JPH04191689A - Method for judging radioactive contamination and method for measuring radiation counting rate - Google Patents

Abstract

PURPOSE:To shorten a judging time by measuring a count value as a function of the elapse time of the total radiation and expressing the counting rate calculated from the count value through a specific formula and comparing upper and lower limit values changing with the elapse of time to judge contamination. CONSTITUTION:Nh1(t) and Nl1(t) being the functions of an elapsed time (t) are calculated from formula (1) (wherein S is magnifying power, T and Tb are measuring times, Nb is the counting rate measured value of background radiation, Eo is the standard deviation of the irregularity based on a cause other than the statistical fluctuation of the count value of background radiation used in the calculation of Nb and Nat is a primary judgement standard counting rate). Next, a counting rate N(t) is calculated from formula 2. When formula (4) is satisfied, the presence of contamination is judged and, when formula 5 is satisfied, the absence of contamination is judged.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for detecting the presence or absence of contamination by radioactive substances (hereinafter, this substance may be referred to as radioactivity) VC emitted from an object to be determined. A method for determining radioactive contamination based on the count rate of radiation emitted from an object to be measured, and a method for measuring the radiation count rate used to measure the count rate of radiation emitted from an object to be measured, especially the time required to determine the presence or absence of radioactive contamination. (Hereafter,
This time is sometimes referred to as determination time. ) and the time required to obtain a count rate measurement value with predetermined accuracy (hereinafter, this time may be referred to as measurement time).

[Conventional technology]

Conventional 1 When determining whether an object is contaminated with radioactive substances, that is, determining whether the object is contaminated with radioactivity, the radiation emitted from the object is usually compared to the presence of background radiation. The time under [
The count rate Nb obtained by counting the amount from 0 for a predetermined measurement time T and subtracting the resulting radiation count, that is, the count rate measurement value N of the net radiation as radiation emitted from the object to be determined, is equal to the predetermined two. The presence or absence of contamination is determined by checking whether the count rate is equal to or higher than the next determination criterion count rate Na. In other words, as is clear from the above, the count value Kg
and counting rate measurement values Ng and N are both functions of the elapsed time from time t0 Kg(t).

Ng(S, N(t), so from time t to time T
At time t1, (t),
Ng (su.

Each part of N(t) is Kg(t t), Ng(tl) *i
'i(tt) as conventional.

N(tl) is calculated using equation (25), and if equation (26) holds true, it is determined that there is contamination, and if equation (27) holds, it is determined that there is no contamination.

N (tl) = NgOt) Nb = Kg (tt)/
TNb・-・・・・(25)N(11)ΣNa
・River...(26)N(tt)<Na---
---(27) In this case, Nb used in equation (25) is the counted value of the background radiation obtained by counting the background radiation in advance over the appropriately set measurement time Tb. It is a count rate measurement obtained by dividing Kb by time Tb.

However, the count rate measurement value NC' obtained as described above
s) Error based on statistical fluctuation Avc of count value Kg (tI) used for calculation of VCtx, Ng (11) and Nb
An error based on the statistical fluctuation B of the count value Kb used in the calculation of
t) and Kl), and in this case, the convolution P in which the true probable count rate Nb (El) exists is the count rate measurement value N
It becomes a normal distribution where the probability P is maximum at (E,).

The standard deviation σ of this normal distribution is calculated by referring to equation (25) and calculating the standard deviation σ of the measurement value N(tt) based on the above-mentioned statistical fluctuation person and causes other than B as E.
), so if N(tt) is calculated as above, the true counting rate Nb(tt) can be calculated by appropriately setting the multiplier S for σ (29)
It will exist within the range of the count rate value shown in the formula.

=C(N(to+Nb)/T+Nb/Tb+F!, l)
M...(28)N(to-8σ4Ng(tt)4
N(tt)+8σ ・・・・−・(29) By the way,
Generally, when determining the presence or absence of radioactive contamination, it must be determined that there is contamination if the true counting rate Ns (t1) exceeds the primary judgment standard counting rate Nat determined by law. This is the principle. Therefore, the counting rate N
1(tI)'m maximum possible value of i (N(E,)
+8σ) is equal to Na@pc, with N (t,) as the first counting rate Nal, the above-mentioned secondary criterion counting rate N
If b is set to be equal to Na□, which satisfies equation (30), in this case, in the state where N(tl) is N (t+ )4Nal, which satisfies equation (26), N1(tt)y
Since there is always a possibility that at, the above-mentioned conventional contamination determination method immediately determines that there is contamination if equation (26) holds (hereinafter, this contamination determination method may be referred to as the first conventional determination method). It can be said that this method is in line with the above judgment principle.

Even if Nal is determined using the formula (30), the above-mentioned value of σ that appears in actual contamination determination cannot be determined due to reasons such as not being able to accurately measure Eo or cE・ being different for each count rate measurement value. This is because it does not necessarily match the value of σ used when

In the first conventional determination method, F! ,, after calculating Na0 from equation (30) or equation (28) by appropriately assuming T, etc. and σ, Ns (t*)ΣN11E
In order to prevent an erroneous determination that there is no contamination despite the above, Na is set to satisfy NJIIΣN11 with some margin.

Na 1+8” ((Nal+Nb)/T+Nb/
Tb+E6 '')'=N1ta...(30) In the first conventional determination method, Na is set as described above, but now the minimum value (N(t , )-sσ) is equal to zero as the second counting rate Naff1, and Na is set as (3
1) If it is set equal to Nll that satisfies the equation, in this case, in the state where N(11) < Nag, Na(ti
) < 0, such that N(tt
) cannot be a significant measurement value. Therefore,
After all, in the first conventional determination method described above, Nll is set so as to satisfy the equation (32).

In this case, Na1l is calculated using E0, T, etc. used to determine Nll, and the assumed value of σ.

N, z-8・((Nms+Nb)/T+Nb/T
b+E,,” )'= O-=・(31) Na1hf
'J, hN11! +++++ (32
) The first conventional determination method described above is based on the average count rate Ncts)c during the measurement time T, and first determines Eo, T, Tb, and Nb based on the presence or absence of radioactive contamination, and then determines the first step. 2 Using T, Nb, and N3 determined in the first step, calculate the left side of equation (33) to determine the judgment criterion count value K.
The second step of calculating ga, and the time 1. Hereinafter, in the presence of background radiation, the total radiation count Kg (
A method for determining radioactive contamination (hereinafter referred to as this The presence or absence of radioactive contamination is also determined using the second conventional determination method.

(N, +N i) ) -T=K ga
...(33) Now, the above-mentioned net radiation count rate measurement value N(tI) includes a measurement error whose standard deviation is σ shown in equation (28), and this measurement error It is clear from equation (28) that the longer the measurement time T becomes, the smaller the difference becomes. In other words, the error of N(tl) depends on T. However, in this case, σ is not equal to N(tl) or E
Even if T is assumed, it is impossible to estimate D in advance since it also depends on D. Therefore, conventionally.

First, E0, Tb and Nb are determined in the same manner as in the first and second determination methods described above, and time T is determined from equation (28) by roughly assuming σ and N(tl), and then The radiation count rate is determined by the radiation count rate measurement method of counting the opening radiation at time T from time t0 to time t, obtaining the count value Kg(tl), and obtaining the measured value of N(tl) using equation (25). N measurements are being made. Hereinafter, this measurement method may be referred to as the conventional measurement method.

[Problem to be solved by the invention]

In the first conventional determination method described above, as described above, E0
, 'r, etc. and σ to determine Nb and compare this Na with N(tl) to determine contamination.
, 1, even when the maximum value of N (tt) that is expected to appear in actual contamination determination work is NmaX, as mentioned above, σ that changes depending on N (tt) and TK is equal to Ell. This will ensure the accuracy of contamination determination.5
rc [, in equation (28), σ=Es 1.
N(11) is measured by counting the open radiation at time T10 that is equal to or greater than the value of T 18 obtained as N(Lx)=Nmax. Therefore, such a time Tl1
) is a contamination determination method that involves counting the amount of

In the normal case where N(1m)<NmaX, even if the time to measure the counting rate N is shorter than T, σzIi! It is clear from equation (28) that σZ
There is a problem in that the contamination determination performed under the Ell conditions takes too much time.

In addition, in the first conventional determination method described above, when Na is determined by assuming T in advance, the standard deviation σ of N(El) that occurs during actual contamination determination is (Nat Na
) 4 The relational expression of Sσ must be satisfied, so
Assuming that the limit value of σ in this relational expression is E82, σ4 E
@! On the other hand, σ and T
Since there is a relationship between vcts and equation (28).

In the first conventional determination method described above, in which Na is determined assuming c and T in order to ensure that σ4ES2 holds true even when N (tr) = Nmax, (2
8) In equation ℃σ=E12, N(tt F Nrna
It is obtained as x.

This is different from the T assumed earlier. Time T for which the value of T is 12 or more
! . N(t11) is measured by counting the open radiation. Therefore, such a time T,. In the contamination determination method that counts the amount of σ1. ．． There is a problem in that the contamination determination performed under the EB2 conditions takes too much time.

Then, in the second conventional determination method described above, vR
It is clear that if the counting rate N of net radiation that appears during the actual contamination determination is greater than Na determined in the first step of this determination method, the contamination determination work will be completed in a shorter time than the measurement time T. However, if N is smaller than Na, then Kg(t
) takes a longer time than T to reach Kgavc, so the second conventional determination method also has the problem that it takes a long time to determine contamination when N is smaller than Na.

Then, in the case of the conventional counting rate measurement method described above, in equation (28), N(t,) is the maximum counting rate Nff1Ik that is expected to appear during actual counting rate measurement.
N(tl) so that the predetermined σ can be obtained even when
Since T is determined assuming that and σ.

When we count the open radiation at time T to find Kg(t+) and calculate N(tS), if this calculated N(tt) is smaller than the Nmax assumed earlier, then 2. It is clear from equation (28) that σ of N(t1) is smaller than the previously assumed σ. Therefore, in this case, the calculated σ of N(t+) may be the same as the assumed σ. Then, the calculated N(tX)
The measurement error of N(tl) assumed in determining T
It is also clear from equation (28) that the measurement time T may be shorter if the measurement error is the same. Therefore, the conventional measurement method described above has a problem in that it may take too much time to measure the count rate even if it is sufficient to always obtain a predetermined measurement accuracy.

The purpose of the present invention is not to determine contamination by determining N(11) by measuring the count value Kg(t) during a predetermined measurement time TI or 1°, but also to determine whether Kg(t) is Predetermined value Kg,
Instead of determining that there is contamination when reaching c,
The count value Kg(t) is measured with the count start time as , and then the counting rate N O) is calculated from this measured Kg(t).
Contamination is determined when (Kg(t)/t-Nb) reaches the critical value or lower limit value that changes over time, and the determination time is shorter than in the first and second conventional determination methods described above. The purpose is to make it possible to obtain contamination determination results.

Then, the purpose of the present invention is not to measure the count value Kg(t,) during a predetermined measurement time T to obtain N(tl), but to obtain the N(t). This N
(t) standard deviation E (t) or relative error R(t)
= E(t)/N(t), and each of these E or R is a predetermined deviation reference value E8. When the relative error reference value Rjl is reached, N(t) at this time is used as the final count rate measurement value, and a count rate measurement result with a predetermined accuracy can be obtained in a shorter measurement time than in the conventional measurement method described above. The aim is to make sure that

[Means to solve the problem]

To achieve the above object, according to the present invention, l) the time of total radiation defined as the sum of background radiation and net radiation as radiation emitted from the object to be determined; Count rate measurement Ng as a function of elapsed time from
(t) to the count rate measurement value N of the background radiation
of the count rate measurement value N(t) as a function of the net radiation obtained by subtracting b from the count rate measurement value N(t) as a function of the total radiation used to calculate the Ng(t); (t), a standard deviation of 11 m of variations based on causes other than statistical fluctuations in the counted value Kb of the background radiation used to calculate the Nb, a magnification S, and measurement times T and Tb. Also, a first step of measuring the Kb between the Tb and calculating the Nb as Kb/Tb=Nb, and n0, s, Tb determined in the given primary criterion counting rate Nut and the first step. From equation (1) using N h 1(t) and Nb, which are functions of the above, respectively
1(t).

The count value Kg(t) is measured at the time 1. Starting from t. Every time a predetermined time τ has elapsed since then, the leftmost side of equation (2) is calculated using the measured value Kg(1τ) of the Kg(t) and the Nb to calculate the N(t), and A third step of monitoring whether the relationship of Equation 31 holds between time t1 defined by the sum of * and T and time (t.+lτ).

(to+lτ)Σt, ...(3) Time (t(1+iτ
) = t, ic and this t! The above Nh 1(t
) and the six values Nh s (tt ) of Nt□(1) and Nt□(-) and the t! The value N of said N(t) at
(11) As soon as the relationship of formula (4) or (superior formula) is established, at least the calculation operation of N(t) is stopped, and if the formula (4) is satisfied, there is contamination. and a fourth step of determining that there is no contamination if the formula (t) is satisfied.

N(t,)ΣN hl(import) ・……(4
)N(tz)<Nz 工(Eri song...
(5) If time passes without the relationships in equations (4) and (5) being satisfied and the relationship in equation (3) is established, immediately stop at least the calculation of N(t) and contaminate the and a fifth step of determining whether there is radioactive contamination, and the determination process in the fourth and fifth steps determines whether or not there is radioactive contamination in the object to be determined, and.

2) hσ notation from the count rate measurement value Ng(t) as a function of the elapsed time from time t0 of the total radiation defined as the sum of background radiation and net radiation as radiation emitted from the determination object of the count rate measurement N(t) as a function of the net radiation obtained by subtracting the count rate measurement Nb of the background radiation;
Due to causes other than statistical fluctuations in the count value Kg(t) of the total radiation used in the calculation of g(t) and the count value Kb of the background radiation used in the calculation of the Nb. The standard deviation Eo of the underlying variation and the magnification S
, measurement times T and Tb are set, and the Tb
a first step of measuring the Kb between and determining the Nb by setting Kb/Tb=Nb;

Using the given primary criterion counting rate Nat and E, S, T, Tb, and Nb determined in the first step, (calculate the first counting rate Nal and the second counting rate Nam from the Φ formula, Thereafter, a second step of determining a secondary criterion counting rate NaY that satisfies the relationship of equation (7).

Nax'= Na'b Nas
-...(7) g0 determined in the first and second steps,
S, Tb.

A third step of calculating Nb2(t) and Nt,(t), which are functions of [, from equation (8) using Nb and N8, respectively.

The measurement of the count value Kg(t) is started from the time to, and the [. When the time t1 and the time (1o4
-it), and a fourth step of monitoring whether the relationship of equation (3) holds.

(t, -1-it)Σt1 ・……(3
) The time (1°+
5τ)=t, the above NbxC in this [,
(9) or (10) between Nhs (ts ) and Na2 (''s) of NZ1 (1) and the value N (tI) of N (t) above t, [ As soon as the relationship in the formula is established, at least the calculation operation of N(t) is stopped, and if the formula (9) is satisfied, it is determined that there is contamination, and if the formula (10) is satisfied, it is determined that there is contamination. and a fifth step to determine that there is no contamination.

N(1B)LNh2(ts,) ・++
P9) N(ts)<Nz2(ts)
・……(lO) Time passes without the relationships in equations (9) and (10) being established, and the time (to-
1-tτ)='4 As soon as the relationship of the above equation (3) is established at vc, at least the calculation operation of the above N(t) is stopped, and the above N(t) is
between the value N(t4) and the above-mentioned Na [If the relationship in equation (11) holds, it is determined that VC is contaminated; if the relationship in equation 12) holds, it is determined that there is no contamination. 6th step and N (t4): 4N B -・・・・
(11) N(”4)<Na ・……(1
2), the method for determining radioactive contamination is configured to determine the presence or absence of radioactive contamination in the object to be determined by the determination processing in the fifth and sixth steps;

3) From the count rate measurement value Ng(t) as a function of the elapsed time from the time to of the total radiation defined as the sum of the background radiation and the net radiation as radiation emitted from the object to be determined, the back of the count rate measurement N(t) as a function of the count rate measurement N(t) of the net radiation obtained by subtracting the count rate measurement Nb of the ground radiation;
(t) of the total radiation as a function of Kg(t) and the background radiation count Kb used to calculate Nb based on causes other than statistical fluctuations. The standard deviation of variation E, the magnification S, the upper limit count rate Nah, the lower limit count rate Nat that satisfies the relationship of equation (13), and the measurement time Tb are set, and the Tb
A first step of measuring the Kb between and determining the Nb as Kb/Tb=Nb, and 2 Nah >Nat'-0..."= (13) Be determined in the first step, 8. Tb, Nbe Nah
Nht(t)-)-8・[(Nhl(s+Nb)/l+
N b / T b + B-) tumor = Nah The measurement of the count value Kg<t) is started from the time t0, and the measured value Kg (1 The above N (t) is calculated by performing the calculation on the left side of (No) using the above Nb and the above Nb, and this calculated N (t) is expressed by the equation (15), (16)
The third monitor monitors which of the following equations is satisfied:
procedure and N(t)ΣNlh(t)
・・・・・・ (15) N(t)=(Nah+Nal)
/2 +++m (16)N(t)jN
ht(t) ・・・・・・ (17
) At time (t.+iτ)=t, the above (15),
As soon as either of formulas (16) and (17) is satisfied, at least the calculation operation of N (t) is stopped, and the N th (t) and Nbz (t) (D) in [II゛] are (tJ and Nhl
(ts) and the above (Nah-141IJaz)/
2 and the value N(ts) of the N(t) at the t and IC, if the relationship of the equation K.-(18) is established, it is determined that there is contamination.

If the relationship in equation (20) holds, it is determined that there is no contamination, and if the relationship in equation (19) holds, the predetermined determination content is determined.N(ts)ΣNlh (t+) ・……(
18) N(ts)=(Nah+Nbt)/2
−・・−(19)N (ts)qNht(ts)
- (20), the method for determining radioactive contamination is configured to determine the presence or absence of radioactive contamination in the object to be determined by the determination process in the fourth step;

4) Time of total radiation defined as the sum of background radiation and net radiation as radiation emitted from the object to be determined 1. Subtract the count rate measurement value Nb of the 1< ivy ground radiation from the count rate measurement value Ng(t) as a function of elapsed time from The counted value Kg(t) as a function of the measured value N(t) used to calculate the Ng(t) and the ground radiation used to calculate the Nb. The standard deviation Eo of the variation based on causes other than each statistical variation of the count value Kb,
Deviation standard value E.

Alternatively, set the relative error reference value Ra and the measurement time Tb, and measure the Kb between the Tb and Kb/T.
a first step of determining the Nb by setting b=Nb;

The measurement of the count value Kg(1) is started from the time to, and every time a predetermined time τ elapses from 0, the measured value Kg(tτ) of the Kg(t) and the Nb are used to calculate ( The above N(t) is calculated by performing the calculation on the left side of the O device, and then using the calculated N(t) and the E, , Tb and Nb determined in the first step, the above is calculated from equation (21). N(
The standard deviation E(t) of the total measurement error at t) as a function of [ is calculated, and if the Rs is set in the first step, the F! After determining (t), the relative error (t) as a function of E(t) defined as the ratio of E(t) and N(t) is determined from equation (22), and the first
If the Ra is not set in the procedure, the E(t) obtained from the equation (21) and the Ea determined in the first procedure are
It is monitored whether the relationship of formula (23) holds true between
) between R(t) obtained from the equation and the Ra determined in the first step [a second step of monitoring whether the relationship of equation (24) holds, and Fi(t)=[(N (t)-1-N
b)/l+Nb/Tb+E, ”) ・……
(21)B(t)4Ea ・−・(
23) R(su,≦Ra
・……(24) Time (t6+”)=’r vc
As soon as the above (23) or (24) is satisfied, at least the calculation operation of the above N (t) is stopped, and the above 1! and a third step of maintaining the value N (ly) of the N (t) at Configure the rate measurement method.

[Effect]

If the method for determining radioactive contamination is configured as described above, the first
In the conventional determination method, the time when time T has elapsed from time to [
Contamination determination results are obtained immediately after .

In addition, in the second conventional determination method, if the counting rate N (t) is smaller than N1, the contamination determination result is obtained at a time later than the time [blade], whereas in the first method of the present invention, N (t) is ) and Ntl(t), the contamination determination result is obtained as soon as equation (4) or (5) is established, and the time at this time is earlier than (,), and ( 4
) or (5) does not hold true, a constant contamination determination result can be obtained immediately after time t1, regardless of the magnitude of the -th column constant reference count rate Nat of N(t). It is also clear that N(t) of the present invention is Nh t
(t) and Nzg(t), (9)
As soon as the equation (9) or (10) is satisfied, the contamination determination result is obtained and the time [, is earlier than tl, and even if the equation (9) or (10) is not satisfied, the time t1 It is clear that a definite contamination judgment result can be obtained depending on the magnitude of N(t,'l with respect to the secondary judgment standard counting rate Na) at time t immediately after VC. Then, furthermore, N(t) of the present invention is Nth(t)
and Nhl(t), regardless of the size of N(t), the time 1. of the intersection of the temporal direction line of Nlh(t) and the temporal curve of Nhl(t) from time t0. It is clear that some kind of contamination determination result is always obtained during the time up to vc, and as described later, by appropriately setting the upper limit and lower limit count rate Nah e Naz, time t6 can be changed to time 1. Since the time can be easily set to an earlier time than the first and second conventional determination methods, any of the three methods of measuring radioactive contamination of the present invention described above can be easily set. The contamination determination result will be obtained within the determination time.

Then, if the method for measuring the radiation count rate is configured as described above, g(t) or R,(t), both of which decrease over time in response to the measurement error of N(t), If the count rate measurement result is obtained immediately when the predetermined value E3 or Rarc is reached, and the elapsed time t from time t0 at this time t is -N ("t) <Nff1ax," then a = Ea* N(t+
)=Nmax, the value of time T obtained from equation (28)'
It is clear from equation (21) that the time is within I'max, so it is true.

According to the radiation count rate measuring method of the present invention described above, N(
When t) is smaller than f'Jmax, a count rate measurement result with a predetermined accuracy can be obtained in a shorter measurement time than with the conventional measurement method.

〔Example〕

FIG. 1 is a 70-chart explaining the configuration of an embodiment of the method for determining radioactive contamination according to the present invention, and FIG. 2 is a 70-chart for explaining the method configuration in FIG. 1 for determining radioactive contamination. It is an explanatory diagram of how to judge contamination in a method.

In FIGS. 1 and 2, Pl is set by setting the standard deviation E61 magnification S, measurement time T, and Tb to the same values as in the first or second conventional determination method, and 1 hour Tb. In the first step, the count rate value Nb of the background radiation is determined by measuring the count value Kb of the background radiation between The calculated primary judgment standard count rate Nat and B0 determined in the first step P1,
This is the second procedure in which N(t) and Ntl(t), which are functions of each of S, Tb, and Nb, are determined from equation (1).

Then, P3 measures the count value Kg(t) at time ta.
Starting from , when a predetermined time τ has elapsed from time 1o, c
Using the measured value Kg(it) of Kg(t) and Nb determined in step Pi, perform the calculation on the left side of the ring of equation (2) to obtain N(1
The work step Ql for calculating N (t) as d) and the measured value Kg used in this step Ql to calculate l'J(it).
(5τ) measurement time (t, -1-it) and time 1. The work stage Q! monitors whether the relationship expressed by equation (3) exists between the above-mentioned time t, which has passed the time T from Q! In the third step consisting of
Nh s(t) and Ntl obtained in step P2 in ,
The relationship of equation (4) or equation (5) holds between each part of (E), Nh 1 (tz) and Nt □ (t, ), and the value N(t*) of N(t) in [2. At work stage Q3 and 1 time 1. In equation (4) or (9
As soon as the formula is satisfied, the calculation of at least N(tτ) in the work step Ql is stopped, and <,1. The m4 procedure consists of a work step Q4 in which it is determined that there is contamination if equation (4) holds true, and that there is no contamination if equation (t) holds true.

Then, in FIG. 2, it is illustrated that the relationship of equation (4) holds true.

(to+lτ)S[, ・……(萄N(it
)ΣNh t (t*) ・……(4)N
(11) <Nz1(tt) ・……(
5) In FIG. 1, P5 finally reaches work stage Q2 after time has elapsed without any of the relationships in equations (4) and (5) being monitored in work stage Q3.
When the relationship of equation (3) is established, the temperature is monitored at ℃.

At least N(lτ
) and determines that there is contamination.
1 is a method for determining radioactive contamination in which the presence or absence of radioactive contamination in the object to be determined is determined by the determination process in steps P4 and P5c, which consists of the above-mentioned steps PI to P5. O Radioactive contamination In determination method 1, Nh 1(t) −N 1
Since 1(t) is the time function obtained as described above, if N(t)ΣNh + (Q 6' holds true, it corresponds to the counting rate measurement value N(t) and the true counting rate Ns (t) is always a value greater than or equal to Nat, and N (t) < N zt
If (t) holds, then N8(t) is always the value of Nat undropped, and Ntl(t) −; Smolder < Nh If 1(t) holds, Na(t) is Ns (S < Nat − Ns (
It is clear that it is unclear which of the following relationships is satisfied: S=Nat, Ns(t)〉Na. However, Ntl(sl N(t) < N h
It is clear from FIG. 2 that when l(t) holds true, it takes a long time for equation (4) or (5) to hold if the difference between N (t) and Nat is small. Therefore 1
In determination method 1, if time elapses without formula (4) or formula (5) being satisfied, then formula (3) is satisfied.

(3) Time when the equation first holds true (to-1-iτ)vc
If Nb(iτ) satisfies Nb(iτ)<Na, then it is unconditionally determined that there is contamination.

In other words, in determination method 1, a contamination determination result is obtained as soon as equation (4) or (5) is established starting at time t, = t, -1-iτ, but at time 1. is always at time t1
It is clear from the above that the time is earlier than Since the contamination determination is made regardless of the magnitude with respect to Natvc, the contamination determination result can be obtained in a determination time of about T at the longest according to determination method 1. However, as mentioned above, in the first conventional determination method, it always takes at least T time to determine contamination regardless of the size of N(t), and in the second conventional determination method, N(t) is
If it is smaller than b, a longer determination time than T is required. Therefore, it can be said that the first determination method 1 is a method that can obtain a determination result in a shorter determination time than either of the first and second conventional determination methods. It is clear from Figure 2 that according to the zero determination method 1, the larger the difference between N (t) and Nat, the shorter the determination time will be to obtain the determination result.Especially, when actually performing contamination determination work, N (Because the state of S<Na is normal.

In such a case, according to the present determination method 1rc, a determination result can be obtained in an extremely short time.

FIG. 3 is a flowchart illustrating the configuration of an embodiment of a radioactive contamination determination method different from determination method 1 of the present invention, and FIG. 4 is a radiation radiation diagram showing a 70-chart for explaining the method configuration in FIG. FIG. 2 is an explanatory diagram of how to determine contamination in a method for determining functional contamination. Figures 3 and 4 refer to Figures 1 and 2.
Figure (the same quantity or thing as shown is the first one for the thing)
The same reference numerals as in FIG. 2 and FIG. 2 are used.

Now, in FIGS. 3 and 4, P6 is E determined using the above-mentioned given primary criterion count rate F'Jat and the first procedure PI. , 8. Using T, Tb and Nb, c (61), (6
2) and (η), the first and second counting rates Na1l
The second procedure P7 in which Naff1 and the secondary criterion count rate Nb are determined is the first and second procedure P1. Using E, , S, Tb, Nb and Nb determined in P6, each is calculated from equation (8) as N h *(t
), Nt, and (E), the third step P8 consists of the same work steps Ql and Q2 as shown in Fig. In the fourth step in which it is monitored whether the relationship in equation (31) holds true, P9 calculates this value at time (to fifteen τ) = t1 when the relationship in equation (3) does not hold yet. 11
Move J [Nbx(t) and Ntl( obtained in P7) in
t), Nhm(ts) and Nz2(Is) and 1. (9) or (
Lo) Calculation operation of at least N(iτ) is carried out in work step Q1 as soon as the relationship of equation (9) or (10) is established in the work step Q5 in which it is monitored whether the relationship in equation (lo) is established or not. If the equation (9) holds true at t, then there is contamination.The &M4 diagram exemplifies that the relationship expressed by the equation (9) holds true at ts.

Na's+8 ・((Na 1+N b)/T 10N
b/T 10Eo”)=Nata-・(61)Na x
8 ・((NB z+Nb)/T+Nb/T+Eo
” Ashi=0−- (62)Na1ΣNaΣNa2
・……(s(t, −1−tτ)Σ(,
・・・・・・ (3) N(t,) hp(ts)
・・・・・・ (9) N(tm)<Nb
(t,)...(10) In Fig. 3, the PIO is monitoring at work stage Q5' (9
) and (10) are not satisfied, and finally, when the relationship of equation (3) monitored in work stage Q2 is established at time (t6+4τ)=[, At least N(
When the calculation operation of iτ) is stopped, rc, time 1. & (If the relationship of formula (11) is established between the value N(t,) of Ogeru N(t) and Na determined in the second step P6, it is determined that there is contamination12) If the relationship of the formula is established, rc is the sixth step in which it is determined that there is no contamination, and 2 is the step PI shown in the figure and the step 1 [P6 to P10]. This is a radioactive contamination determination method that determines the presence or absence of radioactive contamination.

It is the law.

N(-)ΣNa ・……(11
)N(t4) <N11 ・……(
12) In method 2 for determining radioactive contamination, Nhj') -Nz
1(t) is the time function obtained as described above.

N(t)ΣNh! If (t) holds, then the true counting rate N8 (t) corresponding to this N(t) is always a value greater than or equal to N8, and if N(su < Nb!(t) holds, then N11
(t) is always less than Nb, and Nzg(t)4N
(t) <N h7t) holds, Nb(t) is N
5O) < N B * Nz(t) = NJI e
It is clear that it is unclear which relationship of N5(t) > N @ is satisfied, and therefore this determination method 2
In this case, the above-mentioned judgment process is performed in the work step Q6, but if Nlx<') 1-N(1<Nh g(t) holds, then if the difference between N(t) and N8 is small, then (9 )
It is clear from FIG. 4 that it takes a long time for equation (10) to hold true. Therefore, in 1 Judgment Method 2, if time elapses without formula (9) or (lO) being satisfied, and starting at time (to + iτ) = duck (Equation 31 is satisfied, it is exactly the same as the first conventional determination method) The above-described determination process is performed in step PIO.

Since Judgment Method 2 is configured as described above, it is clear that a contamination judgment result can be obtained in Judgment Method 2vc in a judgment time of about T at the longest, similar to Judgment Method lrc. It can be said that the determination method 2 is a method that can obtain a determination result in a generally shorter determination time than either of the first and second conventional determination methods. Furthermore, according to Judgment Method 2, it is clear from Fig. 4 that the larger the difference between N(t) and Na, the shorter the judgment time becomes.Especially when actually performing contamination judgment work, N (Since the state where S<Na is common, in such a case, according to the present determination method 2, it is expected that the determination result can be obtained in an extremely short time as in the determination method lvc.

Note that in determination method 2, Nb<Nlt, so Nhl
-45= (S<Nht(t)), and the probability of determining that there is contamination using the result determination method 2vc is higher than that using the determination method ivc. The standard deviation C(N h
t(S+Nb)/E+Nb/Tb+Ftl,") The reliability of the contamination determination based on the difference between the standard deviation of this Nht(Q) and the actual N(t), which is equal to Q, is the determination method.
This has the advantage of being safer than in the case of

Figure 5 shows the determination method of the present invention! and 70-chart for explaining the configuration of an example of a method for determining radioactive contamination different from 2. FIG. 6 shows a 70-chart for explaining the method configuration in FIG. FIG. 3 is an explanatory diagram of how to determine contamination. In FIGS. 5 and 6, the same quantities or matters as those shown in FIGS. 1 through 4 are given the same reference numerals as in FIGS. 1 through 4.

Now, in FIG. 5 and FIG. 6, P11 is set by setting the standard deviation Eo, magnification S, and measurement time Tb to the same values as in the first or second conventional determination method, respectively, and setting the upper limit count rate Nah, for example. Nat is set to a predetermined value, and the lower limit count rate Nat is set to a predetermined value under the condition of equation (13), and the count value Kb of background radiation during time Tb is measured to obtain Kb/ The first step is to determine the count rate measurement value Nb of the background radiation as Tb=N1), PI3 is E0 determined at the first step pH,
8. Using Tb, Nb, N11h and Nat (
14) From equations, Nht(t) and N
The 2,000th i, PI3, who was determined to find lh (t), performed the same work as the aforementioned work step Q1 using the measured value Kg (iτ) of K (t) and Nb determined by the procedure pH. Work step Q to calculate N(t) as N(iτ)
7, and N(1) calculated at this stage Q7 is (rs),
In the third step, which consists of a work step Q8 to monitor which of the equations (16) and (17) is satisfied, PI3
is (15) at time ((.+iτ)=t, (
16) As soon as either of the equations (17) is satisfied, the calculation operation of at least N(iτ) in the work step Q7vc is stopped, and Nlh(t) at [, t,
and Nbz(t), Nlh (Is) and Nhl(
ts) and vc(Na h+NBz)/2 and Llvc
I'm, (18
), it is determined that there is contamination.

This is the fourth procedure in which it is determined that there is no contamination when the relationship expressed by equation (20) holds, and when the relationship expressed by equation (19) holds, the VC is determined to have a predetermined determination content.

Nah>NazΣ0...(13)
N(Nth(t) ・……(1
5) N(su) (Nah+Nal)/2
−・=(16)N(t)4:Nht(t)
・……(17) N(tl) th(ti)
・……(18)N (tJ=(Nah+Nat
)/2 -- (19)N(El)4 Nht(
(20) 3 in FIG. 5 is a method for determining radioactive contamination in which the presence or absence of contamination in the object to be determined is determined by the attached process in step P14, which includes the illustrated steps pH to 14. FIG. 6 exemplifies that the relationship of equation (18) holds in the equation. ta in FIG. 6 is a time function Nlh (t
) and Nht(t) at the intersection point X.

In method 3 for determining radioactive contamination, the determination process described above is performed, so in this case, the true value Na(t) of N(t) is Na2
If it is confirmed that there is a possibility of existence in the range of counting rate N above, it is determined that there is contamination, and if Ns(t) is less than or equal to Nah,
If it is confirmed that there is a possibility of contamination within the range of
, Nlh(L) are the time functions obtained as described above, so at the intersection X in FIG. 6, Nz(N ah + Na
l)/2 Therefore, in Kono judgment method 3,
Regardless of the size of N(t), when time 1 passes, (15
), (16), and (17) are established, and the contamination determination result will be obtained at the latest at time t6 or immediately after one operation. However.

It is clear from FIG. 6 that in this judgment method 3, the maximum time for contamination judgment of (tate) is adjusted by adjusting the magnitude of (Nah "az).

In other words, this contamination determination method 3 can set the longest contamination determination time to a time within T by appropriately setting -Nah and Niz, so it is faster than either of the first and second conventional methods. Overall, it can be said that this is a method that can obtain contamination determination results in a short determination time.

FIG. 7 is a 70-chart illustrating the configuration of an embodiment of the radiation count rate measuring method according to the present invention.

In this figure, the same quantities or matters as those shown in FIGS. 1 to 6 are designated by the same symbols as in FIGS. 1 to 6. That's right.

In FIG. 7, PI3 is the standard deviation E mentioned above.

and measurement time Tb are set to the same values as in the case of the conventional measurement method described above, and the deviation reference value Ea, which is equal to σ in equation (28), is set to the value of σ in the case of the conventional measurement method, or Set a relative error reference value Ra defined as the ratio of Ea and N(t) set to The first step, Q, is to determine the count rate measurement value Nb of background radiation.
9 starts measuring the count value Kg(t) of total radiation from time 1o, and when a predetermined time τ has passed from this 10, Kg(t) is measured.
(t) measured value Kg(iτ) and N determined in step P15
At the same work stage as Ql described above, in which N(t) is calculated as N(iτ) by performing the calculation on the left side of the odor device using 1st
E, , T1. determined in step P15. From equation (21) using Nb and Nb, the total measurement error at N (t)
This is the work step in which the standard deviation E (t) as a function of E (t) is determined.

E(t)=[(N(t)-I-Nb)/[+Nb/Tb
+E,! ]W...(21) Qll is the E(t) obtained by the first stage QIO when RII is set in the first step P15, and the work stage at which this E(t) was calculated, Ql2
If Ea is set in the first step P15 but Ra1 is not set, then (2
3) a work step of monitoring whether the relationship in the formula holds;
When Ra is set in the first hand pts, Ql3 is (22
PI3 is a second procedure consisting of the above-mentioned work steps Q9 to Q13, which is a work stage for monitoring whether the relationship of formula (24) is established between R(1) obtained from formula ) and formula (24).

E (1),! E a・−・・−・(23)R(su4
:='R, - (24) PI3 is Ql2. Ql
As soon as either one of the relationships in equations (23) and (24) monitored in step 3 holds true at time (le+iτ)=t, the calculation operation for at least N(t) in work step Q9 is stopped, and N(t) at 1 time [,
4 is the third step in which the value N(t?) is held, and 4 is the value of each step P15. This is a radiation count rate measuring method in which the count rate value N(t,) consisting of P16°PI3 and held in one step P17 is used as the count rate measurement value of the radiation emitted from the measurement object.

Radiation count rate measurement method 4 is configured as described above, so E (t) or R (1) shows a large value at the beginning of the calculation of N(t) in one work step Q9vc. As time progresses, the count rate decreases according to formula (21) or (22), and as soon as Ffa or R8 is reached, the count rate measurement result is obtained, but if E (1) or R (1) is Ea or The elapsed time t from time t0 when Ra becomes h′lc is N(t
, ) is smaller than Nm1lX, cr=E8, N(tl)=Nm!, regardless of the size of N(ty). It is clear from equation (21) that IX is shorter than the measurement time T in the conventional measurement method calculated from equation (28). Therefore, in measurement method 4, N(ty) is Nm
If it is smaller than aX, it can be said that this is a radiation count rate measurement method that can obtain measurement results with a predetermined accuracy in a shorter measurement time than in the conventional measurement method, regardless of the size of N(ty).

〔Effect of the invention〕

As described above, in the present invention, 1) the time of total radiation defined as the sum of background radiation and net radiation as radiation emitted from the object to be determined; The count rate measurement N(t) as a function of the net radiation obtained by subtracting the count rate measurement Nb of the background radiation from the count rate measurement Ng(t) as a function of elapsed time since The count value as a function of the total radiation used to calculate Ng(t), and the count value Kb of the background radiation used to calculate (t) and Nb.
The standard deviation Eo of the variation based on causes other than each statistical variation.

While setting the magnification S and measurement times T and Tb,
Measure Kb between b and set Kb/Tb=Nb as Nb
Using E0, S, Tb, and Nb determined in the first step and the given primary criterion count rate r'Jat, each is calculated from equation (1) as a function of N h. 1(t) and Ntl
(t), and the measurement of the count value Kg(t) is started from time t0, and 1. When a predetermined time τ has passed since then, N (t) is calculated by calculating the left-most side of equation (2) using the measured value Kg(iτ) of (t) and Nb, and 1. The third step is to monitor whether the original relationship holds between time [, defined as the sum of and T, and time (t, -1-tt), and K g (iτ)/iτ −Nb=Ng(iτ)−Nb
=N(iτ)(t0+iτ):4t,
...3) Time when the relationship in equation (3) does not hold yet (to + lτ) = t, vc oi'f - this t, IC
Nht(t) and Ntl(t) (7) 6-value Nh
1(l□) and Nt(t2) and t, N(t
) value N(tm), as soon as the relationship of equation (4) or (c5) is established, at least the calculation operation of N(t) is stopped, and if equation (4) is established, the IC is and a fourth step in which it is determined that there is contamination, and if formula 5) is established, it is determined that there is no contamination.

N(11)ΣNh' t ("t) ・...
...(4) N(t*) < Ntl(tt)
・……(5) If time passes without the relationship between equations (4) and (5) being established and the relationship between equation (3) is established, immediately stop the calculation operation of at least N(t) and remove the contamination. The method for determining radioactive contamination is configured such that the presence or absence of radioactive contamination in the object to be determined is determined by the determination processing in the fourth and fifth steps.

2) Back from the count rate measurement value Ng(t) as a function of the elapsed time from the time t of the total radiation, defined as the sum of the background radiation and the net radiation as radiation emitted from the target object. The count rate measurement value N(t) as a function of the net radiation obtained by subtracting the count rate measurement value Nb of the ground radiation, the count value as a function of the total radiation used to calculate Ng(t) Count value Kb of background radiation used for calculation of Kg(t) and Nb
The standard deviation of the variation due to causes other than each statistical variation, E, and.

While setting the magnification S and measurement times T and Tb,
Measure Kb between b and set Kb/Tb=Nb as Nb
Using the given primary judgment standard counting rate Nat and E0, S, T・Tb, and Nb determined in the first procedure, calculate the first counting rate Nal and the second counting rate from equation (6). Find the rate Nap, and then find the secondary criterion counting rate Na that satisfies the relationship of equation (7).
a second step of determining NB 1 'h Na ';hN a R"""(t
) E0 determined in the first and second steps, 8. Tb,
A third step of finding N h g(t) and Nt2(t), which are functions of each from equation (8) using Nb and N8, and Nt,! (t)−+−s・[(Ntz(t)−1
-Nb)/[+Nb/Tb+Eo2] = Na Measure the count value Kg(t) at time 1. rcKg(t
) using the measured values Kg(lτ) and Nb, calculate N(t) by performing the calculation on the left side of the device, and calculate N(t) at time 1 defined by the sum of 1o and T and time (t, - 1-tt) and a fourth step of monitoring whether the relationship of equation (3) holds.

(to-1-iτ) h t * -0-
0(31(time (t, -
1-tt)==tsvc, this t, Nh at c,
(t) and Nt, 6 values of (t) Nhl (ts) and Nt
*c”s) and 1. The value of N (t) at [N(II)
As soon as the relationship of equation (9) or (10) is established between ) formula is established, it is determined that there is no contamination.

N(T,s)ΣNll, (tl)...
・・Rei N(ts)＜Nt□(−)……
(10) As soon as time passes without the relationships in equations (9) and (10) being satisfied and the relationship in equation (3) is established at one time (to-4-;τ)='i[, at least N
When the calculation operation of (t) is stopped, N in F, t,
(t) +7) between value N(t4) and Nb vc (H)
If the relationship in the formula holds true, it is determined that there is contamination.1
2) A sixth step in which it is determined that there is no contamination if the relationship in the formula is established, and N (14) 'h Na... (11) N (t
4) <Na --------・(12)
The determination process in the fifth and sixth steps determines the presence or absence of radioactive contamination in the target object.
It constitutes a method for determining VC radioactive contamination, and also.

3) Measured count rate Ng(t) or Lanoitsukkland as a function of the elapsed time from time t0 of total radiation defined as the sum of backgrass radiation and net radiation as radiation emitted from the object to be determined Subtract the radiation count rate measurement Nb (the net radiation obtained in S from the count rate measurement N (t) as a function of the total radiation used to calculate Ng(t), The count value Kg (
Standard deviation Eo, magnification S, upper limit count rate Nah, and (1
3) Lower limit counting rate Nat and measurement time T that satisfy the relationship of formula
Set b and measure Kb between Tb and calculate K
A first step of determining Nb as b/Tb=Nb.

Nbh>Nbti0...(13) R6 determined in the first step = S e T b - N 1) -
Measure the count value Kg(t), which is a function of Ngh and Nat, from equation (14) at time 1. , and when a predetermined time τ has elapsed from Lo, rcK
Using the measured value K g (ti) of g (t) and Nb, calculate N (t) by performing the calculation on the left side of the device, and calculate the calculated N (Sbl (15) Equation (16) formula,
and a third step of monitoring which of the equations (17) is satisfied.

N(1)ΣNth(t) ・……(15
)N(Lee(Nah+Nal)/2 --
(16) N(su4 Nbz(t)
・……(17) Time (tO+it)==i, Kite (15) As soon as either of equations (16) and (17) is satisfied, stop the calculation operation of at least N (t), and [ , Nt burr and Nhl(t)
Nlh(t, ) and Nht(tll) and v
c(Nah+Nal)/2 and 1. If the relationship of equation (18) holds between the value N(ti) of N(t) in , it is determined that there is contamination, and if the relationship of equation (20) holds, then If it is determined that there is no contamination and the relationship of equation (19) is established, the predetermined determination content is used as the fourth step.
8) N(ts)=(Nah+Nal)/2...
・-・(19) N(ts) (= Nht(-)
... (20), the method for determining radioactive contamination is configured to determine the presence or absence of radioactive contamination on the object to be determined by the determination process in the fourth step,
In addition, 4) From the count rate measurement value Ng(t) as a function of the elapsed time from time t0 of the total radiation defined as the sum of the background radiation and the net radiation as the radiation emitted from the evaluation object. The count rate measurement value N(1) as a function of 1 of the net radiation obtained by subtracting the count rate measurement value Nb of the background radiation is calculated as a function of the total radiation used to calculate Ng(t). Numeric value Kg(t
) and the standard deviation E of the variation based on causes other than statistical fluctuations in the count value Kl) of the background radiation used in the calculation of Nb, the deviation reference value Ea or the relative error reference value Ra, and the measurement time Tb. The first step is to measure Kb between [, Tb and obtain Nb as Kb/Tb=Nb, and to start measuring the count value Kg(t) from time t0 and for a predetermined time τ from h tO. After , using the measured value Kg(iτ) of c Kg (t) and Nb (perform the operation on the left side of the device to calculate N(t),
This calculated N(t) and E0, Tb determined in the first step
and Nb, find the standard deviation E(t) as a function of the total measurement error in N(t) from equation (21),
When R3 is set in the first step, after finding E(t), we further calculate the relative error R(t) as a function of which is defined as the ratio of E(t) and N(1). (22), and if R is not set in the first step, the difference between E(t) found from equation (21) and E8 determined in the first step [(23
) is established, and in the first step R
If a is set, the relationship K between R(t) obtained from equation (22) and Ra determined in the first step. A second step of monitoring whether the relationship of equation (24) holds.

E(t)=((N(t)+Nb)/t+N
b/T b+Ba wealth] ・……(21) E(t)−
;E a --------(23)R
(t)4R3...(24) At time (t.+lτ)=t, (23) or (2
4) As soon as the formula is established, the calculation operation for at least N(t) is stopped, and the third step is to hold the value N(t7) of N(t) in vct and vc, and set N(ty) as the measurement target. A radiation count rate measurement method was configured to measure the count rate of radiation emitted from an object.

Therefore, when the radioactive contamination determination method is configured as described above, the first conventional determination method obtains the contamination determination result immediately after time t1, which is the time T elapsed from the time [・, and the second conventional determination method In the determination method, if the counting rate N(t) is smaller than N3, the contamination determination result is obtained at a time after time 1, whereas the present invention's N(1) is N' h 1(t) and Nz1(t), formula (4) or (
5) As soon as the formula holds, the contamination determination result is obtained, and the time at this time is earlier than t, and (4)
Direct flk at time t1 even if the equation or (5) does not hold.
It is clear that VC can obtain a constant contamination determination result regardless of the magnitude of N(t) with respect to the -order constant reference counting rate N1, and also, if N(t) of the present invention is Nhl
(t) and Nl2(t), (9)
As soon as the formula or (lO) holds true, the contamination determination result is obtained, and the time t at this time is earlier than tl, and even if the formula (9) or (lO) does not hold, the time [ , the time immediately after ! 4, it is clear that some definite contamination determination result can be obtained depending on the magnitude of N(t4) with respect to the secondary determination reference count rate N1IVC. Then, we further convert N(t) of the present invention to Nth(t)
and N h , 7t), N(1)
Regardless of the size of the time 1. to the time 5rc of the intersection of the temporal curve of Nth(t) and the temporal curve of Nhl(t)
By appropriately setting the upper and lower limit counting rates Nah and Naz, time 1. can be set at a time earlier than time t1. Therefore, in the present invention, any of the above-mentioned three types of radioactive contamination measuring methods of the present invention can be used, and neither of the first and second conventional determination methods can be used. This method has the effect of obtaining contamination determination results in a shorter determination time than the method described above.

Then, if the method for measuring the radiation count rate is configured as described above, E(t) or R(t), both of which decrease over time, corresponding to the measurement error of N(t), are each given a predetermined value. In the normal case where the count rate measurement result is obtained immediately when the value Ea or R8Vc is reached, and the elapsed time t from time 1 at this time t is N(t+)<Nmax,
σ= B a+ N (t*)=Nmax (
28) Since it is clear from equation (21) that the time T is within the value 'I'max obtained from equation (28), therefore.

In the radiation count rate measurement method of the present invention, N(t) is Nm
When it is smaller than aX, there is an effect that a count rate measurement result with a predetermined accuracy can be obtained in a shorter measurement time than with the conventional measurement method.

[Brief explanation of the drawing]

Figure 1 shows one method for determining radioactive contamination according to the present invention.
70-Chart illustrating an example configuration. FIG. 2 is an explanatory diagram of how to determine contamination in the method for determining radioactive contamination, which shows a 70-chart for explaining the method configuration in FIG. FIG. 3 is a 70-chart explaining the configuration of an embodiment of a method for determining radioactive contamination that is different from the method for determining radioactive contamination shown in FIG. 1 [70-chart] according to the present invention; FIG. 3 is an explanatory diagram of how to determine contamination in the radioactive contamination determination method in which a 70-chart for explaining the method configuration is shown. FIG. 5 is one of the methods for determining radioactive contamination, which is different from both of the two methods of determining radioactive contamination, each of which has a flowchart shown in FIG. 1 and FIG. 3, according to the present invention! Flowchart illustrating the configuration of the example. FIG. 6 is an explanatory diagram of how to determine contamination in the radioactive contamination determination method in which the 70-chart for explaining the method configuration is shown in FIG. 5. FIG. 7 is an implementation of the radiation count rate measuring method according to the present invention. 70-Chart illustrating an example configuration. l・2.3...Method for determining radioactive contamination, 4...
...Measurement method of radiation count rate, K, ...Count of total radiation, Kb...Count of background radiation, Nyo...Count of total radiation Counting rate, Nb
...Counting rate of background radiation, N...
...Net radiation counting rate, N11ta...-Next row constant standard counting rate, Na...Secondary judgment standard counting rate. Nah... Upper limit counting rate, Nata... Lower limit counting rate - Nh 1(t) - Nhisu, Nt, (E)
, Nt□(su, Nhl(E) , Nlh(1)・
...Function of E., E(t)...Standard deviation, Ea...Standard deviation value, R(t)...
Relative error, Relative error reference value, T, Tb
...Measurement time, S...Magnification, ta...
...Time, 1. ．． 1. ．． 1. . 1, ,1. , 1 glue, E, , t,...
Time, Pl, Pll, Pl5...First step, P
2. P6. Pl2. Pl6... Second step.

Claims (1)

[Claims] 1) Count rate measurement value Ng as a function of elapsed time t from time t_0 of total radiation defined as the sum of background radiation and net radiation as radiation emitted from the object to be determined of the count rate measurement N(t) as a function of the t of the net radiation obtained by subtracting the count rate measurement Nb of the background radiation from (t).
Causes other than statistical fluctuations in the count value Kg(t) of the total radiation used to calculate g(t) as a function of t and the count value K_b of the background radiation used in the calculation of Nb Set the standard deviation E_0 of the original variation, the magnification S, and the measurement times T and T_b, measure the K_b between the T_b, and calculate K_b/T_b=
Using the first step of calculating the N_b as N_b, the given primary criterion counting rate N_a_t, and E_0, S, T_b, and N_b determined in the first step, each function of the above t is calculated from equation (1). Some N_h_1(t) and N
_l_1(t) and ▲Mathematical formulas, chemical formulas, tables, etc.▼...(1) The measurement of the count value Kg(t) is started from the time t_0, and the predetermined time τ is started from the t_0. Each time, the leftmost side of equation (2) is calculated using the measured value Kg(iτ) of the Kg(t) and the N_b to calculate the N(t), and the t_0 and the T are calculated. The third step is to monitor whether the relationship in equation (3) holds between time t_1 and time (t_0+iτ) defined as the sum of ▲Mathematical formulas, chemical formulas, tables, etc.▼...(2) (t_0+iτ)≧t_1...(3) Time (t_0+
iτ)=t_2, the N_h at this t_2
_1(t) and each value N_h_1 of said N_l_1(t)
(t_2) and N_l_1(t_2) and the value N(t_2) of N(t) at t_2, as soon as the relationship of equation (4) or equation (5) is established, at least the calculation of N(t) is performed. a fourth step of stopping the calculation and determining that there is contamination if the above formula (4) holds; and determining that there is no contamination if the above formula (5) holds; N(t_2); )≧N_h_1(t_2)...(4) N(t_2)<N_l_1(t_2)...(5) If time passes without the relationships in equations (4) and (5) being established, the equation (3) ), the calculation operation of at least N(t) is stopped immediately and the determination target object is determined to be contaminated by the determination processing in the fourth and fifth steps. A method for determining radioactive contamination, the method comprising: determining the presence or absence of radioactive contamination. 2) From the count rate measurement value Ng(t) 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 as radiation emitted from the object to be determined, the back of the count rate measurement N(t) as a function of the t of the net radiation obtained by subtracting the count rate measurement N_b of the ground radiation, of the t of the total radiation used to calculate the N_g(t); Standard deviation E_ of variations based on causes other than each statistical variation of the count value K_g(t) as a function and the count value K_b of the background radiation used to calculate the N_b.
0, magnification S, measurement time T and T_b, and measure the K_b during the T_b to obtain K_b/
The first step is to obtain the N_b as T_b=N_b, and the first step is calculated from equation (6) using the given primary criterion count rate N_a_t and E_0, S, T, T_b, and N_b determined in the first step. Counting rate N_a_1 and second counting rate N
_a_2 is determined, and then the second step is to determine the secondary criterion count rate Na that satisfies the relationship of equation (7). ...(7) E_0, S, T_b, determined in the first and second steps,
From equation (8) using N_b and N_a, the above t
The third step is to find N_h_2(t) and N_l_2(t), which are functions of ▲Mathematical formulas, chemical formulas, tables, etc.▼
...(8) The measurement of the count value K_g(t) is started from the time t_0, and the measured value K_g(iτ) of the K_g(t) and the N
_b and perform the operation on the left-most side of equation (2) to obtain the above N
t) and monitors whether the relationship of equation (3) holds between time t_1 defined by the sum of t_0 and T and time (t_0+iτ); , chemical formulas, tables, etc.▼…(2) (t_0+iτ)≧t_1…(3) The time (t_0+
iτ)=t_3, the N_h at this t_3
_2(t) and each value N_h_2 of said N_l_2(t)
(t_3) and N_l_2(t_3) and the value N(t_3) of N(t) at t_3, as soon as the relationship of equation (9) or equation (10) is established, at least the calculation of N(t) is performed. Along with stopping the calculation, the above (9)
If the formula holds true, it is determined that there is contamination and the above (10
) formula is established, it is determined that there is no contamination, and N(t_3)≧N_h_2(t_3)...(9)
_3)<N_l_2(t_3)...(10) (9) above
Time elapses without the relationship of formula and formula (10) being satisfied, and at time (t_0+iτ)=t_4, the above (3) is satisfied.
As soon as the relationship of the formula is established, at least the above N(t)
At the same time, between the value N(t_4) of the N(t) at the t_4 and the N_a, (1
1) A sixth step in which it is determined that there is contamination if the relationship in equation (12) holds, and that there is no contamination if the relationship in equation (12) holds, and N(t_4)≧N_a...( 11) N(t_4)<N_a (12) Radioactivity characterized by determining the presence or absence of radioactive contamination in the object to be determined by the determination processing in the fifth and sixth steps. How to determine contamination. 3) From the count rate measurement value N_g(t) 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 as the radiation emitted from the object to be determined, the back of the count rate measurement N(t) as a function of the t of the net radiation obtained by subtracting the count rate measurement N_b of the ground radiation, of the t of the total radiation used to calculate the N_g(t); Standard deviation E of variations based on causes other than each statistical variation of the count value K_g(t) as a function and the count value K_b of the background radiation used to calculate the N_b
_0, the magnification S, the upper limit count rate N_a_h, the lower limit count rate N_a_l that satisfies the relationship of equation (13), and the measurement time T_b, and the K_b between the T_b is measured as K_b/T_b=N_b. A first procedure for calculating the N_b, N_a_h>N_a_l≧0...(13) E_0, S, T_b, N_b determined in the first procedure,
Using N_a_h and N_a_l, N_h_l(t) and N_l_h, which are functions of the above t, are obtained from equation (14), respectively.
(t), and ▲mathematical formulas, chemical formulas, tables, etc.▼...(14) The measurement of the count value K_g(t) is started from the time t_0, and the predetermined time τ is elapsed from the t_0. The measured value K_g(iτ) of the K_g(t) and the N
_b is used to calculate the left-most side of equation (2) to obtain the above N(
t) and this calculated N(t) is expressed as equation (15),
There is a third step that monitors whether formula (16) or (17) is satisfied, and ▲mathematical formulas, chemical formulas, tables, etc.▼…(
2) N(t)≧N_l_h(t)...(15) N(t)=(N_a_h+N_a_l)/2...(16
)N(t)≦N_h_l(t)...(17) At time (t_0+iτ)=t_5, the above (15),
As soon as either of formulas (16) and (17) is satisfied, at least the calculation operation of N(t) is stopped, and
The N_l_h(t) and the N_ at t_5
Each value of h_l(t) N_l_h(t_5) and N_h_
l(t_5) and the above (N_a_h+N_a_l)
/2 and the value of N(t) at t_5
), if the relationship of equation (18) holds, it is determined that there is contamination; if the relationship of equation (20) holds, it is determined that there is no contamination; If the relationship holds true, the fourth step is to use the predetermined determination content, and N(t_5)≧N_l_h(t_5)...(18)N(
t_5)=(N_a_h+N_a_l)/2...(19
)N(t_5)≦N_h_l(t_5) (20), and the determination of radioactive contamination is characterized in that the presence or absence of radioactive contamination in the object to be determined is determined by the determination process in the fourth step. Method. 4) From the count rate measurement value N_g(t) 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 as the radiation emitted from the object to be determined, the back of the count rate measurement N(t) as a function of the count rate measurement value N_b of the ground radiation obtained by subtracting the count rate measurement value N_b of the said net radiation as a function of the count rate measurement value N(t) of the said total radiation used to calculate said N_g(t). Standard deviation E of variations based on causes other than each statistical variation of the count value K_g(t) as a function and the count value K_b of the background radiation used to calculate the N_b
_0 and deviation reference value E_a or relative error reference value R_a
and a measurement time T_b, and a first step of determining the N_b by measuring the K_b during the T_b and setting K_b/T_b=N_b; and measuring the count value K_g(t) at the time t_a. The measured value K_g(iτ) of the K_g(t) and the N
_b is used to calculate the left-most side of equation (2) to obtain the above N(
t) is calculated, and then (2
1) Find the standard deviation E(t) of the total measurement error in N(t) as a function of t from the formula, and if the R_a is set in the first step, after finding the E(t). Further, the relative error R(t) as a function of the t defined as the ratio of this E(t) and the N(t) is calculated from equation (22), and when the R_a is not set in the first step. monitors whether the relationship in equation (23) holds between the E(t) obtained from the equation (21) and the E_a determined in the first step, and determines the R_a in the first step. is set, a second step of monitoring whether the relationship of equation (24) holds between R(t) obtained from equation (22) and R_a determined in the first step; ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(21) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(22) E(t)≦E_a ...(23) R(t)≦R_a...(24) As soon as the above equation (23) or (24) is established at time (t_0+iτ)=t_7, at least the above N
(t), and a third step of stopping the calculation operation of N(t) and holding the value N(t_7) of the N(t) at the t_7, and converting the N(t_7) into the radiation emitted from the measurement object. A method for measuring a radiation count rate, characterized in that the count rate is a measured value of .