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Open-loop type quick measurement method of radon exhalation rate

A radon extraction rate, open-loop technology, used in the field of nuclear radiation detection

Inactive Publication Date: 2013-08-14
HENGYANG NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0020] This traditional open-loop measurement method needs a long time to wait for the radon concentration in the radon hood to tend to a constant value.

Method used

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  • Open-loop type quick measurement method of radon exhalation rate
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  • Open-loop type quick measurement method of radon exhalation rate

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Comparison scheme
Effect test

Embodiment 1

[0055] Embodiment 1. Using a RAD7 with a correction factor of 1.12, the reference value of radon exhalation rate is 1.48Bq m -2 ·s -1 Measured on the reference device for 40 minutes, the volume of radon accumulator 2 is 4 liters, the bottom area of ​​radon accumulator 2 is 0.043 square meters, the flow rate of the pump in RAD7 is 520ml / min, the half-life of 218Po is 3.1min, λ Po 0.2236min -1 , the two measured values ​​are: 5566Bq / m 3 , 5180Bq / m 3 . RAD7 uses a small drying tube to dry the air entering the radon meter, so that the air humidity in the measuring chamber of the radon meter is below 10%.

[0056] According to formula (15), the exhalation rate of radon obtained from the two measurements is respectively: 1.58Bq m -2 the s -1 , 1.47Bq m -2 the s -1 . very close to the reference value.

[0057] The self-adaptive open-loop radon exhalation rate measurement device provided in this embodiment is composed of a radon collecting hood 2 , a flow meter 3 , a radon m...

Embodiment 2

[0058] Embodiment 2, using a RAD7 with a correction factor of 1.12, the reference value of radon exhalation rate is 1.48Bq m -2 ·s -1 The reference device is measured 5 times, the measurement period is 10 minutes, the volume of the radon accumulator 2 is 4 liters, the bottom area of ​​the radon accumulator 2 is 0.043 square meters, the flow rate of the RAD7 pump is 520ml / min, and the RAD7 uses a small drying tube to dry the incoming The air of the radon measuring instrument makes the air humidity in the measuring room of the radon measuring instrument lower than 10%.

[0059]Formula (8) becomes:

[0060] C Po ( t ) = JS L ( 1 - 0.8944 e - 0.13 t ...

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Abstract

An open-loop type quick measurement method of radon exhalation rate includes two measurement modes. In the first measurement mode, multiple shorter cycles which respectively last for 1-20 minutes are measured after a radon collection case is capped on the surface of a to-be-measured medium so that the radon concentration sequence is acquired, the measurement data of each cycle are approximately regarded as the concentration 218Po of the center point of each measurement cycle, and then the radon exhalation rate can be acquired by means of non-linear data fitting. In the second measurement mode, a longer cycle which lasts for 20-200 minutes is measured after the radon collection case is capped on the surface of the to-be-measured surface, and the radon exhalation rate can be solved by the aid of the measurement value of the longer measurement cycle according the formulas (14) and (15). The open-loop type quick measurement method of the radon exhalation rate is quick in measurement, and the radon exhalation rate can be obtained by calculation according to the measurement data before the radon in the radon collection case balances.

Description

technical field [0001] The invention relates to the technical field of nuclear radiation detection, in particular to a method for measuring radon exhalation rate. Background technique [0002] The radon exhalation rate refers to the activity of radon that is exuded into the air through a unit area of ​​the medium surface in a unit time. Measuring the radon exhalation rate on the surface of the medium is one of the important means to evaluate the natural radiation level and evaluate whether the decommissioning treatment of uranium mines is qualified. [0003] Cumulative method, open-loop method and activated carbon adsorption method are commonly used methods to measure radon exhalation rate. [0004] The activated carbon adsorption method requires a long measurement time, and the measurement results cannot be obtained quickly. [0005] The accumulation method is to buckle a radon collecting hood on the surface of the emanating medium, and seal the surrounding area with an a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01T1/167
Inventor 谭延亮袁红志
Owner HENGYANG NORMAL UNIV
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