JPS6189589A - Water level indicator for nuclear reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a water level gauge for a nuclear reactor used in a light water reactor such as a wooden or pressurized water reactor.

Technical background of the invention and its problems] As is well known, reactor water level gauges used in light water reactors such as boiling water reactors or pressurized water reactors have an output that is equal to or greater than the reactor. Because it is used for water level control, reactor protection systems, and water supply DO systems, it is necessary to transmit accurate water level signals even in the event of a reactor accident.

This reactor water level gauge is partially 1 as shown in Figure 4.
A lower impulse pipe 2 has one end connected to the upper side wall 1a of the reactor accident case 211 shown in cross section only on the u11 plane, and the other end of this upper impulse pipe 2 is connected to a higher position than the upper impulse pipe 2. A quasi-level vessel 3, a lower pressure pipe 5 whose one end is connected to the fixed point 4 at the lower part of the side wall 1a of the reactor pressure vessel 1, and this lower impulse pipe 5 and 3. It is composed of a differential pressure converter 8 that is connected to a reference water head pipe 6 whose upper end is connected to the water level device 3 via valves 7a and 7b and transmits a water level signal. Semi-water level 1 in water level vessel 3
0 is a reference water head in the reference water head pipe 6, 11 is a part of the containment vessel, 12 is a dry well, and 7C is a bypass valve of the lower impulse pipe 5 and the reference water head pipe 6, respectively.

The principle of the reactor water level gauge configured as described above is to calculate the difference between the static water head and the reference water head 10 provided in the dry well 12 and the static water head at the measurement point 4 of the reactor pressure vessel 1. The water level is determined by measuring with a pressure transducer 8.

However, the reactor water level gauge having the above configuration has the following drawbacks.

However, during normal operation of the reactor, steam in the reactor pressure vessel 1 flows into the reference water level gauge 3 from the upper impulse pipe 2 and is condensed to maintain the reference water level 9. The water at the reference water head 10 inside is in a high temperature state. Under these conditions, if the pressure in the reactor pressure vessel 1 suddenly drops due to a rupture in the main steam pipe, etc., the water in the reference water level vessel 3 will undergo a reduced-pressure boiling phenomenon, which will cause differential pressure conversion. A normal pressure of 5° was transmitted to the transducer 8, and the output of the differential pressure transducer 8 showed no abnormal value.

In addition, reactor isolation factor 1 n, 5 cooling system operation u・1, atomic
Since the cooling water sprayed from 9 people enters the upper impulse pipe 2 and blocks the upper impulse pipe 2, the upper impulse pipe 2 and the reference water level device 3
The inside is rapidly cooled and becomes under negative pressure. At this time, the differential pressure converter 8
The output of shows an abnormal value.

Therefore, an erroneous signal is sent to each control device, making their operation unstable.

[Object of the invention] The present invention was made in view of the above-mentioned circumstances, and an object thereof is to provide a water level gauge for a nuclear reactor that is highly reliable even in the event of a nuclear reactor accident and improves operational safety. .

[Summary of the Invention] The present invention provides a first reference water head pipe connected to a reference water level vessel that communicates with a reactor pressure vessel and stores condensed water, and a first reference water head pipe that communicates with the reactor pressure vessel. and second differential pressure transducers respectively connected to the lower impulse pipes for transmitting reactor water pressure. In the water level gauge for a nuclear reactor, an auxiliary water level J1 having a second differential pressure converter connected to a second reference head pipe and a lower impulse pipe, respectively, which open at a position above the penetration part of the lower impulse pipe in the reactor water. By being equipped with this system, it is possible to detect the reactor water level, particularly a drop in the reactor water level, without error, thereby improving operational safety.

Embodiments of the Invention] Hereinafter, an embodiment of the water level gauge for a nuclear reactor of the present invention will be described with reference to the drawings. Note that the same parts as in FIG. 4 are given the same reference numerals and their explanations will be omitted. Furthermore, for convenience of explanation, the conventional reactor water level gauge will be referred to as the main water level gauge. In FIG. 1, the lower impulse pipe of the auxiliary water level gauge 20 is shared with the lower impulse pipe 5 of the main water level gauge. That is, the pipe 5a branched from the middle part of the lower 81S311 pressure pipe 5 is used as the lower pressure pipe. Further, the penetration portion where the lower pressure impulse pipe 5 of the main water level gauge penetrates the reactor pressure vessel 1 is a double pipe 21. Thus, the outer pipe serves as the lower pressure detection end of the main water level gauge as well as the lower pressure detection end of the 7111 auxiliary water level gauge 20. The inner tube is
The side pipe 22a extends further upward into the reactor pressure vessel 1 and opens at the position where it starts to detect the drop in reactor water, and the oil side pipe 22b sends a signal when the reactor water drops via the valve 23 (). It is connected to the differential pressure transducer 24 that transmits the signal.In other words, the pipes 22a and 22b as a whole are connected to the auxiliary water level gauge 20.
1 iB water head tube 22.

In the figure, reference numeral 25 indicates the water level in the furnace, 23b indicates a valve connecting the pipe 22b and the differential pressure converter 24, and 23c indicates a bypass valve between the lower impulse pipe 5a and the pipe 22b.

The auxiliary water level gauge 20 configured as described above monitors the drop in the core water level, and has a function that operates when the water level drops below a certain water level.

Therefore, even if the main water level gauge transmits an erroneous signal for some reason, the auxiliary water level gauge 20 can be used to confirm the correctness of the signal for the core water level, which has a huge impact on the health of the reactor. can be evaluated. In addition, since the reference water head pipe 22 is in the furnace atmosphere (pressure, temperature, etc.) during normal operation, the actual water level is determined from the differential pressure at the lower It force ratio output end! In this case, various corrections required in the conventional method can be omitted, and accuracy can be improved.

In addition, when only checking whether the water level has fallen below a certain standard water level, it is also possible to monitor the water level by asking only the above-mentioned auxiliary water level gauge 20 as shown in Figure 2. . Furthermore, as shown in FIG. 3, if the reference water head pipe 26 is opened above the water level 25 in the furnace and a small amount of water is continuously injected from one side through the water supply device 27,
There is no restriction that water level g1 measurement is below a certain reference water level, and water level measurement over a wide range is possible.

In addition, in the above explanation, the lower impulse pipe 5 and the reference water head pipe 22
The penetration part of the reactor pressure vessel 1 was made into a double pipe 21, the outer pipe was connected to the lower impulse pipe 5, and the inner pipe was connected to the reference water abutment pipe 22, but even if these are reversed. good. Further, it is needless to say that both the penetration parts do not necessarily have to be double pipes, and may be placed at different positions as long as they are at the same height.

[Effects of the Invention] Since the present invention is configured as described above, a highly reliable water level signal can be transmitted, and driving safety can be improved.

[Brief explanation of drawings]

Fig. 1 is a piping connection diagram showing an embodiment of the reactor water level meter of the present invention, Fig. 2 is a piping connection diagram showing an example of applying the auxiliary water level h1 of the present invention, and Fig. 3 is the same as Fig. 2. FIG. 4 is a piping connection diagram showing an application example of the auxiliary water level gauge of the present invention, and FIG. 4 is a piping connection diagram showing a conventional water level gauge for a nuclear reactor. 1...Reactor pressure vessel 3...Base level gauge 5...Lower impulse pipe 6.22...Reference water head pipe 8.24...Differential pressure transmitter 20...Auxiliary water level gauge 25 ...Water level in the reactor (7317) Representative: Patent attorney Noriyuki Chika (and 1 others)
name) l No. 1 Diagram 2

Claims (3)

[Claims] (1) A first reference water head pipe connected to a reference water level vessel that communicates with the reactor pressure vessel and stores condensed water, and a first reference water head pipe that communicates with the reactor pressure vessel and controls the reactor water pressure. In a reactor water level gauge having a first differential pressure transducer connected to each of the lower impulse pipes to which the pressure is transmitted, a second differential pressure transducer is provided which opens at a position above the penetration part of the lower impulse pipe in the reactor pressure vessel.
A water level gauge for a nuclear reactor, comprising an auxiliary water level gauge having a second differential pressure converter connected to the reference water head pipe and the lower impulse pipe, respectively. (2) The water level gauge for a nuclear reactor according to claim 1, wherein the upper position is the target height for measuring the drop in reactor water. (3) The water level gauge for a nuclear reactor according to claim 1, wherein the penetration part of the lower impulse pipe is a double pipe and either the outer pipe or the inner pipe is connected to the second reference water head pipe.