Patent Number: 
Section: claims

1. A water filling system for a nuclear reactor water level gauge comprising:a reactor water level gauge instrumentation pipe connected to two vertically upper and lower portions of a nuclear reactor pressure vessel;a water filling instrumentation pipe connected to the reactor water level gauge instrumentation pipe at an inside of a reactor building and extended outside the reactor building, the water filling instrumentation pipe supplying water to the reactor water level gauge instrumentation pipe; anda water filling device provided outside the reactor building, the water filling device connected to the water filling instrumentation pipe, the water filling device injecting the water into the water filling instrumentation pipe and filling the reactor water level gauge instrumentation pipe with the water. 2. The water filling system for a nuclear reactor water level gauge according to claim 1, further comprising:a first separation valve provided in the water filling instrumentation pipe, the first separation valve being opened when a nitrogen gas or air is injected;a first operating instrumentation pipe connected to the first separation valve and extended outside the reactor building, the first operating instrumentation pipe flowing the nitrogen gas or the air; anda gas cylinder provided outside of the reactor building, the gas cylinder connected to the first operating instrumentation pipe, the gas cylinder supplying the nitrogen gas or the air to the first separation valve through the first operating instrumentation pipe. 3. The water filling system for a nuclear reactor water level gauge according to claim 2, further comprising a stop valve provided between the first separation valve and a joint detachably connecting the gas cylinder that operates the first separation valve, wherein when the stop valve is closed, an internal pressure of the first operating instrumentation pipe is maintained and the first separation valve is maintained in an opened state thereof. 4. The water filling system for a nuclear reactor water level gauge according to claim 3, wherein the water filling instrumentation pipe includes the stop valve outside the reactor building, and the first separation valve is adjacent close to the reactor water level gauge instrumentation pipe in the reactor building. 5. The water filling system for a nuclear reactor water level gauge according to claim 1, the water filling device having:a tank connected to a makeup water instrumentation pipe connecting to any one of a make-up water (MUW) pipe, a reactor cooling water (RCW) pipe, and an emergency countermeasure system tank, the makeup water instrumentation pipe flowing the water; anda pump supplying the water filled in the tank to the reactor water level gauge instrumentation pipe through the water filling instrumentation pipe. 6. The water filling system for a nuclear reactor water level gauge according to claim 5, further comprising:a second separation valve provided in the makeup water instrumentation pipe at the inside of the reactor building;a stop valve provided in the makeup water instrumentation pipe at the outside of the reactor building; anda second operating instrumentation pipe connected to the second separation valve and extended outside the reactor building, another side of the second operating instrumentation pipe connected to a gas cylinder,wherein the gas cylinder supplies nitrogen gas or air to the second separation valve through the second operating instrumentation pipe. 7. The water filling system for a nuclear reactor water level gauge according to claim 5, wherein the makeup water instrumentation pipe and the tank in the water filling device are connected at the outside of the reactor building, and water is supplied to the water filling device through the makeup water instrumentation pipe. 8. The water filling system for a nuclear reactor water level gauge according to claim 1, further comprising:an air vent line connected to the water filling instrumentation pipe on an upstream side of a first separation valve,an air vent valve provided in the air vent line, the air vent valve being is opened with the first separation valve being closed, anda funnel absorbing air contained in the water filling instrumentation pipe, and the air is guided through the air vent line. 9. A water filling system for a nuclear reactor water level gauge comprising:a reactor water level gauge instrumentation pipe connected to two vertically upper and lower portions of a nuclear reactor pressure vessel;a water filling instrumentation pipe connected to the reactor water level gauge instrumentation pipe inside a reactor building and extended outside the reactor building, the water filling instrumentation pipe supplying water to the reactor water level gauge instrumentation pipe; anda makeup water instrumentation pipe connected to a make-up water (MUW) pipe and extended outside the reactor building, another side of the makeup water instrumentation pipe connected to the water filling instrumentation pipe at the outside of the reactor building. 10. The water filling system for a nuclear reactor water level gauge according to claim 9, further comprising:a first separation valve provided in the water filling instrumentation pipe, the first separation valve being opened when a nitrogen gas or air is injected;a second separation valve provided in the makeup water instrumentation pipe, the second separation valve being opened when the nitrogen gas or the air is injected;a first operating instrumentation pipe connected to the first separation valve and extended outside the reactor building, the first operating instrumentation pipe flowing the nitrogen gas or the air;a second operating instrumentation pipe connected to the second separation valve and extended outside the reactor building, the second operating instrumentation pipe flowing the nitrogen gas or the air; anda gas cylinder provided outside of the reactor building, the gas cylinder connected to the first operating instrumentation pipe and the second operating instrumentation pipe, the gas cylinder supplying the nitrogen gas or the air to the first separation valve and the second separation valve. 11. The water filling system for a nuclear reactor water level gauge according to claim 9, wherein the water filling instrumentation pipe and the makeup water instrumentation pipe are provided partially in the reactor building and are connected to each other at the outside of the reactor building. 12. The water filling system for a nuclear reactor water level gauge according to claim 9, further comprising:a third separation valve provide at the inside of the reactor building, the third separation valve being opened/closed by internal pressure of a high pressure injection nitrogen gas supply system (HPIN), by internal pressure of a compression instrument air (IA) system, or by internal pressure of a station air (SA) system. 13. The water filling system for a nuclear reactor water level gauge according to claim 12, further comprising:a transmitter measuring a pressure in the reactor water level gauge instrumentation pipe, and monitoring a hydraulic head pressure of the reactor water level gauge instrumentation pipe. 14. The water filling system for a nuclear reactor water level gauge according to claim 13, further comprising:a control device configured to receive the pressure and the hydraulic head pressure of the reactor water level gauge from the transmitter, and to fill a condensation bath of the reactor water level gauge with the water based on the pressure and the hydraulic head pressure.