JPS58140689A - Device for measuring water level in reactor pressure vessel - 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 an improvement in a water level measuring device for determining the water level of cooling water in a nuclear reactor pressure vessel.

[Technical background of the invention]

FIG. 1 shows a conventional water level measuring device for measuring the water level H of cooling water 2 in a reactor pressure vessel 1. Upper communication pipes 8 are provided at the upper and lower parts of the peripheral wall of the reactor pressure vessel 1, respectively.
1. A reference water head forming section 1 is installed via a lower communication pipe 4.

A fluorostatic pressure transmitter C is inserted into the lower communication pipe 4. The reference water head forming section 5 is constructed by connecting a small-diameter vertical pipe 5B to the bottom of the condensing tank JA.The upper communicating pipe 3 is connected to the peripheral wall of the condensing tank 5A and the peripheral wall of the reactor pressure vessel 1. It communicates with the soil part and is arranged so as to slope downward from the condensation tank sh toward the reactor pressure vessel IK.

The lower communication pipe 4 is arranged substantially horizontally and communicates the lower part of the peripheral wall of the reactor pressure vessel 10 with the lower end of the vertical pipe jB. Then, water is filled into the inside of the reference water control forming part 5 up to the communication position of the upper communication pipe I, and a constant reference water l [h
- The differential pressure transmitter 6 is designed to maintain the reference water head pressure generated by the above reference water head and the water level of the cooling water 2 in the reactor pressure vessel 1 from the differential pressure transmitter - to the water surface of the cooling water 2 in the reactor pressure vessel 1. Differential pressure between water head pressure caused by water lit klo-P
(y7cm”).

With the above configuration, the height from the inner bottom surface of the reactor pressure vessel 1 to the water surface of the cooling water 2, that is, the water level H6I of the cooling water 2 in the reactor pressure vessel 1, can be determined from the following equation.

However, Hl differential pressure transmission #Se from the inner bottom surface of the dual reactor pressure vessel 1
height ←) rt: [Specific weight of cooling water for 1 yen of child reactor pressure vessel (kII/
ns') r, specific weight of steam in the two-reactor pressure vessel 1 (yu7m3) 7t: average specific weight of water in the reference water head forming part d Ckg/r
m) [Points to be followed during backlift technology] For example, in the event of a loss of cooling water accident, the reference water head forming part 1 will be brought to a high temperature by the high temperature cooling water that has flowed out from the reactor pressure content IM11. Become. So Jl.
-The water in the monk 5mu boils under reduced pressure, resulting in a condensation tank 5mu 0.
Standard water a.
By maintaining h, the average specific weight 7t of water in the reference water head forming portion 5 becomes smaller. Therefore, the above (4)
The water RIM obtained from the formula was detected much smaller than the actual water head, making it impossible to accurately measure the water level of cooling water 2, and making it impossible to accurately grasp the amount of cooling water leaked and the scale of the accident. [Objective of the Invention] The purpose of the present invention is to prevent the leakage of high-temperature cooling water from occurring even in the event of a loss of cooling water accident in the reactor pressure vessel. An object of the present invention is to provide a water level measuring device in a nuclear reactor pressure vessel, which can determine the water level with great accuracy and further improve safety.

[Summary of the invention]

The water level measuring device in a reactor pressure vessel according to the present invention is provided with a reference water head forming part that is connected to the reactor pressure vessel side through a downwardly inclined communication pipe, and forms a reference water head. and a lower part of the reactor pressure vessel, a differential pressure transmitter is provided to detect and transmit the difference between the reference head pressure of the reference head forming part and the pressure inside the reactor pressure vessel, and the reference head forming part a heat insulating material surrounding the outer periphery of the reactor pressure vessel, a supply device for supplying cooling water in the reactor pressure vessel to the reference water head forming section, and this supply device cooling the cooling water supplied to the reference water head forming section. This configuration is equipped with a cooling device.

In other words, by suppressing the amount of heat that enters the reference water head forming part from the outside through the insulation material, and by lowering the temperature of the water in the reference water head forming part using the supply device and cooling@snow, the water in the reference water head forming part is boiled under reduced pressure. It is an attempt to suppress the

Therefore, even if a cooling water loss accident occurs in which cooling water flows out from the reactor pressure vessel, etc., the reference water head forming section can always maintain and form a certain reference water head, and the cooling water inside the reactor pressure vessel The water level can be measured accurately.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIGS. 2 and 3.

FIG. 2 shows a water level measuring device according to the present invention that measures the water level H of the cooling water s1 in the reactor pressure vessel 51.

An upper communication pipe 5j is provided in the surrounding wall earth part and the lower part of the reactor pressure vessel 610, respectively.

A reference water head forming section 5s is installed via a lower communication pipe 54. A differential pressure transmitter Ig is connected to the lower communication pipe 54.
is inserted. The reference water head forming part 5J is a condensing tank j
It is constructed by connecting a small diameter vertical pipe 56B to the bottom of the pipe 5A. The upper communication pipe j3 communicates the peripheral wall of the condensing tank 55m with the surrounding wall of the reactor pressure vessel 510, and is arranged so as to have a downward slope from the condensing tank 56m to the reactor pressure vessel 61. has been done. The lower communicating pipe 54 of the trench 9 is arranged substantially horizontally and communicates the lower part of the peripheral wall of the reactor pressure content tiilil with the intermediate part of the vertical pipe 5iyi. The lower end of the vertical pipe aSS is connected to the bottom of the reactor pressure vessel 51 via a supply pipe 51. In this supply pipe si, there is a reference water head forming part 68 containing reactor pressure content!
! ! A supply tank 1 for supplying cooling water j2 of JJ is inserted. This supply system SS is composed of a supply pump J#, a flow rate control valve d0, and a flow rate needle 61 connected in series from the reactor pressure vessel 61@ to the reference water formation section JJK. 60 is closed. Note that the pumping height of the supply pump 5# is the reference water-forming part 55.
This corresponds to the standard wooden head restraint formed by. Further, a part of a heat exchanger 62 is configured between the flow needle #1 of the supply pipe j7 and the vertical pipe 55B.

The heat exchanger #2 has nine configurations in which the cooling pipe 64 of the cooling device 1 is brought close to a part of the supply pipe 51.
4 is installed outside the reactor containment vessel 65 and connected to the cooling water circulation pump 66 and the cooling section 61. On the other hand, the vertical pipe jjB of the standard water test formation section SS is surrounded by a heat insulating material 68 over its entire length KM. This heat insulating material 68 is made of, for example, a pearlite material having a thickness of ITSG degrees.

Next, the operation of this water level measuring device will be explained. First, during normal operation of the reactor, the reference water head forming part 64 is
A constant standard water head is maintained. The differential pressure transmitter 66 transmits the reference water pressure generated by the reference water lIh6dK and the differential pressure transmitter 56 to the reactor pressure vessel 51.
The differential pressure ΔP (ktz/m2) between the water head pressure generated by the water 11Ho up to the water surface of the cooling water j2 in the cooling water j2 is detected. The height from the inner bottom surface of the reactor pressure vessel 51 to the water surface of the cooling water 52, that is, the water level H- of the cooling water s2 in the reactor pressure vessel 51 can be determined from the following equation.

However, Hl: Height from the inner bottom surface of the reactor pressure content (trans) al to the differential pressure transmitter 5g11) 11: Specific weight of the cooling water in the II subreactor pressure content jl
(kll/m black) r: Specific weight of steam in the reactor pressure vessel 51 Ckli/
-”) 7L: Average specific weight of water in the standard water head forming part SS (yu/m
) Next, for example, in the event that a loss of cooling water accident occurs, the high temperature cooling water from the reactor pressure vessel 51 will reach the tvb inside the reactor containment vessel 6j, and the water level established inside the reactor containment vessel-5 will rise. The measuring device will be exposed to high temperatures. At this time, by sensing the temperature, for example, the flow rate v4 moderation valve 60 of the supply device j# is opened as shown in FIG. 3, and at the same time, the supply unit fs9 is activated. Therefore, the cooling water in the reactor pressure vessel 51 is supplied to the reference water head forming section 5syc. At the same time, the cooling water m-ring pump 6 is also started, and the fluid in the cooling pipe 64 is circulated between the cooling s66 and the heat exchanger 62. Cooling water 62 is thereby supplied from the supply device 5I.
is cooled while passing through the heat exchanger 62 and continuously flows into the reference water head forming section 55. In addition, supply piping 5 at this time
The flow rate of the cooling water 52 in the condensing tank ash is regulated by the opening of the flow control valve 60 so that the water level in the condensing tank ash is kept constant. Also, the vertical pipe 55B of the reference water head forming part 55 is heat-insulated. Material #I
The reactor pressure vessel 5 is thermally isolated from the outside by
The temperature of the internal water does not rise due to the high-temperature coolant flowing out from 1.

Furthermore, even if the pressure in the reactor pressure vessel 51 gradually decreases, the cooling water 52 in the reactor pressure vessel al
Since the water is supplied into the reference water head forming section 6s in a cooled state, no boiling under reduced pressure occurs within the reference water head forming section 85, and a constant reference water @h- is always maintained. Therefore, even in a cooling water loss accident, the water level of the cooling water 52 in the reactor pressure capacity SX is determined based on the detection result of the differential pressure transmitter s6 (accurately measured by
It is possible to accurately grasp the amount of spill and the scale of the accident and take appropriate measures.

〔Effect of the invention〕

In order to fix the water level in the reactor pressure vessel according to the present invention, a nine-standard water drop forming part is provided in the reactor pressure vessel and is communicated with the reactor pressure vessel through a downwardly inclined communicating pipe. A differential pressure transmitter is provided that communicates with the reference head forming part and the lower part of the reactor pressure vessel to detect and transmit the difference between the reference head pressure of the reference head forming part and the pressure inside the Kamimachi reactor pressure vessel, and A heat insulating material surrounding the outer periphery of the water head forming part is provided, and a supply device is provided for supplying cooling water in the reactor pressure vessel to the reference water head forming part, and the cooling water supplied to the reference water head forming part by this supply device is provided. This configuration includes a cooling device that cools the water.

Therefore, even if a cooling water loss accident occurs in which cooling water leaks out of the reactor pressure vessel, the reference water head formation department can always maintain a certain standard water head, and the cooling water inside the reactor pressure vessel This has great effects, such as being able to accurately determine the water level, accurately grasping the amount of cooling water flowing out and the scale of the accident, and taking appropriate measures.

[Brief explanation of drawings]

FIG. 1 shows a conventional example, and is a schematic diagram of a water level measuring device, and FIGS. 2 and 3 show an embodiment of the present invention, so FIG. 2 shows a water level measuring device according to the present invention. Figure 3 is a schematic configuration diagram of the water level measurement system showing the state when a cooling water loss accident occurs.Reference water head forming section, 56.Differential pressure transmitter, 68.Insulation material, 58..・Feeding device, 6
3... Cooling device.

Claims (2)

[Claims] (1) The above-mentioned pipe is connected to the reactor pressure vessel via a communicating pipe that slopes downward toward the reactor pressure vessel side, and is connected to the 9 standard water head forming part, and this standard water head forming part and the lower part of the reactor pressure vessel are connected to each other. a differential pressure transmitter that detects and transmits the difference between the reference water head pressure in the reference water head forming part and the pressure in the reactor pressure vessel;
a heat insulating material surrounding the outer periphery of the reference water-forming section; a supply device that supplies cooling water in the reactor pressure vessel to the reference water head forming section; and a supply device that supplies cooling water in the reactor pressure vessel to the reference water III forming section. 9. A water level measuring device in a nuclear reactor pressure vessel, comprising: a cooling device for cooling cooling water. (2) The water level measuring device in a nuclear reactor pressure vessel as set forth in claim 1, wherein the heat insulating material is made of /f-light heat insulating material.