Method for producing chemical sorbent to absorb nuclear fuel fission products

FIELD: environment protection from radionuclides.

SUBSTANCE: proposed method for producing chemical sorbent to absorb nuclear fuel fission products (radionuclides of iodine, ruthenium, and their volatiles) includes impregnation of activated carbon in triethylene diamine followed by its drying at temperature of 110-130 °C. For the purpose use is made of activated carbon produced from raw bituminous coal having micropore volume vmp = 0.28-0.33 cm3/g and total pore volume vΣ = 0.85-1.0 cm3/g. Activated carbon is impregnated until triethylene diamine content is reduced to 1-2% of base mass. Then chemical sorbent obtained in the process is dried out and sifted.

EFFECT: enhanced quality of chemical sorbent obtained.

1 cl, 1 tbl, 9 ex

 

The invention relates to the field of adsorption technology, atomic energy, environment and can be used for trapping radioactive iodine and ruthenium, and their volatile compounds (including methyl iodide and camerahouse ruthenium) from gaseous emissions under normal operating nuclear power plants, nuclear installations, and in case of accidents.

Known methods for producing the chemical sorbent (absorber) on the porous base impregnated with salts of iodides of metals (U.S. CL 252.429, Pat no. 4111833), the action of which is based on the isotopic exchange. Because the isotopic exchange occurs at a slower rate than chemical reactions, these sorbents are inferior in its effectiveness prompted.

Known close to the proposed to the technical essence and the achieved result is a method of obtaining the chemical sorbent, which as of impregnating used amines with nitrate of silver (UK, class B 1 L, Pat. No. 1571052).

The disadvantages of this method are the high cost of produced coal from the use of the precious metal - nitrate of silver, and the poor reliability due to the use of primary amines, which are processed by carbon dioxide contained in the air.

Closest to the proposed appointment and the greatest number of matching significant prize is acov is the way, described in the patent of Russian Federation №2218985, class B 1 J 20/20 from 19.06.02 and consists in the fact that one part of the active carbon of one party with the volume of micropores of at least 0.4 cm3/g is impregnated with a solution of compounds of copper, chromium, silver and triethylenediamine and the other with a solution of Nickel chloride. Both parts are dried at temperatures above 100°to the desired moisture content, followed by mechanical stirring. This method is adopted for the prototype of the invention.

Lack of protetora is the complexity and multi-stage receiving the chemical sorbent due to the large number of chemisorptive additives applied to the activated carbon, consistency of application and frequency of drying and the high cost of the resulting chemical sorbent.

Technical problem on which the invention is directed, is to increase the reliability of protection of the environment from radioactive contamination under normal conditions of operation of NPPs, as well as in emergency situations.

The technical result obtained by solving this problem is the creation of a simple method of obtaining more reliable, cheap, with high sorption properties of the absorber fission products nuclear fuel, in particular radionuclide iodine, ruthenium and their volatile compounds.

This technical result is istihaada fact, in the proposed method of obtaining chemical sorbent to absorb fission products nuclear fuel, comprising impregnating a porous base triethylenediamine and drying at a temperature of 110-130°With that as a basis we take the activated carbon from coal feedstock with vmi=0,28-0,33 cm3/g and vΣ=0,85-1,0 cm3/g, and the impregnation is carried out to the maintenance of triethylenediamine 1-2% by weight of the base.

The difference of the proposed method from the prototype is that as the basis, take activated carbon from coal feedstock with vmi=0,28-0,33 cm3/g and vΣ=0,85-1,0 cm3/g, and the impregnation is carried out to the maintenance of triethylenediamine 1-2% by weight of the base.

The method is as follows: take an active coal AG with a specific microporous structure - vmi=0,28-0,33 cm3/g, vΣ=0,85-1,0 cm3/g, put him on the moisture content of 1-2% of impregnant - triethylenediamine (TED) and carry out the drying in a furnace at a temperature of 110-130°C.

The influence of vmiand vΣon the purification coefficient pairs J-131 displayed on the basis of numerous experiments and are shown in table 1.

Table 1
№ p/pMicropore volume, vmicm3/g The total pore volume vΣcm3/gThe degree of purification pairs J-131, %
10,180,6890,00
20,220,7297,50
30,280,8099,90
40,300,8599,99
50,330,9099,99
60,360,95at 99.95
70,301,1099,92
80,251,2099,30
90,201,3096,80

A similar degree of purification is achieved by testing the claimed chemical sorbent and pairs of radionuclide ruthenium and its volatile compounds.

As a result of numerous studies, and laboratory and experimental work on the production of various samples of chemical sorbent (absorber) AG-And it was found that the optimum degree of cleaning of the radionuclides of iodine and ruthenium (99,99%) is achieved only in the present interval vmiand vΣ.

This is because each act chemisorptive binding of iodine and ruthenium with impregnant - triethylene the other, deposited on the porous base coal AG, must precede the act of their adsorption in micropores, i.e. retention in the adsorbed condition for the occurrence of a chemical reaction, and this, as shown by experimental data, can be achieved in the presence of a developed porous structure of coal AG vmi=0,28-0,33 cm3/g and vΣ=0,85-1,00 cm3/year

With the development of the porous structure of active carbons in the process of progressive activation at the beginning of the formation of micropores in a General increase of the total volume. This process continues until the formation of the maximum amount of micropores, which is characteristic for each type of coal, and then with further increase in total pore volume micropore volume begins to decrease, and their size increase.

On the basis of non-porous: filter material FMS (filter glass), FAN (filter material polyacrylonitrile), and others like them, this chemical reaction of iodine and ruthenium with triethylenediamine almost fails.

With regard to the selected temperature interval drying proposed in this invention, it is based on the experimental results and substantiated by two provisions:

1) first, you must release the micropores and the mesopores from water vapor, so that they are available for the adsorption of radionuclides of iodine and ruthenium,and their volatile compounds, the purpose of the course of chemical reactions with their impregnant - triethylenediamine;

2) secondly, not to exceed the drying temperature of the absorber, so that it does not evaporate impregnant - triethylenediamine, the boiling point of which 148°C.

On the basis of the above justified temperature drying of chemical sorbent - 110-130°C.

Thus, the proposed method allows to obtain an effective absorber of radionuclides of iodine and ruthenium, and their volatile compounds (CH3J - iodine bromide and RUO Li4- camerahouse ruthenium) more cheap and available raw materials - coal. It should be noted that the absorber is not only superior to the prototype for the efficiency of trapping of iodine and volatile compounds, but also capable of absorbing ruthenium and its volatile compounds.

From the above it follows that each of the signs stated together to a greater or lesser extent affect the achievement of the technical result, namely: the creation of a more reliable, efficient, cheap absorber radionuclides of iodine, ruthenium and their volatile compounds, and the entirety is sufficient to characterize the claimed technical solution.

The method of obtaining the chemical sorbent to absorb fission products of nuclear fuel the radioactive iodine, ruthenium and their volatile soy is ineni, includes impregnation of activated carbon with triethylenediamine and drying at a temperature of 110-130°C, characterized in that use activated carbon from coal feedstock with a volume of micropores vmi=0,28-0,33 cm3/g and total pore volume vΣ=0,85-1,0 cm3/g, impregnation of activated carbon lead to the maintenance of triethylenediamine 1-2% weight by weight basis, carry out drying in electric furnaces and dissipate.



 

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