JPH0646229B2 - Reactor water level measuring device - Google Patents

Description

The present invention relates to a reactor water level measuring device, and more particularly to a reactor water level measuring device suitable for use in a pressure tube type heavy water deceleration reactor or the like.

FIG. 1 is a system diagram showing a conventional reactor water level measuring device for a pressure tube reactor. Normal reactor primary coolant (heavy water)
Is pressurized from the steam drum 1 via the downcomer pipe 2 and the mixing ball 3 by the recirculation pump 4, and sent to the pressure pipe 9 in the reactor 8 via the check valve 5, the water drum 6 and the inlet pipe 7. The coolant in the pressure pipe 9 is heated by the fuel assembly 10 installed in the pressure pipe to form a two-layer flow (mixed flow of water and steam), returns to the steam drum 1 via the outlet pipe 11, and Separated into steam. Further, the steam is sent to the turbine system 13 via the main steam pipe 12. Further, the water is mixed with the water supply of the water supply pipe 14 from the turbine system 13 and then recirculated. Mixed sphere 3
Part of the coolant is sent to the residual heat removing system 16 through the residual heat removing system intake pipe 15, and is returned to the water drum 6 through the residual heat removing system return pipe 17 through the furnace cleaning system. An abnormal water injection system 18 is connected to the residual heat removal system return pipe 17.

The reactor water level measuring device is a reference level device 2 connected to an upper part (vapor phase part) of a steam drum 1 by a gas phase pressure measuring pipe 19.
0, steam drum water level measurement pipe 1 at the bottom of the steam drum 1
Steam drum water gauge 22 and mixing sphere 3 connected by 2
Is composed of a reactor water level gauge 24 connected by a reactor water level measuring pipe 23 to each other, and a reference pipe 25 is connected between the reference leveler 20, the steam drum water level gauge 22 and the reactor water level gauge 24. ing. However, the conventional reactor water level gauge 24 having such a configuration indirectly measures the water level of the reactor 8 by measuring the water level of the downcomer pipe 2, and thus has a drawback of low measurement accuracy.

That is, at the time of loss of power source in the station that requires measurement of reactor water level and accident of loss of coolant, coolant is injected into the water drum 6 via the residual heat removal system return pipe 17 by the water injection system 18 at the time of abnormal after scrum. It Due to the check valve 5, the injected coolant does not flow toward the mixing ball 3 and the downcomer pipe 2 but flows into the pressure pipe 9. Therefore, although the actual reactor water level is sufficient, the conventional reactor water level gauge 24, which uses the downcomer pipe water level as the reactor water level, may not be able to detect the true reactor water level.

An object of the present invention is to provide a highly accurate reactor water level measuring device capable of directly measuring the reactor water level.

According to the present invention, the above-mentioned object is focused on that the water drum is located lower than the core part and that the recirculation pump is stopped at the time of scram, and the reactor water level gauge is connected to the water drum to measure the measurement point. It is achieved by changing to a water drum.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a system diagram of an embodiment of the reactor water level gauge according to the present invention. However, the same or the same components as in FIG. 1 are indicated by the same reference numerals.

The primary reactor coolant is pressurized by the recirculation pump 4 from the drum 1 via the downcomer pipe 2 and the mixing sphere, passes through the check valve 5, the water drum 6 and the inlet pipe 7, and enters the pressure pipe 9 in the reactor 8. Sent. The coolant heated by the fuel assembly 10 in the pressure pipe 9 forms a two-layer flow and returns to the steam drum 1 via the outlet pipe 11. Here, the steam is separated into water and steam, and the steam is sent to the turbine system 13 through the main steam pipe 12. The water is mixed with the water supply from the water supply pipe 14 and then recirculated.

In the reactor water level measuring device of the present embodiment, the reference level 20 is connected to the upper part of the steam drum 1, and the steam drum water level gauge 22 is connected to the lower part of the steam drum 1. Up to this point, it is similar to the conventional example, but the feature of this example is that the reactor water level gauge 24
Is connected to the water drum 6 by a reactor water level measuring pipe 23.

Next, the operation of this embodiment will be described. Since there is a water surface in the steam drum 1 at normal times, it is appropriate to regard the water level detected by the steam drum water level gauge 22 as the reactor water level.

When the water level of the steam drum 1 drops, the reactor scrams and the recirculation pump 4 stops. When the water level drops to the downcomer pipe 2, the steam drum water level gauge 22 cannot measure the water level of the reactor. However, in this embodiment, the true reactor water level can be directly measured by the reactor water level gauge 24 connected to the water drum 6 which is always in communication with the pressure pipe 9. Actually, there is an error due to the flow pressure loss between the water drum 6 and the steam drum 1 due to this measured pressure, but in this case, the flow pressure loss due to the abnormal water injection system 18 is about 0.02 kg / cm ² or less (full scale in water level conversion). Is less than 1%) and can be almost ignored.

According to the present embodiment, the reactor water level gauge 24 is connected to the water drum 6 by the reactor water level measurement pipe 23, so that the reactor water level can be directly and accurately measured when the water level of the steam drum 1 is lowered. There are possible effects. Therefore, it has the effect of increasing the reliability of the nuclear power plant.

As is clear from the above description, according to the present invention, it is possible to provide a highly accurate reactor water level measuring device capable of directly measuring the reactor water level by connecting the reactor water level gauge to the water drum.

[Brief description of drawings]

FIG. 1 is a system diagram of a conventional reactor water level measuring device provided in a pressure tube reactor, and FIG. 2 is a system diagram showing an embodiment of a reactor water level measuring device according to the present invention. 1 ... Steam drum, 2 ... Downcomer, 3 ... Mixing ball, 4 ...
... Recirculation pump, 5 ... Check valve, 6 ... Water drum, 8 ... Reactor, 9 ... Pressure pipe, 10 ... Fuel assembly, 12 ... Main steam pipe, 13 ... Turbine system, 18 ……
Abnormality water injection system, 20 …… Standard surface leveler, 21 …… Steam drum water level measurement piping, 22 …… Steam drum water level gauge, 23 ……
Piping for measuring reactor water level, 24 ... Reactor water level gauge.

Claims (1)

[Claims] 1. A reactor water level of a pressure tube type reactor in which a coolant in a steam drum is pressurized by a recirculation pump, and then the coolant is fed into a pressure pipe of a reactor through a water drum located below a core portion. In the measuring device, a reactor water level measuring device is characterized in that a reactor water level gauge for measuring the reactor water level from the pressure difference between the steam drum and the water drum after the recirculation pump is stopped is connected to the water drum by piping.