CN106815453A - Nuclear power plant's ray radiation source strength backstepping method and ray radiation source strength backstepping system - Google Patents
Nuclear power plant's ray radiation source strength backstepping method and ray radiation source strength backstepping system Download PDFInfo
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Abstract
The invention discloses a kind of nuclear power plant's ray radiation source strength backstepping method and ray radiation source strength backstepping system, in the method, the close 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 close rate calculating is carried out to detector position, linear regression analysis is carried out by measured value and calculated value, calculate the key parameters such as standard deviation, slope, intercept, and then calculate quality factor and weigh the acceptable degree of each result of calculation；The Weighted Iterative Methods are proposed simultaneously, the error that the larger detector of uncertainty is introduced is reduced, and using the mode of iteration, above steps may be repeated multiple times until quality factor reach pre-set value, obtains desired radiation source intensity information.
Description
Technical field
The present invention relates to the computational methods and system of radiation source intensity in nuclear power plant, and in particular to a kind of nuclear power plant's line source spoke
Penetrate source strength backstepping method and ray radiation source strength backstepping system.
Background technology
Active region of the radioactivity of nuclear power plant from fuel assembly in pressure vessel, radiation source mainly by fission product,
Actinides and activating product are constituted.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 cooling agent and relevant device table
Face.Radioactivity is strong in itself for radiation source, and the dosage suffered by daily routines of the staff when nuclear power plant normally runs accounts for year total agent
20% or so of amount, and during nuclear power station overhaul, the dosage suffered by staff will account for the 80% of year accumulated dose, in core
Mainly radioactive dose is reduced during power plant's overhaul by shortening staff in the residence time of radiation area.
Distribution of radiation source is especially used with after overhaul than wide by prolonged in nuclear power plant, is passed through according to engineering
Test and be 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 Back ground Information and greatly affected accuracy and practicality, together
When, in the case that current protective equipment and means are not very complete at home, also cause that the illuminated risk of staff is big
It is big to increase.
In the prior art, it is necessary to when calculating radiation source intensity, Sources term analysis method typically be used, first, according to radioactive material
The generation of matter and disappearance approach determine that it produces item (as flowed into item, decay produces item etc.) and disappearance item (such as filtering item, leakage item
Deng), and clearly every physical model, nucleon concentration balance equation is then set up to radioactive substance according to above-mentioned items
(group), last simultaneous equations (group) solve, but there is substantial amounts of simplification and approximate calculation in these calculating process, so its
Result is often larger with actual value gap, in practical application in the presence of many obstacles, in addition, in view of radiation source in itself
The complicated geometry in the harm that is caused to human body, nuclear power plant inside, radionuclide accurate information are difficult to obtain, nuclear power plant is visited
When surveying the factors such as the uncertainty of device measured value, the above method is problematic in that at aspects such as security, accuracys, it would be highly desirable to improve
Or propose new radiation source intensity acquiring way.
For these reasons, the present inventor furthers investigate to the method for existing calculating source strength information, rule of thumb,
The pipeline or component in usual nuclear power plant with homogeneous radiation can be reduced to a line source or one group of line source, so as to set
Count out a kind of nuclear power plant's ray radiation source strength backstepping method and ray radiation source strength backstepping system that can solve the problem that above mentioned problem.
The content of the invention
In order to overcome above mentioned problem, present inventor has performed studying with keen determination, a kind of nuclear power plant's ray radiation source strength is designed
Backstepping method and ray radiation source strength backstepping system, the method and system can fully ensure the situation of human body radiation safety
Under, obtain the line source source strength data under nuclear power plant's inside complex geometry space structure；In the method, the pre-determined bit in nuclear power plant
Placement location detector, and also placed with shielded detector in the position, and then obtain radiation source releasing gamma ray
Average energy；In addition, the detector of multiple monitoring nuclear power plants radiation value is additionally provided with nuclear power plant, to obtain part sampling site
Close rate, the mode combined using Point- kernel integral and weighted least-squares method, while radiation source intensity is spatially carried out it is discrete,
Judge gamma-rays the walking distance and calculating optical distance in space that each discrete source is released using ray tracing method, knot
The information such as condensation material, buildup factor carry out the calculating of equation group coefficient, and then backstepping goes out source strength；Then obtain to detector position
Locate the calculated value of close rate, measured value and calculated value are carried out linear regression analysis treatment, obtain standard deviation, slope, intercept
Deng key parameter, and then obtain representing the quality factor of physical meaning, the quality factor can weigh each result of calculation
Acceptable degree；A kind of the Weighted Iterative Methods are proposed simultaneously, the error that the larger detector of uncertainty is introduced are reduced, using iteration
Mode above steps may be repeated multiple times until quality factor meet default condition, and then obtain desired radiation source intensity and radiation
The uncertainty of field result, so as to complete the present invention.
In particular it is object of the present invention to provide following aspect：
(1) a kind of nuclear power plant's ray radiation source strength backstepping method, it is characterised in that the method comprises the following steps：
Step one, the close rate D in nuclear power plant is detected with detector1,D2,D3…Di,
Step 2, according to the close rate information for detecting, sets up super containing radiation source intensity as shown in following formula ()
Determine equation group,
(1)
Wherein, the coefficient matrix a of the over-determined systemsi,jObtained by following formula (two) and (three),
(2)
(3)
Step 3, radiation source intensity information is obtained by the over-determined systems in least square method calculation procedure two, described
Radiation source intensity is following formula (four)
Sj,0=(aj,i·ai,j)-1·aj,i·Di(4)
Wherein, DiRepresent the close rate that i-th detector detection is obtained；J represents the number of radiation source；M represents radiation source
The maximum that number can reach；SjRepresent j-th intensity of radiation source；Sj,0Represent j-th spoke that initial calculation is not iterated
Penetrate the intensity in source；ai,jExpression coefficient matrix is j-th radiation source to i-th dose response coefficient of detector；Represent
Line source coefficient of dispersion；LjRepresent j-th discrete number of radiation source；Represent the discrete source strength of normalization；BD(E,L(μ(E),r0
→rp) buildup factor is represented, it is E and L (μ (E), r0→rp) function；L(μ(E),r0→rp) represent optical distance, be μ (E) and
r0→rpFunction；μ (E) represents section/linear attenuation coefficient；r0→rpRepresent radiation source to the distance of sensing point；C (E) is represented
Fluence-dose conversion factor, is the function of E；E represents energy, is the average energy of the gamma rays that radiation source sends in nuclear power plant
Amount.
(2) the nuclear power plant's ray radiation source strength backstepping method according to above-mentioned (1), it is characterised in that step 3 it
Afterwards, methods described also comprises the following steps,
Step 4, according to the close rate at the radiation source intensity information calculating detector position obtained in step 3, D1′,
D2′,D3′…Di′；
Close rate information at step 5, the close rate information detected to detector and the detector position being calculated
Linear fit is carried out, the linear equation of the both sides relation after being fitted, and then fitting parameter is obtained, the fitting parameter bag
Include：Average uncertainty, the goodness of fit and corresponding weight matrix；
Step 6, the over-determined systems in new weight matrix iteration to the step 2 that will be obtained in step 5, is added
The overdetermined equation of power, and then repeat step two, step 3 and step 4, until obtaining desired radiation source intensity information；
Wherein, DiThe close rate at i-th detector position that ' expression is calculated.
(3) the nuclear power plant's ray radiation source strength backstepping method according to above-mentioned (1), it is characterised in that for the core
The average energy E of the gamma rays that radiation source sends in power plant, its measuring method includes following sub-step：
Sub-step 1, chooses precalculated position inside nuclear power plant, and the precalculated position is t apart from the distance of radiation source, pre- at this
Positioning placement location detector, collects the close rate I that the detector is detected0,
Sub-step 2, fetches the detector, and the precalculated position is placed on after screen layer is coated outside it, collects institute
State the close rate I that detector is detected；
Or, the detector is fetched, shield is placed in precalculated position, then the detector is placed on shield
It is interior, collect the close rate I that the detector is detected；
Sub-step 3, according to I and I that sub-step 1 and step 2 are obtained0, clad or shield are calculated by following formula (five)
Mass attentuation coefficient μ,
I/I0=BDe-μt(5)
Sub-step 4, according to the result of calculation of sub-step 3, obtains the average energy E of the gamma rays that radiation source sends.
(4) the nuclear power plant's ray radiation source strength backstepping method according to above-mentioned (1), it is characterised in that calculate the light
The method learned apart from L includes following sub-step,
Sub-step a, tracking gamma ray walks process from discrete radiation source to sensing point, and record gamma ray is passed through
The order of radiation areas,
Sub-step b, calculates the distance of each radiation areas respectively, with reference to the linear taper system of each radiation areas material
Number, finally obtains total optical distance L.
(5) the nuclear power plant's ray radiation source strength backstepping method according to above-mentioned (1), it is characterised in that use a most young waiter in a wineshop or an inn
Over-determined systems in multiplication process step 2, and obtain radiation source intensity information process include 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, with the triangle decomposition method solution normal equation of symmetrical matrix, remembers G=ATA, wherein, G is symmetrical matrix；
Sub-step 3-4, G=LDL is solved using triangle decomposition methodT, wherein L is small triangular matrix, and D is diagonal matrix；
Sub-step 3-5, solves lower triangular matrix equation group:LY1=ATb；
Sub-step 3-6, solves diagonal matrix equation group：DY2=Y1；
Sub-step 3-7, solves upper triangular matrix equation group：LTX=Y2。
(6) the nuclear power plant's ray radiation source strength backstepping method according to above-mentioned (2), it is characterised in that in step 5,
Linear fit is carried out by following formula (six),
(6)
Wherein,Represent the close rate estimated；The slope estimated is represented, The intercept estimated is represented,
N represents the maximum that detector number i can reach,Close rate is flat at the detector position that expression is calculated
Average,Represent the average value of the close rate that detector is detected.
(7) the nuclear power plant's ray radiation source strength backstepping method according to above-mentioned (6), it is characterised in that in step 5,
Weighting function is obtained according to uncertainty, then weight matrix W, the weight matrix W are obtained by following formula by weighting function
(7) obtain,
(7)
Wherein, f represents fitting uncertainty, Average fit uncertainty is represented,fiRepresent i-th fitting uncertainty of detector position；；Represent
Weighting function.
(8) the nuclear power plant's ray radiation source strength backstepping method according to above-mentioned (6), it is characterised in that
In step 6, work as Si＞ 0, and quality factor M stops weighted iteration, and output radiation source strength when reaching maximum
Degree information, the radiation source intensity information for now exporting is the desired radiation source intensity information；
Wherein, quality factor a M, the quality factor M are all correspondingly made available when performing step 6 every time and pass through following formula
(8) obtain,
(8)
Wherein, R2Represent the goodness of fit,
(9) a kind of nuclear power plant's ray radiation source strength backstepping system, it is characterised in that the system is used for perform claim requirement 1-
Nuclear power plant's ray radiation source strength backstepping method described in 8.
(10) the nuclear power plant's ray radiation source strength backstepping system according to above-mentioned (9), it is characterised in that the system includes
Detector, gamma rays average energy computing module and radiation source intensity computing module；
The detector has multiple, including precalculated position detector and nuclear power plant's radiation value monitoring detector,
The precalculated position detector is arranged in nuclear power plant radiation areas the pre-determined bit that distance determines and radiation source between
Put, and dismountable screen layer is optionally coated with outside the precalculated position detector；
The precalculated position detector is used for the radiation dose rate information transmission that will detect 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 that will separately detect
Nuclear power plant's middle dosage rate information transmission 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 used to calculate radiation source intensity in nuclear power plant.
The present invention have the advantage that including：
(1) the nuclear power plant's ray radiation source strength backstepping method provided according to the present invention can fully ensure human body radiation peace
In the case of complete, the line source source strength data under nuclear power plant's inside complex geometry space structure are obtained；
(2) the nuclear power plant's ray radiation source strength backstepping method provided according to the present invention is calculated by successive ignition, it is ensured that most
The line source source strength information for obtaining eventually is more adjacent to actual value, with engineering application value very high.
Brief description of the drawings
Fig. 1 shows the overall workflow figure according to a kind of preferred embodiment of the 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
To be become more apparent from clearly with advantage.
Special 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.
According to nuclear power plant's ray radiation source strength backstepping method that the present invention is provided, the method comprises the following steps：
Step one, receives the close rate information D that the detector in power plant is detected1,D2,D3…Di, it is above-mentioned many in order to detect
Individual close rate, it is necessary to use multiple detectors, in the present invention, can be to placing multiple detectors in power plant, it is also possible to direct profit
With the detector existed in nuclear power plant, the detector existed in nuclear power plant is nuclear power plant's radiation value monitoring detector,
Can be combined with using above two mode, be for the status requirement where above-mentioned detector：Radiation source and the position it
Between there is no a shield, heretofore described close rate is radiation dose rate.In the present invention, the quantity of the detector is more than nuclear power
The quantity of radiation source in factory.
Step 2, according to the close rate information for detecting, sets up the over-determined systems containing radiation source intensity, the overdetermination
Equation group is following formula (),
(1)
Step 3, radiation source intensity information is obtained by the over-determined systems in least square method calculation procedure two, described
Radiation source intensity is following formula (four)
Sj,0=(aj,i·ai,j)-1·aj,i·Di(4)
The coefficient matrix a of the over-determined systemsi,jObtained by following formula (two) and (three),
(2)
(3),
After by step 3, have been able to obtain the strength information of radiation source, but the strength information is possible and inadequate
Accurately, so continuing to calculate by following step, the radiation source intensity information of actual value is more pressed close to obtain；
Step 4, according to the close rate at the radiation source intensity information calculating detector position obtained in step 3, D1′,
D2′,D3′…Di′；
Close rate information at step 5, the close rate information detected to detector and the detector position being calculated
Linear fit is carried out, the linear equation of the both sides relation after being fitted, and then fitting parameter is obtained, the fitting parameter bag
Include：Average uncertainty, the goodness of fit and corresponding weight matrix；Heretofore described weight matrix is divided into interior weight matrix
Or outer weight matrix, its computational methods is consistent, and difference is that uncertainty is not by system meter if outer weight matrix
Obtain, but the detector error range being input into by operator's means.
Step 6, the over-determined systems in weight matrix iteration to the step 2 that will be obtained in step 5, is weighted
Overdetermined equation, and then repeat step two, step 3 and step 4, until obtaining desired radiation source intensity information；
In the present invention, D represents the close rate that detector is detected；DiRepresent the close rate that i-th detector detection is obtained；
I represents the number of detector；J represents the number of radiation source；M represents the maximum that radiation source number can reach；S represents radiation source
Intensity；SjRepresent j-th intensity of radiation source；Sj,0Represent the intensity of j-th radiation source that initial calculation is not iterated；
ai,jExpression coefficient matrix is j-th radiation source to i-th dose response coefficient of detector；Represent the discrete system of line source
Number；LjRepresent j-th discrete number of radiation source；Represent the discrete source strength of normalization；BD(E,L(μ(E),r0→rp) represent
Buildup factor, is E and L (μ (E), r0→rp) function；L(μ(E),r0→rp) optical distance is represented, it is μ (E) and r0→rp's
Function, i.e. optical distance is the function of energy and actual range；μ (E) represents linear attenuation coefficient；r0→rpRepresent that radiation source is arrived
The distance of sensing point；C (E) represents fluence-dose conversion factor, is the function of E；E represents energy, is radiation source hair in nuclear power plant
The average energy of the gamma rays for going out；DiThe close rate at i-th detector position that ' expression is calculated.Wherein, the detection
The position of point expression 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 generally containing in this area
Justice is explained and calculated, and it is as follows to provide its computing formula generally 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 source point to the distance for calculating point, mfp；B is the product at a mean free path
The tired factor；a,c,d,XkIt is empirical parameter, when tiring out the selection of factor coefficient, can selects to use log difference mode, i.e.,：
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 of the gamma rays that radiation source sends in the nuclear power plant
Measuring method includes following sub-step：
Sub-step 1, chooses precalculated position inside nuclear power plant, and the precalculated position is t apart from the distance of radiation source, pre- at this
Positioning placement location detector, collects the close rate I that the detector is detected0,
Sub-step 2, fetches the detector, and the precalculated position is placed on after screen layer is coated outside it, collects institute
State the close rate I that detector is detected；
Or, the detector is fetched, shield is placed in precalculated position, then the detector is placed on shield
It is interior, collect the close rate I that the detector is detected；
Sub-step 3, according to I and I that sub-step 1 and step 2 are obtained0, clad or shield are calculated by following formula (five)
Mass attentuation coefficient μ,
I/I0=BDe-μt(5)
Sub-step 4, according to the result of calculation of sub-step 3, tables look-up and obtains the average energy of the gamma rays that radiation source sends
E.The table tabled look-up can be material section table, and the token is loaded 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 of use emittance, all with above-mentioned
Average energy is calculated, if its capacity volume variance of different zones is larger in nuclear power plant, it may be considered that the region is individually calculated, i.e., singly
Solely measuring and calculating average energy, individually calculates radiation source intensity.
In one preferred embodiment, calculating the method for the optical distance L includes following sub-step, sub-step a,
Tracking gamma ray walks process from radiation source to sensing point, and record gamma ray passes through through the order of radiation areas
Ray tracking method calculates radiation source to sensing point apart from r0→rp, wherein r0The position of radiation source is represented, sensing point is represented
Position rp.Sub-step b, calculates the distance of each radiation areas respectively, with reference to the linear taper coefficient of each radiation areas material,
Finally obtain total optical distance L.
Specifically, calculate gamma-rays when walking distance, space is described with combinatorial geometry method, and by different medium
Space is divided into different regions.Obtain respectively the distance between the intersection point of gamma ray and each basic body and entrance Di and
With outlet the distance between Do.Obtain all basic body numbering plus and minus with "+" and "-", the process in each region
Six following steps are may include,
(1) every starting point r of line0The determination of region Ipstart：
If not having "-" basic body in certain region, then in the region, all of "+" basic body must all has been fulfilled for
Point r0In all of "+" basic body, then it is considered that the initiation region of ray is the region；If having in the region
"-" basic body, then "+" basic body all of in the region must all is fulfilled for starting point r0In all of "+" basic body, and
And all of "-" basic body must all is fulfilled for the starting point r not comprising this ray0, then the initiation region for thinking ray is the area
Domain.
(2) every terminal r of linepThe determination of region Ipend：
If likewise, not having "-" basic body in certain region, then in the region, all of "+" basic body is all necessary
Meet terminal rpIn all of "+" basic body, then it is considered that the termination area of ray is the region；If the region
In have "-" basic body, then "+" basic body all of in the region must all is fulfilled for terminal rpPositioned at all of "+" basic body
In, and all of "-" basic body must all is fulfilled for the terminal r not comprising this rayp, then the termination area for thinking ray is
The region.
(3) every starting point r of line0Determination of the corresponding regional export in region number apart from Zo：
If there is no "-" basic body in gamma-rays initiation region number, the basic body conveying end of "+" all of in initiation region 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
Own the basic body conveying end of "+" in beginning region minimum in Do, then own "-" basic bodies and take import in Di most
Small, the maximum for taking both is the outlet distance of the gamma-rays initiation region.
(4) determination of the numbering IP in each region that ray passes through：
Terminal is not under outermost areas case, if not having "-" basic body in regional number, adjacent subarea domain is carried out first
Judgement, for all of "+" basic body, basic body import distance less than or equal to region import distance and less than basic body
Outlet apart from when (Di<=Zin<Do), the region is the adjacent area in a upper region, obtains corresponding zone number IP；
If there is "-" basic body in gamma-rays regional number, for all of "+" basic body, basic body import distance is less than or equal to region
Import distance and less than basic body outlet distance (Di<=Zin<Do), and to all "-" basic bodies, basic body import
Distance is more than zone inlet distance or basic body outlet distance less than or equal to zone inlet distance (Di>Zin or Do<=Zin)
When, the region is the adjacent area in a upper region, obtains corresponding zone number IP.
(5) import in each region that ray passes through is apart from Zi and exports the determination apart from Zo：
If not having "-" basic body in the above-mentioned adjacent area obtained, the regional export distance is the basic body of all "+"
Outlet minimum in Do, the import distance in the region is the outlet distance in a upper region；If the above-mentioned adjacent region obtained
There is "-" basic body in domain, first obtain the basic body conveying end of all "+" reckling in Do, obtaining the basic of all "-"
Body import reckling in Di, the maximum for then taking both is the outlet distance in the region, and the import distance in the region is
It is the outlet distance in a upper region.
(6) terminal finds all of basic body numbering aa of outermost layer under outermost areas case, first, for region
Middle "+" basic body includes basic body aa, when "-" basic body does not include the region of basic body aa, looks for whether there is ray process
In region "-" import of basic body distance more than region import distance (Di (k, minus (i, m))>Zi (k, n)) "-" base
Body, if it does, regional export distance takes all "-" basic body import recklings in Di, if it does not, region goes out
Mouth distance is ray length.
Trace into rpPut region IPend and radiation exit is apart from termination when being equal to ray length.So as to obtain γ
Ray walks distance.
The number of times of ray crossing area and the calculating for walking distance every time are carried out again：
If the crossing area numbering of ray is not 0, then the gamma-ray distance of walking in the region is equal to zone inlet distance
Cut regional export distance, gamma-rays is walked number of times and plus 1；If gamma-ray crossing area numbering is 0, stop tracking.
γ section μ are obtained using the material of γ mass attentuation coefficients and Region Mediumn；
Process is walked during by above-mentioned record gamma-rays by region, the optical distance in each region is obtained respectively then
Sue for peace again, i.e.,：Wherein, N represents the quantity of radiation areas, and the quantity is main
Determined by factory building internal environment.
In one preferred embodiment, using the over-determined systems in Least Square in Processing step 2, and obtain
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, with the triangle decomposition method solution normal equation of symmetrical matrix, remembers G=ATA, wherein, G is symmetrical matrix；
Sub-step 3-4, G=LDL is solved using triangle decomposition methodT, wherein L is small triangular matrix, and D is diagonal matrix；
Sub-step 3-5, solves lower triangular matrix equation group:LY1=ATb；
Sub-step 3-6, solves diagonal matrix equation group：DY2=Y1；
Sub-step 3-7, solves upper triangular matrix equation group：LTX=Y2。
Wherein, X=(ATA)-1ATB and Sj,0=(ai,j T·ai,j)-1·ai,j T·DiIt is corresponding, by 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 area
Overdetermined equation calculation method.
In one preferred embodiment, in step 5, linear fit is carried out by following formula (six),
(6)
Wherein,Represent the close rate estimated；The slope estimated is represented, The intercept estimated is represented,
N represents the maximum that detector number i can reach,Close rate is flat at the detector position that expression is calculated
Average,Represent the average value of the close rate that detector is detected.
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 by weighting function acquisition weight matrix W, it is described
Weight matrix W is obtained by following formula (seven),
(7)
Wherein, f represents fitting uncertainty,fiRepresent that the fitting of i-th detector position is not true
Fixed degree；Average fit uncertainty is represented, Represent 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 SiDuring ＞ 0, and quality factor M reaches maximum, that is, work as Si＞ 0, and quality factor M stop when reaching maximum plus
Power iteration, and output radiation source strength information, the radiation source intensity information is exactly the desired radiation source intensity for finally giving,
It is closest to the radiation source intensity of actual value.
It is an object of the invention to obtain the radiation source intensity closest to actual value, and the radiation source intensity that step 3 is obtained
Reliability ratio it is relatively low, its error between actual value can be than larger, so the accuracy in order to improve the numerical value, that is, obtain
Closest to the radiation source intensity of actual value, the weighted iteration process of step 4 to step 6 is given in the present invention, and finally set
Determine the condition of iteration ends, workload has been reduced as far as possible with the case of ensureing that result is accurate, shortened the activity duration, improve number
According to the efficiency for obtaining.According to above-mentioned the Weighted Iterative Methods and the criterion of iteration ends.In addition, the radiation obtained in the present invention
Source strength than Sources term analysis method obtain radiation source intensity it is more accurate, more press close to actual value, ensure that acquisition value with
Actual value is within an order of magnitude.In one preferred embodiment, one is all correspondingly made available when performing step 6 every time
Individual quality factor M, the quality factor M are obtained by following formula (eight),
(8)
Wherein, R2Represent the goodness of fit,
In one preferred embodiment, over-determined systemsMatrix form see below formula (nine)
(9)
Wherein, ε represents the error that each detector is introduced；Consider physics meaning, actually cause at each sensing point
Error may be considered what radiation source caused, then above-mentioned equation simplification is following formula (ten),
(10),
Wherein S*Expression considers the radiation source intensity of error, and then it can be found that, coefficient matrix ai,jIt is equivalent to j-th
Radiation source is discrete in space coordinates (A, B, C) by radiation source for line source to i-th dose response coefficient of detector, that
Discrete point source is to the response coefficient of detector
Above-mentioned equation group is changed into after discrete
ForAcquisition, with radiation source S* 1As a example by, radiation source is discrete on the one-dimensional coordinate of space, thenCan
Obtained by following formula (11),
(11)
Wherein,
I.e.
Wherein, XLCoordinate after expression is discrete；Cosine constant is represented, the numerical value can artificially be input into, and default value is 0；L
Represent discrete number, will line source be divided into the number that several pieces be divided into during discrete calculation.
According to a kind of nuclear power plant's ray radiation source strength backstepping system that the present invention is provided, the system is used to perform the present invention
Nuclear power plant's ray radiation source strength backstepping method described in text.
Preferably, the system includes detector, gamma rays average energy computing module and radiation source intensity computing module；
The detector has multiple, including precalculated position detector and nuclear power plant's radiation value monitoring detector,
The precalculated position detector is arranged in nuclear power plant radiation areas the pre-determined bit that distance determines and radiation source between
Put, and dismountable screen layer is optionally coated with outside the precalculated position detector；The precalculated position distance radiation
The distance in source can occur in follow-up calculating as known quantity；
The precalculated position detector is used for the radiation dose rate information transmission that will detect to gamma rays average energy
Computing module, is used to calculate gamma rays average energy；
Nuclear power plant's radiation value monitoring detector is distributed in the radiation areas of nuclear power plant, respectively the institute in the present invention
The key position stated, for the nuclear power plant's middle dosage rate information transmission that will separately detect 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 used to calculate radiation source intensity in nuclear power plant.
Experimental example：
Using NB281 rooms in No. 1 unit nuclear island of Daya Bay nuclear power plant as experimental subjects, the room is in nuclear island control zone
For placing the place equipped with radioactive wastewater collecting vessel, wastewater collection bucket inner radiation liquid source strength is 0.7586E+
10MeV/cm3.s (or 4.2898E+14/s).Wastewater collection bucket is reduced to 4 vertical line sources, in wastewater collection bucket
Between part every 50cm, one detector is set, totally five detectors, the probe value that each detector is obtained is 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 provided according to the present invention obtain average energy for 1.3MeV, using the present invention
The source strength backstepping method and system of offer, the four point source source strengths for respectively obtaining are respectively
1.4836E+12MeV/ (cm.s) (or 1.1869E+14MeV/s),
1.0739E+12MeV/ (cm.s) (or 0.8591E+14MeV/s),
1.2566E+12MeV/ (cm.s) (or 1.0053E+14MeV/s),
1.2635E+12MeV/ (cm.s) (or 1.0108E+14MeV/s).
Knowable to final result, the radiation intensity sum of four line sources for obtaining is true with the radiation intensity of the radiation source
Value is basically identical, it is possible to illustrate that the method and system of present invention offer are obtained in that the radiation source intensity letter of actual value
Breath.
Above in association with preferred embodiment the present invention is described, but these implementation methods are only exemplary
, only play illustrative effect.On this basis, various replacements and improvement can be carried out to the present invention, these each fall within this
In the protection domain of invention.
Claims (10)
1. a kind of nuclear power plant's ray radiation source strength backstepping method, it is characterised in that the method comprises the following steps：
Step one, the close rate D in nuclear power plant is detected with detector1,D2,D3…Di；
Step 2, according to the close rate information for detecting, sets up the overdetermination side containing radiation source intensity as shown in following formula ()
Journey group,
(1)
Wherein, the coefficient matrix a of the over-determined systemsi,jObtained by following formula (two) and (three),
(2)
(3)；
Step 3, by the over-determined systems in Least Square in Processing step 2, obtains the radiation source intensity as shown in following formula (four)
Degree information,
Sj,0=(aj,i·ai,j)-1·aj,i·Di(4)；
Wherein, DiRepresent the close rate that i-th detector detection is obtained；J represents the number of radiation source；M represents radiation source number energy
The maximum for reaching；SjRepresent j-th intensity of radiation source；Sj,0Represent j-th radiation source that initial calculation is not iterated
Intensity；ai,jExpression coefficient matrix is j-th radiation source to i-th dose response coefficient of detector；Represent line source from
Dissipate coefficient；LjRepresent j-th discrete number of radiation source；Represent the discrete source strength of normalization；BD(E,L(μ(E),r0→rp)
Buildup factor is represented, is E and L (μ (E), r0→rp) function；L(μ(E),r0→rp) optical distance is represented, it is μ (E) and r0→
rpFunction；μ (E) represents section/linear attenuation coefficient；r0→rpRepresent radiation source to the distance of sensing point；C (E) represents logical
Amount-dose conversion factor, is the function of E；E represents energy, is the average energy of the gamma rays that radiation source sends in nuclear power plant.
2. nuclear power plant's ray radiation source strength backstepping method according to claim 1, it is characterised in that after step 3,
Methods described also comprises the following steps,
Step 4, according to the close rate at the radiation source intensity information calculating detector position obtained in step 3, D '1,D′2,
D′3…D′i；
Close rate information at step 5, the close rate information detected to detector and the detector position being calculated is carried out
Linear fit, the linear equation of the both sides relation after being fitted, and then fitting parameter is obtained, the fitting parameter includes：It is flat
Equal uncertainty, the goodness of fit and corresponding weight matrix；
Step 6, the over-determined systems in weight matrix iteration to the step 2 that will be obtained in step 5, the overdetermination for being weighted
Equation, and then repeat step two, step 3 and step 4, until obtaining desired radiation source intensity information；
Wherein, D 'iThe close rate at i-th detector position that expression is calculated.
3. nuclear power plant's ray radiation source strength backstepping method according to claim 1, it is characterised in that for the nuclear power plant
The average energy E of the gamma rays that middle radiation source sends, its measuring method includes following sub-step：
Sub-step 1, chooses precalculated position inside nuclear power plant, and the precalculated position is t apart from the distance of radiation source, in the pre-determined bit
Placement location detector, collects the close rate I that the detector is detected0,
Sub-step 2, fetches the detector, and the precalculated position is placed on after screen layer is coated outside it, collects the spy
Survey the close rate I that device is detected；
Or, the detector is fetched, shield is placed in precalculated position, then the detector is placed in shield, receive
Collect the close rate I that the detector is detected；
Sub-step 3, according to I and I that sub-step 1 and step 2 are obtained0, the quality of clad or shield is calculated by following formula (five)
Attenuation coefficient mu,
I/I0=BDe-μt(5)
Sub-step 4, according to the result of calculation of sub-step 3, obtains the average energy E of the gamma rays that radiation source sends.
4. nuclear power plant's ray radiation source strength backstepping method according to claim 1, it is characterised in that calculate the optics away from
Method from L includes following sub-step,
Sub-step a, tracking gamma ray walks process from discrete radiation source to sensing point, and record gamma ray passes through radiation
The order in region,
Sub-step b, calculates the distance of each radiation areas respectively, with reference to the linear taper coefficient of each radiation areas material, most
Total optical distance L is obtained afterwards.
5. nuclear power plant's ray radiation source strength backstepping method according to claim 1, it is characterised in that use least square method
Over-determined systems in process step two, and obtain radiation source intensity information process include 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, with the triangle decomposition method solution normal equation of symmetrical matrix, remembers G=ATA, wherein, G is symmetrical matrix；
Sub-step 3-4, G=LDL is solved using triangle decomposition methodT, wherein L is small triangular matrix, and D is diagonal matrix；
Sub-step 3-5, solves lower triangular matrix equation group:LY1=ATb；
Sub-step 3-6, solves diagonal matrix equation group：DY2=Y1；
Sub-step 3-7, solves upper triangular matrix equation group：LTX=Y2。
6. nuclear power plant's ray radiation source strength backstepping method according to claim 2, it is characterised in that in step 5, leads to
Crossing following formula (six) carries out linear fit,
(6)
Wherein,Represent the close rate estimated；The slope estimated is represented,
The intercept estimated is represented,
N represents the maximum that detector number i can reach,The average value of close rate at the detector position that expression is calculated,Represent the average value of the close rate that detector is detected.
7. nuclear power plant's ray radiation source strength backstepping method according to claim 6, it is characterised in that in step 5, root
Weighting function is obtained according to uncertainty, then weight matrix W, the weight matrix W are obtained by following formula (seven) by weighting function
Obtain,
(7)
Wherein, f represents fitting uncertainty, Average fit uncertainty is represented,fiRepresent i-th fitting uncertainty of detector position；Represent power
Weight function.
8. nuclear power plant's ray radiation source strength backstepping method according to claim 6, it is characterised in that
In step 6, work as Si＞ 0, and quality factor M stops weighted iteration when reaching maximum, and output radiation source strength is believed
Breath, the radiation source intensity information for now exporting is the desired radiation source intensity information；
Wherein, quality factor a M, the quality factor M are all correspondingly made available when performing step 6 every time and pass through following formula (eight)
Obtain,
(8)
Wherein, R2Represent the goodness of fit,
9. a kind of nuclear power plant's ray radiation source strength backstepping system, it is characterised in that the system is used for described in perform claim requirement 1-8
Nuclear power plant's ray radiation source strength backstepping method.
10. nuclear power plant's ray radiation source strength backstepping system according to claim 9, it is characterised in that the system includes visiting
Survey device, gamma rays average energy computing module and radiation source intensity computing module；
The detector has multiple, including precalculated position detector and nuclear power plant's radiation value monitoring detector,
The precalculated position detector is arranged in nuclear power plant radiation areas the precalculated position that distance determines and radiation source between, and
Dismountable screen layer is optionally coated with outside the precalculated position detector；
Radiation dose rate information transmission to the gamma rays average energy that the precalculated position detector is used to detect is calculated
Module,
Nuclear power plant's radiation value monitoring detector is distributed in the radiation areas of nuclear power plant, for the nuclear power that will be separately detected
Factory's middle dosage rate information transmission 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 used to calculate radiation source intensity in nuclear power plant.
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