RU2448377C2 - Method to diagnose resonant pulsations of pressure in high-power channel-type reactor discharge circuit by means of primary converter of ball flow meter storm-32m - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: invention relates to methods for measurement of pressure dynamics in a high-power channel-type reactor discharge circuit in different modes of its operation, in particular, to methods for diagnostics of resonant pulsations of pressure in the discharge circuit of the high-power channel-type reactor. In systems with control facilities connected to inputs of a computer, the measurement and recording devices connected with more than one parallel connected working channel of fluid agents displacement, take and record readings of measurement devices, besides, for fuel channels of the high-power channel-type reactor arranged in one distribution group header, during registration of readings of measurement devices, records of EMF of magnetic induction converters (MIC) are made in the primary converter of the ball flow meter STORM-32M, for the time interval, in which EMF of selected channels MIC was recorded. Data on total feed of a reactor coolant pump is summed and compared in the appropriate half of the reactor and by total flow of water for this half. Time rows of EMF are graphically processed in MIC of selected process channels, with simultaneous detection of 1/f -noise (flicker-noise) and the fact of total water flow reduction, the fact of resonant oscillations detection in the discharge circuit of the high-power channel-type reactor is registered, and operational parameters are corrected: flow rate, water pressure, reactor capacity.

EFFECT: improving nuclear power plant operation reliability and safety.

7 dwg

Description

Area of use

The invention relates to methods for measuring the dynamics of pressure in the pressure path of RBMK in various modes of its operation, in particular to methods for diagnosing resonant pressure pulsations in the pressure path of RBMK.

This invention can be used, in particular, to establish and study the signs characterizing the occurrence of pressure pulsations in the pressure path of the RBMK nuclear reactor in various modes of its operation, can also be used in other types of reactors with water as a coolant, in research thermohydraulic stands used for modeling processes in nuclear power plants (NPPs), as well as in other industries, such as oil.

In all these areas of use, the reliability of the readings of the working flow meters is important, for example, established by comparing the sum of the readings of the flow rate of the medium to many consumers to the total volume allocated to them from a common source, which must match. However, in practice, when using ball meters, in many cases this equality is not fulfilled.

List of Abbreviations

SHADR-32M - primary converter of a ball flowmeter SHTORM-32M

(SHADR - ball sensor of a flowmeter).

SHTORM-32M - a ball flowmeter, the sensor of which is ShADR-32M.

RBMK - channel high power reactor.

KMPTs - a circuit of multiple forced circulation.

RGK - distribution group collector.

SAM - shut-off and control valve.

MIP is a magnetic induction converter of a primary converter of a ball flow meter.

MCP - main circulation pump.

EMF is an electromotive force.

КРВ - water flow control.

PSD - Power Spectral Density - power spectral density.

CPSD - Cross Power Spectral Density - mutual power spectral density.

NPP - nuclear power plant.

A known method of controlling pressure pulsations in power plants (for example, in steam turbines) using dynamic pressure sensors (for example, "Pressure sensor measuring DDI-220 5D2.328.000 TU"). Such sensors are based on the use of piezoelectricity and are made of materials that exclude their long-term operation in reactor conditions - high temperature, aggressiveness and radioactivity of the medium. This well-known solution does not provide adequate timely identification and elimination of the causes of pulsations in the circulation circuit, which is necessary to increase the reliability and safety of operation of nuclear power plants.

The standard pressure monitoring devices in the nuclear power plant are based on pressure measurement methods suitable for measuring only static pressure due to their inertia (RBMK Channel Nuclear Power Reactor. / Under the general editorship of Yu.M. Cherkashov, - M .: GUP NIKIET, 2006, p. 355 )

The STORM-32M flowmeter used to measure water flow in RBMK fuel channels is based on measuring the frequency of EMF pulses generated in a magneto-induction transducer (MIP) coil during rotation of a ferromagnetic ball A in a permanent magnet field (see Fig. 1 and Fig. 2) . (Lysikov B.V., Prozorov V.K. Thermometry and flow metering of nuclear reactors. - M .: Energoatomizdat, 1985). The ball is driven into rotation by a stream of contour water. Thus, this standard device is based on the analysis of the dynamic characteristics of the ball. This circumstance can be used to study dynamic processes in the RBMK circulation loop, since the device is built into the circuit and, therefore, the movement of the ball is affected by pressure pulsations that occur in the circuit.

There is also known a solution that can be considered as the closest analogue of the prototype.

There is also known a solution that can be considered as the closest analogue prototype, which includes operations provided by automation, regulation, parameters registration, associated with more than one parallel working channel for moving fluid agents, measuring instruments, technological means of protection parameters and controls.

The system of channel-by-channel control of water flow (RCC) using SHTORM-32M flowmeters at the RBMK reactor provides every 2 minutes: measuring and recording water flow in all channels of the core and determining the total water flow in the technological channels of the left and right halves of the reactor, as well as for the entire reactor. To measure the flow of the MCP (water flow provided by the main circulation pumps) throttle washers and differential pressure gauges are installed, while the feed of the MCP to each half of the reactor is controlled using the SCALA centralized control system. (Channel nuclear power reactor RBMK. / Under the general editorship of Yu. M. Cherkashov. - M.: Publishing House "GUP NIKIET", 2006, p. 366).

However, this known solution also does not adequately extract information indicative of the existence of resonant pressure pulsations in the RBMK circulation loop (CMPC).

The technical result to which this invention is directed is to extract information contained in the stochastic signals of the EMF of the magnetic induction transducer (MIP) of the SHTORM-32M ball flowmeter, indicating the existence of resonant pressure pulsations in the circulation circuit in order to identify and eliminate the causes of their occurrence to increase reliability and safety of operation of nuclear power plants.

This result is provided by the proposed set of essential features.

A method for diagnosing resonant pressure pulsations in the pressure path of RBMK, namely, in systems having control means connected to the inputs of a computing device, measuring and recording devices associated with more than one parallel working channel for moving fluid agents are taken, readings are recorded measuring devices, moreover, for RBMK fuel channels located in one distribution group collector (RGC), when registering the readings of measuring devices, they record EMF MIP of the primary converter of a ball flow meter SHTORM-32M, for the time period during which EMF MIP of the selected channels was recorded, print the data of the system for monitoring the technological parameters of the reactor, summarize and compare data on the flow rate of water through the MCP of the corresponding half of the reactor and on the total water flow rate for this half, determined by the ball flow meters SHTORM-32M, and for the previously obtained time series of the EMF MIP of the selected technological channels, a graph is constructed and spectral density power (PSD) and mutual spectral density spectral density (CPSD) graphs, for the PSD of each series, graphs are also plotted in double logarithmic coordinates, PSD characteristic points that are the intersection points of the regression lines are detected on the constructed graphs, while 1 / f ^α - noise (flicker noise) and the fact of a decrease in the total water flow, determined by the SHTORM-32M ball flow meters, relative to the total supply of the MCP, the fact of detecting resonant oscillations in the pressure path is recorded RBMK and make adjustments to operational parameters: flow rate, water pressure, reactor power.

The invention is illustrated by the accompanying drawings.

Figure 1. Primary converter of a ball flowmeter SHTORM-32M.

Figure 2. Ball in the magnetic field MIP.

Figure 3. Power spectral density EMF MIP channel 1.

Figure 4. Power spectral density EMF MIP channel 2.

Figure 5. Flicker noise EMF MIP channel 1.

6. Flicker noise EMF MIP channel 2.

7. Mutual power of spectral density EMF MIP in channels 1 and 2.

In figure 1, the positions indicated:

1 - latch MIP;

2 - a permanent magnet;

3 - MIP coil;

4 - MIP building;

5 - camera rotation of the ball;

6 - laying;

7 - pin;

8 - durable case;

9, 11 - sensor housing;

10 - jet straightener;

12 - sleeve;

13 - ball;

14 - auger;

15 - nut.

Typical graphs of PSD and CPSD EMF MIP, as indicated, are shown in Fig.3, 4, 7.

Plots with slopes of the regression lines that indicate the existence of 1 / f ^α noise (α≤2) (Timashev S.F. Flicker noise spectroscopy. Information in chaotic signals. - M .: Fizmatlit, 2007) arising due to metastable states and phase transitions of water in the rotation chamber of the ball of the primary converter of the SHTORM-32M ball flowmeter, as well as PSD characteristic points, which are the intersection points of PSD regression lines in neighboring sections, indicating a different nature of the phase transition s and metastable states (see FIG. 5 and FIG. 6, points A, B, C). (Skokov V.N., Reshetnikov A.V., Koverda V.P. "Self-organization of critical fluctuations and 1 / f spectra in crisis boiling modes." - Thermophysics of High Temperatures, Volume 38, No. 5, 2000, p. 86- 791).

Such an analysis makes it possible to determine common for the selected channels and, therefore, characteristic for the entire pressure path RBMK, oscillation frequencies of the EMF MIP;

The design of the primary converter of the SHTORM-32M ball flow meter is such that the chamber in which the ferromagnetic ball rotates forms a dead end tank from which the gas phase cannot exit (see pos. 5 in Fig. 1).

The work of structural elements shown in figure 1, is as follows. Water entering the primary converter through the inlet pipe passes through a jet straightener 10, partially equalizing the flow of water, and a three-blade screw 14, the main purpose of which is to twist the stream in the ball rotation chamber. In this case, the measured flow has both axial and peripheral velocity components. The peripheral component of the velocity of the measured flow, acting on the sensing element of the primary transducer - ball 13, causes it to rotate around the longitudinal axis of the primary transducer. The speed of rotation of the ball in this case is greater, the greater the density and speed of water. The movement of the ball using the coil 3 of the magneto-inductive transducer MIP 4 is converted into an electrical pulse signal, the frequency of which has a certain relationship with the frequency of rotation of the ball.

For some operating parameters of the coolant, the amplitudes of the pressure pulsations in the RBMK path can reach such a value that the coolant in the chamber where the ball rotates (pos. 13 in Fig. 1) will be in a saturation state. In this case, the chamber is steamed, the density of the medium, under the dynamic influence of which the ball moves, decreases. This leads to a decrease in the speed of rotation of the ball, and as a result, according to the indications of the standard RBMK water flow control system (RCS), a false decrease in the coolant flow rate in the reactor fuel channel is recorded.

If at the same time 1 / f ^α - noise is detected and the fact of a decrease in the total water flow determined by the SHTORM-32M ball flow meters relative to the total supply of the MCP is detected, then a conclusion is made about the existence of resonant oscillations in the RBMK pressure path.

This information is a signal to identify the causes of resonant pressure fluctuations in the KMPTs and take measures to eliminate them in order to ensure safe operating conditions of the reactor, and, in particular, to prevent ruptures of the KMPTs pipelines, loss of stability of the MCC operation, etc.

Claims (1)

A method for diagnosing resonant pressure pulsations in the pressure path of RBMK, namely, in systems having control means connected to the inputs of a computing device, measuring and recording devices associated with more than one parallel working channel for moving fluid agents are taken, readings are recorded measuring devices, moreover, for RBMK fuel channels located in one distribution group collector, when registering readings of measuring devices, recording EMF of magnetic induction converters (MIP) of the primary transducer of the SHTORM-32M ball flowmeter for the period of time in which the EMF of MIP of the selected channels was recorded, print the data of the reactor technological parameters monitoring system, summarize and compare the data on the total supply of the MCP of the corresponding half of the reactor and the total the water flow for this half, determined by the ball flow meters SHTORM-32M, characterized in that for the previously obtained time series EMF MIP in For the selected technological channels, spectral density power (PSD) graphs and spectral density mutual power graphs (CPSD) are plotted, double logarithmic coordinates are also plotted for the PSDs of each series, PSD characteristic points, which are the intersection points of the regression lines, are revealed on detection of 1 / f ^α f noise (flicker noise) reduction and the fact that the total water flow rate as determined by the ball flowmeters STORM-32M, relative to the total feed MCP register fact Detect zheniya resonant oscillations in the discharge path and produce RBMK adjustment of operational parameters: flow, water pressure, reactor power.

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