CN210090686U - Radiation monitoring device for main steam pipeline - Google Patents
Radiation monitoring device for main steam pipeline Download PDFInfo
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- CN210090686U CN210090686U CN201920209534.3U CN201920209534U CN210090686U CN 210090686 U CN210090686 U CN 210090686U CN 201920209534 U CN201920209534 U CN 201920209534U CN 210090686 U CN210090686 U CN 210090686U
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Abstract
The utility model provides a main steam pipeline radiation monitoring device, including setting up in main steam pipeline16N radiation monitor and inert gas radiation detector, said16N radiation monitor pass monitoring16N nuclide judges the leakage condition of the steam generator; the inert gas radiation detector monitors the main steam pipeline85Kr and133total activity concentration of Xe; and16with N radiation monitors connected16N in situ radiation processing module, andthe inert gas radiation detector is connected with the inert gas in-situ radiation processing module. And16a computer control connected to the N radiation monitor and the inert gas radiation detector, the16The N radiation monitor and the inert gas radiation detector receive control signals of the computer control part, send measured radiation data and give out sound and light alarm and indication signals.
Description
Technical Field
The utility model relates to a nuclear power plant exhaust monitoring technology field, concretely relates to main steam pipeline radiation monitoring device.
Background
The nuclear power plant of a pressurized water reactor nuclear power plant is generally composed of two closed circulation circuits, called a first circuit and a second circuit. The primary loop comprises a nuclear reactor (sealed in a pressure container), a main cooling water pump, a pressure stabilizer and other equipment, and the pressure is kept at 120-160 atmospheric pressures; the second loop includes a steam generator, a condenser, a main cooling water pump, etc., and the pressure is maintained at 70 atm. The primary circuit connects the core and the steam generators in the secondary circuit.
After absorbing the heat energy of the primary loop cooling water, the secondary loop cooling water is heated to boiling (the temperature is about 260 ℃) to form water vapor. The water vapor is filtered to remove mixed liquid water and then is sent to a steam turbine to drive a turbine engine to operate to generate electricity. The cooling water of the two loops flowing out from the steam turbine is condensed into liquid water by the condenser and then flows back to the steam generator.
There are tens of thousands of heat transfer tubes inside the steam generator. In order to improve the heat transfer efficiency, the wall of each heat transfer pipe is made very thin, only 1.09 mm. Since high-temperature and high-pressure cooling water flows in the heat transfer pipe, the heat transfer pipe is easily damaged by mechanical damage and corrosion, and leakage occurs.
SUMMERY OF THE UTILITY MODEL
In view of this, the main objective of the present invention is to provide a radiation monitoring device for main steam pipeline.
The utility model adopts the technical proposal that:
the utility model also provides a main steam pipeline radiation monitoring devices, including steam generator, set up at the inside U type pipe of steam generator, set up the main steam pipeline on steam generator, steam generator keeps apart with the containment, and its characterized in that is provided with on main steam pipeline16N radiation monitor and inert gas radiation detector, and16with N radiation monitors connected16N in situ radiation processing module, inert gas in situ radiation processing module connected with inert gas radiation detector, and16a computer control connected to the N radiation monitor and the inert gas radiation detector, the16The N radiation detector and the inert gas radiation detector receive control signals of the computer control part, send measured radiation data and give out sound and light alarm and indication signals;
and a power supply case, for16N radiation monitor, inert gas radiation detectionA machine, a computer control part,16The N in-situ radiation processing module and the inert gas in-situ radiation processing module are powered.
Further, the16The N radiation monitor and the inert gas radiation detector are arranged on the bracket.
The utility model discloses set up steam generator heat-transfer pipe leakage monitoring device at pressurized-water reactor nuclear power plant, carry out on-line monitoring to nuclear power plant's second way radioactivity protection protective screen, cause the radioactive substance to pollute two return circuits equipment of nuclear power plant after avoiding the heat-transfer pipe to leak, unexpected emission even, it is very important to be meaningful.
Drawings
FIG. 1 is a schematic frame diagram of the present invention;
FIG. 2 is a structural diagram of the present invention;
FIG. 3 is a schematic structural view of a filter assembly according to the present invention;
FIG. 4 is a schematic circuit diagram of the continuous radiation monitoring device for the aerosol of the medium nuclear power station of the present invention;
FIG. 5 is a schematic diagram of an aerosol detector according to the present invention;
FIG. 6 is a graph of α, β spectra of typical radon and thorium daughters of the present invention;
fig. 7 is a schematic circuit diagram of the inert gas radiation detector of the present invention.
Detailed Description
The invention will be described in detail with reference to the drawings and specific embodiments, wherein the exemplary embodiments and descriptions are provided to explain the invention, but not to limit the invention.
A radiation monitoring method for main steam pipeline includes
Arranged in the main steam pipeline and with primary side to secondary side 113 l/d-757 l/d16An N radiation monitor and an inert gas radiation detector,
the above-mentioned16N radiation monitor pass monitoring16N nuclide judges the leakage condition of the steam generator;
the inert gas radiation detectionIn the main steam pipeline85Kr and133total activity concentration of Xe;
and16with N radiation monitors connected16N in situ radiation treatment module, the16N in situ radiation processing modules for processing detected16Acquiring, processing and displaying N nuclide signals;
an inert gas in situ radiation processing module connected to the inert gas radiation detector for processing the detected inert gas in situ radiation85Kr and133acquiring, processing and displaying signals of total activity concentration of Xe;
and16a computer control connected to the N radiation monitor and the inert gas radiation detector, the16The N radiation monitor and the inert gas radiation detector receive control signals of the computer control part, send measured radiation data and give out sound and light alarm and indication signals.
Further, the air conditioner is provided with a fan,16obtained after data processing of the N in-situ radiation processing module16The specific processing method of the leakage rate of N is as follows:
damaged part of heat transfer pipe in main steam generator16N leakage rate and measurement by a detector located beside the main steam line16The gamma ray count rate produced by N decay has the following relationship:
in the formula:
q is the leakage rate (L/h) of the heat transfer pipe,
n is the measurement site16Gamma radiation count rate(s) of N-1)，
C is the calculated transmission coefficient(s) of the leakage rate of the heat transfer tube-1·L-1·h)，
Transmission coefficient C and detector geometry factor K1Detector efficiency factor K2And unit leakage rate of heat transfer tube16In the main steam pipeline at the N detection points16Gamma radioactivity of N is off, i.e.:
C＝K1·K2·Av(6.3)
in the formula:
Avat unit leakage rate of heat transfer pipe16In the main steam pipeline at the N detection points16The gamma-radioactivity of the N,
Avas shown in the following formula:
Av＝(Aρ/Q)·(ρv/ρp)·e-λt(6.4)
in the formula:
Aρis the primary side of the leakage part16Activity of N activity (Bq. cm)-3) Changes with the nuclear power and the position of the leakage point,
q is the steam flow (L.h) in the main steam pipe-1)，
ρvMainly steam density (kg. m)-3)，
ρpIs the average density (kg · m) of the coolant-3)，
λ is16N radiation decay constant(s)-1)，
t is16N is the transit time(s) from the heat transfer tube leakage to the detection point,
according to the structural dimensions, physical parameters and the like of the reactor, the steam generator and the main steam pipe16N radiation monitoring point parameters can be calculated16N transmission time, detector geometry factor K1Detector efficiency factor K2(ii) a Then, calculating a transmission coefficient c according to the above formulas; finally, calculating the damaged position of the heat transfer pipe in the main steam generator according to the transmission system c and the counting rate n16Leakage rate of N.
Further, the air conditioner is provided with a fan,16the method for detecting the transmission time t from the leakage position of the heat transfer pipe to the detection point of the N comprises the following steps:
16the method for detecting the transmission time from the leakage point to the measurement point is based on the following hypothetical model:
(1) the small leak is assumed: because the leakage amount is small, the steam generated by the leaked water can not obviously influence the heat transfer and flow processes of the primary side and the secondary side of the steam generator, namely, the steam generator is still in a stable operation state;
(2) the consistency assumption is that: the movement of the steam formed by the leakage of the water at the primary side to the secondary side is consistent with the flow process of the secondary side;
(3) one-dimensional assumption: working medium in the secondary side flows in one dimension in a tube bundle area, a steam-water separation area, a drying area and a main steam pipeline of the steam generator;
(4) isolated flow path assumption: the mass, momentum and energy between two cold and hot channels at the secondary side of the steam generator are not changed;
as can be seen from the above-described hypothetical model,16n is a heated two-phase flow in a tube bundle area, is an adiabatic two-phase flow in a steam-water separation area, is a single-phase steam flow in a drying area and a main steam pipeline, can be calculated by a thermal hydraulic program, and has the following calculation formula:
in the formula: z is a radical of1In order to be a z-coordinate of the leak rate,
z2is the z-direction coordinate of the vertex of the bent pipe area,
wn1(z) is the velocity component of the secondary side medium in the z direction,
in the formula: z is a radical of2Is the z-direction coordinate of the outlet of the steam-water separation area,
z1same as z in formula (6.5)2，
wn2(z) is the velocity component of the steam-water separation area medium in the z direction,
in the formula: rhovIn order to be the density of the steam,
Vdis the volume of the space in the drying zone,
q is the mass flow rate of the steam,
in the formula: l is the length between the steam generator outlet and the main steam line detector,
s is the section of the main steam pipeline,
ρvq is the same as (6.7),
in the above formula, the first and second carbon atoms are,
t1for the time of transit in the zone of heating of the tube bundle, i.e. the transit time from the feed water inlet to the feed water header, t1Because the positions of the leakage points are different, t of the positions of a hot end, a cold end and a bent pipe of the heat transfer pipe is usually calculated11、 t12And t13，t1Are their average values; t is t2The transmission time in the steam-water separation region is the transmission time from the water supply header to the steam header; t is t3The transmission time in the drying box, namely the transmission time from the steam header to the outlet of the steam ring box; t is t4The transit time from the outlet of the steam ring box to the location of the main steam pipe detector.
Furthermore, the inert gas radiation detector is provided with a main ionization chamber and a differential ionization chamber, the high-voltage working polarity of the main ionization chamber and the differential ionization chamber is opposite, the direction of the generated current is also opposite, so that the environment background gamma radiation contributing to the two ionization chambers can be counteracted,
the output current of the ionization chamber causes a count of:
n＝I·Kf(7.1)
in the formula: n is the measured count rate in units of s-1，
I is the output current of the ionization chamber, in pA,
Kffor current frequency conversion factor, unit s-1/pA，
After the sensitivity of the ionization chamber is obtained through calibration, the activity concentration of the radioactive inert gas in the main steam pipeline can be calculated through formal calculation:
in the formula: s is the ionization chamber sensitivity, in units of S-1/Bq。
16The detection efficiency of the N detection system is mainly determined by the geometric factor K of the detection device1、16Intrinsic efficiency K of gamma rays in detector accompanied by decay of β of N2And the like.
16N emits 69% 6.13MeV and 5% 7.12MeV high-energy gamma photons in the main vapor line from generation to recording by the gamma detector primarily through two historical stages: the first stage being in the main steam line16Whether the N gamma photon source can penetrate the main steam pipeline or not; the second stage is the process of counting caused by the fact that whether gamma photons penetrating through the main steam pipeline can enter the detector system or not and penetrate through the detector cladding layer to interact with the detector crystal.
According to the structure of the main steam pipeline and the detector, see fig. 2, the detector detects the inside of the main steam pipeline16The peak source efficiency of the gamma rays produced by the N decay is very low:
the main steam pipeline has relatively thick steel pipe layer, so that the main steam pipeline is internally provided with16Only a portion of the gamma photon source produced by the N decay penetrates the main steam line.
Only a small part of the high-energy gamma photons penetrating through the main pipeline can enter the detector system, and the gamma photons entering the detector also penetrate through each shell layer of the detector and can enter the detector crystal after certain attenuation.
Only a portion of the gamma photons incident on the detector crystal deposit energy in the crystal, i.e., there is some intrinsic efficiency to the incident gamma photon detector crystal.
16The two types of single-energy gamma photons of 6.13MeV and 7.12MeV emitted by N decay automatically generate to the incident detector crystal, and the photons can reach the detector crystal after passing through the shielding layers of the main steam pipeline, the air layer between the main steam pipeline and the detector and the envelope layers of the detector. In the process, two kinds of single-energy gamma photons of 6.13MeV and 7.12MeV may have interacted with each shielding layer medium through photoelectric effect, Compton scattering, electron pair effect and the like to generate secondary photons and secondary electrons, and the secondary electrons can further generate next generation secondary photons and the like in the interaction with the surrounding medium, so that the gamma photons finally actually incident to the detector crystal are no longer only two kinds of single-energy gamma photons of 6.13MeV and 7.12 MeV. Therefore, in the spectrum of 4.5MeV to 7MeV measured by the detector, the components are very complex, and specifically include:
full energy peak, single-escape peak and double-escape peak of 6.13MeV gamma photon, which are the major components.
A certain amount of single and double escape peaks for 7.12MeV gamma photons.
A portion of a long continuous electron energy spectrum left after scattered photons generated in the detector crystal due to compton scattering escape is superimposed by the 6.13MeV and 7.12MeV monoenergetic gamma photons.
16N gamma photons compton scatter through the respective envelope layers of the detection system. Compton scattered photons with energies above 4.5MeV before entering the detector crystal may eventually cause counts in the spectrum of 4.MeV 5-7 MeV.
16The N gamma photon passes through each shell layer of the detection system to generate photoelectron, Compton scattered electron, and secondary electrons such as positive electron and negative electron, the secondary electrons can interact with a medium to generate bremsstrahlung photons with energy exceeding 4.5MeV, secondary photons such as flight annihilation photons, and the like, and can finally cause counting in the energy spectrum of 4.5 MeV-7 MeV.
Due to fluctuation of the output voltage amplitude pulse of the detector, the actual deposition energy of gamma photons incident to the detector crystal in the crystal is out of the range of 4 MeV.5-7 MeV, and counting can be caused in the output energy spectrum of 4.5 MeV-7 MeV.
From the above analysis, the detection efficiency factor K1And K2Mainly depends on the following aspects:
16the photon energy is still more than 4.5 after gamma photons generated by N decay penetrate through the main steam pipelinePenetration rate of MeV, i.e. photon of energy greater than 4.5MeV per unit time penetrating the main steam pipe16Ratio of radioactivity of N source. The photons referred to herein include the 6.13MeV and 7.12MeV high energies that penetrate the main vapor pipe directly16N gamma photons and other photons with energies greater than 4.5MeV scattered photons and bremsstrahlung photons, etc., i.e. the transmission rate also includes16Accumulation factor of N monoenergetic gamma photons.
Whether the high-energy photons with energy larger than 4.5MeV can be incident to the incidence rate of the detector system after penetrating through the main steam pipeline is determined, namely, the high-energy photons with energy larger than 4.5MeV form a geometric factor between the cylindrical surface source and the detector system which are distributed in a certain way after penetrating through the main steam pipeline. The geometry factor is directly related to the size of the main steam line and the detector and the relative position between them.
The energy of the high-energy photons with the incident detector outer casing energy larger than 4.5MeV can enter the penetration rate of the detector crystal after penetrating through each outer casing layer of the detector crystal, namely the attenuation effect of the detector outer casing on the source photons is considered.
Intrinsic efficiency of the detector crystal deposition energy in the interval of 4.5 MeV-7 MeV, namely the ratio of the counting rate of the deposition energy in the interval of 4.5 MeV-7 MeV to the number of photons actually incident to the detector crystal in unit time. Related to the detector crystal material itself and also to the position of the gamma-photon source and the detector crystal.
The volume of the main steam line and the steam flow rate. Since for the same in the pipeline16The radioactivity of N and the volume of the main steam pipeline are different,16the N radioactive volume specific activity will be different and the efficiency factor will be different. And because in the main steam line16N is carried by the steam in the pipeline, so the flow rate or flow velocity of the steam determines16The N radioactive source is distributed in the main steam pipeline.
In view of16Specificity of the N detection devices and the above analysis, for the detection efficiency factor K1And K2The experimental determination of the prototype problem is quite difficult and can only be obtained by theoretical calculation at present.
Main steam pipeline16N detection systemSystem detection16The relationship between the count rate N and leak rate L for both gamma rays, 6.13MeV and 7.12MeV for N decay, can again be written as:
where K is a factor related to the distance of the leak from the detector, the flow rate of the high pressure steam, the emission probability of gamma rays, lambda, etc., and the detection efficiency η is a key physical quantity that determines the leak rate L, depending on the size of the detector and its distance from the source and the shielding around the detector, as well as on the size of the source and its geometry, etc. η can be measured using a source and a point source of theoretically calculated and experimentally known intensity, and we use a point source instead of a source to scale the detection efficiency as long tube sources of 6.13MeV gamma rays are difficult to obtain in experimental measurements.
First a coordinate system is defined. The z-axis is the axis of the steel tube, the y-axis is perpendicular to the horizontal plane, and the x-axis is on the axis of the detector. In the cylindrical coordinate system r is the distance z from the axis of the steel tube and phi is the azimuth angle of r.
In a stable state16N leakage rate, N ═ e (r) of the gamma ray count rate0，φ0，z0)λeγ∫∫∫I(r，φ，z)R(r，φ，z)rdrdφdz (6.10)
Wherein eγIs the emission probability of 6.13 MeV-gamma rays, I (R, phi, z) and R (R, phi, z) are each16The density and relative efficiency of N is spatially distributed,
is a volume element.
Is set at a reference point r0＝0，φ0＝0，z0A standard source is placed at the position of 0, the activity is A, and the number of gamma particles recorded by an electronic instrument is n0Then, the absolute detection efficiency of the reference source is:
placing a standard source at any point (r, phi, z), with activity A and recorded particle number n, then
Then the relative detection efficiency spatial distribution of any point of the radioactive source in the long tube is as follows:
(r，φ，z)＝ε(r，φ，z)/ε(r0，φ0，z0) (6.13)
if I (r, φ, z) is independent of r and φ, then:
I(z)＝I0exp[-λ(L0+z)/v](6.14)
wherein I0At the point of leakage16Density of N, L0Is the distance of the leak point from the detector and upsilon is the flow rate of the high pressure vapor.
Then there are the following three formulas:
L＝I0vS (6.15)
η＝ε(r0，φ0，z0)∑(ξ) (6.16)
K＝v-1·eλ·Z0·λ·exp(-λL0/v) (6.17)
wherein S is a cross-sectional area of an inner diameter of the steel pipe, Z0At 1cm, Σ (ξ) is the cumulative integral at the convergence point:
r (z) is the integral of R (R, phi, z) over R and phi, which is symmetrical with respect to z 0cm, z0Is introduced for eliminating the dimension of the (6.10) expression integral, if upsilon is more than or equal to 10m/s, z is more than or equal to 2.5m, lambdaz is less than or equal to 0.0243 and less than or equal to 1, e-zAnd ezTaylor expansion is possible, and taking the first term of z, then:
then relative toThe detection efficiency factor η is η ═ epsilon0(r0，φ0，z0)∑(ξ) (6.20)。
The invention also provides a radiation monitoring device for the main steam pipeline, which comprises a steam generator, a U-shaped pipe 2 arranged in the steam generator 3 and a main steam pipeline 4 arranged on the steam generator 3, wherein the steam generator 3 is isolated by the containment vessel 1, and the main steam pipeline 4 is provided with a safety shell16N radiation monitor 6 and inert gas radiation detector 5, and16n radiation monitors 6 connected16N in situ radiation treatment module 8, inert gas in situ radiation treatment module 9 connected to inert gas radiation detector 5, and16a computer control part 10 connected with the N radiation monitor 6 and the inert gas radiation detector 5, the16The N radiation monitor 6 and the inert gas radiation detector 5 receive signals controlled by the computer control part 10, send the measured radiation data and give out sound and light alarm and indication signals;
and a power supply case 11, are16An N radiation monitor 6, an inert gas radiation detector 5, a computer control part 10,16The N in situ radiation processing module 8 and the inert gas in situ radiation processing module 9 are powered.
Further, the16The N radiation monitor 6 and the inert gas radiation detector 5 are arranged on a support 7.
Referring to fig. 3, the present invention also provides a high temperature16N radiation monitor, comprising
The detector comprises a shield 601, a shielding chamber arranged in the shield, an insulating layer 603 arranged on the inner wall of the shielding chamber, a detector crystal 602 arranged in the insulating layer 603, a pre-processing plate 605 arranged at the front end of the detector crystal 602, and at least one group of sodium chloride stabilized sources 604 arranged on the periphery of the detector crystal 602.
The detector crystal 602 is sealed in a stainless steel casing, and the other side of the stainless steel casing is sealed with an insulating layer 603. In the present invention, the detector crystal 602 is NaI crystal with density of 3.667g/cm3(ii) a The outer shell layer of the crystal is A3 stainless steel with density7.8kg/cm3The top surface is 0.3cm thick, and the side surface of the cylinder is 0.6cm thick; the insulating layer 603 is mineral wool or SiO2One of the aerogel, in the utility model discloses in, preferably silica aerogel, silica aerogel is the minimum solid of coefficient of heat conductivity known at present, can regard as super heat-insulating material, and the heat-insulating body has the stainless steel shell outward, and one end is sealed with the welding, and the other end is sealed with O type circle. The whole probe is waterproof, heat-insulating and vibration-resistant. Thermal-protective coating SiO2Aerogel density of 0.06g/cm3The thicknesses of the top surface and the side surface of the cylinder are both 6 cm; the outer shell layer is A3 stainless steel with density of 7.8kg/cm3The top surface is 0.5cm thick, and the side surface of the cylinder is 0.3cm thick.
The shielding cavity is in a 4 pi lead shielding chamber, and the thickness of the lead shielding chamber is 50 mm.
Referring to fig. 4, the pre-processing board 604 includes a pre-amplifying unit, a digital multichannel, an ARM processing board, a high voltage releasing unit, and16the N in-situ radiation processing module 8 comprises a preamplifier unit connected with a phototransistor, the phototransistor is arranged at a stable common source of sodium chloride, the digital multichannel is respectively connected with the preamplifier unit and an ARM processing board, the ARM processing board is connected with a high-voltage release unit, the high-voltage release unit is connected with the phototransistor, and the N in-situ radiation processing module is characterized in that the preamplifier unit is connected with the phototransistor16The N local radiation processing module 8 is communicated with the ARM processing board through an RS485 interface.
After the output signal of NaI (Tl) detector is preamplified by a certain gain, it directly enters 2048 digital multi-channel for collection.
The ARM processing board analyzes and processes the gamma energy spectrum acquired by the digital multi-channel acquisition, and adjusts the high power supply voltage of the main detector when necessary to stabilize the spectrum.
The digital multichannel and ARM processing boards are designed on different circuit boards to form a front-end processing unit and are arranged at the output end of the detector.
The front-end processing unit is connected with the front-end processing unit through an RS485 interface16The N local radiation processing module 8 carries out communication, and transmits the measured data to a local radiation processing module (LRP) for processing and displaying.
Referring to FIG. 5, the16The N local radiation processing module 8 comprises an ARM main processor, a display screen, an input keyboard, a network interface and a plurality of I/O ports,
the display screen displays the measurement data according to a set format;
the keyboard inputs corresponding information;
the RS485 port transmits or receives data sent by the front-end processing unit;
the network port realizes communication and data exchange with an external computer;
the I/O port receives ambient or measured temperature, pressure and flow signals and outputs alarm or switch control signals.
16The N local radiation processing module 8(LRP) is communicated with the front-end processing unit through an RS485 interface, receives and processes data sent by the front-end processing unit, displays the measured data according to a set format, and automatically switches dimensions; displaying or sending out corresponding state indication or audible and visual alarm signals according to a preset threshold value; and inputting corresponding information through a panel keyboard according to the requirements of the program.
The in-situ radiation processing module provides the following measurement data, status indications or audible and visual alarm signals:
measured value (1 way analog quantity)
High value alarm (switching value)
High value alarm (switching value)
Fault sum (or) failure alarm (switching value)
Inspection source start or monitor is testing (on-off)
In addition, the in-situ radiation processing module may also provide various averages (e.g., 1min, 10min, 1h, day, etc.) of the measured radiation data.
When the leakage rate data is displayed, when the power P is more than or equal to 20% FP, the measured data is displayed according to the format, and the dimension is automatically switched; and when the power P is less than 20% FP, measuring (0.2-2.2) the total gamma counting rate in the MeV energy region, and displaying the measured data according to a pulse counting format.
Referring to fig. 6 and 7, the present invention also provides an inert gas radiation detector including
The plasma ionization device comprises a shield 501, wherein the shield 501 is hollow, a steel sleeve 502 is arranged along the inner wall of the shield 501, a heat insulating layer 503 is embedded in the inner wall of the steel sleeve 502, silica aerogel is preferably selected as the heat insulating layer 503, a main ionization chamber positioning groove 506 and a differential ionization chamber positioning groove 508 are respectively arranged at the upper end and the lower end of the inside of the heat insulating layer 503, a main ionization chamber 505 and a differential ionization chamber 504 are respectively arranged at the main ionization chamber positioning groove 508 and the differential ionization chamber positioning groove 508, a connecting sleeve 507 is arranged between the main ionization chamber 505 and the differential ionization chamber 504, a gland 509 is arranged at the upper end of the shield 501, and the main ionization chamber 505 and the differential ionization chamber 504 are connected with a front processing module 512 arranged outside through cables.
The gland 509 comprises a left gland and a right gland which are mutually butted, and a butt joint section 511 is arranged between the left gland and the right gland to form a sealing structure.
The left and right glands are fixed to the shield 501 by screws or bolts 510.
The differential ionization chamber 504 includes a measurement chamber and a compensation chamber.
The utility model provides a detector is installed in the department of 5cm apart from main steam conduit, and measuring range is 3.7 x 109Bq/m3～3.7×1013Bq/m3Spanning 4 orders of magnitude. When the activity concentration of the radioactive inert gas in the pipeline is 3.7 multiplied by 109Bq/m3And the dose equivalent at the detector is estimated to be about 4.32 MuSv/h, and if the wall thickness of the pipeline after 50mm is considered, the actual dose rate is estimated to be 0.2 MuSv/h and is basically in an environment background state. The sensitivity of the ionization chamber must reach the detection level of the environmental level to meet the on-site monitoring requirement. The differential ionization chamber 504 is made of stainless steel, the size of the measuring chamber and the size of the compensation chamber are both about phi 75mm multiplied by 144mm (0.5 liter), the wall thickness is 2.5mm, and argon inert gas with 10 atmospheric pressures is filled in the ionization chamber in order to improve the sensitivity and the detection efficiency of the ionization chamber.
The background of an external gamma field of a detector installation site is 2.5 mu Gy/h, the external shielding is considered to be reduced to the level of the environmental background, a 4 n lead shielding body is selected as a shielding body of the ionization chamber detector, the thickness of the 4 n lead shielding body is at least 40mm, and the attenuation multiple is more than 40 times.
In order to avoid the influence of severe environments such as high temperature, high humidity and the like on electronic components of the detector, electronic circuits required for detection are not designed in the detector, but a pre-processing module 512 is designed, and the pre-processing module 512 is arranged in another measuring room; the ionization chamber detector is connected to the pre-processing module 512 by a high temperature resistant hard cable.
The pre-processing module 512 comprises an adjustable gain amplifier, an I/F conversion unit and an ARM control unit, wherein the adjustable gain amplifier is respectively connected with the measuring chamber and the compensation chamber through cables, the adjustable gain amplifier is connected with the ARM control unit through the I/F conversion unit, and the ARM control unit is connected to the in-situ radiation processing unit through an RS485 interface.
The output signal of the differential ionization chamber 504 is transmitted to an adjustable gain amplifier through a hard cable for proper amplification, then enters an I/F conversion module, and then enters an acquisition and processing circuit of an ARM control unit. When the differential ionization output current is larger, the ARM controls the adjustable gain amplification circuit to reduce the amplification factor.
The adjustable gain amplifier, the I/F converter and the ARM processing circuit form a front-end processing module which is arranged between different measurements of the detector.
The front-end processing unit is communicated with the local radiation processing unit of the inert gas monitor through an RS485 interface, and the measured data is transmitted to the local radiation processing unit to be processed and displayed.
The local radiation processing unit comprises an ARM main processor, a display screen, an input keyboard, a network interface and a plurality of I/O ports, wherein the display screen is connected with the ARM main processor and displays measurement data according to a set format; the keyboard inputs corresponding information; the RS485 port transmits or receives data sent by the front-end processing unit; the network port realizes communication and data exchange with an external computer; the I/O port receives ambient or measured temperature, pressure and flow signals and outputs alarm or switch control signals.
The technical solutions disclosed in the embodiments of the present invention are introduced in detail, and the principles and embodiments of the present invention are explained herein by using specific embodiments, and the descriptions of the above embodiments are only applicable to help understand the principles of the embodiments of the present invention; meanwhile, for a person skilled in the art, according to the embodiments of the present invention, there may be variations in the specific implementation manners and application ranges, and in summary, the content of the description should not be construed as a limitation to the present invention.
Claims (2)
1. The radiation monitoring device for the main steam pipeline comprises a steam generator, a U-shaped pipe arranged inside the steam generator and a main steam pipeline arranged on the steam generator, wherein the steam generator is isolated by a containment vessel, and the radiation monitoring device is characterized in that the main steam pipeline is provided with a containment vessel16N radiation monitor and inert gas radiation detector, and16with N radiation monitors connected16N in situ radiation processing module, inert gas in situ radiation processing module connected with inert gas radiation detector, and16a computer control part connected with the N radiation monitor and the inert gas radiation detector, and a power supply box16N radiation monitor, inert gas radiation detector, computer control part,16The N in-situ radiation processing module and the inert gas in-situ radiation processing module are powered.
2. A main steam line radiation monitoring device as claimed in claim 1, wherein the main steam line radiation monitoring device is a steam line radiation monitoring device16The N radiation monitor and the inert gas radiation detector are arranged on the bracket.
Priority Applications (1)
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109712727A (en) * | 2018-10-16 | 2019-05-03 | 陕西卫峰核电子有限公司 | A kind of main steam line Radiation monitoring method and device |
| CN111679312A (en) * | 2020-06-21 | 2020-09-18 | 陕西卫峰核电子有限公司 | Spectrum stabilizing method for N-16 radiation monitor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109712727A (en) * | 2018-10-16 | 2019-05-03 | 陕西卫峰核电子有限公司 | A kind of main steam line Radiation monitoring method and device |
| CN109712727B (en) * | 2018-10-16 | 2024-06-18 | 陕西卫峰核电子有限公司 | Main steam pipeline radiation monitoring method and device |
| CN111679312A (en) * | 2020-06-21 | 2020-09-18 | 陕西卫峰核电子有限公司 | Spectrum stabilizing method for N-16 radiation monitor |
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