The method of disposal of shavings from depleted uranium

 

The invention relates to the field of recycling of depleted uranium. The inventive method of disposal of shavings from depleted uranium is in the oxidation of uranium oxide concentrate uranium. The oxidation of lead in two stages: oxidation of uranium to uranium dioxide with water at 1005oWith subsequent oxidation of uranium dioxide up to nitrous oxide of uranium in air at 70010oC for 3-5 h of the advantages of the invention consist in providing a safe way, through temperature control and improvement of environmental safety by eliminating the formation of dust-gas mixture. 2 C.p. f-crystals., 3 Il.

The invention relates to the field of disposal of depleted uranium, in particular, in the form of chips.

Currently stored by different enterprises of nuclear industry has accumulated a significant amount of chips from depleted uranium.

The high chemical activity of uranium, a large specific surface area of the chip, the possibility of sparking and ignition mechanical effects, long-term storage and transport of uranium metal shavings pre is akrasanee environment, etc. ).

A radical solution to security issues during long-term storage of uranium chips is the translation of it in the fire and explosion safe product: nitrous oxide of uranium, which is the most stable oxide of uranium.

To date, the receipt of this product was carried out by direct combustion of uranium metal in air or in oxygen.

Closest to the claimed method of disposal of shavings from depleted uranium is a method consisting in briquetting (pressing) chip and then burning it in the working capacity of the installation, which serves the air heated to a temperature of 400oC. (Initial requirements for the design of the incineration chips. Combine elektrohimpribor", 2000).

The interaction of uranium with oxygen flows through the reaction: U+O2=UO2, (1) 3U+4O2=U3O8; (2) 3UO2+O2=U3O8. (3) Exothermic nature of the chemical reaction (2), i.e., emitting a large amount of heat increases the temperature of the uranium shavings to 450-550oC. Further, the temperature control chip is made by changing the flow of reagent gas (air), changes in the concentration of acid the surrounding air, supplied in a shirt working volume.

The maximum chip temperature does not exceed 600oC. the Resulting powder of the oxides of uranium remains partially within the working volume of the installation, and partly in the form of dust goes in the gas phase, which creates difficulties in ensuring environmental safety requirements for disposal of uranium shavings.

The task on which the invention is directed is to provide safe method of disposal of uranium shavings due to the controllability of the temperature mode of carrying out the method, and more environmentally-friendly way by eliminating the formation of dust-gas mixture of uranium.

This proposed method of disposal of shavings from depleted uranium, which consists in the oxidation of uranium oxide concentrate uranium, characterized in that the oxidation of lead in two stages: oxidation of uranium to uranium dioxide with water at a temperature of 1005oWith subsequent oxidation of uranium dioxide up to nitrous oxide of uranium in air at a temperature of 70010oC for 3-5 hours.

Thus the oxidation of uranium dioxide to uranium lead by boiling in water for 25-30 hours.

Also the oxidation of Wii by the reaction:which is endothermic (C. S. Emelianov, A. I. Evstyuhin - metallurgy nuclear fuel, Atomizdat, 1964).

Then, the resulting uranium dioxide (UO2) oxidized in air at a temperature of 70010oWith up to nitrous oxide of uranium (U3O8) according to reaction (3). Both of these chemical reactions are endothermic, i.e., the oxidation of uranium takes place with absorption of heat, and thus full control of temperature regimes ongoing processes of oxidation and does not form a powder-gas mixture of uranium, creating an environmental hazard works in direct burning uranium.

In Fig. 1 shows the oxidation of uranium chips in boiling water (1005oC). As the ordinate of this diagram shows the oxidation state of uranium. This value is calculated from the experimental values of the gain chip by the formulawhere is the oxidation state of uranium in percent, Rho - weight source chips,
P is the weight of the chips after the cycle test,
Puo2- the estimated weight of the chips, oxidized to uranium dioxide (UO2) according to reaction (4).

In Fig. 2 shows the oxidation process uraoka uranium dioxide (UO2) in air at a temperature of 70010oC. as the ordinate of this diagram shows the degree of oxidation of uranium dioxide (K) calculated by the formula

where Puo2- the weight of the chips after the first stage of testing,
P is the weight of the chips after the cycle test,
Pu3o8- the estimated weight of the original chip in the oxidation to U3O8.

The method was carried out as follows.

In the experimental laboratory setup, which includes a cylindrical vessel with a volume of 12 l (autoclave), made of stainless steel, and electric stove, inspected the alleged oxidation of uranium chips to powder of uranium dioxide.

On the lid of the autoclave has a pressure gauge, hermetical input for thermocouples, two valve pressure (operating and emergency) and the valve for adjusting the pressure of the steam in the autoclave. The speed of the steam output is measured by a flow meter (l/min) connected to the output of the regulating valve. Typically, the exit velocity of the steam, measured by the flow meter was within ~15 l/min, which is close to the calculated value obtained by weight wikipeda water.

The temperature of the chip and the steam in the autoclave is the doctrine of the kinetics of the oxidation of the chips in boiling water in the autoclave was placed in a vessel with a pre-weighed chips and filled with water (~4 liters). Water heating and maintaining the mode of its boiling was carried hobs. Weighing chip was carried out every 4-5 hours, and the chips were dried in a drying Cabinet to constant weight. Control the degree of oxidation was carried out by the gain chip (Fig.1). The numbers indicate number of experiments.

It is seen that the oxidation chip uranium in boiling water to uranium dioxide is carried out at 25-30 hours. The observed difference in experiments 1-4 is determined by some heterogeneity chip thickness.

To study the kinetics of the oxidation of the chips in water steam in the autoclave was filled with water (~4 l) and put the vessel with a pre-weighed chips above the water level. Otherwise, these experiments were conducted similar experiments in boiling water. The results of these experiments are shown in Fig. 2, indicate that the oxidation chip uranium in water vapour (1005oC) to uranium dioxide enough 4-6 hours.

To identify which formed during these experiments products in the form of powders was carried out x-ray phase analysis on the General purpose diffractometer DRON-3M, which confirmed the oxidation of uranium chips to cubic phase UO2.

Gave 70010oWith on the air. The measurements were carried out every hour. The results of this experiment, shown in Fig.3, show that the complete oxidation of the powder of uranium dioxide up to nitrous oxide of uranium is achieved in 3-5 hours.

Thus, the invention will allow for the utilization of chips from depleted uranium is safe and environmentally friendly way.


Claims

1. The method of disposal of shavings from depleted uranium, which consists in the oxidation of uranium oxide concentrate uranium, characterized in that the oxidation of lead in two stages: oxidation of uranium to uranium dioxide with water at 1005oWith subsequent oxidation of uranium dioxide up to nitrous oxide of uranium in air at 70010oC for 3-5 hours

2. The method according to p. 1, characterized in that the oxidation of uranium dioxide to uranium lead by boiling in water for 25-30 hours

3. The method according to p. 1, characterized in that the oxidation of uranium dioxide to uranium lead in water vapour within 4-6 hours

 

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