JP2557885B2 - Differential pressure reactor water level measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a differential pressure type reactor water level measuring apparatus suitable for measuring the reactor water level of a reactor pressure vessel.

(Prior Art) There are various methods for measuring the reactor water level, but in the reactor power plant, a differential pressure type reactor water level measuring device that does not require maintenance and inspection work in the reactor containment vessel during operation is used. It

FIG. 4 shows a conventional example of such a differential pressure type reactor water level measuring device. The reactor pressure vessel 2 housed in the reactor containment vessel 1 communicates with the inside and the reactor water level is Standard water column piping 3 at the upper limit position and variable water column piping 4 at the lower limit position
Is attached. These water column pipes 3 and 4 penetrate the reactor containment vessel 1 and are connected to the differential pressure transmitter 6 of the reactor water level measuring device 5, where the reactor water level differential pressure ΔP at the upper and lower limit positions is detected. The detected differential pressure ΔP is taken into the water level calculator 7 to calculate the reactor water level L and displayed on the indicator 8. With this configuration, the maintenance and inspection work inside the reactor containment vessel 1 is not necessary at all, and the water level of the reactor pressure vessel 2 can be measured outside the reactor containment vessel 1.

(Problems to be Solved by the Invention) However, in the above-described conventional apparatus, in calculating the reactor water level L from the reactor water level differential pressure ΔP, it is assumed that the two have a linear relationship, and L = S × ΔP + β. 1), the proportional constant δ and the constant term β were uniquely determined based on the measured values during rated operation to measure the reactor water level.

Therefore, in the above-described conventional apparatus, when the operation of the nuclear reactor deviates from the rated operation, the temperature and pressure inside the reactor fluctuate greatly, resulting in a very large measurement error. For example,
When the pressure changes from the rated operating state, a large measurement error occurs as shown in FIG. When the lower limit position of the reactor water level is set to 0 and the upper limit position is set to 1500 mm, this measurement error becomes larger as it approaches the upper limit position, and there is a problem that it cannot be used as a measuring device.

Therefore, an object of the present invention is to provide a differential pressure type reactor water level measuring device which can solve the above problems and accurately measure the reactor water level regardless of the operating state of the reactor.

[Structure of the Invention] (Means for Solving Problems) The present invention is directed to a reactor water level differential pressure W _C (U) at the time of the reactor water level upper limit and a reactor water level at the time of the reactor water level lower limit according to the temperature and pressure at that time. Differential pressure W _C
(L) is calculated and the reactor water level differential pressure W _C (U), W
Based on c (L), the distance l between the reactor water level upper and lower limit positions, and the reactor water level differential pressure ΔP measured by the differential pressure transmitter, the reactor water level between the upper and lower limit positions A water level correction calculation device for calculating is calculated.

(Operation) With this configuration, even if the operating state of the nuclear reactor deviates from the rated value and the temperature and pressure inside the reactor fluctuate significantly, the reactor water level L considering this temperature and pressure is calculated, and the reactor water level L with less error is calculated. Can be measured.

(Embodiment) FIG. 1 is a block diagram of a differential pressure reactor water level measuring device according to an embodiment of the present invention. 4th in the figure
The same reference numerals as those in the figure indicate the same or corresponding portions, and the difference from FIG. 4 is that a water level correction calculation device 9 for calculating the reactor water level corrected according to temperature and pressure is provided instead of the water level calculation device 7. .

As shown in FIG. 2, the water level correction computing device 9 includes a reference water column piping temperature detector 11 outside the reactor containment vessel for detecting the temperature of the reference water column piping outside the reactor containment vessel, and a reactor outside the reactor containment vessel. Fluctuating water column piping temperature detector 12 outside the reactor containment vessel for detecting the temperature of the fluctuating water column piping, and reference water column piping temperature detector 13 inside the reactor containment vessel for detecting the temperature of the reference water column piping inside the reactor containment vessel And a variable water column piping temperature detector 14 in the reactor containment vessel that detects the temperature of the variable water column piping in the reactor containment vessel, and a reactor water temperature detector 15 that detects the reactor water temperature in the reactor pressure vessel. ,
Temperature detected by the vapor pressure detector 16 inside the reactor pressure vessel that detects the vapor pressure inside the reactor pressure vessel, the reference water column piping temperature detector outside the reactor containment vessel, and the variable water column piping temperature detector outside the reactor containment vessel Of the temperature of the water column piping outside the reactor containment vessel and the reference temperature of the water column piping inside the reactor containment vessel and the temperature of the fluctuation water column piping inside the reactor containment vessel Obtained from the water column piping temperature averaging device 18 in the containment vessel, the vapor pressure detector in the reactor pressure vessel, the water column piping temperature averaging device outside the reactor containment vessel and the water column piping temperature averaging device in the reactor containment vessel, at that time Water level differential pressure W at the upper limit of reactor water level at various pressures and temperatures
_C (U) and reactor water level differential pressure W _C (L) at the lower limit of reactor water level are calculated by calculating reactor water level differential pressure W _C (U) calculating means 19 and reactor water level differential pressure W _C (L) calculating means 20. The reactor water level upper / lower limit differential pressure correction calculation means 21 is provided, a memory 22, and a reactor water level calculation means 23.

With the above configuration, as shown in FIG. ₁ , the distance between the reactor water level L of the reactor pressure vessel 2 and the A portion of the reference water column pipe 3 attached to the reactor water level upper limit position is now l ₁ , and the reactor water level L is The distance between the A'part of the variable water column pipe 4 is l ₂ , the distance between the A'part and the B'part of the variable water column pipe 4 is l ₃ , and the distance between the A and B parts of the reference water column pipe 3 is l ₄ The distance between the B part of the standard water column pipe 3 and the B'part of the variable water column pipe 4 is l ₅ , and the distance between the A part of the standard water column pipe 3 and the A'part of the variable water column pipe 4 is l.

Va: Specific water volume (constant) at the reference temperature Vg: Saturated steam volume in the reactor pressure vessel according to the steam pressure in the reactor pressure vessel at that time Vf ₁ : Reactor according to the reactor water temperature at that time Specific volume of saturated water in the pressure vessel Vc: Specific volume of pressurized water in the water column piping in the reactor containment vessel according to the average temperature of the water column piping in the reactor containment vessel at that time Vt: Average temperature of the water column piping outside the reactor containment vessel at that time Specific volume of pressurized water in the water column piping outside the reactor containment vessel according to the following: l ( ₁ , _L ): l ₁ (constant) at the lower limit of the reactor water level measurement device l ( ₂ , _L ): l _{2 at the} lower limit of the reactor water level measurement device (Constant) l ( ₁ , _U ): l _{1 at the} upper limit of the reactor water level measuring device l (Constant) l ( ₂ , _U ): l _{2 at the} upper limit of the reactor water level measuring device If defined as the (constant), the reference aqueous line A, Pressure at B, C, D P _A ,
P _B , P _C , P _D is P _A = P ∞ −l ₁ / Vg …… (2) P _B ＝ P _A ＋ l ₄ / Vc …… (3) P _C ＝ P _B ＋ (l ₄ −l ₄ ) / Vt = P _B …… (4) P _D ＝ P _C ＋ l ₅ / Vt …… (5) The pressure A _A ′, P _B ′, P _C ′ in the fluctuating water column lines A ′, B ′, C ′ is P _A ′ = P ∞ + l ₂ / Vf ₁ (6) P _B ′ = P _A ′ ＋ l ₃ / Vc …… (7) PC _C ′ ＝ P _B ′ ＋ (l ₃ −l ₃ ) / Vt ＝ P _B ′ …… (8). Thus, the differential pressure DP of the theoretical obtained differential pressure transmitter _{6, DP = P C '-P D} = (l 1 / Vg + l 2 / Vf 1 + l 3 / Vc) - (l 4 / Vc + l 5 / Vt ……
It can be expressed as (9). Therefore, when the reactor water level differential pressure W _C (U) when the reactor water level is at the upper limit position L _U is calculated by using this equation (9) and the above definition, W _C (U) = V _a [( l ( ₁ , _U ) / V _g +1 ( ₂ , _U ) / Vf ₁ ＋ l ₃ / Vc) − (l ₄ / Vc + l ₅ / Vt)] ... (10). Similarly, when the reactor water level is at the lower limit position L _L , the reactor water level differential pressure W _C (L) is W _C (L) = Va [(l ( ₁ , _L ) / Vg + l ( ₂ , _L ) / Vf _{1 + l 3 / Vc) - (} l 4 / Vc + l 5 / Vt)] obtained with the ... (11).

On the other hand, assuming that there is a linear relationship between the reactor water level differential pressure and the reactor water level, the differential pressure W _C (U), W _C (L) at the reactor water level upper and lower limit positions calculated by the equations (10) and (11) above. When the reactor water level L at that time is obtained from the reactor water level differential pressure ΔP measured using And the reactor water level L with a small error in consideration of the temperature and pressure at that time is obtained.

A concrete block diagram for realizing this is shown in FIG. 2, and fixed information such as l ₁ to l ₅ , l, Va is stored in advance in the reactor water level upper and lower limit differential pressure correction calculation means 21.

On the other hand, through each of the detectors 11 to 16 and the averaging devices 17 and 18, the aqueous pipe temperature average value at that time, the reactor water temperature, and the in-reactor steam pressure are taken into the reactor water level upper and lower limit differential pressure correction calculation means 21, Vg, Vf ₁ , Vc, and Vt corresponding to these temperatures and pressures are calculated.

Next, based on these calculated values and the stored data from the memory 22, the reactor water level differential pressure W _C (U) calculating means 19, when the reactor water level is at the upper limit,
Reactor water level differential pressure W _C (L) at the reactor water level lower limit The reactor water level upper and lower limit differential pressure W _C (U), W according to the equations (10) and (11) calculated by the calculating means 20.
_C (L) is calculated.

As a result, the reactor water level calculation means 23 fetches W _C (U) and W _C (L) from the reactor water level upper and lower limit differential pressure correction calculation means 21, the memory 22 from l, and ΔP from the differential pressure transmitter 6, and The reactor water level L can be obtained by calculating the equation (12).

In this way, by displaying the reactor water level L corrected and calculated by the water level correction arithmetic unit 9 on the indicator 8, the reactor water level L can be accurately measured and displayed regardless of the operating state of the reactor.

FIG. 3 shows the measurement error at this time.
It can be seen that the measurement error is much smaller than the conventional case shown in the figure even when the rated operating state is greatly deviated.

The arithmetic processing in the water level correction arithmetic device 9 may be realized by an analog arithmetic device, or may be realized by using a microcomputer or an electronic calculator.

[Effect of the Invention] As described above, according to the present invention, a differential pressure type reactor water level measuring device capable of accurately measuring the reactor water level regardless of the operating state of the reactor can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block configuration diagram of a differential pressure reactor water level measuring device showing an embodiment of the present invention, FIG. 2 is a detailed block diagram of a water level correction computing device of FIG. 1, and FIG. FIG. 4 is an actual measurement diagram of measurement error by the apparatus of FIG. 1, FIG. 4 is a block diagram of a conventional differential pressure type reactor water level measurement apparatus, and FIG. 5 is an actual measurement figure of measurement error by the apparatus of FIG. 6 ... Differential pressure transmitter, 9 ... Water level correction calculation device, 15 ... Reactor water temperature detector, 16 ... Reactor pressure vessel vapor pressure detector,
17 …… Temperature averaging device for the water column outside the reactor containment vessel, 18 ……
Water column piping temperature averaging device in the reactor containment vessel 18, 19 …… Reactor water level differential pressure W _C (U) calculation means at water level upper limit, 20 …… Reactor water level differential pressure W _C (L) calculation means at reactor water level lower limit , 21 …… Reactor water level upper / lower limit differential pressure correction calculation means, 22 …… Memory, 23 …… Reactor water level calculation means.

Claims (1)

(57) [Claims] 1. A differential pressure between a reference water column pipe attached to a reactor water level upper limit position of a reactor pressure vessel and a variable water column pipe attached at a distance l from the reference water column lower limit position at a reactor water level lower limit position. Connect to the transmitter to detect the reactor water level differential pressure ΔP,
The reactor water level L is calculated based on the detected reactor water level differential pressure ΔP,
In the differential pressure type reactor water level measuring device displayed on the indicator, the reactor water temperature detector that detects the reactor water temperature in the reactor pressure vessel and the reactor pressure vessel vapor pressure that detects the vapor pressure in the reactor pressure vessel Detector and reference water column piping temperature detector inside the reactor containment vessel that detects the temperature of the reference water column piping inside the reactor containment vessel, and reactor containment that detects the temperature of the reference water column piping outside the reactor containment vessel Reference water column piping temperature detector outside the vessel, fluctuation water column piping temperature detector inside the reactor containment vessel that detects the temperature of the fluctuation water column piping inside the reactor containment vessel, and temperature of the fluctuation water column piping outside the reactor containment vessel The temperature detected by the fluctuation water column piping temperature detector outside the reactor containment vessel, the reference water column piping temperature detector outside the reactor containment vessel, and the fluctuation water column piping temperature detector outside the reactor containment vessel The average temperature of the water column piping outside the reactor containment vessel, the reference water column piping temperature detector inside the reactor containment vessel, and the fluctuation water column piping temperature detector inside the reactor containment vessel Water column piping temperature averaging device in the vessel, the reactor pressure vessel vapor pressure detector, the water column piping temperature averaging device outside the reactor containment vessel and the water column piping temperature averaging device in the reactor containment vessel, the pressure at that time And the reactor water level upper and lower limit differential pressure correction calculation means for calculating the reactor water level differential pressure W _C (U) at the time of the reactor water level upper limit and the reactor water level differential pressure W _C (L) at the time of the reactor water level lower limit, and the reactor water level Based on the differential pressures W _C (U), W _C (L), the distance 1 and the reactor water level differential pressure ΔP, the reactor water level L is L = (ΔP−W _C (L)) × l / (W _C (U ) -W _C (L)) as a reactor water level calculation means, and A differential pressure type reactor water level measuring device characterized by being provided.