.