CN106814384B - Nuclear power plant's point source radiation source strength backstepping method and point source radiation source strength backstepping system - Google Patents
Nuclear power plant's point source radiation source strength backstepping method and point source radiation source strength backstepping system Download PDFInfo
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Abstract
The invention discloses a kind of nuclear power plant's point source radiation source strength backstepping method and point source radiation source strength backstepping systems, in this method, the dosage rate of multiple positions is obtained by detector, normalization radiation source intensity is spatially carried out discrete, optical distance is calculated using ray tracing method, the information such as bond material, buildup factor carry out the calculating of equation group coefficient, and backstepping goes out source strength；Then dosage rate calculating is carried out to detector position, by the way that measured value and calculated value are carried out linear regression analysis, calculates the key parameters such as standard deviation, slope, intercept, and then calculate quality factor to measure the acceptable degree of each calculated result；It proposes the Weighted Iterative Methods simultaneously, reduces the error that the biggish detector of uncertainty introduces, above steps may be repeated multiple times in the way of iteration until quality factor reach pre-set value, obtains desired radiation source intensity information.
Description
Technical field
The present invention relates to the calculation method of radiation source intensity in nuclear power plant and systems, and in particular to a kind of nuclear power plant's point source spoke
Penetrate source strength backstepping method and point source radiation source strength backstepping system.
Background technique
The active region of the radioactivity of nuclear power plant fuel assembly in pressure vessel, radiation source mainly by fission product,
Actinides and activating product composition.In system operation, radiation source is with coolant flow through primary Ioops main system (including pressure
Container, main pump, voltage-stablizer, main pipeline etc.), chemical vessel control system etc., Distribution of radiation source is in coolant and relevant device table
Face.Radiation source radioactivity itself is strong, and dosage suffered by daily routines of the staff when nuclear power plant operates normally accounts for year total agent
20% or so of amount, and during nuclear power station overhaul, dosage suffered by staff will account for the 80% of year accumulated dose, in core
Radioactive dose mainly is reduced in residence time of radiation area by shortening staff during power plant's overhaul.
Distribution of radiation source especially after prolonged use and overhaul, is passed through than wide according to engineering in nuclear power plant
It tests and is increasingly difficult to be inferred to the radiation intensity of each position radiation source, so in very multidata calculating, especially foundation
In the calculating of radiation source intensity, because it is difficult to obtain accurate basic information and greatly affected accuracy and practicability, together
When, in the case that current protective equipment and means are not very complete at home, but also staff it is illuminated risk it is big
It is big to increase.
In the prior art, when needing to calculate radiation source intensity, Sources term analysis method is generally used, firstly, according to radioactive material
The generation of matter and disappearance approach determine its generation item (as flowed into item, decay generates item etc.) and disappearance item (such as filtering item, leakage item
Deng), and every physical model is defined, nucleon concentration balance equation then is established to radioactive substance according to above-mentioned items
(group), last simultaneous equations (group) solve, however there are a large amount of simplification and approximate calculation in these calculating process, so its
As a result often larger with actual value gap, in practical application, there are many obstacles, in addition, considering radiation source itself
Harm, geometry complicated inside nuclear power plant caused by human body, radionuclide accurate information are difficult to obtain, nuclear power plant is visited
When surveying the factors such as uncertainty of device measured value, the above method safety, in terms of be problematic in that, it would be highly desirable to improve
Or propose new radiation source intensity acquiring way.
The present inventor furthers investigate the existing method for calculating source strength information due to the above reasons, rule of thumb,
All radioactive components can simplify in usual nuclear power plant can simplify for a point source or one group of point source, such as a thermal valve
For a point source, a pipeline with homogeneous radiation can be reduced to a point source every several feet, ultimately form one group
Point source, to design a kind of nuclear power plant's point source radiation source strength backstepping method for being able to solve the above problem and point source radiation source strength
Backstepping system.
Summary of the invention
In order to overcome the above problem, present inventor has performed sharp studies, design a kind of nuclear power plant's point source radiation source strength
Backstepping method and point source radiation source strength backstepping system, this method and system can be in the situations for sufficiently ensureing human body radiation safety
Under, obtain the point source source strength data inside nuclear power plant under complex geometry space structure；Pre-determined bit in this method, in nuclear power plant
Placement location detector, and also place in the position with shielded detector, and then obtain radiation source and release gamma ray
Average energy；In addition, being additionally provided with the detector of multiple monitoring nuclear power plant's radiation values, in nuclear power plant to obtain part sampling site
Dosage rate, by Point- kernel integral and weighted least-squares method combine in the way of, while will normalization radiation source intensity spatially into
Row is discrete, using ray tracing method judge gamma-rays that each point source is released space walk distance and calculate optics away from
From the information such as bond material, buildup factor carry out the calculating of equation group coefficient, and then backstepping goes out source strength；Then it obtains to detection
Measured value and calculated value are carried out linear regression analysis processing by the calculated value of dosage rate at device position, obtain standard deviation, tiltedly
The key parameters such as rate, intercept, and then obtain to indicate the quality factor of physical meaning, which can measure each calculating
As a result acceptable degree；A kind of the Weighted Iterative Methods are proposed simultaneously, reduce the error that the biggish detector of uncertainty introduces, benefit
With the mode of iteration, above steps may be repeated multiple times until quality factor meet preset condition, and then obtains desired radiation source intensity
With the uncertainty of radiation field result, thereby completing the present invention.
In particular it is object of the present invention to provide following aspect:
(1) a kind of nuclear power plant's point source radiation source strength backstepping method, which is characterized in that this method comprises the following steps:
Step 1, with the dosage rate D in detector detection nuclear power plant1,D2,D3…Di,
Step 2 is established super containing radiation source intensity as shown in following formula (one) according to the dosage rate information detected
Determine equation group,
Wherein, the coefficient matrix a of the over-determined systemsi,jIt is obtained by following formula (two),
Step 3 calculates the over-determined systems in step 2 by least square method and obtains radiation source intensity information, described
Radiation source intensity is following formula (three)
Sj,0=(aj,i·ai,j)-1·aj,i·Di(3)
Wherein, DiIndicate the dosage rate that i-th of detector detects；The number of j expression radiation source；M indicates radiation source
The attainable maximum value of number；SjIndicate the intensity of j-th of radiation source；Sj,0Indicate j-th of spoke that initial calculation is not iterated
Penetrate the intensity in source；ai,jIt indicates coefficient matrix, is dose response coefficient of j-th of radiation source to i-th of detector；BD(E,L(μ
(E),r0→rp) indicate buildup factor, it is E and L (μ (E), r0→rp) function；L(μ(E),r0→rp) indicate optical distance, be
μ (E) and r0→rpFunction；μ (E) indicates section/linear attenuation coefficient；r0→rpDistance of the expression radiation source to sensing point；C
(E) it indicates fluence-dose conversion factor, is the function of E；E indicates energy, is the gamma rays that radiation source issues in nuclear power plant
Average energy.
(2) nuclear power plant's point source radiation source strength backstepping method according to above-mentioned (1), which is characterized in that step 3 it
Afterwards, the method also includes following steps,
Step 4, the dosage rate at the radiation source intensity information calculating detector position according to obtained in step 3, D '1,
D′2,D′3…D′i；
Dosage rate information at step 5, the dosage rate information detected to detector and the detector position being calculated
Linear fit, the linear equation of the both sides relation after being fitted are carried out, and then obtains fitting parameter, the fitting parameter packet
It includes: average uncertainty, the goodness of fit and corresponding weight matrix；
Step 6 is added over-determined systems of the weight matrix iteration new obtained in step 5 into step 2
The overdetermined equation of power, and then repeat Step 2: step 3 and step 4, until obtaining desired radiation source intensity information；
Wherein, D 'iIndicate the dosage rate at calculated i-th of detector position.
(3) nuclear power plant's point source radiation source strength backstepping method according to above-mentioned (1), which is characterized in that for the core
The average energy E for the gamma rays that radiation source issues in power plant, measuring method includes following sub-step:
Sub-step 1, chooses predetermined position inside nuclear power plant, and distance of the predetermined position apart from radiation source is t, pre- at this
Placement location detector is positioned, the dosage rate I that the detector detects is collected0,
Sub-step 2 fetches the detector, is placed on the predetermined position after shielded layer is coated outside it, collects institute
State the dosage rate I that detector detects；
Alternatively, fetching the detector, shield is placed in predetermined position, then the detector is placed on shield
It is interior, collect the dosage rate I that the detector detects；
Sub-step 3, the I and I obtained according to sub-step 1 and step 20, clad or shield are calculated by following formula (four)
Mass attentuation coefficient μ,
I/I0=BDe-μt(4)
Sub-step 4 obtains the average energy E of the gamma rays of radiation source sending according to the calculated result of sub-step 3.
(4) nuclear power plant's point source radiation source strength backstepping method according to above-mentioned (1), which is characterized in that calculate the light
The method for learning distance L includes following sub-step,
Sub-step a tracks gamma ray and walks process from radiation source to sensing point, and record gamma ray passes through radiation area
The sequence in domain,
Sub-step b calculates separately the distance of each radiation areas, in conjunction with the linear taper system of each radiation areas material
Number, finally finds out total optical distance L.
(5) nuclear power plant's point source radiation source strength backstepping method according to above-mentioned (1), which is characterized in that use minimum two
Over-determined systems in multiplication process step 2, and the process for obtaining radiation source intensity information includes following sub-step:
Sub-step 3-1, by over-determined systemsAX=b is expressed as with the form of matrix；
Sub-step 3-2 seeks the normal equation A of the matrixTAX=ATB, i.e. X=(ATA)-1ATb；
Sub-step 3-3 remembers G=A with the triangle decomposition method solution normal equation of symmetrical matrixTA, wherein G is symmetrical matrix；
Sub-step 3-4 solves G=L using triangle decomposition methodsDLs T, wherein LsIt is small triangular matrix, D is diagonal matrix；
Sub-step 3-5 solves lower triangular matrix equation group: LsY1=ATb；
Sub-step 3-6 solves diagonal matrix equation group: DY2=Y1；
Sub-step 3-7 solves upper triangular matrix equation group: Ls TX=Y2。
(6) nuclear power plant's point source radiation source strength backstepping method according to above-mentioned (2), which is characterized in that in step 5,
Linear fit is carried out by following formula (five),
Wherein,Indicate the dosage rate of estimation；Indicate the slope of estimation, Indicate the intercept of estimation,
N indicates the attainable maximum value of detector number i,Indicate the flat of dosage rate at calculated detector position
Mean value,Indicate the average value for the dosage rate that detector detects.
(7) nuclear power plant's point source radiation source strength backstepping method according to above-mentioned (6), which is characterized in that in step 5,
Weighting function is obtained according to uncertainty, then weight matrix W is obtained by weighting function, the weight matrix W passes through following formula
(6) it obtains,
Wherein, f indicates fitting uncertainty, Indicate average fit uncertainty,fiIndicate the fitting uncertainty of i-th of detector position；；Indicate power
Weight function.
(8) nuclear power plant's point source radiation source strength backstepping method according to above-mentioned (6), which is characterized in that
In step 6, work as Si> 0, and when quality factor M reaches maximum value, stops weighted iteration, and output radiation source strength
Information is spent, the radiation source intensity information exported at this time is the desired radiation source intensity information；
Wherein, quality factor a M, the quality factor M are all correspondingly made available when executing step 6 every time and passes through following formula
(7) it obtains,
Wherein, R2Indicate the goodness of fit,
(9) a kind of nuclear power plant's point source radiation source strength backstepping system, which is characterized in that the system requires 1- for perform claim
Nuclear power plant's point source radiation source strength backstepping method described in 8.
(10) nuclear power plant's point source radiation source strength backstepping system according to above-mentioned (9), which is characterized in that the system includes
Detector, gamma rays average energy computing module and radiation source intensity computing module；
The detector has multiple, including predetermined position detector and nuclear power plant's radiation value monitoring detector,
The pre-determined bit that distance determines between radiation source is arranged in nuclear power plant radiation areas in the predetermined position detector
It sets, and is optionally coated with dismountable shielded layer outside the predetermined position detector；
The predetermined position detector is used to the radiation dose rate information detected being transferred to gamma rays average energy
Computing module,
Nuclear power plant's radiation value monitoring detector is distributed in the radiation areas of nuclear power plant, for what will be separately detected
Nuclear power plant's middle dosage rate information is transferred to radiation source intensity computing module,
The gamma rays average energy computing module is used to calculate the average energy E of gamma rays,
The radiation source intensity computing module is for calculating radiation source intensity in nuclear power plant.
Beneficial effect possessed by the present invention includes:
(1) the nuclear power plant's point source radiation source strength backstepping method provided according to the present invention can sufficiently ensure human body radiation peace
In the case where complete, the point source source strength data inside nuclear power plant under complex geometry space structure are obtained；
(2) the nuclear power plant's point source radiation source strength backstepping method provided according to the present invention is calculated by successive ignition, it is ensured that most
The point source source strength information obtained eventually is more adjacent to true value, has very high engineering application value.
Detailed description of the invention
Fig. 1 shows a kind of overall workflow figure of preferred embodiment according to the present invention.
Specific embodiment
Below by drawings and examples, the present invention is described in more detail.Illustrated by these, the features of the present invention
It will be become more apparent from advantage clear.
Dedicated word " exemplary " means " being used as example, embodiment or illustrative " herein.Here as " exemplary "
Illustrated any embodiment should not necessarily be construed as preferred or advantageous over other embodiments.
The nuclear power plant's point source radiation source strength backstepping method provided according to the present invention, this method comprises the following steps:
Step 1 receives the dosage rate information D that the detector in power plant detects1,D2,D3…Di, above-mentioned more in order to detect
A dosage rate, needs to use multiple detectors, and in the present invention, multiple detectors can be placed into power plant, can also direct benefit
With detector already existing in nuclear power plant, already existing detector is nuclear power plant's radiation value monitoring detector in nuclear power plant,
Can be combined with using above two mode, be for the status requirement where above-mentioned detector: radiation source and the position it
Between without shield, heretofore described dosage rate is radiation dose rate.In the present invention, the quantity of the detector is greater than nuclear power
The quantity of radiation source in factory.
Step 2 establishes the over-determined systems containing radiation source intensity, the overdetermination according to the dosage rate information detected
Equation group is following formula (one),
Step 3 calculates the over-determined systems in step 2 by least square method and obtains radiation source intensity information, described
Radiation source intensity is following formula (three)
Sj,0=(aj,i·ai,j)-1·aj,i·Di(3)
The coefficient matrix a of the over-determined systemsi,jIt is obtained by following formula (two),
After step 3, the strength information for obtaining radiation source is had been able to, but the strength information is possible and inadequate
Accurately, so continuing to calculate by following step, to obtain the radiation source intensity information more close to true value；
Step 4, the dosage rate at the radiation source intensity information calculating detector position according to obtained in step 3, D '1,
D′2,D′3…D′i；
Dosage rate information at step 5, the dosage rate information detected to detector and the detector position being calculated
Linear fit, the linear equation of the both sides relation after being fitted are carried out, and then obtains fitting parameter, the fitting parameter packet
It includes: average uncertainty, the goodness of fit and corresponding weight matrix；Heretofore described weight matrix can be interior weight square
Battle array or outer weight matrix, preparation method are consistent, and uncertainty is not by system if difference is outer weight matrix
The detector error range for being calculated, but being inputted by operator's means.
Step 6 is weighted over-determined systems of the weight matrix iteration into step 2 obtained in step 5
Overdetermined equation, and then repeat Step 2: step 3 and step 4, until obtaining desired radiation source intensity information；
In the present invention, D indicates the dosage rate that detector detects；DiIndicate the dosage rate that i-th of detector detects；
The number of i expression detector；The number of j expression radiation source；M indicates the attainable maximum value of radiation source number；S indicates radiation source
Intensity；SjIndicate the intensity of j-th of radiation source；Sj,0Indicate the intensity for j-th of radiation source that initial calculation is not iterated；
ai,jIt indicates coefficient matrix, is dose response coefficient of j-th of radiation source to i-th of detector；BD(E,L(μ(E),r0→rp) table
Show buildup factor, is E and L (μ (E), r0→rp) function；L(μ(E),r0→rp) indicate optical distance, it is μ (E) and r0→rp
Function, that is, optical distance is the function of energy and actual range；μ (E) indicates linear attenuation coefficient；r0→rpIndicate radiation source
To the distance of sensing point；C (E) indicates fluence-dose conversion factor, is the function of E；E indicates energy, is radiation source in nuclear power plant
The average energy of the gamma rays of sending；D′iIndicate the dosage rate at calculated i-th of detector position.Wherein, the spy
Measuring point indicates the position of detector, is more precisely the position that radiation information is received on detector.
Heretofore described buildup factor is professional term commonly used in the art, can refer to usually containing in this field
Justice is explained and is calculated, and it is as follows that its calculation formula under normal circumstances is provided in the present invention:
Wherein KxFitting formula it is as follows:
K (E, x)=cxa+d[tanh(x/Xk-2)-tanh(-2)]/[1-tanh(-2)]；
Wherein E is photon energy, MeV；X is distance of the source point to calculating point, mfp；B is the product at a mean free path
The tired factor；a,c,d,XkIt can choose when tiring out the selection of factor coefficient using log difference mode for empirical parameter, it may be assumed that
a(Ea)={ a (E1)·[log(E2)-log(Ea)]+a(E2)·[log(Ea)-log(E1)]}/[log(E2)-log
(E1)]
In one preferred embodiment, the average energy E's for the gamma rays that radiation source issues in the nuclear power plant
Measuring method includes following sub-step:
Sub-step 1, chooses predetermined position inside nuclear power plant, and distance of the predetermined position apart from radiation source is t, pre- at this
Placement location detector is positioned, the dosage rate I that the detector detects is collected0,
Sub-step 2 fetches the detector, is placed on the predetermined position after shielded layer is coated outside it, collects institute
State the dosage rate I that detector detects；
Alternatively, fetching the detector, shield is placed in predetermined position, then the detector is placed on shield
It is interior, collect the dosage rate I that the detector detects；
Sub-step 3, the I and I obtained according to sub-step 1 and step 20, clad or shield are calculated by following formula (four)
Mass attentuation coefficient μ,
I/I0=BDe-μt(4)
Sub-step 4 tables look-up to obtain the average energy of the gamma rays of radiation source sending according to the calculated result of sub-step 3
E.The table tabled look-up can be material section table, which is documented in ANSI/ANS 6.4.3, " Gamma-ray
Attenuation Coefficients and Buildup Factor for Engineering Materials”,
American Nuclear Society, 16-67 pages of 1991..In the present invention, all use radiation energies, all with above-mentioned
Average energy calculates, if its capacity volume variance of different zones is larger in nuclear power plant, it may be considered that individually calculate to the region, i.e., singly
Solely measuring and calculating average energy, individually calculates radiation source intensity.
In one preferred embodiment, the method for calculating the optical distance L includes following sub-step, sub-step a,
It tracks gamma ray and walks process from radiation source to sensing point, record gamma ray passes through the sequence of radiation areas, that is, passes through
Ray tracking method calculates radiation source to the distance r of sensing point0→rp, wherein r0The position for indicating radiation source, indicates sensing point
Position rp.Sub-step b calculates separately the distance of each radiation areas, in conjunction with the linear taper coefficient of each radiation areas material,
Finally find out total optical distance L.
Specifically, gamma-rays is calculated when walking distance, describes space with combinatorial geometry method, and by different medium
Space is divided into different regions.Find out respectively the distance between intersection point and the entrance of gamma ray and each basic body Di and
The distance between outlet Do.Find out all basic body the number plus and minus in each region with "+" and "-", the process
It may include six following steps,
(1) the starting point r of every line0The determination of region Ipstart:
If there is no "-" basic body in some region, then all "+" basic bodies all must satisfy in the region
Point r0In all "+" basic bodies, then it is considered that the initiation region of ray is the region；If having in the region
"-" basic body, then "+" basic body all in the region all must satisfy starting point r0In all "+" basic bodies, and
And all "-" basic bodies all must satisfy the starting point r not comprising this ray0, it is considered that the initiation region of ray is the area
Domain.
(2) the terminal r of every linepThe determination of region Ipend:
If likewise, there is no "-" basic body in some region, then all "+" basic bodies are all necessary in the region
Meet terminal rpIn all "+" basic bodies, then it is considered that the termination area of ray is the region；If the region
In have "-" basic body, then "+" basic body all in the region all must satisfy terminal rpPositioned at all "+" basic bodies
In, and all "-" basic bodies all must satisfy the terminal r not comprising this rayp, it is considered that the termination area of ray is
The region.
(3) the starting point r of every line0The determination of the corresponding regional export distance Zo in region number:
If there is no "-" basic body in gamma-rays initiation region number, in initiation region the basic body outlet of all "+" away from
With a distance from the outlet that reckling in Do is the gamma-rays initiation region.If there is "-" basic body in gamma-rays initiation region, rise first
It is the smallest in the basic body outlet distance Do of all "+" in beginning region, then own "-" basic bodies and takes in import distance Di most
Small, take the maximum value of the two for the outlet distance of the gamma-rays initiation region.
(4) determination of the number IP in each region that ray passes through:
Terminal is not under outermost areas case, if not having "-" basic body in regional number, carries out adjacent subarea domain first
Judgement, for all "+" basic bodies, basic body import distance is less than or equal to the import distance in region and is less than basic body
Outlet apart from when (Di≤Zin < Do), the region be a upper region adjacent area, find out corresponding zone number IP；
If there is "-" basic body in gamma-rays regional number, for all "+" basic bodies, basic body import distance is less than or equal to region
Import distance and the outlet distance (Di≤Zin < Do) for being less than basic body, and to all "-" basic bodies, basic body import
Distance is greater than zone inlet distance or basic body outlet distance is less than or equal to zone inlet distance (Di > Zin or Do≤Zin)
When, which is the adjacent area in a upper region, finds out corresponding zone number IP.
(5) determination of the import distance Zi in each region that ray passes through and outlet distance Zo:
If not having "-" basic body in the above-mentioned adjacent area found out, which is the basic body of all "+"
Export the smallest in distance Do, the outlet distance in an import distance as upper region in the region；If the above-mentioned adjacent region found out
There is "-" basic body in domain, first find out reckling in the basic body outlet distance Do of all "+", is finding out the basic of all "-"
Then reckling in body import distance Di takes the maximum value of the two for the outlet distance in the region, the import distance in the region is
For the outlet distance in a upper region.
(6) terminal finds all basic body number aa of outermost layer, for region under outermost areas case first
Middle "+" basic body includes that basic body aa looks for whether that there are ray processes when "-" basic body does not include the region of basic body aa
In region "-" import of basic body distance be greater than region import distance (Di (k, minus (i, m)) > Zi (k, n)) "-" base
Ontology, if it does, regional export distance takes reckling in all "-" basic body import distance Di, if it does not, region goes out
Mouth distance is ray length.
Trace into rpIt is terminated when putting region IPend and radiation exit distance equal to ray length.To obtain γ
Ray walks distance.
The number of ray crossing area is carried out again and walks the calculating of distance every time:
If the crossing area number of ray is not 0, then the gamma-ray distance of walking in the region is equal to zone inlet distance
Regional export distance is cut, gamma-rays walks number and adds 1；If gamma-ray crossing area number is 0, stop tracking.
The section γ μ is obtained using the material of γ mass attentuation coefficient and Region Mediumn；
Process is walked when by above-mentioned record gamma-rays by region, finds out the optical distance in each region respectively then
It sums again, it may be assumed thatWherein, N indicates that the quantity of radiation areas, the quantity are main
It is to be determined by workshop internal environment.
In one preferred embodiment, it using the over-determined systems in Least Square in Processing step 2, and obtains
The process of radiation source intensity information includes following sub-step:
Sub-step 3-1, by over-determined systemsAX=b is expressed as with the form of matrix；
Sub-step 3-2 seeks the normal equation A of the matrixTAX=ATB, i.e. X=(ATA)-1ATb；
Sub-step 3-3 remembers G=A with the triangle decomposition method solution normal equation of symmetrical matrixTA, wherein G is symmetrical matrix；
Sub-step 3-4 solves G=L using triangle decomposition methodsDLs T, wherein LsIt is small triangular matrix, D is diagonal matrix；
Sub-step 3-5 solves lower triangular matrix equation group: LsY1=ATb；
Sub-step 3-6 solves diagonal matrix equation group: DY2=Y1；
Sub-step 3-7 solves upper triangular matrix equation group: Ls TX=Y2。
Wherein, X=(ATA)-1ATB and Sj,0=(ai,j T·ai,j)-1·ai,j T·DiIt is corresponding, pass through the sub-step 3-1
The evaluation of radiation source intensity is obtained to sub-step 3-7, heretofore described least square method is general in this field
Overdetermined equation calculation method.
In one preferred embodiment, in step 5, linear fit is carried out by following formula (five),
Wherein,Indicate the dosage rate of estimation；Indicate the slope of estimation, Indicate the intercept of estimation,
N indicates the attainable maximum value of detector number i,Indicate the flat of dosage rate at calculated detector position
Mean value,Indicate the average value for the dosage rate that detector detects.
In one preferred embodiment, after linear fit, the average not true of linear fit is also respectively obtained
Fixed degree, the goodness of fit, quality factor, weighting function and corresponding weight matrix, the quality factor represent current iteration calculating
Confidence level.In step 5, weighting function is obtained according to uncertainty, then weight matrix W is obtained by weighting function, it is described
Weight matrix W is obtained by following formula (six),
Wherein, f indicates fitting uncertainty,fiIndicate that the fitting of i-th of detector position is uncertain
Degree；Indicate average fit uncertainty, Indicate weighting function.
In one preferred embodiment, in step 6, the judgement of the desired radiation source intensity information is obtained
Condition is to work as SiWhen > 0, and quality factor M reaches maximum value, that is, works as Si> 0, and when quality factor M reaches maximum value stop plus
Iteration is weighed, and output radiation source strength information, the radiation source intensity information are exactly finally obtained desired radiation source intensity,
It is closest to the radiation source intensity of true value.
It is an object of the invention to obtain the radiation source intensity closest to true value, and the radiation source intensity that step 3 obtains
Reliability ratio it is lower, the error between true value can be bigger, so obtaining to improve the accuracy of the numerical value
Closest to the radiation source intensity of true value, the weighted iteration process of step 4 to step 6 is given in the present invention, and finally set
The condition of iteration ends is determined, to reduce workload to the greatest extent in the case where guaranteeing the accurate situation of result, has shortened the activity duration, improve number
According to the efficiency of acquisition.According to the judgment criteria of above-mentioned the Weighted Iterative Methods and iteration ends.In addition, being radiated obtained in the present invention
Source strength is more more acurrate than the radiation source intensity that the method for Sources term analysis obtains, more close to true value, can guarantee acquisition value with
True value is within an order of magnitude.In one preferred embodiment, one is all correspondingly made available when executing step 6 every time
A quality factor M, the quality factor M are obtained by following formula (seven),
Wherein, R2Indicate the goodness of fit,
In one preferred embodiment, over-determined systemsMatrix form see below formula (eight)
Wherein, ε indicates the error that each detector introduces；Consider physics meaning, at actually each sensing point caused by
Caused by error may be considered radiation source, then above-mentioned equation simplification is following formula (nine),
And then it can be found that, coefficient matrix ai,jJ-th of radiation source is equivalent to the dose response coefficient of i-th of detector,
Wherein, the dose response coefficient of detector is calculated using Point- kernel integral technology, and the Point- kernel integral technology meter is this field
Middle conventional calculation method.
A kind of nuclear power plant's point source radiation source strength backstepping system provided according to the present invention, the system is for executing the present invention
Nuclear power plant's point source radiation source strength backstepping method described in the text.
Preferably, which includes detector, gamma rays average energy computing module and radiation source intensity computing module；
The detector has multiple, including predetermined position detector and nuclear power plant's radiation value monitoring detector,
The pre-determined bit that distance determines between radiation source is arranged in nuclear power plant radiation areas in the predetermined position detector
It sets, and is optionally coated with dismountable shielded layer outside the predetermined position detector；The predetermined position distance radiation
The distance in source can occur in subsequent calculating as known quantity；
The predetermined position detector is used to the radiation dose rate information detected being transferred to gamma rays average energy
Computing module, to calculate gamma rays average energy；
Nuclear power plant's radiation value monitoring detector is distributed in the radiation areas of nuclear power plant, is located at institute in the present invention
The key position stated, nuclear power plant's middle dosage rate information for will separately detect are transferred to radiation source intensity computing module,
The gamma rays average energy computing module is used to calculate the average energy E of gamma rays,
The radiation source intensity computing module is for calculating radiation source intensity in nuclear power plant.
Experimental example:
Using the room NB281 in No. 1 unit nuclear island of Daya Bay nuclear power plant as experimental subjects, which is in nuclear island control zone
For placing the place that radioactive wastewater collecting vessel is housed, wastewater collection bucket is a hydrostatic column, inner radiation fluid supply
It is by force 0.7586E+10MeV/cm3.s (or 4.2898E+14/s).Now 4 sections, every section are divided axially into along this wastewater collection bucket
It is reduced to a point source, one detector is set every 50cm in wastewater collection bucket middle section, totally five detectors, each spy
Survey device obtain probe value be respectively 2.032mSv/hr, 0.685mSv/h, 0.255mSv/h, 0.1446mSv/h,
0.0929mSv/h, the as D in the present invention1,D2,D3,D4,D5, the average energy acquisition methods and system that provide according to the present invention
Obtaining average energy is 1.3MeV, and using source strength backstepping method and system provided by the invention, four points respectively obtained are in a steady stream
It is by force respectively 1.0256E+14MeV/s, 1.3471E+14MeV/s, 0.9277E+14MeV/s, 1.1058E+14MeV/s.
From final result it is found that the radiation intensity true value of the sum of radiation intensity of four obtained points and the radiation source
It is almost the same, it is possible to illustrate that method and system provided by the invention can obtain the radiation source intensity letter close to true value
Breath.
Combining preferred embodiment above, the present invention is described, but these embodiments are only exemplary
, only play the role of illustrative.On this basis, a variety of replacements and improvement can be carried out to the present invention, these each fall within this
In the protection scope of invention.
Claims (9)
1. a kind of nuclear power plant's point source radiation source strength backstepping method, which is characterized in that this method comprises the following steps:
Step 1, with the dosage rate D in detector detection nuclear power plant1,D2,D3…Di；
Step 2 establishes the overdetermination side containing radiation source intensity as shown in following formula (one) according to the dosage rate information detected
Journey group,
Wherein, the coefficient matrix a of the over-determined systemsi,jIt is obtained by following formula (two),
Step 3 obtains the radiation source intensity as shown in following formula (three) by the over-determined systems in Least Square in Processing step 2
Information is spent,
Sj,0=(aj,i·ai,j)-1·aj,i·Di(3)；
Wherein, DiIndicate the dosage rate that i-th of detector detects；The number of j expression radiation source；M indicates radiation source number energy
The maximum value reached；SjIndicate the intensity of j-th of radiation source；Sj,0Indicate j-th of radiation source that initial calculation is not iterated
Intensity；ai,jIt indicates coefficient matrix, is dose response coefficient of j-th of radiation source to i-th of detector；BD(E,L(μ(E),r0
→rp) indicate buildup factor, it is E and L (μ (E), r0→rp) function；L(μ(E),r0→rp) indicate optical distance, be μ (E) and
r0→rpFunction；μ (E) indicates section/linear attenuation coefficient；r0→rpDistance of the expression radiation source to sensing point；C (E) is indicated
Fluence-dose conversion factor is the function of E；E indicates energy, is the average energy for the gamma rays that radiation source issues in nuclear power plant
Amount；
After step 3, the method also includes following steps,
Step 4, the dosage rate at the radiation source intensity information calculating detector position according to obtained in step 3, D '1,D′2,
D′3…D′i；
Dosage rate information at step 5, the dosage rate information detect to detector and the detector position being calculated carries out
Linear fit, the linear equation of the both sides relation after being fitted, and then fitting parameter is obtained, the fitting parameter includes: flat
Equal uncertainty, the goodness of fit and corresponding weight matrix；
Step 6, by over-determined systems of the weight matrix iteration into step 2 obtained in step 5, the overdetermination weighted
Equation, and then repeat Step 2: step 3 and step 4, until obtaining desired radiation source intensity information；
Wherein, D 'iIndicate the dosage rate at calculated i-th of detector position.
2. nuclear power plant's point source radiation source strength backstepping method according to claim 1, which is characterized in that for the nuclear power plant
The average energy E for the gamma rays that middle radiation source issues, measuring method includes following sub-step:
Sub-step 1, chooses predetermined position inside nuclear power plant, and distance of the predetermined position apart from radiation source is t, in the pre-determined bit
Placement location detector collects the dosage rate I that the detector detects0,
Sub-step 2 fetches the detector, is placed on the predetermined position after coating shielded layer outside it, collects the spy
Survey the dosage rate I that device detects；
Alternatively, fetching the detector, shield is placed in predetermined position, then the detector is placed in shield, received
Collect the dosage rate I that the detector detects；
Sub-step 3, the I and I obtained according to sub-step 1 and step 20, the quality of clad or shield is calculated by following formula (four)
Attenuation coefficient mu,
I/I0=BDe-μt(4)
Sub-step 4 obtains the average energy E of the gamma rays of radiation source sending according to the calculated result of sub-step 3.
3. nuclear power plant's point source radiation source strength backstepping method according to claim 1, which is characterized in that calculate the optics away from
It include following sub-step from the method for L,
Sub-step a tracks gamma ray and walks process from radiation source to sensing point, and record gamma ray passes through radiation areas
Sequentially,
Sub-step b calculates separately the distance of each radiation areas, in conjunction with the linear taper coefficient of each radiation areas material, most
Total optical distance L is found out afterwards.
4. nuclear power plant's point source radiation source strength backstepping method according to claim 1, which is characterized in that use least square method
Over-determined systems in processing step two, and the process for obtaining radiation source intensity information includes following sub-step:
Sub-step 3-1, by over-determined systemsAX=b is expressed as with the form of matrix；
Sub-step 3-2 seeks the normal equation A of the matrixTAX=ATB, i.e. X=(ATA)-1ATb；
Sub-step 3-3 remembers G=A with the triangle decomposition method solution normal equation of symmetrical matrixTA, wherein G is symmetrical matrix；
Sub-step 3-4 solves G=L using triangle decomposition methodsDLs T, wherein LsIt is small triangular matrix, D is diagonal matrix；
Sub-step 3-5 solves lower triangular matrix equation group: LsY1=ATb；
Sub-step 3-6 solves diagonal matrix equation group: DY2=Y1；
Sub-step 3-7 solves upper triangular matrix equation group: Ls TX=Y2。
5. nuclear power plant's point source radiation source strength backstepping method according to claim 1, which is characterized in that in step 5, lead to
It crosses following formula (five) and carries out linear fit,
Wherein,Indicate the dosage rate of estimation；Indicate the slope of estimation, Table
Show the intercept of estimation,
N indicates the attainable maximum value of detector number i,Indicate the average value of dosage rate at calculated detector position,Indicate the average value for the dosage rate that detector detects.
6. nuclear power plant's point source radiation source strength backstepping method according to claim 5, which is characterized in that in step 5, root
Weighting function is obtained according to uncertainty, then weight matrix W is obtained by weighting function, the weight matrix W passes through following formula (six)
It obtains,
Wherein, f indicates fitting uncertainty, Indicate average fit uncertainty,fiIndicate the fitting uncertainty of i-th of detector position；Indicate power
Weight function.
7. nuclear power plant's point source radiation source strength backstepping method according to claim 5, which is characterized in that
In step 6, work as Si> 0, and when quality factor M reaches maximum value, stops weighted iteration, and output radiation source strength is believed
Breath, the radiation source intensity information exported at this time is the desired radiation source intensity information；
Wherein, it is all correspondingly made available quality factor a M, the quality factor M when executing step 6 every time and passes through following formula (seven)
It obtains,
Wherein, R2Indicate the goodness of fit,
8. a kind of nuclear power plant's point source radiation source strength backstepping system, which is characterized in that the system requires to appoint in 1-7 for perform claim
Nuclear power plant's point source radiation source strength backstepping method described in meaning one.
9. nuclear power plant's point source radiation source strength backstepping system according to claim 8, which is characterized in that the system includes detection
Device, gamma rays average energy computing module and radiation source intensity computing module；
The detector has multiple, including predetermined position detector and nuclear power plant's radiation value monitoring detector,
The predetermined position that distance determines between radiation source is arranged in nuclear power plant radiation areas in the predetermined position detector, and
Dismountable shielded layer is optionally coated with outside the predetermined position detector；
The predetermined position detector is used to for the radiation dose rate information detected to be transferred to gamma rays average energy and calculate
Module,
Nuclear power plant's radiation value monitoring detector is distributed in the radiation areas of nuclear power plant, the nuclear power for that will separately detect
Factory's middle dosage rate information is transferred to radiation source intensity computing module,
The gamma rays average energy computing module is used to calculate the average energy E of gamma rays,
The radiation source intensity computing module is for calculating radiation source intensity in nuclear power plant.
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