JP2661362B2 - Judgment method of radioactive contamination and measurement method of radiation counting rate - Google Patents

Description

[Detailed Description of the Invention] [Industrial application field] In the present invention, the presence or absence of contamination by a radioactive substance (hereinafter, this substance may be referred to as radioactivity) of an object to be determined is emitted from the object to be determined. Method for determining radioactive contamination based on the counting rate of radiation and method for measuring the counting rate of radiation used for measuring the counting rate of radiation emitted from the object to be measured, particularly the time required for determining the presence or absence of radioactive contamination ( Since then
This time may be referred to as a determination time. ) And a time required to obtain a count rate measurement value of a predetermined accuracy (hereinafter, this time may be referred to as a measurement time).

[Conventional technology]

Conventionally, when determining whether or not an object to be determined is contaminated by a radioactive material, that is, when determining whether or not the object is contaminated by radioactivity, the radiation emitted from the object is usually determined by the presence of background radiation. Time under
counted between t ₀ of a given measurement time T, the resulting radiation counts K _g a count rate measurements of the background radiation from the radiation counting rate measurements N _g obtained by dividing the time T N _b
The presence or absence of contamination is determined based on whether the count rate N obtained by subtracting the above, that is, the count rate measurement value N of the net radiation as the radiation emitted from the determination target is equal to or greater than _a predetermined secondary determination reference count rate Na. That is being done. In other words, the count value _Kg and the count rate measured value
N _g and N are functions K of the elapsed time t from time t _{0.
g (t), N g (} t), N from a (t), K the time has elapsed time T from the time t ₀ at t _1, the time _{t 1 g (t), N} g
The values of (t) and N (t) are defined as K _g (t ₁ ), N _g (t ₁ ) and N (t ₁ ), and conventionally, N (t ₁ ) is obtained by equation (25) to obtain (26) )
If the equation holds, it is determined that there is contamination, and if the equation (27) holds, it is determined that there is no contamination.

N (t ₁ ) = N _g (t ₁ −N _b = K _g (t ₁ / T−N _b ) (25) N (t ₁ ) Na (26) N (t ₁ ) <N _a ... ... (27) then, in this case, the N _b used in (25), the count value of the background radiation obtained by counting previously during the measuring time T _b which sets the background radiation as appropriate the K _b is the count rate measurements obtained by dividing the time T _b.

However, the count rate measurement value N obtained as described above
(T ₁ ) includes an error based on the statistical variation A of the count value K _g (t ₁ ) used for calculating N _g (t ₁ ), and a statistical value of the count value K _b used for calculating N _b. An error based on the fluctuation B and an error based on a cause other than the fluctuations A and B, for example, an inaccuracy of a measuring device for measuring K _g (t ₁ ) and K _b are included. count rate N _s probability (t ₁₎ is present P becomes a normal distribution probability P becomes the maximum in the count rate measurements N (t _1), the standard deviation σ of the normal distribution, the above statistical variation a
If the standard deviation of the variation of the measured value N (t ₁ ) based on causes other than B and B is E ₀ , it is known that Equation (28) is obtained with reference to Equation (25). When N (t ₁ ) is obtained in this manner, the true count rate N _s (t ₁ ) exists within the range of the count rate value shown by the equation (29) by appropriately setting the magnification S for σ. Will be.

σ = ｛N _g (t ₁ ) / T + N _b / T _b + E _o ² ｝ ^1/2 = [｛N (t ₁ ) + N _b ｝ / T + N _b / T _b + E _o ² ] ^1/2 …… (28 N (t ₁ ) −SσN _s (t ₁ ) N (t ₁ ) + Sσ (29) By the way, in general, when determining the presence or absence of radioactive contamination, the true count rate N _s (t ₁ ) the must determine that there is always pollution After becoming the primary criterion counting rate N _at greater than or equal to a decided in the law is the principle of judgment. Therefore,
The maximum value that may occur count rate _{N s (t 1) {N} (t 1)
As + Sσ} is N _at equal Such N (t ₁₎ a first count rate N _a1, set equal to N _a1 to satisfy the above-mentioned secondary criterion counting rate N _a (30) formula Then, in this case, N (t ₁₎ to N (t ₁₎ satisfies the equation (26) in the state of _{N a1 N s (t 1)} N at enabling made of is always (2
6) If the equation is satisfied, it is immediately determined that there is contamination.
It may be called a conventional determination method. ) Is capable of being methods with the principles of the determination, is (30) the value of σ described above appearing in the actual contamination determination be determined N _a1 by formula, accurate measurement of E ₀ Because it is not possible, or because E ₀ differs for each count value measuring device, it does not always match the value of σ used when determining _{Na 1,} and therefore, in the first conventional determination method described above, , E ₀ , T, etc. and σ are appropriately assumed to obtain the equation (30) or (28)
After having calculated the N _a1 from the equation, N _s (t ₁₎ to look at the room in order to N erroneously determined that a is even though no contamination _at the determination is to prevent the occurrence to satisfy the N _a1 N _a to set the N _a is performed.

N _a1 + S ｛(N _a1 + N _b ) / T + N _b / T _b + E _o ² ｝ ^1/2 = N _at ... (30) In the first conventional determination method, _Na is set as described above. as there is now, N _s minimum that may occur _{(t 1) {N (t} 1) -Sσ} is equal to zero such N (t ₁₎ a second count rate N _a2, N _{If a} is set to be equal to N _a2 that satisfies the expression (31), in this case, there is always a possibility that N _s (t ₁ <0) when N (t ₁ ) <N _a2. such would not be a N (t ₁₎ significant measure. Therefore, after all, in the first prior art determination methods described above have been set so as to satisfy the N _a is (32), of course,
In this case, N _a2 is calculated using E ₀ , T, etc. used for determination of N _a1 and the assumed value of σ.

N _a2 −S · ｛(N _a2 + N _b ) / T + N _b / T _b + E ₀ ² ｝ ^1/2 = 0 (31) N _a1 N _Na N _a2 ... (32) The first conventional determination method described above. Is a method for determining the presence or absence of radioactive contamination based on the average count rate N (t ₁ ) during the measurement time T. Conventionally, apart from this first conventional determination method, the first conventional determination method First, E ₀ ,
T, T _b: a first procedure for obtaining the N _a after determining the and N _b, by using the T and N _b and N _a determined in the first procedure (33) left side criterion meter performs an operation of The second procedure for _{obtaining the} numerical value K _ga and the time t
_A third procedure of measuring the count value K _g (t) of the total radiation as described above in the presence of background radiation after ₀ ,
_g (t) = K _ga There contamination stop the measurement of K _g (t) When satisfied with the determined fourth steps and the determination method of radioactive contamination consisting (hereinafter, it the judgment method of the second conventional determination method Is also used to determine the presence or absence of radioactive contamination.

(N _a + N _b ) · T = K _ga (33) By the way, the measurement error D with the standard deviation of σ shown in the equation (28) is used as the count rate measurement value N (t ₁ ) of the net radiation. It is apparent from the equation (28) that the measurement error D decreases as the measurement time T increases. That is,
The error D of N (t ₁ ) depends on T. However, in this case, since σ also depends on N (t ₁ ) and E ₀ , it is impossible to estimate D in advance even if T is assumed.
Therefore, conventionally, E ₀ , T _b , and N _b are first determined in the same manner as in the first and second determination methods described above, and σ and N _b are further determined.
By assuming (t ₁ ), the time T is obtained from the equation (28), and thereafter, during the time T from the time t ₀ to t ₁ , all the radiations are counted to obtain the count value K _g (t ₁ ). By equation (25)
The radiation count rate N is measured by a radiation count rate measurement method of obtaining a measured value of (t ₁ ). Hereinafter, this measuring method may be referred to as a conventional measuring method.

[Problems to be solved by the invention]

In the first conventional determination method described above, as described above,
E _0, so that to determine the N _a by appropriately assuming T like or sigma perform contamination determination by comparing the N _a and N (t ₁ 9, but further, in this method, sigma _Is assumed to be E _s1 in advance, even when the maximum value N _max of N (t ₁ ) expected to appear in the actual contamination determination work is N
(28) In order to ensure that (t ₁ ) and σ that changes according to T are equal to E _s1 and the accuracy of contamination determination is ensured, (28)
_{Σ = E s1, N (t} 1) = the value of N _max as obtained T T ₁ or more are counted between radiation time T ₁₀ and so as to measure the N (t ₁₎ in the formula. Therefore, such a time T
_The contamination determination method for counting for ₁₀ may be such that, in the normal case where N (t ₁ ) <N _max , even if the time for measuring the count rate N is shorter than T, it becomes σE _s1 (28 ), There is a problem that it takes too much time to perform the contamination determination performed under the condition of σE _s1 .

Then, again, in the above-mentioned first conventional determination method, T
If you decide to N _a previously assuming a standard deviation of yielding upon actual contamination determination N (t ₁₎ σ is (N _at -N _a) Sσ
Must be satisfied, the limit value of σ in this relational expression must be σE _s2 where E _s2 is a limit value. On the other hand, the relation of equation (28) is defined between σ and T. Therefore, in order for σE _{s2 to} be satisfied even when N (t ₁ ) = N _max , the above-described first conventional determination method in which T _a is determined to determine Na is further provided by ( in 28) _{σ = E s2, N (t} 1) = N is obtained as a _max, previously different from the assumed T, by counting the radiation between the values T ₂ or more time T ₂₀ of the T N (t ₁ ) Try to measure. Thus, even contamination determination method of performing counting during such time _{T 20, N (t 1)} < if normal is N _max, that takes too long to contamination determination performed under the conditions of? En _s2 There is a problem.

Then, In the second conventional determination method I described above, if the counting rate N of the net radiation appearing in the determination actual contamination is greater than N _a determined in the first procedure of this determination method, the measurement time T contamination determination work in less time than it is clear that ended, if N is smaller than N _a K _g (t) is K
Since it takes longer than T to reach _ga , the second
N is disadvantageously takes a long time to contamination determination if N _a smaller even in the conventional determination method.

Further, in the case of the above-described conventional counting rate measuring method, N (t ₁ ) in Expression (28) becomes the maximum counting rate _Nmax expected to appear in the actual counting rate measurement. Since T is determined by assuming N (t ₁ ) and σ so that a predetermined σ can be obtained even at the time, radiation is counted during time T to obtain K _g (t ₁ ), and N When (t ₁ ) is calculated, assuming that the calculated N (t ₁ ) is smaller than the previously assumed N _max , at this time, the calculated σ of N (t ₁ ) is larger than the previously assumed σ. It is clear from the equation (28) that the value becomes smaller. Therefore, in this case, if the calculated σ of N (t ₁ ) can be the same as the assumed σ, that is, the calculated N
It is assumed that the measurement error of (t ₁ ) is N in determining T.
Assuming that the measurement error can be the same as (t ₁ ), it is clear from equation (28) that the measurement time T can be shorter. Therefore, the conventional measuring method described above has a problem that the counting rate measurement may take too much time if it is sufficient to always obtain a predetermined measuring accuracy.

An object of the present invention is not to measure the count value K _g (t) during a predetermined measurement time T ₁₀ or T ₂₀ and obtain N (t ₁ ) to judge contamination, but also to determine K _g. (t) is not to determine that there is contamination when it reaches the predetermined value K _ga, it was measured thereafter the measured count value K _g as counted starting time (t) of t ₀
Count rate N (t) obtained from K _g (t) = ｛K _g (t) / t−
When N _bに reaches an upper limit or a lower limit that changes with time, a contamination judgment is performed, and the first and second contaminations described above are performed.
An object of the present invention is to obtain a contamination determination result in a shorter determination time than in the conventional determination method.

Thus, the object of the present invention is not to measure the count value K _g (t ₁ ) during a predetermined measurement time T to obtain N (t ₁ ), but to calculate the N (t). This N
(T) standard deviation E (t) or relative error R (t) = E
(T) / N seek (t), these E or R predetermined deviation reference value E _a, relative error reference value N (t) the final count rate measured at this time when it reaches the R _a, respectively In order to obtain a count rate measurement result with a predetermined accuracy in a shorter measurement time than in the above-described conventional measurement method, it is an object of the present invention to provide a count value.

[Means for solving the problem]

To achieve the above object, according to the present invention, 1) the background radiation and the object to be judged from the elapsed time t from the time t ₀ of the total radiation which is defined as the sum of the net radiation as the radiation emitted the count rate measurements as a function N _g (t) count rate measurements as a function of said t of the net radiation obtained by subtracting the count rate measured value N _b of the background radiation from N (t), the Each statistical variation of the count K _g (t) of the total radiation used to calculate N _g (t) as a function of the t and the count K _b of the background radiation used to calculate the N _b Standard deviation E _{0 of} variation based on factors other than the above, magnification S, measurement time T and
And sets the T _b, by measuring the K _b between the T _b
Using a first procedure for obtaining the K _b / T _b = N _b as the N _b, it was determined as the primary criterion count rate N _at given in the first procedure E _0, S, and T _b and N _b A second procedure for _obtaining N _h1 (t) and N ₁ (t), which are functions of t, respectively, from equation (1); Starts the measurement of the count value K _g (t) from the time t _0, the K _g each time a predetermined time elapses τ from the t ₀
Wherein the measured value K _g of (t) (iτ) by using the N _b (2) by performing the calculation of the most left-side expression to calculate the N (t) and the t ₀
T ₁ and time (t ₀ + iτ) defined by the sum of
A third procedure for monitoring whether or not the relationship of equation (3) holds between The time (t ₀ + i) at which the relationship of the above equation (3) does not hold yet.
wherein the tau) = t ₂ in the t ₂ N _h1 (t) and the respective values of _{N 1 (t) N h1 (} t 2) and _{N 1} (t ₂₎ and the in the t ₂ N of (t) Between the value N (t ₂ ) and (4)
As soon as the relationship of the formula or the formula (5) is established, at least the calculation of the N (t) is stopped. If the formula (4) is satisfied, it is determined that there is contamination, and the formula (5) is determined. A fourth procedure for determining that there is no contamination if the condition holds, and N (t ₂ ) N _h1 (t ₂ ) (4) N (t ₂ ) <N ₁ (t ₂ ) (5) As soon as time elapses without the relations of the equations (4) and (5) being established and the relation of the equation (3) is established, at least the calculation calculation of the N (t) is stopped and it is determined that there is contamination. A radiological contamination determination method is configured to determine the presence or absence of radioactive contamination in the object to be determined by the determination processing in the fourth and fifth procedures. Net radiation as ground radiation and radiation emitted from the target The net obtained by subtracting the count rate measured value N _b of the background radiation from the elapsed time count rate measurements as a function of t N _g (t) from the time t ₀ of the total radiation which is defined as the sum of the the count rate measurements as a function of said t radiation N (t), the N _g the used to calculate the (t) counts as a function of said t of the total radiation K _g (t) and the N _b and the background count K _b standard deviation E ₀ variations based on factors other than the statistical variation of the radiation used for calculation of the magnification S, measurement time T and
And sets the T _b, by measuring the K _b between the T _b
A first procedure for obtaining the K _b / T _b = N _b as the N _b, was determined by the primary criterion count rate N _at which said given first procedure E _0, S, T, and T _b and N _b Using Equation (6), the first
It determined the counting rate N _a1 and a second count rate N _a2, a second to determine a secondary criterion count rate N _a which satisfies thereafter (7) Relationship
Instructions, N _a1 N _a N _a2 (7) E ₀ , S, T _b , N _b and N _a determined in the first and second procedures
From equation (8), N _h2
A third procedure for determining (t) and N _l2 (t); Starts the measurement of the count value K _g (t) from the time t _0, the K _g each time a predetermined time elapses τ from the t ₀
Wherein the measured value K _g of (t) (iτ) by using the N _b (2) by performing the calculation of the most left-side expression to calculate the N (t) and the t ₀
T ₁ and time (t ₀ + iτ) defined by the sum of
And a fourth procedure for monitoring whether or not the relationship of equation (3) holds, and K _g (iτ) / iτ−N _b = N _g (iτ) −N _b = N (iτ) = N
(T) ...... (2) where, i = 1,2,3, ...... (t 0 + iτ) t 1 ...... (3) above (3) the relationship of expression is not yet established time (t ₀ + i
τ) = t ₃ , the values of N _h2 (t) and N _l2 (t) at this t _3, N _h2 (t ₃ ) and N _l2 (t ₃ ), and N (t) at t ₃ When the relationship of the expression (9) or the expression (10) is established with the value N (t ₃ ), at least the calculation of the N (t) is immediately stopped, and the expression (9) is satisfied. A fifth procedure for determining that there is contamination and determining that there is no contamination when the equation (10) is satisfied; and N (t ₃ ) N _h2 (t ₃ )... (9) N (t ₃ ) <N _l2 (t ₃ ) (10) At time (t ₀ + iτ) = t ₄ , time elapses without the relation of the above equations (9) and (10) being established, and the above equation (3) As soon as the relationship is established, at least N
(T) stops the calculation operations, when the (11) equation relationship between the values N and (t ₄₎ and the N _a of the N (t) in the t ₄ are satisfied pollution The sixth procedure for determining that there is contamination and determining that there is no contamination when the relationship of equation (12) holds, and N (t ₄ ) N _a ... (11) N (t ₄ ) <N _a. 12) a radiological contamination determination method configured to determine the presence or absence of radioactive contamination in the determination target by the determination processing in the fifth and sixth procedures; and 3) the background radiation Counting the background radiation from the count rate measurement N _g (t) as a function of the time t elapsed from time t _{0 of the} total radiation defined as the sum of the net radiation as the radiation emitted from the object to be determined measuring count rate as a function of said t of the net radiation obtained by subtracting the rate measurements N _b The value N of (t), a total of the background radiation is used for the calculation of the N _g the used to calculate the (t) counts as a function of said t of the total radiation K _g (t) and the N _b The standard deviation E _{0 of the} variation based on the cause other than each statistical variation of the numerical value K _b, the magnification S, the upper limit count rate N _ah and (1
3) sets the lower limit counting rate N _al and measurement time T _b which satisfy the relationship of expression, by measuring the K _b between the T _b K _b / T _b
= With a first procedure as N _b obtains the _{N b, N ah> N al} 0 ...... (13) wherein E ₀ determined by the first _{procedure, S, T b, N b} , the N _ah and N _al From equation (14), N is a function of t
_hl and a second procedure for obtaining the N _lh (t) and _{(t), N hl (t} ) + S · _{[{N hl (t) + N} b} / t + N b / T b +
E ₀ ² ] ^1/2 = N _ah Starts the measurement of the count value K _g (t) from the time t _0, the K _g each time a predetermined time elapses τ from the t ₀
Wherein the measured value K _g of (t) (Aitau) by using the N _b (2) expression by performing a calculation top left side of calculating the N (t) and the calculated N (t) is (15) A third procedure for monitoring which of formulas (16) and (17) is satisfied; N (t) N _lh (t) (15) N (t) = (N _ah + N _al ) / 2 (16) N (t) N _hl (t) (17) Time (t ₀ ) + iτ) = t in the above ₅ (15), (16) and (both 17) one of formula stops calculating operation immediately least the N (t) When satisfied, the in the t ₅ N _lh (t) and the N values N _lh of _hl (t) (t ₅₎ and N _hl (t ₅₎ and said _{(N ah + N al) /} 2 to the value N of the N (t) in the t ₅ (t ₅₎ If the relationship of equation (18) is established, it is determined that there is contamination. If the relationship of equation (20) is established, it is determined that there is no contamination, and (1)
If the relationship of the expression 9) is established, the fourth procedure with the predetermined judgment content and N (t ₅ ) N _lh (t ₅ ) (18) N (t ₅ ) = (N _ah + N _al ) / 2 (19) N (t ₅ ) N _hl (t ₅ ) (20), and the presence or absence of radioactive contamination in the determination object is determined by the determination processing in the fourth procedure. And 4) the elapsed time t from the time t _{0 of} all radiation defined as the sum of the background radiation and the net radiation as radiation radiated from the object to be determined. the count rate measurements as a function of N _g (t) count rate measurements as a function of said t of the net radiation obtained by subtracting the count rate measured value N _b of the background radiation from N (t), wherein N _g (t) counts K _g as the function of the t of all the radiation used for the calculation of (t) and A serial N _b standard deviation E ₀ variations based on factors other than the statistical variation of the count value K _b of the background radiation is used for the calculation of the deviation reference value E _a or relative error reference value R _a, measured Time _Tb, and _Tb
A first process for obtaining the N _b as K _b / T _b = N _b by measuring the K _b between the measurement of the count value K _g (t) and starts from the time t _0, the Every time a predetermined time τ elapses from t _{0, the} K _g
Using measurements of (t) K _g and (iτ) and the N _b (2) formula to calculate the N (t) by performing the calculation top left side of the the calculated N (t) and E ₀ , T _b and
By using the N _b (21) the standard deviation E (t) as a function of said t the total measurement error in the N (t) from the equation
When the _Ra is set in the first procedure, the relative error R as a function of the t, which is defined as a ratio of the E (t) to the N (t) after the E (t) is obtained. (T) is obtained from the equation (22), and when the _Ra is not set in the first procedure, the E (t) obtained from the equation (21) and the first
Whether (23) the relationship between the E _a determined in step is established and monitored, the case of setting the R _a in the first procedure was determined from the equation (22) R (t ) And the Ra determined in the first step, _a second step of monitoring whether the relationship of equation (24) holds, E (t) = _{[{N (t) + N b} } / t + N b / T b + E 0 2 ] ^1/2
…(twenty one) E (t) E _a (23) R (t) R _a (24) At time (t ₀ + iτ) = t ₇ , the above (23) or (2)
4) and a third procedure to hold the value N (t ₇₎ of the N (t) in the t ₇ with stops calculating operation immediately least the N (t) When satisfied, the N (t ₇ ) Is set as the radiation count rate measurement method so that) is the count rate measurement value of the radiation emitted from the measurement object.

[Action]

When configuring the method of determining the radioactive contamination as described above, the time t ₁ in the first prior art determination method has elapsed time T from the time t ₀
Whereas the contamination determination result is obtained immediately after, also the second conventional determination method in contamination determination result after time t ₁ a counting rate N (t) is less than N _a is obtained in, In the case of the method of comparing N (t) with N _h1 (t) and N ₁ (t) according to the present invention, the contamination determination result is obtained immediately after the expression (4) or (5) is satisfied, and the time at this time is obtained. t ₂ is a time earlier than t _1, and (4) primary criterion count rate or (5) is not satisfied immediately after also the time t ₁ to N (t) N
It is clear that a certain contamination judgment result can be obtained regardless of the magnitude of _at .
In the case of the method of comparing (t) with N _h2 (t) and N _l2 (t), as soon as the expression (9) or (10) is satisfied, a contamination determination result is obtained, and the time t ₃ at this time is t a time earlier than _1, also with respect to the secondary criterion counting rate N _a of equation (9) or (10) are not satisfied at time t ₄ immediately after time t ₁ be N (t ₄₎ It is clear that any determined contamination determination result is obtained depending on the magnitude. Then, further, N (t) of the present invention is changed to N _lh (t) and N
_hl case of the method to compare (t), N regardless of whether the magnitude of the (t), over time curve from time t ₀ N _lh (t) and N _hl (t)
Observe and some contamination determination result that is obtained is clear, also appropriately set the upper and lower counting rate N _ah · N _al as described below between reaching the time t ₆ of the intersection of the time curve of the time it is possible to easily set the time earlier than the time t ₆ to time t ₁ by three of the first by any of the methods of the method of measuring the radioactive contamination and second conventional determination method of the present invention described above The contamination determination result can be obtained in a shorter determination time than by any of the methods.

Then, when the method of measuring the radiation count rate is configured as described above, E (t) or R (t) corresponding to the measurement error of N (t), each of which decreases with time, is a predetermined value. E _a or R immediately count rate measurement upon reaching _a is obtained, the elapsed time from the time t ₀ of time t ₇ when the t
Is the normal case where N (t ₁ ) <N _max , σ = E _a , N (t ₁ )
= From the N _max (28) to be a time within the value T _max of the time T obtained from the equation it is apparent from equation (21), therefore, according to the measuring method of the radiation counting rate of the present invention described above When N (t) is smaller than _Nmax, a count rate measurement result with a predetermined accuracy can be obtained in a shorter measurement time than in the conventional measurement method.

[Embodiment] FIG. 1 is a flowchart for explaining the configuration of an embodiment of a method for determining radiation contamination according to the present invention, and FIG. 2 is a method for determining radioactive contamination, the flowchart of which is shown in FIG. It is explanatory drawing of the method of contamination determination in FIG.

In FIGS. 1 and 2, P1 standard deviation E ₀ is that each described above, sets the magnification S, the values of the measurement time T and T _b to the same values as in the first or the second conventional method of determining the above with, in the first procedure to determine the measures the count value K _b background radiation K _b / T _b = N _b as count rate measurements N _b of the background radiation during the time T _b , P2 primary criterion count rate given by laws and regulations N _at a first
Using E ₀ , S, T _b , and N _b determined in the procedure P1, N _h1 (t) and N ₁ (t), which are functions of t, are obtained from Equation (1). There are two procedures.

Then, P3 is, K from time t ₀ to start the measurement of the count value K _g (t) from the time t ₀ every time a predetermined time elapses τ
_Using the measured value K _g (iτ) of _g (t) and N _b determined in step P1, perform the operation on the leftmost side of equation (2) to calculate N (t) as N (iτ) Q1 and N at this stage Q1
The measurement time (t ₀ + iτ) of the measurement value K _g (iτ) used for the calculation of (iτ) and the above-mentioned time when the time T has elapsed from the time t ₀
In the third procedure consisting of working phase Q ₂ Metropolitan performing (3) whether the relationship of Formula exists monitored during the t _1, P4 is (3) relations are still met with no time (t ₀ + Iτ) = t ₂ , N _h1 (t) and N ₁ obtained by procedure P2 at t ₂
(4) or (5) the relationship between the value of (t) N _h1 (t ₂₎ and _{N 1} (t ₂₎ The value of N (t) in the t ₂ N (t ₂₎ Operation stage Q3 for monitoring whether or not
Together at time t ₂ (4) or (5) to stop the calculation of the at least N (Aitau) in immediate work stages Q1 Once established, with t ₂ (4) There are contamination if satisfied with the determination and, at t ₂ (5) a fourth procedure consisting of formulas without contamination if satisfied with the determined working step Q4 Prefecture. Thus, it is in FIG. 2 with t ₂ (4) equation relationship is established is illustrated.

(T ₀ + iτ) t ₁ (3) N (t ₂ ) N _h1 (t ₂ ) (4) N (t ₂ ) <N ₁ (t ₂ ) (5) In FIG. P5 is monitored in the work stage Q3, time passes without any of the relations of the expressions (4) and (5) being established, and finally the work is monitored in the work stage Q2. As soon as the relationship is established, work phase Q1
In the fifth step of stopping the calculation of at least N (iτ) and determining that there is contamination, 1 is composed of the above-described procedures P1 to P5, and the radiation in the determination target is determined by the determination processing in steps P4 and P5. This is a method for determining radioactive contamination in which the presence or absence of radioactive contamination is determined.

In the method 1 for determining radioactive contamination, N _h1 (t) and N ₁ (t)
Is the time function determined as described above,
(T) When N _h1 (t) is _met Count value N
If the true count rate N _s (t) corresponding to (t) is always a value equal to or more than N _at and N (t) <N ₁ (t) holds, N
_s (t) is always less than N _at , and N ₁ (t) N
When (t) <N _h1 (t) holds, N _s (t) becomes N _s (t)
_{<N at, N s (t} ) = N at, N s (t)> N at any of the relationship appears to be unknown or satisfy the, above this end, in the determination method 1, the working step Q4 Although to perform the determination _{process, N 1 (t) N (} t) <N h1 (t)
_Holds when the difference between N (t) and N _at is small (4)
It is clear from FIG. 2 that it takes a long time for the expression or the expression (5) to be satisfied. Therefore, in the determination method 1, if the time elapses without satisfying the expression (4) or the expression (5) and the expression (3) is satisfied, the N at the time (t ₀ + iτ) when the expression (3) is first satisfied is satisfied. _s (iτ) is N _s (iτ)
Even if the value satisfies <N _at , it is unconditionally determined that there is contamination.

That is, in the determination method 1, the contamination determination result is obtained immediately when the expression (4) or the expression (5) is satisfied starting from the time t ₂ = t ₀ + iτ, but the time t ₂ is always a time earlier than the time t _1. It is apparent from the above description that N (t) is always equal to or immediately after time t ₁ even if time elapses without satisfying the expression (4) or (5).
Since the contamination determination is made regardless of the magnitude of N _at , the contamination determination result can be obtained with a determination time of at most T according to the determination method 1 after all. However, as described above, at least requires a T time, also N (t) is smaller than N _a in the second conventional determination method always contaminated determined regardless of the magnitude of N (t) in the first conventional determination method And a determination time longer than T is required. Therefore, it can be said that the determination method 1 is a method in which a determination result can be obtained in a shorter determination time as a whole than any of the first and second conventional determination methods. According to this determination method 1, N
(T) and the shorter determination time determination is a large difference between N _at that is obtained evident from Figure 2, in particular, the state where N (t) << N _at that actually does the contamination determination work Since it is customary, in such a case, according to the present determination method 1, a determination result can be obtained in a very short time.

FIG. 3 is a flowchart for explaining the configuration of an embodiment of a radioactive contamination determination method different from the determination method 1 of the present invention;
FIG. 4 is an explanatory diagram of a method of determining contamination in the method of determining radioactive contamination, the flowchart of which is shown in FIG. 3 and 4, the same reference numerals as those in FIGS. 1 and 2 denote the same amounts or matters as those shown in FIGS. 1 and 2.

Now, in Figure 3 and Figure 4, P6 was determined by the primary criterion counting rate N _at the first procedure P1 given of the aforementioned E
_0, S, T, T case of _b and N _b as the first conventional method using the exactly the same way (61), (62) and (7) the first and second from the formulas of
The second procedure to determine the count rate N _a1, N _a2 and secondary criteria count rate N _a, E ₀ determined by the first and second procedures P1, P6 is _{P7, S, T b, N} b and a third process for obtaining the N _h2 and (t) N _l2 and (t) is a function of t, respectively from equation (8) using N _a, exactly the same working step as are shown in FIG. 1, respectively P8
It is composed of Q1 and Q2.
In a fourth procedure in which (t) is calculated and whether or not the relationship of equation (3) is established, P9 is a time (t ₀ + iτ) = t when the relationship of equation (3) is not yet established. in ₃ determined in Step P7 in the t ₃ N _h2 (t) and N
_l2 (t) values N _h2 (t ₃ ) and N _l2 (t ₃ ) and N at t ₃
A working phase Q5 performing (9) or (10) whether the relationship equation holds monitoring between the (t) value N (t _3), at time t ₃ (9) or (10 ) is stopped at least calculating operation of N (iτ) in immediate working phase Q1 When relationship equation is established, with t ₃ (9) equation is determined that there is contamination if established, with t ₃ (10) a fifth procedure consisting of no pollution if expression is satisfied determines working phase Q ₆ Prefecture. Then, that relationship t ₃ of equation (9) in FIG. 4 is established is illustrated.

N _a1 + S ｛(N _a1 + N _b ) / T + N _b / T + E ₀ ² ｝ ^1/2 = N _at … (61) _{Na 2} + _SＳ (N _a2 + N _b ) / T + N _b / T + E ₀ ² ｝ ^{1 / 2} = 0 ... (62) N _a1 N _a N _a2 ... (7) (T ₀ + iτ) t ₁ (3) N (t ₃ ) N _h2 (t ₃ ) (9) N (t ₃ ) <N _l2 (t ₃ ) (10) In FIG. In P10, time elapses without any of the relations of the expressions (9) and (10) being monitored in the work stage Q5, and finally the work is monitored in the work stage Q2 in the expression (3). If the relationship is established at time (t ₀ + iτ) = t ₄ ,
At least N (iτ) that is immediately performed in work phase Q1
Is stopped, and N (t) at time t ₄ is stopped.
Values N and (t ₄₎ between N _a determined in the second procedure P6 (11)
If the relationship of the formula is established, it is determined that there is contamination (1
2) A sixth procedure for determining that there is no contamination when the relationship of the equation is established. The second procedure is composed of the illustrated procedure P1 and procedures P6 to P10. This is a method for determining radioactive contamination in which the presence or absence of radioactive contamination is determined.

N (t ₄ ) N _a (11) N (t ₄ ) <N _a (12) In the radioactive contamination determination method 2, N _h2 (t) and N _l2 (t) are _{calculated as} described above. Since the time function is found, N
(T) When N _h2 (t) is satisfied, the true count rate N _s (t) corresponding to N (t) is always _a value equal to or greater than Na, and N
_{(T) <N l2 (t} ) is a value when N _s (t) is less than always N _a which _{satisfies, N l2 (t) N (} t) < If N _h2 (t) is satisfied N _s ( t) is _{N s (t) <N a} , N s (t) = N a, N
_s (t)> any relationship is found to be either satisfied unclear the N _a, Thus, the work stage in the determination method 2
The above-mentioned judgment processing is performed in Q6.
_l2 (t) N if N (t) <N _h2 (t)
(T) and the difference between the N _a is small (9) or (10) can take a long time is established is evident from Figure 4. Therefore, in the determination method 2, the time elapses without satisfying the expression (9) or the expression (10), and the time (t ₀ +
iτ) = starting with t ₄ (3) is the equation is the established the first conventional determination method exactly similar above determination processing performed in Step P10.

Since the determination method 2 is configured as described above, it is apparent that the contamination determination result can be obtained in the determination method 2 with a determination time of at most T as in the determination method 1 at the longest. Method 2 includes the first and second
It can be said that this is a method that can obtain a determination result in a shorter determination time generally than any of the conventional determination methods. Then, also, evident that the higher the determined time difference according to the determination method 2 N (t) and N _a is large is shortened from Figure 4, in particular, when actually performing contamination determination work since the state of N (t) «N _a is customary, in this case, so that the judgment result is obtained similarly quite a short time as in the determination method 1 according to the present determination method 2.

In the determination method 2, since N _a <N _at , N _h2 (t) <
Although the relationship of N _h1 (t) has occurred and the result determination method 2 has a higher probability of producing a determination result indicating that contamination is present than the determination method 1 does, N is assumed at time t described in equation (1). _h1 (t) the standard deviation of _{[{N h1 (t) + N} b} / t + N b T b
+ E ₀ ² ] ^1/2 is different from the actual standard deviation of N (t) equal to N _h1 (t), whereby the reliability of the contamination determination is improved to a safer side than in the case of the determination method 1. There are advantages.

FIG. 5 is a flowchart for explaining the configuration of an embodiment of a method for determining radioactive contamination different from the determination methods 1 and 2 of the present invention, and FIG. 6 is a flowchart showing the flowchart for explaining the method configuration in FIG. It is explanatory drawing of the contamination determination method in a method of determining contamination. In FIG. 5 and FIG.
The same amounts or matters as those shown in FIGS. 1 to 4 are denoted by the same reference numerals as those in FIGS.

Now, in FIGS. 5 and 6, P11 is the standard deviation E
₀ and the ratio S measured time T _b were set to the same value as in the first or the second conventional determination method respectively and to set the upper limit counting rate N _ah example to a predetermined value, such as N _at and lower counting rate N _al Is set to a predetermined value under the condition of equation (13), and time
Measure the count value _Kb of the background radiation during _Tb and calculate _Kb
/ T _b = N _b , the background radiation count rate measured value
First procedure to determine the N _b, P12 is a function of the first steps E ₀ determined in _{P11, S, T b, N} b, by using the N _ah and N _al (14), respectively from the equation t A second procedure for _{obtaining a} certain N _hl (t) and N _lh (t), P13 is a measured value of K _g (t) K
_{g (iτ)} and N steps with a N _b determined in P11 by performing the same tasks and work stages Q1 described above as N (iτ)
A work stage Q7 for calculating (t) and a work stage Q8 for monitoring whether N (t) calculated in this stage Q7 satisfies any of the equations (15), (16) and (17) In the third procedure,
P14 is (15), (16), at time (t ₀ + iτ) = t ₅
Work stage as soon as any of the formulas in (17) hold
The calculation operation of at least N (iτ) in Q7 is stopped, and the respective values N _lh of N _lh (t) and N _hl (t) at t ₅ are stopped.
(T ₅₎ between the N (t) of the value N (t ₅₎ in and N _hl (t ₅₎ and _{(N ah + N al) /} 2 and t _5, (18) the relationship of equation is established If the relationship is satisfied, it is determined that there is contamination. If the relationship of Expression (20) is established, it is determined that there is no contamination. If the relationship of Expression (19) is satisfied, a predetermined determination is made. This is the fourth procedure.

N _ah > N _al 0 (13) N (t) N _lh (t) (15) N (t) = (N _ah + N _al ) / 2 (16) N (t) N _hl (t) ... (17) N (t ₅ ) N _lh (t ₅ ) (18) N (t ₅ ) = (N _ah + N _al ) / 2 (19) N (t ₅ ) N _hl (t ₅ ) (20) FIG. 3 consists of the illustrated procedures P11 to 14,
Procedure determination method of radioactive contamination to perform the determination of the presence or absence of contamination in the determination object by the judgment processing in P14, exemplified by 6 in FIG at t ₅ (18) equation relationship is satisfied Have been. In FIG. 6, t ₆ is a time function N _lh
This is the time at the intersection X of (t) and N _hl (t).

The decision method 3 of radioactive contamination, since the determination process as described above, may be present in the range of the true value N _s (t) is N _al least count rate N in this case N (t) When it is confirmed that there is contamination, it is determined that there is no contamination when it is confirmed that there is a possibility that N _s (t) is in the range of N equal to or less than N _ah , and in this case, N _hl ( t), N _lh (t)
Is the time function obtained as described above,
At the intersection X in the figure, N = (N _ah + N _al ) / 2. Therefore, in this determination method 3, when the time t elapses regardless of the magnitude of N (t), (15), (16), and (17) ) satisfied any of the formulas, so that contamination determination result is obtained at the latest time t _6, or immediately thereafter eventually. However, it is clear from FIG. 6 that the maximum time for the contamination determination of (t ₆ −t ₆ ) can be adjusted by adjusting the size of (N _ah −N _al ) in this determination method 3. That is, in the contamination determination method 3, since the longest contamination determination time can be set to a time within T by appropriately setting N _ah and N _al , any of the first and second conventional methods can be used. It can be said that this is a method that can obtain a contamination determination result in a shorter determination time as a whole.

FIG. 7 is a flowchart illustrating the configuration of an embodiment of the radiation counting rate measuring method according to the present invention. In this drawing, the same amount or matter as the amount or matter shown in FIGS. 1 to 6 is used. 1 to 6 have the same reference numerals. Then, in Figure 7, P15 is the above-mentioned standard deviation E ₀ and the measurement time T _b and a case equal deviation reference to σ settings vital (28) to the same value of the respective conventional measuring method described above sets the relative error reference value R _a which is defined the value E _a as the ratio of E _a set to either set or such a value of σ of the conventional measuring methods and N (t), the time T by measuring the count value K _b of the background radiation between the _b
K _b / T _b = N _b as a first procedure to determine the count rate measurements N _b of the background radiation, Q9 start the measurement of the count value K _g of total radiation (t) from the time t ₀ Then, every time a predetermined time τ elapses from t _0, the measured value of K _g (t) K _g (iτ)
With a N _b determined in Step P15 and (2) in the same working step as the aforementioned Q1 for calculating the N (t) as performing arithmetic top left of N (iτ), Q10 working steps Using the N (t) calculated in Q9 and E ₀ , T _b and N _b determined in the first procedure P15, the standard deviation E of the total measurement error in N (t) as a function of T is obtained from the equation (21). This is the work stage for obtaining (t).

K _g (iτ) −N _b = N _g (iτ) −N _b = N (iτ) = N
(T) .... (2) However, i = 1,2,3, ...... E ( t) = _{[{N (t) + N b} } / t + N b / T b + E 0 2 ] ^1/2 ... ( 21) Q11 is, in the case of setting the R _a in the first procedure P15, step Q10
E (t) obtained in the above and the stage used for calculating this E (t)
A work step in which the relative error R (t) as a function of t is obtained from the equation (22) using the N (t) obtained in Q9,
Q12, if the first steps P15 to set the E _a not set R _a, and the work step Q10 E _a set in the first procedure P15 (2
The work stage of monitoring whether or not the relationship of Eq. (23) holds between E (t) obtained from Eq. (1), Q13 is the first procedure P
When _Ra is set in step 15, the value (2) is set between _Ra set in step P15 and R (t) obtained from equation (22) in work stage Q11.
4) In the work stage for monitoring whether or not the relationship of the expression is established, P16 is a second procedure including the above-described work stages Q9 to Q13.

E (t) E _a ... (23) R (t) R _a ... (24) P17 is monitored by Q12 and Q13. As soon as the time (t ₀ + iτ) = t ₇ holds, the calculation calculation of at least N (t) in the work stage Q9 is stopped, and the value N (t ₇ ) of N (t) at the time t ₇ is held. In the third procedure, 4 includes the above-described procedures P15, P16, and P17, and the count rate value N (t ₇ ) held in the procedure P17 is used as the measured count rate of the radiation emitted from the measurement object. This is a method for measuring the radiation count rate.

Since the measurement method 4 of the radiation count rate is configured as described above, E (t) or R (t), which shows a large value at the beginning of the calculation of N (t) in the work stage Q9, is changed to the time t. Although it passed as (21) or (22) reduced to finally E _a or R _a to become as soon as the counting rate measurements below according formula is obtained, the E (t) or R (t) is E _a
Or the elapsed time t from the time t ₀ of the R _a or less at the time t ₇ when turned, when N (t ₇₎ is N _max smaller, regardless of whether the magnitude of N (t _7), σ = _{E a, N (t 1)} = a N _max (2
It is clear from equation (21) that the time is shorter than the measurement time T in the conventional measurement method obtained from equation (8). Therefore, when N (t ₇ ) is smaller than N _max , the measurement method 4 can obtain a measurement result with a predetermined accuracy in a shorter measurement time than in the conventional measurement method regardless of the magnitude of N (t ₇ ). It can be said that this is a method for measuring the radiation count rate.

[Effect of the Invention As described above, in the present invention, 1) the background radiation and the elapsed time from the time t ₀ of the total radiation which is defined as the sum of the net radiation as the radiation emitted from the object to be judged Count rate measurement of background radiation from count rate measurement N _g (t) as a function of t
N count rate measurements of _b as a function of t net radiation obtained by subtracting the N of (t), N _g count as a function of t for all radiation used to calculate (t) K _g (t) And the standard deviation E _{0 of the} variation based on the cause other than each statistical variation of the count value K _b of the background radiation used for the calculation of N _b and the magnification S
And measurement time T and _Tb, and _Kb between _Tb
A first procedure for obtaining the N _b as K _b / T _b = N _b by measuring one given primary criterion counting rate N _at the E ₀ was determined in the first procedure, S, and T _b and N _b From equation (1) using
A second method for _obtaining N _h1 (t) and N ₁ (t), which are functions of
Instructions, The measurement of the count value K _g (t) starts at time t ₀ , and
Every time a predetermined time τ elapses from t _0, the measured value K _g of K _g (t)
By using the (iτ) and N _b (2) formula time t _1, which is defined as the sum of the calculated vital t ₀ and T a N (t) by performing the calculation top left side of
A third procedure of monitoring whether or not the relationship of equation (3) holds between the time and the time (t ₀ + iτ); (T ₀ + iτ) t ₁ (3) Time (t ₀ + iτ) at which the relationship of equation (3) does not yet hold
= N In t ₂ in the t _{2 h1} (t) and N
₁ each value of (t) N _h1 (t ₂₎ and _{N 1} (t ₂₎ and (4) between N (t) of the value N (t ₂₎ at t ₂ or (5) the relationship Is established at least N
A fourth procedure for stopping the calculation of (t), determining that contamination is present when equation (4) is satisfied, and determining that there is no contamination when equation (5) is satisfied; N (t ₂ ) N _h1 (t ₂ ) (4) N (t ₂ ) <N ₁ (t ₂ ) (5) The time without the relation of the equations (4) and (5) being established. And the fifth step of immediately stopping the calculation of N (t) and determining that there is contamination as soon as the relationship of equation (3) is established, and the determination object is determined by the determination processing in the fourth and fifth procedures The method for determining radioactive contamination is configured to judge the presence or absence of radioactive contamination in an object, and 2) defined as the sum of background radiation and net radiation as radiation emitted from the object to be determined. The count rate measurement N _g as a function of the time t elapsed from time t _{0 of} all radiation ( t) from background radiation count rate measurement
N count rate measurements of _b as a function of t net radiation obtained by subtracting the N of (t), N _g count as a function of t for all radiation used to calculate (t) K _g (t) And the standard deviation E _{0 of the} variation based on the cause other than each statistical variation of the count value K _b of the background radiation used for the calculation of N _b and the magnification S
And measurement time T and _Tb, and _Kb between _Tb
The measured K _b / T _b = N a first procedure for obtaining the N _b as _b, the primary criterion counting rate given N _at a determined in the first procedure _{E 0, S, T, T} b and N by using the _b (6) determined the first counting rate N _a1 and a second count rate N _a2 from equation, the determined secondary criterion count rate N _a which satisfies thereafter (7) relationship Two steps, N _a1 N _a N _a2 (7) Using E ₀ , S, T _b , N _b and N _a determined in the first and second procedures, N _h2 ( t) and N
a third procedure for determining _l2 (t); N _l2 (t) + S · [{N _l2 (t) + N _b } / t + N _b / T _b +
E ₀ ^2] and starts from ^1/2 = N _a count K time t ₀ the measurement of _g (t),
Every time a predetermined time τ elapses from t _0, the measured value K _g of K _g (t)
By using the (iτ) and N _b (2) formula time t _1, which is defined as the sum of the calculated vital t ₀ and T a N (t) by performing the calculation top left side of
A fourth procedure for monitoring whether or not the relationship of equation (3) holds between the time and the time (t ₀ + iτ); (T ₀ + iτ) t ₁ (3) Time (t ₀ + iτ) at which the relationship of equation (3) does not yet hold
= N In t ₃ in the t _{3 h2} (t) and N _l2 values N _h2 (t ₃₎ of the (t) and N _l2 (t ₃₎ and the value of N (t) at t ₃ N (t ₃₎ As soon as the relationship of the formula (9) or the formula (10) holds, the calculation of at least N (t) is stopped, and if the formula (9) holds, it is determined that there is contamination ( A fifth procedure for determining that there is no contamination if the equation (10) holds, and N (t ₃ ) N _h2 (t ₃ ) (9) N (t ₃ ) <N _l2 (t ₃ ) .. (10) At time (t ₀ + iτ) = t ₄ , the relationship of the formula (3) is established at a time (t ₀ + iτ) = t ₄ without the relationship of the formulas (9) and (10) being established, at least N (t) It stops the calculation operation, the value N (t ₄₎ of N (t) at t ₄ and
N _a there contamination if (11) the relationship is satisfied between the determined (12) without contamination if the relationship is established as determined sixth procedures and N ( t ₄ ) N _a (11) N (t ₄ ) <N _a (12) The determination processing in the fifth and sixth procedures determines whether radioactive contamination is present in the determination target. And 3) a method of determining radioactive contamination, and 3) the elapsed time t from time t _{0 of} all radiation defined as the sum of background radiation and net radiation as radiation emitted from the object to be determined. Count rate measurement of background radiation from count rate measurement N _g (t) as a function
N count rate measurements of _b as a function of t net radiation obtained by subtracting the N of (t), N _g count as a function of t for all radiation used to calculate (t) K _g (t) And the standard deviation E _{0 of the} variation based on the cause other than each statistical variation of the count value K _b of the background radiation used for the calculation of N _b, the magnification S, the upper limit count rate N _ah, and the relationship of the equation (13) are satisfied. Lower limit count rate N
and sets the _al and the measurement time T _b, a first procedure for obtaining the N _b as K _b / T _b = N _b by measuring K _b between _{T b, N ah> N al} 0 ...... ( 13) Using E ₀ , S, T _b , N _b , N _ah, and N _al determined in the first procedure, N _hl (t) and N _lh, which are functions of t, respectively, from equation (14).
A second procedure for determining (t); The measurement of the count value K _g (t) starts at time t ₀ , and
Every time a predetermined time τ elapses from t _0, the measured value K _g of K _g (t)
(Aitau) by using the N _b and (2) to calculate the N (t) by performing the calculation top left side of and the calculated N (t) is (15)
A third procedure for monitoring which of formula (16) and formula (17) is satisfied; _{N (t) = N ah +} N al) / 2 ...... (16) N (t) N hl (t) ...... (17) the time (t ₀ + iτ) = t in ₅ (15), (16) and ( 17) As soon as any of the formulas is satisfied, at least N
(T) stops the calculation operations, N in t _5
lh (t) and N _hl values N _lh of (t) (t ₅₎ and N _hl (t ₅₎
And the value N of (N) at (N _ah + N _al ) / 2 and t ₅
If the relationship of equation (18) holds true with (t ₅ ), it is determined that there is contamination, and if the relationship of equation (20) holds, it is determined that there is no pollution. If the relationship of the expression (19) is established, the fourth procedure is a predetermined judgment content and N (t ₅ ) N _lh (t ₅ ) (18) N (t ₅ ) = (N _ah + N _al ) / 2 ... (19) N (t ₅ ) N _hl (t ₅ ) ... (20), and the determination processing in the fourth step is performed so as to determine the presence or absence of radioactive contamination in the determination target. configure determination method of radioactive contamination, also 4) a function of the elapsed time t from the time t ₀ of the total radiation is defined from the background radiation and the object to be judged as the sum of the net radiation as the radiation emitted Count rate measurement value of background radiation from count rate measurement value N _g (t) as
N count rate measurements of _b as a function of t net radiation obtained by subtracting the N of (t), N _g count as a function of t for all radiation used to calculate (t) K _g (t) and N _b and the standard deviation E ₀ variations based on factors other than the statistical variation of the count value K _b background radiation used for calculation of the deviation reference value E _a or relative error reference value R _a, the measurement time and sets the T _b, by measuring the K _b between _{T b K b / T b =} N b as N _b
And the measurement of the count value K _g (t) is started at time t ₀ , and
Every time a predetermined time τ elapses from t _0, the measured value K _g of K _g (t)
It is calculated (iτ) and by using the N _b a (2) N (t) by performing the calculation top left side of the equation, E was determined with the calculated N (t) in the first procedure _0, T _b From equation (21) using _Nb and Nb
The standard deviation E (t) as a function of t of the total measurement error at (t) is obtained, and when _Ra is set in the first procedure, E is obtained.
After obtaining the (t) further this E (t) N relative error R as a function of t, which is defined as the ratio of the (t) (t) determined from (22), the first procedure R _a If not set monitors whether established (23) of the relationship between E _a was determined in the first procedure (21) E obtained from the equation (t), the first procedure R _a When R is set, R calculated from equation (22)
(T) and a second procedure for monitoring whether (24) established relationship of the expression moth between R _a determined in the first procedure, E (t) = _{[{N (t) + N b} } / t + N b / T b + E 0 2 ] ^1/2
…(twenty one) E (t) E _a (23) R (t) R _a (24) As soon as the formula (23) or (24) is satisfied at the time (t ₀ + iτ) = t ₇ , at least N (t) the calculating operation and a third procedure for holding the N value N (t ₇₎ in (t) at t ₇ is stopped, and the count rate measurements of the radiation emitted N a (t ₇₎ from the object to be measured The measurement method of the radiation count rate was configured to perform the measurement.

Therefore, when configuring the method of determining the radioactive contamination as described above, contamination determination result immediately after time t ₁ in the first prior art determination method has elapsed time T from the time t ₀ is obtained, and determining a second conventional time and count rate N (t) is less than N _a in the process
whereas contamination determination result at a later time than t ₁ is obtained, if the method of comparing N (t) of the present invention N _h1 (t) and N ₁ and _{(t), (4)} expression or As soon as equation (5) holds, a contamination determination result is obtained, and the time t ₂ at this time is
The time is earlier than t ₁ , and even after the expression (4) or (5) does not hold, immediately after the time t ₁ , it depends on the magnitude of the primary determination reference count rate N _at of N (t). It is evident that a constant contamination determination result can be obtained, and in the case of the method of the present invention for comparing N (t) with N _h2 (t) and N _l2 (t), equation (9) or (9) 10) immediately contaminated determination result is obtained Once established the time t ₃ at this time is a time earlier than t _1, and (9) or (10) is a time t ₁ may not satisfied the time t ₄ immediately after it is apparent both be N (t ₄₎ of any finalized contamination determination result in accordance with the magnitude for the secondary criterion counting rate N _a is obtained.
Then, further, N (t) of the present invention is changed to N _lh (t) and N
_hl case of the method to compare (t), N regardless of whether the magnitude of the (t), over time curve from time t ₀ N _lh (t) and N _hl (t)
Always it is clear that some contamination determination result is obtained, also possible to set upper and lower limits counting rate N _ah, the N _al appropriately as described above until reaching the time t ₅ at the intersection of the time curve of the it is possible to set the time t ₆ to time earlier than the time t ₁ by the present invention, three types of radioactive contamination of the measurement the first and second by any of the methods of the method of the present invention described above There is an effect that a contamination determination result can be obtained in a shorter determination time than in any of the conventional determination methods.

Then, when the method of measuring the radiation count rate is configured as described above, E (t) or R (t) corresponding to the measurement error of N (t), each of which decreases with time, is a predetermined value. E _a or R immediately count rate measurement upon reaching _a is obtained, the elapsed time from the time t ₀ of time t ₇ when the t
Is the normal case where N (t ₁ ) <N _max , σ = E _a , N (t ₁ )
= From the N _max (28) to be a time within the value T _max of the time T obtained from the equation it is apparent from equation (21), therefore, the method of measuring the radiation count rate of the present invention, N
When (t) is smaller than _Nmax, there is an effect that a count rate measurement result with a predetermined accuracy can be obtained in a shorter measurement time than in the conventional measurement method.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining the configuration of an embodiment of a method for determining radioactive contamination according to the present invention, and FIG. 2 is a flowchart for explaining the configuration of the method for determining radioactive contamination shown in FIG. FIG. 3 is a flowchart for explaining the configuration of an embodiment of a radioactive contamination determination method different from the radioactive contamination determination method shown in the flowchart of FIG. 1 according to the present invention; FIG. FIG. 3 is a flowchart for explaining the method of determining radioactive contamination, showing a flowchart for explaining the method configuration in FIG. 3. FIG. 5 is a flowchart showing the flowcharts in FIGS. 1 and 3 according to the present invention. FIG. 6 is a flowchart for explaining the configuration of an embodiment of a radioactive contamination determination method different from any of the two radioactive contamination determination methods. FIG. 6 is a flowchart for explaining the method configuration in FIG. Illustration of how contamination determination method for determining a radioactive contamination shown, FIG. 7 is a flowchart for explaining the structure of an embodiment of a method of measuring the radiation count rate in accordance with the present invention. 1,2,3 ...... determination method of radioactive contamination, 4 measuring method ...... radiation counting rate, K _g ...... count of the total radiation, K _b ...... background radiation count value, N _g ...... All Radiation counting rate, N _b …
... count rate of background radiation, counting rate of N ...... net radiation, N _at ...... primary criteria count rate, N _a ...... secondary criteria count rate, N _ah ...... maximum count rate, N _al ...... Lower counting rate,
N _h1 (t), N _h2 (t), N ₁ (t), N _l2 (t), N
_hl (t), N _lh (t) ... function of t, E ₀ , E (t) ... standard deviation, E _a ... deviation reference value, R (t) ... relative error, _Ra
…… Relative error reference value, T, T _b …… Measurement time, S …… Magnification,
t ...... _{time, t 0, t 1, t} 2, t 3, t 4, t 5, t 6, t 7 ...... time, P1, P11, P15 ...... first procedure, P2, P6, P12, P16 ... second
Procedure, P3, P7, P13, P17 …… Third procedure, P4, P8, P14 …… Fourth
Procedure, P5, P9 ... Fifth procedure, P10 ... Sixth procedure.

Claims (4)

(57) [Claims] 1. A count rate measurement value N _g as a function of the elapsed time t from time t _{0 of the} total radiation defined as the sum of the background radiation and the net radiation emitted from the object to be determined. count rate measurements as a function of said t of the net radiation obtained by subtracting the count rate measured value N _b of the background radiation from t) N of (t), the N _g
(T) calculated on the each non-statistical variation of the count value K _b of the background radiation is used for the calculation of the count value K _g (t) and the N _b as a function of said t of all radiation using the the standard deviation E ₀ variations based on the cause, the a ratio S, and sets the measurement time T and T _b, as the measures to _{K b K b / T b =} N b between the T _b a first procedure for obtaining the N _b, was determined by the primary criterion count rate N _at which said given first procedure E _0, S, using a T _b and N _b (1) of each of the t from the equation A second procedure for determining the functions N _h1 (t) and N ₁ (t); The measurement of the count value K _g (t) is started from the time t _0, and the K is measured every time a predetermined time τ elapses from the t _0.
g wherein the measured value K _g of (t) (iτ) by using the N _b (2)
The above-mentioned N (t) is calculated by performing an operation on the leftmost side of the equation, and
t ₀ and the T and the time t ₁ and the time defined by the sum of (t ₀ + i
τ), a third procedure for monitoring whether the relationship of equation (3) holds, and The time (t ₀ + i) at which the relationship of the above equation (3) does not hold yet.
tau) = the at t ₂ in the t ₂ N _h1 (t) and the _N 1 (each value N _h1 of t) (t ₂₎ and _{N 1} (t ₂₎ and the
stops the calculating operation of the equation (4) or soon (5) of the relationship is satisfied at least the N (t) between the value of the N (t) at t ₂ N (t _2), the ( 4)
When the formula is satisfied, it is determined that there is contamination, and the above (5) is determined.
A fourth procedure for determining that there is no contamination if the equation holds, and N (t ₂ ) N _h1 (t ₂ )... (4) N (t ₂ ) <N ₁ (t ₂ ). 5) As soon as time elapses without the relation of the above equations (4) and (5) being established and the relation of the above equation (3) is established, at least the calculation calculation of the N (t) is stopped and there is contamination. A radiological contamination determination method, comprising determining whether radioactive contamination is present in the determination target by the determination processing in the fourth and fifth procedures. 2. The count rate measurement value N _g as a function of the elapsed time t from time t _{0 of the} total radiation defined as the sum of the background radiation and the net radiation emitted from the object to be determined. count rate measurements as a function of said t of the net radiation obtained by subtracting the count rate measured value N _b of the background radiation from t) N of (t), the N _g
(T) calculated on the each non-statistical variation of the count value K _b of the background radiation is used for the calculation of the count value K _g (t) and the N _b as a function of said t of all radiation using the the standard deviation E ₀ variations based on the cause, the magnification S and sets a measurement time T and Tb, the as said by measuring the _{K b K b / T b =} N b between the T _b N _b using a given primary judgment reference count rate N _at and E ₀ , S, T, T _b and N _b determined in the first procedure, from the equation (6), seeking a rate N _a1 and the second count rate N _a2, a second procedure for determining the secondary criterion count rate N _a which satisfies thereafter (7) of the relationship, N _a1 N _a N _a2 (7) Using E ₀ , S, T _b , N _b and N _a determined in the first and second procedures, N is a function of the t from equation (8).
_a third procedure for determining _h2 (t) and _Nl2 (t); The measurement of the count value K _g (t) is started from the time t _0, and the K is measured every time a predetermined time τ elapses from the t _0.
g wherein the measured value K _g of (t) (iτ) by using the N _b (2)
The above-mentioned N (t) is calculated by performing an operation on the leftmost side of the equation, and
t ₀ and the T and the time t ₁ and the time defined by the sum of (t ₀ + i
τ), a fourth procedure for monitoring whether the relationship of equation (3) holds, and The time (t ₀ + i) at which the relationship of the above equation (3) does not hold yet.
τ) = t ₃ , the values of N _h2 (t) and N _l2 (t) at this t _3, N _h2 (t ₃ ) and N _l2 (t ₃ ), and N (t) at t ₃ When the relationship of the expression (9) or the expression (10) is established with the value N (t ₃ ), at least the calculation of the N (t) is immediately stopped, and the expression (9) is satisfied. A fifth procedure for determining that there is contamination and determining that there is no contamination when the equation (10) is satisfied; and N (t ₃ ) N _h2 (t ₃ )... (9) N (t ₃ ) <N _l2 (t ₃ ) (10) At time (t ₀ + iτ) = t ₄ , the time elapses without the relation of the above equations (9) and (10) being established, and the above (3)
As soon as the relationship of the formula is established, at least N (t)
Stops the calculation operation, the in the t ₄ N
Between the N _a value of _{(t) N (t 4)} , (11) if equation if the relationship is established in which it is determined that there is contamination (12) relationship is satisfied And (6) N (t ₄ ) N _a (11) N (t ₄ ) <N _a (12), which is determined by the determination processing in the fifth and sixth procedures. A method for determining radioactive contamination, comprising determining the presence or absence of radioactive contamination in the object to be determined. 3. The count rate measurement value N _g as a function of the elapsed time t from the time t _{0 of the} total radiation defined as the sum of the background radiation and the net radiation emitted from the object to be determined. count rate measurements as a function of said t of the net radiation obtained by subtracting the count rate measured value N _b of the background radiation from t) N of (t), the N _g
(T) calculated on the each non-statistical variation of the count value K _b of the background radiation is used for the calculation of the count value K _g (t) and the N _b as a function of said t of all radiation using the standard deviation E of the variation based on cause ₀ and the magnification S and the upper limit counting rate
N _ah and (13) relationship sets a lower limit counting rate N _al and measurement time T _b which satisfies the equation, as K _b / T _b = N _b by measuring the K _b between the T _b above using a first procedure for obtaining a _{N b, N ah> N al} 0 ...... (13) wherein E ₀ determined by the first _{procedure, S, T b, N b} , the N _ah and N _al (14) From the formula, N, which is a function of the t,
_hl and a second procedure for obtaining the N _lh (t) and _{(t), N hl (t} ) + S · _{[{N hl (t) + N} b} / t + N b / T b +
E ₀ ² ) ^1/2 The measurement of the count value K _g (t) is started from the time t _0, and the K is measured every time a predetermined time τ elapses from the t _0.
g wherein the measured value K _g of (t) (iτ) by using the N _b (2)
A third operation is performed to calculate the above N (t) by performing an operation on the leftmost side of the expression, and monitor whether the calculated N (t) satisfies Expression (15), Expression (16) or Expression (17). Instructions, N (t) N _lh (t) (15) N (t) = (N _ah + N _al ) / 2 (16) N (t) N _hl (t) (17) Time (t ₀ ) + iτ) = t in the above ₅ (15), (16) and (both 17) one of formula stops calculating operation immediately least the N (t) When satisfied, the in the t ₅ N _lh (t) And the respective values of N _hl (t), N _lh (t ₅ ) and N
Between the _hl (t ₅₎ and the value N (t ₅₎ of the _{(N ah + N al) /} 2 and the in the t ₅ N (t), if the established relationship (18) Determines that there is contamination, determines that there is no contamination when the relationship of Expression (20) is established, and determines the predetermined determination content when the relationship of Expression (19) is satisfied. Procedure and N (t ₅ ) N _lh (t ₅ )… (18) N (t ₅ ) = (N _ah + N _al ) / 2… (19) N (t ₅ ) N _hl (t ₅ ) (20) A method for determining radioactive contamination, comprising determining whether radioactive contamination is present in the object to be determined by the determining process in the fourth step. 4. A count rate measurement value N _g as a function of the elapsed time t from time t _{0 of the} total radiation defined as the sum of the background radiation and the net radiation emitted from the object to be determined. count rate measurements as a function of said t of the net radiation obtained by subtracting the count rate measured value N _b of the background radiation from t) N of (t), the N _g
(T) calculated on the each non-statistical variation of the count value K _b of the background radiation is used for the calculation of the count value K _g (t) and the N _b as a function of said t of all radiation using the the standard deviation E ₀ variations based on the cause, the deviation reference value E _a or relative error reference value R _a, and sets the measurement time T _b, the measuring the K _b K _b between the T _b / T _b = N _b , a first procedure for obtaining the N _b , and the measurement of the count value K _g (t) is started from the time t _0, and each time a predetermined time τ elapses from the t ₀ , K
_g wherein the measured value K _g of (t) (iτ) by using the N _b (2)
The above-mentioned N (t) is calculated by performing the calculation on the leftmost side of the equation. The equation (21) is obtained by using the calculated N (t) and E ₀ , T _b and N _b determined in the first procedure. The standard deviation E (t) of the total measurement error in the N (t) as a function of the t is obtained from the above, and when the _Ra is set in the first procedure, the E is obtained.
After determining (t), the relative error R as a function of t is defined as the ratio of E (t) to N (t).
The (t) from (22) determined, wherein if not set R _a in the first procedure above (21) from the obtained with the E _a determined the E (t) and in the first procedure It is monitored whether the relationship of equation (23) is established between them, and when the _Ra is set in the first procedure, R (t) obtained from the equation (22) is determined in the first procedure. A second procedure for monitoring whether or not the relationship of equation (24) holds with respect to the _Ra ; E (t) = _{[{N (t) + N b} } / t + N b / T b + E 0 2 ] ^1/2
…(twenty one) E (t) E _a (23) R (t) R _a (24) At time (t ₀ + iτ) = t ₇ , the above (23) or (24)
And a third procedure to hold the value N (t ₇₎ of the N (t) in the t ₇ with formula stops calculating operation immediately least the N (t) When satisfied, the N (t ₇₎ A radiation count rate measurement value of the radiation emitted from the measurement object.