Abstract: A method of manufacturing an optical fiber probe includes: stretching one end of the optical fiber in an axial direction thereof to form a first tapered portion in a first conical shape in which a diameter is gradually decreased toward a leading end of the optical fiber probe at a first ratio in an axial direction of the optical fiber probe to a point spaced a predetermined distance from a point fixed to a probe holder; and immersing and etching an end of the first tapered portion in an etching solution to form a second tapered portion formed in a second conical shape in which a diameter is gradually decreased at a second ratio greater than the first ratio in the axial direction from an end of the first tapered portion to form the leading end of the optical fiber probe.

Abstract: A coolant recirculation system of a nuclear power plant is provided that may include: a reactor vessel configured to accommodate a reactor core and a reactor coolant therein; a steam generator configured to transfer a gas, converted from a liquid phase to a gaseous phase by exchanging heat with the reactor coolant, to a turbine system; a pressurizer configured to control pressure of the reactor coolant in the reactor vessel; a primary system pressure reducing valve located above the pressurizer and configured to open at a predetermined pressure to discharge the reactor coolant into a containment building for rapid depressurization; and a moisture separator connected to the primary system pressure reducing valve to separate moisture. The moisture separator may separate the reactor coolant into a gaseous phase and a liquid phase. Then, the liquid phase reactor coolant may be returned to the reactor vessel to be recirculated.

Abstract: Disclosed is an optical fiber probe for measuring parameters of a local two-phase flow, which is fixed to a probe holder of a two-phase flow measuring device and is installed in a flow path of a two-phase flow of a liquid phase fluid and a gas phase fluid. The optical fiber probe includes: a first tapered portion which is formed in a conical shape in which a diameter is gradually decreased at a certain ratio in an axial direction thereof to a point spaced a certain distance from a point thereof fixed to a probe holder, toward a leading end of the optical fiber probe; and a second tapered portion which is formed in a conical shape in which a diameter is gradually decreased at a greater ratio than that of the first tapered portion in an axial direction thereof from an end of the first tapered portion.