JPS6013287A - Measuring device for water level of boiling water 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 measuring device for a boiling water reactor (BWR).

[Technical Background of the Invention] A device for measuring the water level in the pressure vessel of a BWR is constructed as shown in FIG. That is, it communicates with the natural air dome 2 of the pressure vessel 1, has a steam condensing tank 3 at the upper end, and communicates at the lower end with the differential pressure measuring device 4 for measuring the autumn zone water level and the differential pressure measuring device 5 for wide band water level measurement. Narrow band water level t1 downstream pressure tap 7 which connects the upper pressure tap 6, which connects the upper part of the liquid phase part of the pressure vessel 1 and the differential pressure measuring device 4 for narrow band water level measurement.
and a lower pressure tap 8 for measuring the wide-band water level t1 which connects the lower part of the liquid phase portion of the pressure vessel 1 to the lower pressure tap 7 for measuring the narrow-band water level 51 and the differential pressure measuring device 5 for wide-band water level measurement. It consists of J'3, 9 in the figure is the water level indicator, 10
is the reactor core, 11 is the recirculation system, 12 is its suction pipe, 13 is its pump, 14 is its flow rate adjustment valve, 15 is its discharge pipe,
16 is the diene 1~pump.

In the upper air configuration, each water level measuring differential pressure measuring device 41,
The reactor water level can be determined from the differential pressure obtained in step 5.

[Background Art Problems] During operation of a BWR, its output is controlled by adjusting the recirculation flow rate of the coolant.

The dynamic pressure caused by this recirculation flow (fi) will be added to the detection pressure of the lower pressure tap 8 for broadband water level autopsy.

During normal operation of the BWR, the narrow band water level Klal! is located at a position that is not affected by the dynamic pressure, such as the upper pressure tap 6. Since the water level can be adjusted to J based on the differential pressure with the lower pressure tap 7 for l, dynamic pressure will not cause shoulder side errors.

However, in the event of an accident such as complete closure of the live fish tracheal isolation valve, the water level may drop significantly and the water level may drop to below the upper pressure tap 7 for measuring the narrow band water level 81.

In such a case, the water level will be measured based on the differential pressure between the broadband water level δ1 and the downstream pressure tap 8 and the upper pressure tap. Since the pressure detected by the lower pressure tap 8 of the broadband water level 31 contains the dynamic pressure described above, the water level set as described above will be slightly lower than the actual level.

This measurement error is caused by the differential pressure measuring device α5 for broadband water level J1 measurement.
Emergency core cooling activated by the signal outputted as J:) 4
[This is not desirable as it causes unnecessary startup of the system.

[Object of the Invention] The present invention was made based on the above-mentioned circumstances, and an object of the present invention is to obtain a BWR water level a1 measuring device that does not cause errors due to the recirculation flow rate.

[Summary of the Invention] The BWR water level measuring device of the present invention has one end opened in a steam dome of a reactor pressure vessel equipped with a recirculation system, a steam condensing tank provided at the upper end, and a narrow band, The upper pressure tap is connected to a differential pressure measuring device for broadband water level measurement, and one end is opened at a position where it is not affected by the dynamic pressure caused by the recirculating water flow in the pressure vessel, and the other end is connected to a narrow-band water level measurement device. A lower pressure tap for narrow band water level measurement is connected to a differential pressure measuring device for measurement, and one end is opened at a position affected by dynamic pressure, with one end connected to the recirculating water flow in the pressure horn container. The flow rate of the recirculating water flow in the pressure vessel generated by the recirculation system is measured in a device that has a lower pressure horn tap for wide-band water level measurement connected to a differential pressure measuring device for wide-band water level measurement. and an arithmetic device that predetermines a water level measurement error correction coefficient determined by the relationship between the output signal of the flow meter 1 and the difference between the output signals of the two differential pressure measuring devices as a relationship between the output signal of the flow meter. and a storage device for storing this obtained function, and a water level measurement error uniquely determined by the output signal of the flowmeter and the function stored in the storage device. It is characterized by the installation of a production device that corrects the output horn signal of the differential pressure measuring device for water level measurement.

3. [Embodiment of the Invention] FIG. 1 and FIG. 2, in which parts 111 are given the same reference numerals, show an embodiment of the present invention. In the present invention, the recirculation system 1
A flow opening 17 is provided in the suction pipe 12 of 1. The output signal of this droplet system is input to the water level error correction coefficient operator 18 along with the output signal of the differential pressure measuring device 4.5. In addition, the output signal of the flow meter 17 is combined with the output signal of the broadband water level four-side device 5, the output signal of the C memory device 19 that stores the calculation result of the water level error correction coefficient 18, and the water level correction arithmetic device 20. has been entered. The calculation result is displayed on the water level indicator l\9.

The calculation device for water level error correction coefficient t1 calculates the difference between the output signals of the narrow band and wide band water level measuring device 4.5, and the output signal of the flow meter 17 indicating the difference and the recirculation flow. From this, a water level error correction coefficient uniquely determined for the recirculation flow rate is determined, and this is stored in the storage device 19 as a function of the recirculation flow m.

The influence of the recirculation flow ffi is the width of the lower pressure tap 8 for the wide band water level ff1l side (=density and flow velocity of water near J,
Let the IJ7i areas of pressure vessel 1 be ρ, υ, and A, respectively, and the movement given by (1/2) ρυ' = (1/2) rt+'/ρ (where r++ -ρυA, recirculation flow rate) Although it is presumed that this is due to (1/2) (
TII) Door/ρ. Figure 3 shows this. The curve in this figure has an error due to the actual recirculation flow rate (
Curve B shows the relationship between the error due to the dynamic pressure (1/2)li12/ρ and the respective flow rates. From this figure, it can be seen that once the (city) is found in the coefficient depending on the flow rate, the water level error can be uniquely determined from the flow rate.

The correction coefficient (rt+) is written as follows:

During a full-open main steam pipe isolation valve test conducted as one of the BWR start-up tests, the narrow band water level L was
Measures ns broadband water level 1-w1 recirculation. Water level L obtained by narrow band water level I measuring ax pressure measuring device 4
n does not include the dynamic pressure error. In addition, the water level Lw obtained by the broadband water level h1 measuring river differential pressure measuring device 5 is /V.

Therefore, if we take the difference between the water levels Ln and Lw measured at the same time, the difference is equal to the error (1/2) due to the dynamic pressure of the recirculation flow rate (
rt+) Door/ρ is equal to the moon. This error is (1/
2) Dividing by Ijl'/ρ gives the error correction coefficient (
rf+) is compared to the current flow rate Ill.

Due to (rt+) error (1/2) for flow mTn, 2/
Although the broadband water level Lw can be corrected by subtracting ρ, the reason why il−RL is used as the correction coefficient up to (rt+) is as follows. In other words, the measurement range of the differential pressure measuring device 4 for narrow band water level 51 measurement is narrow, and over the entire measurement range of the wide band water level G1 measuring device 5, the difference between the water level Ln and the same Lw, the error that is recorded in the flow rate city. (1/2) (If) X
Although fil'/ρ cannot be estimated and must be estimated by extrapolation, it is easier to extrapolate (m) to the correction coefficient.

The above calculation was carried out for the operating conditions at various flow rates during the start-up test, and the correction coefficient (lil) was extrapolated to a certain extent, and the resulting correction coefficient (m) was set as a function of the flow rate city. Record g5 in the storage device 19.

Atomic short chain IIl/, 11. ! In I, the water level correction calculation device 20 calculates a correction coefficient k(
rt+) from the storage device 19 and calculate the water level measurement error with respect to the output signal of the flow position needle 17, that is, (1/2) to (T
tl) Open the X door/ρ and correct the output signal of the broadband water level 51 measuring device 5.

The arithmetic units 18 and 20 used for automatic control of chemical plans 1 to 1 can be used as they are,
It may be of any type, analog or digital. Also B
It is also possible to use a part of the computer for WR control.

Note that the calculation result of the water level correction calculation device 20 is displayed on the water level indicating device 9.

As is clear from the above, according to the device of the present invention, errors in the dynamic pressure of the recirculation flow rate of the broadband water level 51 measuring device are corrected, and the correct water level is indicated.

In other words, the conventional device (Utility Model Publication 1982-134)
! 50 and Japanese Patent Publication No. 57-35721>, the recirculation flow 11H+ is
As increases, the error increases in a quadratic manner, and the water level Lw
Even if it is actually constant as shown in one straight line,
Unlike the curve E, which appears low, this does not occur in the present invention. J5, recirculation flow■
The installation position of the flow Φ meter that measures
(,) J: Yes.

[Effect of the invention] According to the present invention, the error based on the dynamic pressure of the recirculation flow rate of the differential pressure measuring device for wide-band water level A1 measurement is corrected. Emergency core cooling IJ
There is no risk of unnecessary startup of IG systems, etc.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional water level measuring device, FIG. 2 is a schematic diagram of an embodiment of the device of the present invention, and FIG. 913 and FIG. 4 are graphs for explaining its operation. DESCRIPTION OF SYMBOLS 1... Pressure no. ...Tsuchibe Tsunotap 7...Narrow band water level iil' if! ! Hand pressure tap 8...Broadband water level 9! Lower pressure tab 9...
・Indication device 10... Core 11... Recirculation system 12... Suction pipe 17... Flow f
Li1 18...Water level error correction related to the old Q operation device 19...
Memory installation 20...Water level 1111 positive arithmetic unit application fee immediate person valve 3! LH Practitioner Kikuchi Part 5 Figure 1 Figure 2

Claims (1)

[Claims] An upper pressure tap with one end opening into the steam dome of a reactor pressure vessel equipped with a recirculation system, a steam condensing tank provided at the upper end, and an upper pressure tap with the lower end communicating with a differential pressure measuring device for narrow-band and wide-band water level measurement, respectively. , one end is opened at a position that is not affected by the dynamic pressure due to the recirculating water flow in the upper pressure horn container, and the other end is connected to a differential pressure measuring device for narrow band water level measurement. Tap and lower pressure for broadband water level measurement with one end open at a position affected by the dynamic pressure of the recirculating water flow in the upper pressure vessel and the other end communicating with a differential pressure measuring device for broadband water level measurement. What is the difference between the flow rate t1, which measures the flow rate of the recirculating water flow in the pressure vessel generated by the recirculation system, and the output signal of this flow rate and the output signals of the two differential pressure measuring devices mentioned above? a calculation device for presetting a water level measurement error correction coefficient determined by the relationship between the output signal of the flow rate system; a storage device for storing this calculated function; It is characterized by the provision of a production device that calculates a water level measurement error stirrup uniquely determined by a function stored in a memory device, and uses this to correct the output signal of the differential pressure measuring device for broadband water level measurement. Water level measuring device for Tozuru boiling water reactor.