Automatic pretreatment device and treatment method for liquid effluent 14C of nuclear power plant

Abstract

The invention discloses an automatic pretreatment device and method for liquid effluent 14C of a nuclear power plant, and the device comprises a cracking furnace, a condensation tank, a filter and an absorption bottle, the cracking furnace is used for instantly gasifying liquid effluent sample water of the nuclear power plant into mixed gas of 14CO2 and tritiated water vapor under the assistance of high-purity oxygen and a catalyst at the temperature of 790-810 DEG C; the condensing tank is used for condensing the mixed gas so as to separate out 14CO2 carrying residual tritiated water vapor; the filter is used for filtering the residual tritiated water vapor in the 14CO2 carrying the residual tritiated water vapor to obtain filtered 14CO2, and the 3H residual rate in the filtered 14CO2 is lower than 0.001%; and the absorption bottle is used for containing a NaOH solution so as to absorb the filtered 14CO2, so that an absorption solution is obtained. Unification of automation and accuracy can be realized.

Description

technical field [0001] The invention relates to liquid effluents from nuclear power plants 14 C monitoring technical field, especially relate to a kind of nuclear power plant liquid effluent 14 C Automatic pre-processing device and processing method. Background technique [0002] Water body radioactivity monitoring has always been an important aspect of my country's environmental radiation monitoring. The discharge of liquid effluent from nuclear power plants is one of the important sources of radioactivity in water bodies, which contains 14 C in particular needs attention. [0003] 14 C is a radioactive isotope of carbon, its half-life is as long as 5730 years, it is a pure β emitter, and its maximum energy is 156keV. 14 C has a high isotope exchange rate and strong environmental migration ability, and it is very easy to participate in the carbon cycle of the biosphere. It enters the environmental water body through various channels and is absorbed and assimilated by l...

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Problems solved by technology

[0004] In 2020, Japan’s decision to dump 1.23 million tons of waste water from the Fukushima nuclear power plant into the Pacific Ocean once again touched the sensitive nerves of the public. Science specially published an article referring to the release of nuclear wastewater 14 Concerns were expressed about the potential human impacts of C on sedimentation and uptake by marine organisms

[0010] The wet oxidation method has a large sample volume and low oxidation efficiency. It is often necessary to combine auxiliary oxidation methods such as heating, ultraviolet light or ozone to improve the oxidation efficiency. The process is complex and time-consuming, and it is difficult to achieve automatic continuous measurement.

[0011] The high-temperature combustion method has a small amount of sample injection, and the method can achieve a higher minimum detectable activity concentration; poor control of the oxidation temperature will easily lead to changes in the pressure of the injection pipeline, resulting in poor repeatability of the injection volume; at the same time, the use of catalysts is prone to "adsorption and desorption” effect, that is, the target radionuclide may be adsorbed on the surface of the solid catalyst particle, and at the same time, the target radionuclide adsorbed by the solid catalyst particle is also gradually desorbed and released, which affects the homogeneity of the prepared sample; in addition, During the sample preparation process of water samples with different activity concentrations, due to factors such as adsorption on the wall of the vessel, the residual radionuclides from the previous sample injection will enter into the next sample, which will affect the accuracy of the measurement results.

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