JPS61240121A - Apparatus for measuring water level of nuclear reactor - Google Patents

Abstract

PURPOSE:To make it possible to accurately measure the water level of a nuclear reactor, by correcting the output signal of a level measuring device, which measures pressure difference between a reference water head and the pressure take-out point below a reactor water level, by the output signal of a density measuring device for measuring the pressure difference between two places below the reactor water level. CONSTITUTION:The same level measuring device 6 as a conventional one is provided below a reactor water level 2 and pressures are guided from two pressure take-out points 8a, 8b separated by a certain distance in an up-and- down direction through pressure guide pipings 9a, 9b and pressure difference is measured by a density measuring device 10. The output signal D of this density measuring device 10 comes to the value proportional to the water density of a nuclear reactor. A level correcting device 11 performs the correction of the output signal DELTAP of the level measuring device 6 by the output signal D of the density measuring device 10 to output a nuclear reactor water level signal L receiving no effect of the change in the water density of the nuclear reactor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a reactor water level measuring device that is not affected by changes in reactor water density in reactor water level measuring device equipment for a boiling water nuclear reactor for power generation.

[Technical Background of the Invention] Generally, in nuclear power plants, the reactor water level is measured and the results are used for water level monitoring during normal operation, scram in the event of a pipe rupture accident, and as a start signal for engineering safety equipment. ing.

FIG. 2 shows an example of the configuration of a conventional reactor water level measuring device. A condensing tank 5 is connected, and the lower end of this condensing tank 5 is connected to one of the pressure detection ports of a differential pressure type level measuring device 6 through a pressure guiding pipe 7b, and the other pressure detecting port of the level measuring device 6 is connected to the condensing tank 5. is connected to a pressure take-off point 3b that opens below the reactor water level 2 by a pressure piping 7a.

In the reactor water level measuring device having such a configuration, the inside of the condensing tank 5 is connected to the steam layer inside the pressure vessel 1, and the reactor steam that flows into the condensing tank 5 is cooled and liquefied there, and the excess condensation is carried out. The water is passed through the pressure vessel 1 through the downhill conduction arrangement 14.
Therefore, the liquid level in the condensing tank 5 is always constant and forms a reference water head.

Therefore, the signal is a differential pressure signal between the fluid pressures in the pressure guiding pipes 7a and 7b, and is a signal proportional to the reactor water level.

[Problems with the Background Art] In the reactor water level measuring device as described above, in order for the output signal of the level measuring device 6 to be a signal proportional to the reactor water level, the reactor water density must be constant. . However, the reactor water density is determined by the reactor pressure and temperature, and although the reactor pressure and temperature are always controlled within a certain range, loss of coolant accidents (
If a transient change occurs in the reactor such as during LOCA),
There are cases where the reactor water density fluctuates outside the control range, and in such a case, an error will occur in the reactor water level signal. Furthermore, in the event that a transient change occurs in the reactor, it is desirable to provide operators with particularly accurate reactor water level information in order to deal with this.

[Object of the Invention] The object of the present invention is to provide a reactor water level measuring device that can obtain an accurate reactor water level signal that does not affect the water level signal even if the reactor water density changes due to transient changes in the reactor. Our goal is to provide the following.

[Summary of the invention] The reactor water level measuring device of the present invention measures the pressure difference between a reference water head formed by a condensing tank communicating with a steam layer of a pressure vessel and a pressure take-off point below the reactor water level. Input the level measuring device used to measure the level, the density measuring device measuring the pressure difference between two pressure take-off points below the reactor water level, the output signal of the level measuring device, and the output signal of the density measuring device. and a level corrector for correcting the output signal of the level measuring device with the output signal of the density measuring device.

[Embodiments of the Invention] The present invention will be described below with reference to FIG. 1. In FIG. 1, the same reference numerals as in FIG. 2 indicate the same parts, so the explanation thereof will be omitted. In the present invention, the level measuring device 6 is the same as the conventional one, but furthermore, the pressure piping 9a is connected to two pressure take-off points 8a and 8b located below the reactor water level 2 and separated by a certain distance in the vertical direction. , 9b, and the density measuring device 10 measures the pressure difference. The output signal of this density measuring device 10 has a value proportional to the reactor water density. Further, the level corrector 11 is configured to correct the output signal ΔP of the level measuring device 6 using the output signal of the density measuring device 10 and output a reactor water level signal that is not affected by changes in the reactor water density. ing.

In the reactor water level measuring device of the present invention configured as described above, the output signal ΔP of the level measuring device 6 is expressed as in equation (1).

ΔP=ρ+ H+ +R+ ...(1
) Here, ρ1 is the reactor water density, Hl is the vertical distance between the pressure take-off point 3b and the reactor water level 2, and aR+ representing the reactor water level is a constant. Further, the output signal of the density measuring device 10 is expressed as in equation (2).

D-ρ+H2...(2) Here, H2 represents the vertical distance between the pressure take-off points 8a and 8b. The output signal of the level corrector 11 is expressed as in equation (3) using ΔP and D.

Therefore, the output signal of the level corrector 11 is at the reactor level H.
It becomes a value equal to 1, and becomes unrelated to the reactor water density ρ1.

[Effects of the Invention] As explained above, according to the present invention, the output signal of the level measuring device that measures the pressure difference between the reference water head and the pressure take-off point below the reactor water level is By configuring the system to correct the pressure difference between the two pressure take-off points using the output signal of the density measuring device, it is possible to measure the reactor water level more accurately without being affected by changes in the reactor water density. As a result, even if a transient change occurs in the reactor and the reactor water density fluctuates, an accurate reactor water level signal can be generated and the reactor can be operated safely and reliably.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a reactor water level measuring device of the present invention, and FIG. 2 is a block diagram showing a conventional reactor water level measuring device. 1... Pressure vessel 2... Reactor water level 3a, 3b, 8a, 8b... Pressure take-off point 4.7a,
'7b, 9a, 9b - Pressure piping 5... Condensation tank 6... Level measuring device 10... Density measuring device 11... Level corrector (8733) Agent Patent attorney Yoshiaki Inomata (and 1 more
Figure 2 3

Claims (2)

[Claims] (1) A level measuring device that measures the pressure difference between the reference head formed by the condensing tank communicating with the steam layer of the pressure vessel and the pressure take-off point below the reactor water level, and a level measuring device below the reactor water level. A density measuring device that measures the pressure difference between two pressure take-off points is input, and the output signal of the level measuring device and the output signal of the density measuring device are input, and the output signal of the level measuring device is outputted from the density measuring device. A nuclear reactor water level measuring device comprising a level corrector that corrects using a signal. (2) The reactor water level measuring device according to claim 1, characterized in that the condensing tank communicates with a steam layer in the pressure vessel via a descending pressure impulse piping.