CN113724904A - Method for measuring power of reactor core of pressurized water reactor - Google Patents

Method for measuring power of reactor core of pressurized water reactor Download PDF

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Publication number
CN113724904A
CN113724904A CN202111013210.0A CN202111013210A CN113724904A CN 113724904 A CN113724904 A CN 113724904A CN 202111013210 A CN202111013210 A CN 202111013210A CN 113724904 A CN113724904 A CN 113724904A
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pressurized water
detection
water reactor
cylindrical
nai scintillator
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杜俊涛
庞龙浩
刘杰
花锋
杨妮莹
毕仙鹏
刘进辉
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Xi'an Zhonghe Nuclear Apparatus Co ltd
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Xi'an Zhonghe Nuclear Apparatus Co ltd
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G21C17/10—Structural combination of fuel element, control rod, reactor core, or moderator structure with sensitive instruments, e.g. for measuring radioactivity, strain
    • G21C17/104—Measuring reactivity
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G21C17/02—Devices or arrangements for monitoring coolant or moderator
    • G21C17/032—Reactor-coolant flow measuring or monitoring
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Abstract

The invention discloses a method for measuring the power of a reactor core of a pressurized water reactor, which comprises the following steps: firstly, constructing a pressurized water reactor core power measuring device; secondly, determining the size of the NaI scintillator; thirdly, determining the distance between the NaI scintillator and the outer side face of the main loop pipeline; fourthly, determining the thickness of the shielding body and the diameter of the cylindrical detection channel; fifthly, determining the actual distance between the first detection mechanism and the second detection mechanism and the actual average speed of the coolant flowing through the main pipeline of the primary circuit; and sixthly, measuring the power of the pressurized water reactor core. The device is novel and reasonable in design, the radioactive activity of gamma rays generated by decay of N-16 nuclides in the main pipeline of the primary circuit of the pressurized water reactor is detected by adopting the pressurized water reactor core power measuring device, the power of the pressurized water reactor core is measured according to the gamma radioactive activity value detected by the pressurized water reactor core power measuring device, the measurement is convenient, the time and the labor are saved, and the measurement precision is high.

Description

Method for measuring power of reactor core of pressurized water reactor
Technical Field
The invention belongs to the technical field of nuclear reactor monitoring, and particularly relates to a method for measuring the power of a pressurized water reactor core.
Background
About hundreds of nuclear power units are in operation all over the world, wherein the majority of the nuclear power units are light water reactors, the rest are heavy water reactors, advanced gas cooled reactors and the like, the light water reactors are mainly two types of pressurized water reactors and boiling water reactors, about 75 percent of the light water reactors are pressurized water reactors, most of nuclear power stations put into operation and to be built in China are pressurized water reactors, during the operation of the nuclear power stations, the core power of the pressurized water reactors is an important parameter for ensuring the safe and economic operation of the pressurized water reactors, the accurate and efficient measurement of the core power of the pressurized water reactors has very important significance for the safe, reliable and economic operation of the nuclear power stations and other nuclear power devices, the existing methods for measuring the core power of the pressurized water reactors generally have two types, namely nuclear measurement and thermal measurement, the nuclear measurement speed is high, but the measurement result is not accurate enough, and the nuclear measurement is greatly influenced by geometric conditions and control rod positions simultaneously, this method requires frequent calibration of the measuring device, which is complicated and therefore time-consuming; the measurement result of the thermal engineering mode is more accurate compared with the measurement result of the nuclear, but the response speed is lower, and meanwhile, the measurement can be carried out under the condition of steady-state heat balance, and the condition required by the thermal engineering measurement is harsher.
Disclosure of Invention
The invention aims to solve the technical problem that the defects in the prior art are overcome, and the method for measuring the power of the core of the pressurized water reactor is novel and reasonable in design, detects the radioactivity of gamma rays generated by decay of N-16 nuclides in the main pipeline of the primary circuit of the pressurized water reactor by using the device for measuring the power of the core of the pressurized water reactor, measures the power of the core of the pressurized water reactor according to the gamma radioactivity value detected by the device for measuring the power of the core of the pressurized water reactor, is convenient to measure, saves time and labor, has high measurement precision and is convenient to popularize and use.
In order to solve the technical problems, the invention adopts the technical scheme that: a method for measuring the power of a pressurized water reactor core is characterized by comprising the following steps:
step one, constructing a pressurized water reactor core power measuring device: the detection device comprises a main loop pipeline, a gamma detector, a signal processing module, a shielding body, a first detection mechanism, a second detection mechanism and a pressurized water reactor core power measurement device, wherein the gamma detector is used for detecting gamma radioactivity of N-16 nuclides in the main loop pipeline, the signal processing module is used for processing radioactive signals detected by the gamma detector, the gamma detector is arranged in the shielding body, the gamma detector and the signal processing module form one detection mechanism, the number of the detection mechanisms is two, the two detection mechanisms are positioned on the same side of the main loop pipeline, the two detection mechanisms are respectively a first detection mechanism and a second detection mechanism, and the first detection mechanism and the second detection mechanism form the pressurized water reactor core power measurement device;
the shielding body is sleeved on the outer side of the gamma detector, the shielding body and a main loop pipeline are vertically arranged, a cylindrical detection channel is formed at one end, close to the main loop pipeline, of the shielding body, and a wire passing hole is formed at one end, far away from the main loop pipeline, of the shielding body;
the gamma detector comprises a NaI scintillator, a photomultiplier and a preamplifier circuit, and the NaI scintillator detects gamma radioactivity around a main loop pipeline through a cylindrical detection channel;
the signal processing module comprises a main amplifying circuit and a multichannel analyzer connected with the main amplifying circuit, wherein the input end of the main amplifying circuit is connected with the output end of the pre-amplifying circuit;
determining the size of the NaI scintillator;
step three, determining the distance between the NaI scintillator and the outer side face of a main loop pipeline: determining the distance L between the NaI scintillator and the outer side of the main pipe of a primary circuitd；
Step four, determining the thickness of the shielding body and the diameter of the cylindrical detection channel;
and step five, determining the actual distance between the first detection mechanism and the second detection mechanism and the actual average speed of the coolant flowing through the main pipeline of the primary circuit, wherein the process is as follows:
step 501, simulating different experimental distances L between the first detection mechanism and the second detection mechanism in MCNP software0Under the condition that the gamma radioactivity A detected by the first detection mechanism1And gamma-radioactivity A detected by the second detection means2；
502, according to a formula
Figure BDA0003239566380000021
Calculating the length L of coolant flowing through the main pipeline of a loop0Time of pipe section
Figure BDA0003239566380000031
The unit is s; wherein λ is the decay constant of the N-16 species;
step 503, according to the formula
Figure BDA0003239566380000032
Calculating a primary loop main line coolant flow measurement Q'0The unit is kg/h; wherein the content of the first and second substances,
Figure BDA0003239566380000033
for coolant flowing through main loop pipeline and having length L0The average velocity of the pipe section of (a),
Figure BDA0003239566380000034
s is the cross-sectional area of the main loop pipeline, and S is pi multiplied by r2R is the inner circle radius of the main loop pipeline, and rho is the density of the coolant;
step 504, when | Q'0-Q0When the L is minimum, determining the corresponding experimental interval L between the first detection mechanism and the second detection mechanism0Is the actual distance L between the first and second detecting means, and determines the length L of coolant flowing through the main conduit of the primary circuit0Corresponding to the pipe section ofL0For actual averaging of coolant flow through main conduit of primary circuitA speed v; wherein Q is0Is a coolant flow estimate;
step six, measuring the power of the pressurized water reactor core:
step 601, according to the formula
Figure BDA0003239566380000035
Calculating the gamma radioactivity average value A measured by the first detection mechanism and the second detection mechanism;
step 602, according to the formula
Figure BDA0003239566380000036
Calculating the power of the core of the pressurized water reactor in the unit of n/cm2S; where K is the conversion coefficient between the gamma radioactivity of the N-16 nuclear species and the reactor power, C is a constant 6.439, λ is the decay constant of the N-16 nuclear species, tcTime of primary coolant flowing through core active area, tc＝4.36s，t1Is the total circulation time, t, of the primary coolant1V is the actual average velocity of coolant flowing through the main conduit of the primary circuit at 163.1 s.
The method for measuring the power of the core of the pressurized water reactor is characterized by comprising the following steps: in the step one, the NaI scintillator is a cylindrical scintillator;
when the size of the NaI scintillator is determined in the second step, the NaI scintillator with the size of 50mm multiplied by 50mm and the NaI scintillator with the size of 76mm multiplied by 76mm are selected as the NaI scintillators, the distance between the detection end of the NaI scintillator and the outer side face of the main pipeline of the loop is kept unchanged, and the detection efficiency E of the NaI scintillator with the size of 50mm multiplied by 50mm is simulated in MCNP software50And detection efficiency E of 76mm × 76mm NaI scintillator76，
When E is76-E50When the NaI scintillator of the gamma detector is larger than or equal to 10%, the NaI scintillator of 76mm multiplied by 76mm is selected;
when E is76-E50When the NaI scintillator of the gamma detector is less than 10 percent, the NaI scintillator with the diameter of 50mm multiplied by 50mm is selected.
The method for measuring the power of the core of the pressurized water reactor is characterized by comprising the following steps: determination of NaI scintillator in step threeWhen the distance between the NaI scintillator and the outer side face of the main loop pipeline is spaced, the detection efficiency of the gamma detector under different distances between the NaI scintillator and the outer side face of the main loop pipeline is simulated in MCNP software according to the determined size of the NaI scintillator, and when the detection efficiency of the gamma detector is the highest, the distance L between the NaI scintillator and the outer side face of the main loop pipeline is determinedd。
The method for measuring the power of the core of the pressurized water reactor is characterized by comprising the following steps: when the thickness of the shielding body is determined in the fourth step, according to the determined size of the NaI scintillator and the distance between the NaI scintillator and the outer side face of the main pipeline of the primary circuit, the full-wrap type shielding bodies with different thicknesses are used for wrapping the gamma detector in MCNP software, the counting rate response value of the gamma detector to background radiation under the condition of the full-wrap type shielding bodies with different thicknesses is calculated, when the counting rate response value of the gamma detector to the background radiation is the highest, the thickness of the full-wrap type shielding body is determined, and then the thickness of the shielding body is determined; wherein the thickness of the shield is equal to the thickness of the full wrap shield;
and when the diameter of the cylindrical detection channel is determined in the fourth step, according to the determined thickness of the shielding body, opening cylindrical detection channels with different diameters at the end part of the simulated shielding body in MCNP software, calculating the counting rate response value of the gamma detector to the background radiation under the condition of the cylindrical detection channels with different diameters, and when the counting rate response value of the gamma detector to the background radiation is the highest, determining the diameter of the cylindrical detection channel.
The method for measuring the power of the core of the pressurized water reactor is characterized by comprising the following steps: the shield body is a cylindrical shield body and comprises two semi-cylindrical bodies, a semi-cylindrical mounting groove is formed in the middle of each semi-cylindrical body, and the two semi-cylindrical mounting grooves form a cylindrical mounting groove for mounting the gamma detector;
the cylindrical detection channel consists of two semi-cylindrical detection channels, and the two semi-cylindrical detection channels are respectively positioned on two semi-cylinders.
The method for measuring the power of the core of the pressurized water reactor is characterized by comprising the following steps: the cylindrical detection channel is communicated with the cylindrical mounting groove, the cylindrical detection channel and the cylindrical mounting groove are coaxially arranged, and the diameter of the cylindrical detection channel is larger than that of the cylindrical mounting groove.
The method for measuring the power of the core of the pressurized water reactor is characterized by comprising the following steps: the shield is a lead shield, the length of the shield is greater than that of the gamma detector, and the shield is used for wrapping the gamma detector.
Compared with the prior art, the invention has the following advantages:
1. the device for measuring the power of the pressurized water reactor core is used for detecting the gamma rays generated by decay of N-16 nuclides in the main pipeline of the primary circuit of the pressurized water reactor, and comprises a first detection mechanism and a second detection mechanism, wherein the first detection mechanism and the second detection mechanism are used for simultaneously detecting the radioactivity of the gamma rays around the main pipeline of the primary circuit, and the detection results of the first detection mechanism and the second detection mechanism are used for calculating the power of the pressurized water reactor core, so that the detection is convenient, the detection precision is high, the power of the pressurized water reactor core can be quickly obtained, and the time and labor are saved.
2. The structure of the first detection mechanism and the structure of the second detection mechanism are the same, the first detection mechanism and the second detection mechanism respectively comprise a shielding body, a gamma detector and a signal processing module, the gamma detector is detachably mounted in the shielding body, the signal processing module comprises a main amplifying circuit and a multi-channel analyzer, the main amplifying circuit is used for processing an output signal of the gamma detector, the multi-channel analyzer can be used for analyzing gamma rays generated by decay of N-16 nuclide detected by the gamma detector and outputting a radioactivity value detected by the gamma detector, the power of a pressurized water reactor core is convenient to calculate, the whole detection mechanism is simple in structure and reasonable in design, the purposes of miniaturization and light weight of the whole measuring device are achieved, and the popularization and the use are convenient.
3. The end part of the shield in the pressurized water reactor core power measuring device, which is close to the main loop pipeline, is provided with the cylindrical detection channel, in the actual operation process of the pressurized water reactor, the intensity of gamma rays near the main loop pipeline is very high, and if the shield is not arranged, the gamma detector counts and accumulates blockage, so that when the gamma radioactivity in the main loop pipeline is detected, the gamma ray intensity after multiple scattering is reduced to a certain degree by sleeving the shield on the gamma detector and arranging the cylindrical detection channel on the shield, the gamma detector in the shield is convenient to obtain a proper counting value, the problem that the gamma detector is blocked due to too high gamma ray intensity is effectively solved, and the measuring precision of the measuring device is ensured.
4. The method for measuring the power of the pressurized water reactor core has simple steps, and comprises the steps of firstly, constructing a pressurized water reactor core power measuring device, determining the size of a NaI scintillator in the pressurized water reactor core power measuring device, ensuring the detection efficiency and simultaneously reducing the cost, then determining the distance between the NaI scintillator and the outer side surface of a main pipeline of a primary circuit, determining the thickness of a shield, and determining the length and the thickness of the shield and the diameter of a cylindrical detection channel according to the diameter of the cylindrical detection channel; secondly, determining the actual distance between the first detection mechanism and the second detection mechanism and the actual average speed of the coolant flowing through the main loop pipeline; and finally, the power of the reactor core of the pressurized water reactor is quickly calculated according to a formula, so that the time and labor are saved, and the measurement precision is high.
In conclusion, the device is novel and reasonable in design, the radioactive activity of the gamma rays generated by decay of the N-16 nuclide in the main pipeline of the primary circuit of the pressurized water reactor is detected by adopting the pressurized water reactor core power measuring device, and the power of the pressurized water reactor core is measured according to the gamma radioactive activity value detected by the pressurized water reactor core power measuring device, so that the measurement is convenient, time-saving and labor-saving, and the measurement precision is high.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
FIG. 1 is a schematic structural diagram of a pressurized water reactor core power measuring device according to the present invention.
Fig. 2 is a schematic view of the connection between the semi-cylinder and the gamma detector according to the present invention.
FIG. 3 is a schematic block diagram of the electrical circuit of the pressurized water reactor core power measuring device of the present invention.
Fig. 4 is a partially enlarged view of a portion a in fig. 1.
FIG. 5 is a flow chart of a PWR core power measurement method of the present invention.
Description of reference numerals:
1-a shield; 2-a main loop pipe; 3-cylindrical detection channel;
4-gamma detector; 4-1-NaI scintillator; 4-2-photomultiplier tube;
4-3-a pre-amplification circuit; 5-a wire through hole; 6, a semi-cylinder;
7-a main amplifying circuit; 8-a multi-channel analyzer; 9-a semi-cylindrical mounting groove;
10-signal processing box; 11-hasp.
Detailed Description
As shown in fig. 1 to 5, the method for measuring the power of the pressurized water reactor core according to the present invention includes the following steps:
step one, constructing a pressurized water reactor core power measuring device: the method comprises the steps that gamma radioactivity of N-16 nuclides in a main loop pipeline 2 is detected by a gamma detector 4, radioactive signals detected by the gamma detector 4 are processed by a signal processing module, the gamma detector 4 is installed in a shield 1, the gamma detector 4 and the signal processing module form a detection mechanism, the number of the detection mechanisms is two, the two detection mechanisms are located on the same side of the main loop pipeline 2, the two detection mechanisms are respectively a first detection mechanism and a second detection mechanism, and the first detection mechanism and the second detection mechanism form a pressurized water reactor core power measuring device;
the shielding body 1 is sleeved on the outer side of the gamma detector 4, the shielding body 1 is vertically arranged with the main loop pipeline 2, a cylindrical detection channel 3 is arranged at one end of the shielding body 1 close to the main loop pipeline 2, and a wire passing hole 5 is arranged at one end of the shielding body 1 far away from the main loop pipeline 2;
the gamma detector 4 comprises a NaI scintillator 4-1, a photomultiplier tube 4-2 and a preamplifier circuit 4-3, and the NaI scintillator 4-1 detects gamma radioactivity around the main loop pipeline 2 through a cylindrical detection channel 3;
the signal processing module comprises a main amplifying circuit 7 and a multichannel analyzer 8 connected with the main amplifying circuit 7, wherein the input end of the main amplifying circuit 7 is connected with the output end of the preamplifier circuit 4-3;
it should be noted that, when a coolant of a primary circuit of a pressurized water reactor flows through a core of the pressurized water reactor, O-16 atoms in the coolant are irradiated by fast neutrons in the pressurized water reactor, the O-16 atoms and the N-16 atoms generate nuclear reaction to generate N-16 nuclides, the half-life period of the N-16 nuclides is 7.13S, the N-16 nuclides can emit gamma rays of 69% of 6.13MeV and 5% of 7.12MeV during decay, the radioactivity of the gamma rays generated by the decay of the N-16 nuclides in the primary circuit 2 is detected by arranging a first detection mechanism and a second detection mechanism at the same time, the gamma detector 4 is detachably mounted in the shield 1, the cylindrical detection channel 3 is arranged at the end part of the shield 1 close to the primary circuit 2, the intensity of the gamma rays around the primary circuit 2 is high during the actual operation of the pressurized water reactor, and if the shield 1 is not arranged, the gamma detector 4 is directly used for detecting the gamma rays around the primary circuit 2 Survey, can make gamma detector 4 count accumulation jam, consequently when surveying the gamma radioactivity in a return circuit trunk line 2, through establish shield 1 and set up cylindrical detection passageway 3 on shield 1 on gamma detector 4 cover, make the gamma ray intensity after the multiple scattering reduce to certain extent, be convenient for make the gamma detector 4 in the shield 1 obtain suitable count rate value, effectively improved because gamma ray intensity too high leads to the problem that gamma detector 4 blockked up, and it is high to survey the precision.
It should be noted that, a first electronic circuit board is arranged in the γ detector 4, the preamplifier circuit 4-3 is integrated on the first electronic circuit board, and the circuit schematic diagram of the preamplifier circuit 4-3 can refer to the circuit schematic diagram of the preamplifier circuit disclosed in the fast reactor coverage gas γ activity monitor of the chinese utility model patent No. 202021350288.2; the signal processing module still includes signal processing case 10, be provided with the second electronic circuit board in the signal processing case 10, main amplifier circuit 7 is integrated on the second electronic circuit board, main amplifier circuit 7's circuit schematic can refer to the chinese utility model patent that patent number is 202021350288.2 and disclose in the fast reactor covers gaseous gamma activity monitor circuit schematic, and leading amplifier circuit 4-3's output passes through the wire and is connected with main amplifier circuit 7's input, the wire is worn out shield 1 through crossing line hole 5 and is connected with main amplifier circuit 7's input.
Determining the size of the NaI scintillator;
step three, determining the distance between the NaI scintillator and the outer side face of a main loop pipeline: determining the distance L between the NaI scintillator 4-1 and the outer side surface of the main loop pipeline 2d；
Step four, determining the thickness of the shielding body and the diameter of the cylindrical detection channel;
and step five, determining the actual distance between the first detection mechanism and the second detection mechanism and the actual average speed of the coolant flowing through the main pipeline of the primary circuit, wherein the process is as follows:
step 501, simulating different experimental distances L between the first detection mechanism and the second detection mechanism in MCNP software0Under the condition that the gamma radioactivity A detected by the first detection mechanism1And gamma-radioactivity A detected by the second detection means2；
502, according to a formula
Figure BDA0003239566380000081
Calculating the length L of coolant flowing through the main pipe 2 of the primary loop0Time of pipe section
Figure BDA0003239566380000082
The unit is s; wherein λ is the decay constant of the N-16 species;
step 503, according to the formula
Figure BDA0003239566380000083
Calculating a primary loop main pipe 2 coolant flow measurement Q'0The unit is kg/h; wherein the content of the first and second substances,
Figure BDA0003239566380000091
for coolant flowing through a main loop pipe 2 and having a length L0The average velocity of the pipe section of (a),
Figure BDA0003239566380000092
s is the cross-sectional area of the main loop pipe 2, and S is pi x r2R is the inner circle radius of the main loop pipe 2, and ρ is the density of the coolant;
step 504, when | Q'0-Q0When the L is minimum, determining the corresponding experimental interval L between the first detection mechanism and the second detection mechanism0Is the actual distance L between the first and second detecting means and determines the length L of coolant flowing through the main loop pipe 20Corresponding average velocity of pipe section
Figure BDA0003239566380000093
Is the actual average velocity v of the coolant flowing through the main loop conduit 2; wherein Q is0Is a coolant flow estimate;
step six, measuring the power of the pressurized water reactor core:
step 601, according to the formula
Figure BDA0003239566380000094
Calculating the gamma radioactivity average value A measured by the first detection mechanism and the second detection mechanism;
step 602, according to the formula
Figure BDA0003239566380000095
Calculating the power of the core of the pressurized water reactor in the unit of n/cm2S; where K is the conversion coefficient between the gamma radioactivity of the N-16 nuclear species and the reactor power, C is a constant 6.439, λ is the decay constant of the N-16 nuclear species, tcTime of primary coolant flowing through core active area, tc＝4.36s，t1Is the total circulation time, t, of the primary coolant1V is the actual average velocity of coolant flowing through the main conduit of the primary circuit at 163.1 s.
In the embodiment, it should be noted that the power measurement device of the pressurized water reactor core is constructed to measure the gamma radioactivity of the N-16 nuclide in the main pipeline 2 of the primary circuit, and then the measurement of the power of the pressurized water reactor core is realized according to the method for measuring the power of the pressurized water reactor core, so that the problems of slow measurement response and large measurement error in the conventional power measurement of the pressurized water reactor core can be effectively solved, the flux distortion cannot be caused, and the measurement effect is good; the N-16 nuclide is an activated product of a primary coolant, the gamma radioactive intensity of the N-16 nuclide is in direct proportion to the neutron flux rate of the pressurized water reactor core, and the neutron flux rate of the pressurized water reactor core is in direct proportion to the power of the pressurized water reactor core, so that the gamma radioactive intensity of the N-16 nuclide is in direct proportion to the power of the pressurized water reactor core; therefore, the power measuring device of the pressurized water reactor core is arranged beside the main loop pipe 2 to measure the intensity of gamma rays generated by N-16 nuclear decay, so that the power of the pressurized water reactor core can be measured in real time, the measuring precision is high, and the influence of the surrounding environment is hardly caused.
In this embodiment, it should be noted that in step 504, | Q'0-Q0When the L is minimum, determining the corresponding experimental interval L between the first detection mechanism and the second detection mechanism0Is the actual distance L between the first and second detecting means and determines the length L of coolant flowing through the main loop pipe 20Corresponding to the pipe section ofL0Is the actual average velocity v of coolant flowing through the main circuit pipe 2, at which the coolant flow measurement Q 'in the main circuit pipe 2 is calculated'0More accurate, the actual distance L between the first detection mechanism and the second detection mechanism is more suitable, and the actual average speed of the coolant flowing through the main loop pipeline is more accurate, so that the measurement result of the core power is more accurate.
As shown in fig. 1 and 5, in the present embodiment, in the first step, the NaI scintillator 4-1 is a cylindrical scintillator;
when the size of the NaI scintillator is determined in the second step, the NaI scintillator with the size of 50mm multiplied by 50mm and the NaI scintillator with the size of 76mm multiplied by 76mm are selected as the NaI scintillator 4-1, and the space between the detection end of the NaI scintillator 4-1 and the outer side face of the main loop pipeline 2 is keptThe detection efficiency E of a 50mm x 50mm NaI scintillator was simulated in MCNP software with the distance unchanged50And detection efficiency E of 76mm × 76mm NaI scintillator76，
When E is76-E50When the NaI scintillator 4-1 of the gamma detector 4 is larger than or equal to 10 percent, the NaI scintillator with the size of 76mm multiplied by 76mm is selected;
when E is76-E50When the concentration is less than 10 percent, the NaI scintillator 4-1 of the gamma detector 4 is 50mm multiplied by 50mm NaI scintillator.
In this embodiment, it should be noted that the commonly used sizes of the existing NaI scintillator 4-1 are 50mm × 50mm and 76mm × 76mm, the NaI scintillator with 50mm × 50mm means that the diameter and the length of the NaI scintillator 4-1 are both 50mm, the NaI scintillator with 76mm × 76mm means that the diameter and the length of the NaI scintillator 4-1 are both 76mm, and by comparing the detection efficiencies of the existing NaI scintillator with 50mm × 50mm and 76mm × 76mm, the size of the NaI scintillator comprehensively considered according to the detection efficiency and the cost of the NaI scintillator is considered when the E is equal to the E76-E50When the concentration is more than or equal to 10%, selecting a NaI scintillator with the size of 76mm multiplied by 76mm as the NaI scintillator 4-1 of the gamma detector 4, and ensuring the detection efficiency of the gamma detector 4; when E is76-E50Below 10%, the detection efficiency of the NaI scintillator 50mm × 50mm is close to that of the NaI scintillator 76mm × 76mm, and the NaI scintillator 50mm × 50mm is inexpensive, so that it is found that the concentration of the NaI scintillator in E is low76-E50When the concentration is less than 10 percent, NaI scintillators with the diameter of 50mm multiplied by 50mm are selected as NaI scintillators 4-1 of the gamma detector 4.
As shown in fig. 1 and 5, in this embodiment, when the distance between the NaI scintillator and the outer side surface of the main loop pipeline is determined in the third step, according to the size of the NaI scintillator 4-1 that has been determined, the detection efficiency of the gamma detector 4 at different distances between the NaI scintillator 4-1 and the outer side surface of the main loop pipeline 2 is simulated in the MCNP software, and when the detection efficiency of the gamma detector 4 is the highest, the distance L between the NaI scintillator 4-1 and the outer side surface of the main loop pipeline 2 is determinedd。
In this embodiment, it should be noted that, in general, the smaller the distance between the NaI scintillator 4-1 and the primary loop pipe 2, the higher the detection efficiency of the γ detector 4, but the NaI scintillation is consideredWhen the distance between the body 4-1 and the main loop pipeline 2 is small, the gamma rays in the main loop pipeline 2 cannot be attenuated and directly enter the NaI scintillator 4-1 to cause the problem that the gamma detector 4 is blocked, the distance between the NaI scintillator 4-1 and the main loop pipeline 2 is adjusted according to the determined size of the NaI scintillator 4-1, and when the detection efficiency of the gamma detector 4 is highest, the distance L between the NaI scintillator and the outer side surface of the main loop pipeline 2 is determineddThe measurement precision of the measurement device is improved.
As shown in fig. 1 and 5, in this embodiment, when the thickness of the shield is determined in the fourth step, according to the size of the NaI scintillator 4-1 and the distance between the NaI scintillator 4-1 and the outer side surface of the main pipe 2 of the primary circuit, the full-enclosure shields with different thicknesses are used to encapsulate the gamma detector 4 in the MCNP software, count rate response values of the gamma detector 4 to the background radiation under the condition of the full-enclosure shields with different thicknesses are calculated, and when the count rate response value of the gamma detector 4 to the background radiation is the highest, the thickness of the full-enclosure shield is determined, so as to determine the thickness of the shield 1; wherein the thickness of the shield 1 is equal to the thickness of a full-wrap shield;
and when the diameter of the cylindrical detection channel is determined in the fourth step, according to the determined thickness of the shielding body 1, the cylindrical detection channel 3 with different diameters is arranged at the end part of the simulated shielding body 1 in the MCNP software, the counting rate response value of the gamma detector 4 to the background radiation under the condition of the cylindrical detection channel 3 with different diameters is calculated, and when the counting rate response value of the gamma detector 4 to the background radiation is the highest, the diameter of the cylindrical detection channel 3 is determined.
In this embodiment, it should be noted that, the γ -ray detector 4 is installed in the cylindrical installation groove of the shielding body 1, the outer side surface of the γ -ray detector 4 is attached to the surface of the cylindrical installation groove of the shielding body 1, the thickness of the shielding body 1 and the diameter of the cylindrical detection channel 3 on the shielding body 1 are determined according to the counting rate response effect of the γ -ray detector 4 to the background radiation, and the miniaturization and light weight of the whole detection device can be effectively achieved.
As shown in fig. 1 and fig. 2, in this embodiment, the shield 1 is a cylindrical shield, the shield 1 includes two half cylinders 6, a half-cylindrical mounting groove 9 is formed in a middle portion of each half cylinder 6, and the two half-cylindrical mounting grooves 9 form a cylindrical mounting groove for mounting the γ -detector 4; the cylindrical detection channel 3 is composed of two semi-cylindrical detection channels which are respectively positioned on two semi-cylinders 6.
As shown in fig. 1, fig. 2 and fig. 4, in this embodiment, two half cylinders 6 are mutually matched to form a cylindrical shield, one end of one half cylinder 6 in the length direction of the two half cylinders 6 is hinged to one end of the other half cylinder 6 in the length direction through a hinge, the other end of the one half cylinder 6 in the length direction is detachably connected to the other end of the other half cylinder 6 in the length direction through a plurality of buckles 11, so as to install and detach the gamma detector 4 between the two half cylinders 6, and the plurality of buckles 11 are arranged in the length direction of the half cylinders 6.
As shown in fig. 1 and fig. 2, in this embodiment, the cylindrical detection channel 3 is communicated with the cylindrical mounting groove, the cylindrical detection channel 3 is coaxially arranged with the cylindrical mounting groove, and the diameter of the cylindrical detection channel 3 is larger than that of the cylindrical mounting groove.
In this embodiment, in practical use, the diameter of the cylindrical detection channel 3 is greater than the diameter of the cylindrical mounting groove, that is, the diameter of the cylindrical detection channel 3 is greater than the diameter of the NaI scintillator 4-1, so that the gamma rays can conveniently enter the NaI scintillator 4-1 through the cylindrical detection channel 3, and the detection efficiency of the gamma detector 4 is ensured.
As shown in fig. 1 and fig. 2, in this embodiment, the shield 1 is a lead shield, the length of the shield 1 is greater than that of the gamma detector 4, and the shield 1 is used to wrap the gamma detector 4.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiment according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims (7)

1. A method for measuring the power of a pressurized water reactor core is characterized by comprising the following steps:
step one, constructing a pressurized water reactor core power measuring device: the method comprises the steps that gamma radioactivity of N-16 nuclides in a main loop pipeline (2) is detected by a gamma detector (4), radioactive signals detected by the gamma detector (4) are processed by a signal processing module, the gamma detector (4) is installed in a shielding body (1), the gamma detector (4) and the signal processing module form a detection mechanism, the number of the detection mechanisms is two, the two detection mechanisms are located on the same side of the main loop pipeline (2), the two detection mechanisms are respectively a first detection mechanism and a second detection mechanism, and the first detection mechanism and the second detection mechanism form a pressurized water reactor core power measuring device;
the shielding body (1) is sleeved on the outer side of the gamma detector (4), the shielding body (1) is vertically arranged with the main loop pipeline (2), a cylindrical detection channel (3) is arranged at one end of the shielding body (1) close to the main loop pipeline (2), and a wire passing hole (5) is arranged at one end of the shielding body (1) far away from the main loop pipeline (2);
the gamma detector (4) comprises a NaI scintillator (4-1), a photomultiplier (4-2) and a preamplifier circuit (4-3), and the NaI scintillator (4-1) detects gamma radioactivity around the main loop pipeline (2) through a cylindrical detection channel (3);
the signal processing module comprises a main amplifying circuit (7) and a multichannel analyzer (8) connected with the main amplifying circuit (7), wherein the input end of the main amplifying circuit (7) is connected with the output end of the pre-amplifying circuit (4-3);
determining the size of the NaI scintillator;
step three, determining the distance between the NaI scintillator and the outer side face of a main loop pipeline: determining the distance L between the NaI scintillator (4-1) and the outer side surface of a main loop pipeline (2)d；
Step four, determining the thickness of the shielding body and the diameter of the cylindrical detection channel;
and step five, determining the actual distance between the first detection mechanism and the second detection mechanism and the actual average speed of the coolant flowing through the main pipeline of the primary circuit, wherein the process is as follows:
step 501, simulating different experimental distances L between the first detection mechanism and the second detection mechanism in MCNP software0Under the condition that the gamma radioactivity A detected by the first detection mechanism1And gamma-radioactivity A detected by the second detection means2；
502, according to a formula
Figure FDA0003239566370000021
Calculating the length L of coolant flowing through the main loop pipe (2)0Time of pipe section
Figure FDA0003239566370000022
The unit is s; wherein λ is the decay constant of the N-16 species;
step 503, according to the formula
Figure FDA0003239566370000023
Calculating a coolant flow measurement Q 'in the main loop pipe (2)'0The unit is kg/h; wherein the content of the first and second substances,
Figure FDA0003239566370000024
for coolant flowing through a main loop pipe (2) and having a length L0The average velocity of the pipe section of (a),
Figure FDA0003239566370000025
s is the cross-sectional area of the main loop pipeline (2), and S is pi multiplied by r2R is the inner circle radius of the main loop pipe (2), and rho is the density of the coolant;
step 504, when | Q'0-Q0When the L is minimum, determining the corresponding experimental interval L between the first detection mechanism and the second detection mechanism0Is the actual distance L between the first and second detecting means and determines the length L of coolant flowing through the main loop pipe (2)0Corresponding average velocity of pipe section
Figure FDA0003239566370000028
Is the actual average velocity v of the coolant flowing through the main loop pipe (2); wherein Q is0Is a coolant flow estimate;
step six, measuring the power of the pressurized water reactor core:
step 601, according to the formula
Figure FDA0003239566370000026
Calculating the gamma radioactivity average value A measured by the first detection mechanism and the second detection mechanism;
step 602, according to the formula
Figure FDA0003239566370000027
Calculating the power of the core of the pressurized water reactor in the unit of n/cm2S; where K is the conversion coefficient between the gamma radioactivity of the N-16 nuclear species and the reactor power, C is a constant 6.439, λ is the decay constant of the N-16 nuclear species, tcTime of primary coolant flowing through core active area, tc＝4.36s，t1Is the total circulation time, t, of the primary coolant1V is the actual average velocity of coolant flowing through the main conduit of the primary circuit at 163.1 s.
2. The method for measuring the power of the pressurized water reactor core as claimed in claim 1, wherein: in the step one, the NaI scintillator (4-1) is a cylindrical scintillator;
when the size of the NaI scintillator is determined in the second step, the NaI scintillator with the size of 50mm multiplied by 50mm and the NaI scintillator with the size of 76mm multiplied by 76mm are selected as the NaI scintillator (4-1), the distance between the detection end of the NaI scintillator (4-1) and the outer side face of the main loop pipeline (2) is kept unchanged, and the detection efficiency E of the NaI scintillator with the size of 50mm multiplied by 50mm is simulated in MCNP software50And detection efficiency E of 76mm × 76mm NaI scintillator76，
When E is76-E50When the concentration is more than or equal to 10 percent, the NaI scintillator (4-1) of the gamma detector (4) is 76mm multiplied by 76mm NaI scintillator;
when E is76-E50When the concentration is less than 10 percent, the NaI scintillator (4-1) of the gamma detector (4) is 50mm multiplied by 50 mm.
3. The method for measuring the power of the pressurized water reactor core as claimed in claim 1, wherein: when the distance between the NaI scintillator and the outer side face of the main loop pipeline is determined in the third step, according to the size of the determined NaI scintillator (4-1), the detection efficiency of the gamma detector (4) under different distances between the NaI scintillator (4-1) and the outer side face of the main loop pipeline (2) is simulated in MCNP software, and when the detection efficiency of the gamma detector (4) is highest, the distance L between the NaI scintillator (4-1) and the outer side face of the main loop pipeline (2) is determinedd。
4. The method for measuring the power of the pressurized water reactor core as claimed in claim 1, wherein: when the thickness of the shielding body is determined in the fourth step, according to the determined size of the NaI scintillator (4-1) and the distance between the NaI scintillator (4-1) and the outer side face of the main pipeline (2) of the primary circuit, the gamma detector (4) is wrapped by the full-wrapping shielding bodies with different thicknesses in MCNP software, counting rate response values of the gamma detector (4) to background radiation under the condition of the full-wrapping shielding bodies with different thicknesses are calculated, when the counting rate response value of the gamma detector (4) to the background radiation is the highest, the thickness of the full-wrapping shielding body is determined, and then the thickness of the shielding body (1) is determined; wherein the thickness of the shield (1) is equal to the thickness of a full wrap shield;
and when the diameter of the cylindrical detection channel is determined in the fourth step, according to the determined thickness of the shielding body (1), the cylindrical detection channel (3) with different diameters is arranged at the end part of the simulated shielding body (1) in MCNP software, the count rate response value of the gamma detector (4) to the background radiation under the condition of the cylindrical detection channel (3) with different diameters is calculated, and when the count rate response value of the gamma detector (4) to the background radiation is the highest, the diameter of the cylindrical detection channel (3) is determined.
5. The method for measuring the power of the pressurized water reactor core as claimed in claim 1, wherein: the shielding body (1) is a cylindrical shielding body, the shielding body (1) comprises two semi-cylinders (6), a semi-cylindrical mounting groove (9) is formed in the middle of each semi-cylinder (6), and the two semi-cylindrical mounting grooves (9) form a cylindrical mounting groove for mounting the gamma detector (4);
the cylindrical detection channel (3) consists of two semi-cylindrical detection channels, and the two semi-cylindrical detection channels are respectively positioned on the two semi-cylinders (6).
6. The method for measuring the power of the pressurized water reactor core as claimed in claim 5, wherein: the cylindrical detection channel (3) is communicated with the cylindrical mounting groove, the cylindrical detection channel (3) and the cylindrical mounting groove are coaxially arranged, and the diameter of the cylindrical detection channel (3) is larger than that of the cylindrical mounting groove.
7. The method for measuring the power of the pressurized water reactor core as claimed in claim 1, wherein: the shielding body (1) is a lead shielding body, the length of the shielding body (1) is greater than that of the gamma detector (4), and the shielding body (1) is used for wrapping the gamma detector (4).
CN202111013210.0A 2021-08-31 2021-08-31 Method for measuring power of reactor core of pressurized water reactor Pending CN113724904A (en)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20190180885A1 (en) * 2017-12-12 2019-06-13 Westinghouse Electric Company Llc Subcritical core reactivity bias projection technique

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Publication number Priority date Publication date Assignee Title
US20190180885A1 (en) * 2017-12-12 2019-06-13 Westinghouse Electric Company Llc Subcritical core reactivity bias projection technique

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Title
汪伦: "基于氮-16γ能谱测量的反应堆功率监测仪设计", 《南华大学硕士学位论文》 *
顾国兴: "利用反应堆_(16)N_γ噪声监测一回路冷却剂流量", 《核动力工程》 *

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