JPS61205626A - Hydrolysis of uranium hexafluoride - Google Patents

Abstract

PURPOSE:To obtain an aqueous solution of UO2F2 having uniform concentration, easily, by contacting UF6 gas with pure cooling water at the tip of an ejector to effect the continuous decomposition of the gas, transferring the produced aqueous solution of UO2F2 in a receptor tank, measuring the concentration of the UO2F2, and feeding back the measured value to the ejector system. CONSTITUTION:Cooled pure water is supplied to the core tube 7a of the ejector 7 from the top, and UF6 gas is supplied to the side of the ejector 7 in a manner sucked toward the core tube 7a. The pure water is made to contact with the UF6 gas at the tip of the nozzle 7b of the ejector 7, and the UF6 gas is hydrolyzed to form an aqueous solution of UO2F2. The UO2F2 solution is introduced into a receptor tank 8 stirred by the circulation process. The concentration of UO2F2 is measured automatically in the receptor tank 8, and the measured value is fed back to the automatic control valves 14, 25 for the control of the flows of pure water and UF6 gas. The size of apparatus can be reduced and an aqueous solution of UO2F2 having uniform concentration can be produced continuously by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field) The present invention relates to a method for hydrolyzing uranium hexafluoride in which uranium hexafluoride is continuously hydrolyzed to obtain an aqueous uranyl fluoride solution having a constant concentration.

(Prior Art and its Problems) As a method for producing uranium dioxide powder, which is a raw material for nuclear reactor fuel for power generation, the ADU method using ammonium deuterate (ADU) is widely used.

That is, this method uses solid ura hexafluoride/(UFs)
is heated and vaporized, and this hexafluoride crane gas is fused with pure water and hydrolyzed to form a dilute aqueous solution of uranyl fluoride (UO2F2), and an ammonia aqueous solution is added to this aqueous solution to precipitate ammonium deuterate (ADU). In this method, the powder is further overdried and then subjected to a roasting and reduction process to obtain U 02 powder.

However, in this conversion process, UO! In order to obtain powder without variation, it is necessary to maintain the operating conditions of the above-mentioned steps at constant conditions, and the precipitation conditions of ADU are particularly important. This ADU
The uranium concentration of the uranyl fluoride aqueous solution is a factor that greatly affects the precipitation conditions of uranyl fluoride.In the process of hydrolyzing uranium hexafluoride, it is necessary to produce a uranyl fluoride (UO2F2) aqueous solution with a constant uranium concentration. Moreover, for mass production, it is also required to continuously hydrolyze uranium hexafluoride.

Problems with the prior art include the following.

(The general method for hydrolyzing 110Fa is to use a scrubber type.This method uses UF from the bottom of the hydrolysis column.
Supply sF2 gas and spray pure water from above to UO, F.
In order to increase the gas-liquid contact rate (reaction rate), a packing material such as telesitite is often placed in the column, and the reaction apparatus is relatively large.

(2) When preparing an aqueous solution of U Os F at a constant concentration, a continuous batch method is required, and a complicated sequence of operations is required.

(Objective of the Invention) The object of the present invention is to solve the problems of the prior art described above and to provide a method for continuously producing an aqueous uranyl fluoride solution of a constant concentration by hydrolyzing uranium hexafluoride using a compact device. be.

In order to achieve this objective, the present inventors have studied and found that U
Fa gas easily reacts with water, and the reaction with water is an exothermic reaction of about 100 kcal/mo 1
Focusing on the fact that the reaction heat of UFs is generated, which causes the liquid temperature of UO and Fffi to rise, pure water that has been cooled to a predetermined temperature is supplied from above the ejector.
UFsF2 is sucked in from the side of the 1000-degree ejector.
By supplying gas, UFa gas can be easily and continuously hydrolyzed with a very compact device, and the hydrolyzed UOtFx aqueous solution is received in a receiver tank for liquid ratio measurement, and the liquid ratio is measured. Determine the tyotpx concentration from the mold,
By feeding back the measured values to the respective control valves of UFa gas and pure water supplied to the ejector, a constant concentration of UO, F! It was discovered that an aqueous solution can be produced continuously, and the present invention was achieved.

(Structure of the Invention) That is, according to the present invention, in a method for hydrolyzing uranium hexafluoride, pure water cooled in advance to 4 to 20° C. is supplied from above the ejector into the central pipe of the ejector, and the ejector The uranium hexafluoride gas is supplied in the form of suction from the side toward the central pipe of the ejector, and the pure water and the uranium hexafluoride are brought into contact at the tip of the ejector, and the uranium hexafluoride is hydrated. The uranyl fluoride aqueous solution is decomposed, and the uranyl fluoride aqueous solution is introduced into a receiving tank which is stirred by a pump circulation method, and the a degree of the uranyl fluoride is automatically measured in the receiving tank, and the measured value is The uranium hexafluoride is characterized in that an aqueous uranyl fluoride solution of a constant concentration is continuously produced by feeding back the uranyl hexafluoride/gas and pure water to the respective flow rate adjustment valves supplied to the ejector. A hydrolysis method is obtained.

Next, the present invention will be explained with reference to the drawings.

The drawing is a flow sheet diagram of one embodiment of the present invention.

In the figure, 1 is pure water, 2 is a cooler (heat exchanger), 3 is cold water, 4 is ordinary gas, 5 is UFe gas, 6 is a feedback circuit, 7 is an ejector (hydrolyzer), and 8 is for concentration measurement. U O *
F is the storage tank, 9 is the I)ff automatic measuring device, IO is the pump,
11 is UO*Fm aqueous solution, 12 is overflow (next process m
), 13 is the pump circulation path, 14 is the pure water flow J#, 8! l
15 is a UFs')fi amount adjusting valve.

In the figure, pure water 1 to be reacted with UF. is cooled in advance to 4 to 20°C in a heat exchanger 2. If the cooling is less than 4℃, the pure water may freeze, which is unfavorable from a temperature standpoint, and if it exceeds 20℃, the temperature of the UO*Fg aqueous solution will decrease to 6() due to the reaction with UFs. Since the temperature rises above ℃, VCHFf1 on the reactor is also
Both are inappropriate because they generate gas.

U F@ +2 Ht04UO* F * +4 HF
Furthermore, in the present invention, the contact and reaction between pure water and UR gas is carried out at the tip of the ejector 7. That is, pure water cooled to a predetermined temperature is supplied from above the ejector 7 into the central pipe 7a of the ejector 7, and UPI gas is supplied from all sides of the ejector 7 in the form of suction towards the central pipe 7a of the ejector 7. Then, at the tip of the nozzle 7b, pure water and U
Contact with Fs gas causes hydrolysis of UF. The material of the nozzle 7b is preferably a corrosion-resistant material such as Teflon.

The UOmFt aqueous solution produced by hydrolysis is introduced into the receiving tank 8, which is being stirred by a pump circulation system using a bong 7'10. In the receiver tank 8, by measuring the differential pressure ΔP in the liquid column at a constant height, the 'UOgF of the aqueous solution! F
By automatically determining t ill iK and feeding this value back to the automatic control valves 14 and 15 for the pure water supplied to the ejector 7 and the UF/gas flow rate, UOLF and aqueous solution at a constant degree of s are continuously produced. becomes possible.

In the present invention, pure water and UF are used in the ejector 7.

UF/
Since the gas is hydrolyzed, it is possible to downsize the hydrolysis device.

(Effects of the Invention) By adopting the above configuration, the present invention can exhibit the following effects.

(1) A constant concentration of UOxF with a compact hydrolysis device
m aqueous solutions can be produced continuously. Moreover, since it is a compact device, it is also preferable in terms of criticality safety management.

(21UF@Can be hydrolyzed without increasing the gas pressure, and there is no need to increase the heating temperature of UF6 too much.
safe from death.

(3) Since UFs can be suctioned and hydrolyzed, the amount of UFs remaining in the UF and cylinder can be reduced.

[Brief explanation of the drawing]

The drawing is a system diagram of an apparatus used in an embodiment of the present invention. In the figure, 1-111 pure water 2-111 cooler (heat exchanger) 3-111 cold water 4---- N2 gas 5---- UF, gas 6---- Feedback circuit 7-----Ejector 7a-m-Ejector central pipe 7b-m-Ejector nozzle 8-11~Concentration measurement U Ox F receiving tank 9-111 Concentration automatic measuring device 10---Pump 11 --- UO*FtOx liquid 12 --- Overflow 13 --- Bo/B circulation path 14 --- Pure water flow rate control valve

Claims (1)

[Claims] (1) In a method of hydrolyzing uranium hexafluoride, pure water pre-cooled to 4 to 20°C is supplied from above the ejector into the center pipe of the ejector, and from the side of the ejector in the direction of the center pipe of the ejector. uranium hexafluoride gas is supplied in a suctioned form, and the pure water and the uranium hexafluoride gas are brought into contact at the tip of the ejector, and the uranium hexafluoride is hydrolyzed to form a uranyl fluoride aqueous solution. A uranyl fluoride aqueous solution is introduced into a receiving tank that is being stirred by a pump circulation method, the concentration of the uranyl fluoride is automatically measured in the receiving tank, and the measured value is used to add uranium hexafluoride gas and pure water to be supplied to the ejector. A uranium hexafluoride hydrolysis method characterized by continuously producing a uranyl fluoride aqueous solution at a constant concentration by feeding back to each flow rate adjustment valve.