Experimental device for preparing carbon-14 liquid sample in radioactive graphite

Abstract

The invention discloses an experimental device for preparing a carbon-14 liquid sample in radioactive graphite. The experimental device comprises a pressure-bearing steel cylinder, a top end cover, a sealing cover, two electrodes, an igniting wire, a sample crucible bracket, a charging-discharging valve and an adsorption device, wherein the adsorption device contains tritiated water vapor; when in use, the adsorption device is arranged in the pressure-bearing steel cylinder; an internal space of the pressure-bearing steel cylinder is partitioned into a first space and a second space; the adsorption device is provided with a plurality of through holes; the first space communicates with the second space only through the adsorption device.

Description

technical field [0001] The invention relates to the technical field of nuclear industry, in particular to a device and a method for preparing a carbon-14 liquid sample in radioactive graphite. Background technique [0002] A large amount of graphite materials are used in the nuclear industry, and graphite becomes radioactive after being irradiated by neutrons. In order to deal with radioactive graphite, it is necessary to establish an analytical method for the radioactivity contained in graphite, especially to accurately determine the content of carbon-14 in it. The difficulty in the analysis of carbon-14 is to prepare the carbon-14 in the solid graphite material into a liquid sample, which is convenient for subsequent analysis of carbon-14 with sophisticated radioactive analysis instruments. [0003] At present, the "combustion-absorption method" is widely used to prepare liquid samples of carbon-14. That is, the graphite containing carbon-14 is ignited in air or oxygen t...

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Problems solved by technology

However, the method and device have the following disadvantages: (1) complex equipment, many parts, large volume, and poor integration; (2) it is difficult to achieve standardization, and most of them are temporary experimental devices, which are not conducive to large-scale production and popularization; (3) Difficult to control: too small a gas flow rate is not conducive to the complete combustion of graphite, and too high a gas flow rate is not conducive to the complete absorption of carbon dioxide gas by the absorption liquid; (4) There are many radioactive wastes: the entire pipeline will be contaminated by carbon-14 and tritium ; (5) The equipment is dangerous: graphite powder has a large specific surface area, and it is easy to explode when mixed with oxygen

However, this method and device still have the following disadvantages: (1) In addition to the sample combustion device, additional devices for removing tritium-containing water vapor and absorbing carbon dioxide are required: the equipment is complex, poorly integrated, and most of them require temporary construction to remove water and absorb carbon dioxide device, which is not conducive to the promotion and use of the device

If there is no supporting device, the interference of tritium cannot be removed, and it is difficult to be used for the accurate analysis of C-14; (2) the gas release operation of the sample combustion device must be manually controlled, and the work intensity is high: the gas release operation of the sample combustion device needs to be performed according to Internal residual pressure to mediate a deflation valve to keep the deflation rate slow and steady

At present, this operation can only be completed by manually controlling the spiral air release valve, and the staff needs to continue to mediate for several hours, and the work intensity is very high; (3) The manual air release operation causes the absorption to be unstable, and the experimental error is large: the sample combustion device releases The gas also requires slow passage of tritium water adsorption material and sodium hydroxide solution, and the passing speed has a direct impact on the absorption effect of tritium water and carbon dioxide

In particular, when the passing speed is too fast, the absorption rate will decrease, which will affect the measured carbon-14 content

However, by manually controlling the spiral deflation valve to adjust the deflation rate, the deflation rate fluctuates greatly, the absorption is unstable, the experimental error is large, and the repeatability of the results is poor.

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