TWI413793B - A method of radioactivity measurement for distinguishing dose from different direction - Google Patents

Abstract

This method uses the simple partitions and measure radiation dose at the both sides of the partition using TLD or other measurement tool. This measurement method can distinguish dose from different direction through the simple calculation of measurement data. This measurement method is the same as the original procedure, only to increase the two partitions, the cost is extremely low and the procedures are quite simple.

Description

A measuring method for differentiating doses in different directions

The invention relates to a measuring method for distinguishing doses in different directions, in particular to measure the thickness or material of the separator, and only need to use a separator of suitable material and thickness which can generate attenuation, and then measure To achieve the effect of distinguishing doses in different directions.

In radiation environments, including nuclear facilities, dose rate measurements for some test points are often performed, and currently used measurement devices include detectors or TLDs, however, regardless of the use of a detector or TLD, The measured value is the sum of the dose rates of the detection points in all directions.

In some cases, it is necessary to assess the contribution of the dose rate of the test point in different directions. For example, in the decommissioning process of a nuclear facility, the removal or movement of components and equipment in a certain direction will be the dose at the test point. How much impact is the rate, these assessments need to be analyzed by the information of the dose rate from the direction of the detection point, and the dose rate from the direction of the detection point is difficult to be measured by the general measurement, so some new measurements are needed. The method or measurement device is used to obtain the following defects: the detectors currently used are somewhat directional, but the directionality means that the detectors have different values for the doses from different directions, such as : The dose from the front can be measured to 100%, and the amount from the side can be up to 80%. These can be obtained from the calibration report of the instrument, but basically the detector still measures the total dose from all directions, so the detection The measurement of the device does not distinguish the contribution of the dose rate from the different directions.

The TLD currently in use accepts doses in all directions through the test point and does not distinguish between doses from different directions.

It is feasible to set up a heavy shielding to block the dose in other directions. It is feasible to measure only the single direction dose, but it is necessary to prepare a thick screen and the operation is inconvenient, and some narrow places are even more impossible.

The main purpose of the present invention is to achieve the measurement effect without knowing the thickness or material of the separator, and only using a separator of suitable material and thickness which can produce attenuation.

In order to achieve the above object, the present invention is a measuring method for distinguishing doses in different directions, and in the first embodiment, the following steps are included:

Step 1: At the position of a detection point, the measurement of the single-layer separator is performed, and the doses on the upper and lower sides of the separator are measured to obtain the measurement value above the single-layer separator and the measurement value under the single-layer separator. The partition is placed facing upwards and downwards.

Step 2: At this detection point, the measurement using the double-layer separator is performed, and the doses on the upper and lower sides of the separator are measured to obtain the measurement value above the double-layer separator and the measurement value under the double-layer separator. The partition is placed facing upwards and downwards.

Step 3: Perform a non-separator dose measurement at the same inspection point to obtain a non-separator measurement value.

Step 4: Calculate the dose from the top, the dose from the bottom, and the dose from the side based on the measured values.

In the second embodiment of the present invention, the following steps are included:

Step 1: At the position of the detection point, perform the measurement using the separator, measure the dose on the upper and lower sides of the separator, and obtain the measured value above the partition and the measured value under the partition, and the partition is oriented Above and below.

Step 2: Another non-separator dose measurement is performed at the same inspection point, and no separator measurement value is obtained.

Step 3: Calculate the dose from the top and the dose from below.

Please refer to FIG. 1 for a schematic view of the first embodiment of the present invention. As shown in the figure: the present invention is a measuring method for distinguishing doses in different directions, and the dose source of the detecting points can be distinguished from the upper dose X, the lower dose Y and the side dose Z (surrounding dose), and at least the following Implementation steps:

Step 1: At the position of the detection point 10, the measurement using the single-layer separator 11 is performed, and the doses on the upper and lower sides of the separator 11 are measured to obtain the measured value a above the single-layer separator 11 and the single-layer partition. The value b is measured below the plate 11, and the partitioning direction of the partition 11 faces upward and downward, and at the same time, the partition 11 causes a damping ratio μ to the dose from above and the partition 11 causes a damping ratio λ to the dose from below.

Step 2: At the detection point 10, the measurement of the double-layer separator 12 is performed, and the doses on the upper and lower sides of the separator 12 are measured to obtain the measured value d and the double-layer partition above the double-layer separator 12. The value e is measured below the plate 12, and the partition 12 is placed facing upward and downward, and at the same time, the double-layer separator 12 causes an attenuation ratio μ ^{2 to} the dose from above and the partition 12 causes a decay ratio of the dose from below. ^2.

Step 3: Perform a non-separator dose measurement at the same inspection point 10 to obtain a non-separator measurement value c.

Step 4: Calculate the dose X from the upper dose, the dose Y from the lower side and the dose Z from the side according to the measured values, respectively, as follows:

By combining the measured relationships from step one to step three, you can obtain:

The measured value a above the single-layer separator is the dose attenuation ratio λ × the lower dose Y + the side dose Z below the upper dose X+, that is, the matching diagram can show a=X+λ×Y+Z.

The measured value b = the upper dose attenuation ratio μ × the upper dose X + the lower dose Y + the side dose Z below the single layer separator, that is, the figure shows that b = μ × X + Y + Z.

No separator measurement c = upper dose X + lower dose Y + side dose Z, that is, with the illustration, c = X + Y + Z can be expressed.

The measured value d above the double-layer partition is the dose attenuation ratio λ ² × the lower dose Y + the side dose Z below the upper dose X+, that is, the figure shows that d=X+λ ² ×Y+Z.

The measured value e = the dose attenuation ratio above the double-layer baffle μ ² × the upper dose X + the lower dose Y + the side dose Z, that is, the figure shows that e = μ ² × X + Y + Z.

Based on the above five unknowns (X, Y, Z, μ, λ), five equations can be solved by using five equations in the following way:

When the dose is calculated over the X, from the top line to dose X = (value measured without separator separator c- monolayer amount below the measurement value b) ² / (measured value no partition c + measured amount below the double-layered separator The value e-2 × the measured value b) under the single-layer separator, that is, the matching diagram can show that X = (cb) ² / (c + e - 2 × b).

When the lower dose Y is calculated, the dose from the lower dose Y = (no separator measurement c - the measured value a above the single-layer separator a) ² / (no separator measurement c + above the double-layer separator) The value d-2 × the measured value a) above the single-layer separator, that is, the figure shows Y=(ca) ² /(c+d-2×a).

When calculating the side dose Z, it is derived from the side dose Z = no separator measurement c - from the upper dose X - from the lower dose Y, that is, Z=c-X-Y can be represented by the illustration.

Please refer to FIG. 2, which is a schematic view of a second embodiment of the present invention. As shown in the figure: in addition to the method of the first embodiment described above, if the radiation environment is simple, the source is only from the upper and lower sides, that is, only the upper dose X and the lower dose Y are distinguished, and the main nuclear species are irradiated. The same steps can be simplified as follows:

Step 1: At the position of the detection point 20, the measurement using the partition plate 21 is performed, and the doses on the upper and lower sides of the partition plate 21 are measured to obtain the measured value a above the partition 21 and the measured value below the partition plate b. The partitioning direction should face upward and downward, and at the same time, the partition 21 causes an attenuation ratio μ from the upper and lower doses.

Step 2: Perform a non-separator dose measurement at the same inspection point 20 to obtain a separatorless measurement value c.

Step 3: Calculate the upper dose X and the lower dose Y based on the measured values, respectively, as follows:

Since there is no side dose, and the upper dose X is the same as the main nuclear species of the lower dose Y, the direction is the straight line direction (indicating the same travel distance of the path in the partition), so the partition 21 has the same degree of attenuation for the upper and lower sides, so By combining the measured relationships of steps 1 and 2, the following relationship can be obtained:

The measured value a above the upper plate = the upper dose X + the upper and lower dose attenuation ratio μ × the lower dose Y, that is, the figure shows that a = X + μ × Y.

The measured value b below the separator is the upper and lower dose attenuation ratio μ × the upper dose X + the lower dose Y, that is, the figure shows that b=μ×X+Y.

The relationship between the measured value c without the partition is the upper dose X + the lower dose Y, that is, the figure shows that c = X + Y.

By the above three equations, the three unknowns (X, Y, μ) are obtained:

Upper dose X = (no separator measurement c ² - lower measurement b × no separator measurement c) / (2 × no separator measurement c - upper measurement a - lower measurement b), that is, with the illustration, X = (c ² - b × c) / (2 × cab).

Lower dose Y=(no separator measurement c ² - upper measurement a × no separator measurement c) / (2 × no separator measurement c - upper measurement a - lower measurement b), that is, with the illustration, Y = (c ² - a × c) / (2 × cab).

In summary, the measuring method for distinguishing doses in different directions can effectively improve various disadvantages of the conventional use, and it is not necessary to know the thickness or material of the partition, but only the partition material of appropriate material and thickness which can generate attenuation is needed. The effect of the measurement can be achieved; furthermore, the invention can be made more progressive, more practical, and more in line with the needs of the consumer, and has indeed met the requirements of the invention patent application, and the patent application is filed according to law.

However, the above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto; therefore, the simple equivalent changes and modifications made in accordance with the scope of the present invention and the contents of the invention are modified. All should remain within the scope of the invention patent.

10, 20. . . check Point

11. . . Single layer partition

12, 21. . . Double layer

a. . . Measurement value above the single layer separator

b. . . Measurement under the single layer partition

c. . . No separator measurement

d. . . Measurement above the double baffle

e. . . Measurement under the double partition

μ. . . Single layer separator pair dose attenuation ratio from above

λ. . . Single layer separator pair dose attenuation ratio from below

μ ² . . . Double-layer separator pair dose attenuation ratio from above

λ ² . . . Double-layer separator for dose attenuation ratio from below

X. . . From above dose

Y. . . From below dose

Z. . . From the side dose

μ. . . The dose attenuation ratio of the upper and lower sides of the separator

Fig. 1 is a schematic view showing a first embodiment of the present invention.

Fig. 2 is a schematic view showing a second embodiment of the present invention.

10. . . check Point

11. . . Single layer partition

12. . . Double partition

a. . . Measurement value above the single layer separator

b. . . Measurement under the single layer partition

c. . . No separator measurement

d. . . Measurement above the double baffle

e. . . Measurement under the double partition

μ. . . Single layer separator pair dose attenuation ratio from above

λ. . . Single layer separator pair dose attenuation ratio from below

μ ² . . . Double-layer separator pair dose attenuation ratio from above

λ ² . . . Double-layer separator for dose attenuation ratio from below

X. . . From above dose

Y. . . From below dose

Z. . . From the side dose

Claims (7)

A measuring method for differentiating doses in different directions comprises the following steps: Step 1: measuring the dose of a single layer of separator at a position of a detecting point, measuring the dose on the upper and lower sides of the partition, to obtain a single layer The measured value above the separator and the measured value under the single-layer separator, and the partitioning direction faces upward and downward; Step 2: At this inspection point, the measurement using the double-layer separator is performed, and the upper surface of the separator is measured. The dose on the lower two sides of the surface is obtained by taking the measurement value above the double-layer separator and the measurement value under the double-layer separator, and the partitioning direction is facing upward and downward; Step 3: performing the separator-free dose at the same inspection point Measured to obtain a non-separator measurement value; and step 4: Calculate the upper dose, the lower dose, and the side dose according to the measured value. A method for distinguishing doses in different directions according to the scope of claim 1 of the patent application, wherein the dose from the top = (no separator measurement - measured under the single layer separator) ² / (no separator Measured value + measured under the double-layer baffle - 2 × measured under the single-layer baffle). A method for distinguishing doses in different directions according to item 1 of the patent application scope, wherein the dose from the lower side = (no separator measurement value - measured value above the single layer separator) ² / (no separator Measured value + measured value above the double-layer baffle - 2 × measured value above the single-layer baffle). A method for distinguishing doses in different directions according to claim 1 of the scope of the patent application, wherein the dose from the side = no separator measurement - from the upper dose - is from the lower dose. A method for distinguishing doses in different directions includes the following steps: Step 1: at the position of the detection point, performing measurement using a separator, measuring the dose on the upper and lower surfaces of the separator, and obtaining the measurement above the partition The value and the measured value under the partition, and the partitioning direction is upward and downward; Step 2: The non-separator dose measurement is performed at the same inspection point, and no separator measurement value is obtained; and Step 3: Calculated From the upper dose and from the lower dose. A method for differentiating doses in different directions according to item 5 of the patent application scope, wherein the dose from the upper side = (no separator measurement value ² - lower measurement value × no separator measurement value) / ( 2 × no separator measurement value - upper measurement value - lower measurement value). In different doses depending on the direction of one of the patent in item 5 distinguished range measuring method, wherein the dosage from beneath = (measured value without separator ² - Value measured amount above the measured value × None separator) / ( 2 × no separator measurement value - upper measurement value - lower measurement value).