JPS5895300A - Treatment of powdery dangerous matter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION 81 BACKGROUND OF THE INVENTION The present invention relates to a method for processing powdered hazardous materials typically generated, for example, in nuclear material recovery facilities.

A typical nuclear material recovery facility generates radioactive waste materials including, for example, uranium, plutonium, and the like. Due to the increasing costs associated with operating nuclear facilities, it has become cost effective to recover concentrated fissile material from waste. During recovery, there are materials that are generally radioactive and pose a health hazard if they are not recovered or treated in a manner that prevents radioactive materials from escaping into the atmosphere.

Therefore, it is appropriate to develop means to systematically recover or dispose of materials in a way that prevents them from escaping into the atmosphere so that they are not harmful to public health and safety. Summer C is here. One such method, which is well known in the art, involves grinding the waste material into a powder so that it can be more easily processed. The present invention is particularly applicable to the method of recovering or processing the radioactive waste powder described above.

In one particular processing unit, known as a uranium purifier, enriched uranium is recovered from waste material. In that device, a pipe or feeder is used to feed the waste in powder form into the dissolver. The dissolver consists of a container of heated acid.

However, in the operation of the above-mentioned or other equipment for handling powdered radioactive materials, the physical nature of the powder and the obvious health hazards make feeding it into the dissolver a particularly difficult task. do'. Until now, 1. The powder was carefully dumped from the feeder into the acid container. The acid tended to condense and build up at the feeder inlet and clog the feeding mechanism. Powder flow characteristics are typically poor, requiring the use of complex vibratory equipment. Often it is necessary to hammer the pipe to facilitate the flow of powder into the melter. Thus, in addition to the health hazards associated with the entry of powdered radioactive material into the atmosphere and its introduction into a container of heated acid, the device generally avoids dust. The slow and slow work is a problem.

10 OBJECTS OF THE INVENTION Accordingly, one object of the present invention is to provide a new and improved method for processing pulverized hazardous substances.

Another object of the invention is to provide a method for processing pulverized hazardous materials in a safe, simple and cost effective manner.

Another object of the present invention is to provide a method for processing radioactive powder material that minimizes the health risks associated with inhaling radioactive powder.

Another object of the invention is to provide a method for processing radioactive waste material in which the powder is easily packaged in preparation for processing.

Another object of the present invention is to provide a method for processing radioactive powder material that reduces the problems associated with handling radioactive powder.

Another object of the present invention is to provide a method for processing radioactive powder material that eliminates powder handling problems in the dissolver stage, such as clogging or dust.

Another object of the present invention is to provide a method for processing radioactive powder material that minimizes the health risks posed by disposing the radioactive powder into a container of heated acid.

Another object of the invention is to provide a method for processing radioactive powder material that is critically safe and thus prevents self-sustaining chain reactions of radioactive material.

Another object of the invention is to provide a method for processing radioactive powder material that presents little or no disruption to subsequent operations.

Another object of the present invention is to provide a method for cost-effectively and simply processing any meltable powder material with extremely poor flow properties in a dissolver environment. be.

Another object of the present invention is to provide a method for cost-effectively and simply dispersing any undissolved powders with poor flow characteristics in a dissolver environment.

Yet another object of the present invention is to provide a method for processing radioactive powder material that utilizes relatively simple implementation equipment, thus maintaining simplicity in operation and maintenance.

These and other objects and advantages will be apparent from the following detailed description, and the novel features are particularly pointed out in the claims.

C1 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be better understood from the following description, taken in conjunction with the accompanying drawings. - The drawings illustrate each step involved in the method for processing waste hazardous materials. The substances referred to above may be in many forms. One form is a radioactive powder 10 formed by crushing radioactive waste material. Since the powder is processed by being dissolved in an acid solution, it is first placed in a dissolvable container in a first step. The container is conveniently shown as a metal can 12.

Although dissolvable containers such as metal cans 12 are disclosed in this document, other dissolvable containers such as paper bags, vinyl, alcohol, plastic bags, or disposable cans constructed of other materials may also be used. Emphasize what is also intended.

The cans used in this invention are similar to cans used in the food industry, and therefore the means for filling and sealing such cans in the canned food industry is to fill the cans with radioactive powder and seal them. can be easily applied to The use of such canning technology in the method for processing radioactive material contained in containers as disclosed in this document provides significant cost effectiveness. Similarly, in the 14-way method, cans of standardized sizes are handled and filled;
The use of known machines for sealing, marking and conveying does not require any substantial changes to such machines used in the food industry.

Those skilled in the art will appreciate that the exemplary can 12 disclosed in this section is formed from electroplated hot rolled steel. The tin is electroplated onto steel to a thickness of 15 to 1000 x 10 inches. The tin plating on standard open top food piles is approximately 0.00635 inch (1-0.00025 inch) thick and therefore can be rapidly dissolved when immersed in acidic solutions. For example, can 12 was found to dissolve very quickly in 8M HNO3 at all temperatures above 30°C. At 20°C, 5 moles of l-
Acid plating of the tin-plated surface in lN0a
Assivation) occurred, but it dissolved after about 4 minutes.

More specifically, the first. Hikaiguha,
The radioactive powder material is introduced into the can 12 or other dissolvable container from a suitable hopper or the like. Since the radioactive material is in the form of powder 10, care must be taken to prevent it from escaping into the atmosphere. The can 12' disclosed in this article is presized to have a predetermined capacity and is presized with reference to the capacity and dimensions of the acid solution container, preferably a No. .

1 size, which has a capacity of 296cc (10 fluid ounces) and a 0.7510.25 inch tin plating (i.e., used in the food industry, 0.00075 inch inside).
019 mm) and 0.00025 inch (0,006 mm) outside
This type of can has a tin plating of 35 nua).

Furthermore, NO', 1 can is approximately 68°31111 (2,6
It has a diameter of 9 inches (9 inches) and a height of 4 inches (1,01.5 mm). Due to the critical nature of the radioactive material, the rough dimensions of the can must be related to the size of the tank of acid solution, which will be further mentioned in step 5. Similarly, and without facing criticality problems,
Cans of other dimensions may be used in the practice of the invention, e.g.
O62 or N093 can easily be used. A can of size No. 1 holds about 1.2 hl and 1.3 kg of calcined UO3, and on the other side of the range of the can,
No. 3 size cans have a maximum UO3 capacity of approximately 4 kilograms or 32 fluid ounces per can.

Now referring to the second stage, the previously filled container is
It is sealed in a manner that ensures that its contents remain virtually damage-proof without leaking or spilling. One useful device for sealing tin-plated cans is an automatic can sealer (automatic 5
ealer). An example of a suitable automatic sheep is Fr
uend Can 5ealer Model No. E
L-12252-1, which is NOl.

Can sizes of N002 and No.3 can be sealed. However, the container can be hermetically sealed by a variety of methods and means known in the art. It is of vital importance to those skilled in the art that such means of sealing containers of radioactive materials are used in accordance with the present invention for materials to be dissolved in heated acid containers. One thing will be understood. After sealing the container, it can be metered to demonstrate the heavy chains of contaminants contained within it.

Whenever you work with hazardous materials, always make an inventory of the materials, especially radioactive waste materials.
counting for ) is important.

Although it was stated above that the container can be weighed to determine the amount of substance contained within the container,
It is also appropriate to inventory the material before placing it in the container and sealing it. Thus, in this method,
The addition or deletion of steps from the method would still be within the spirit and scope of the claims. Furthermore, because the radioactive material is in powder or granular form, it can be easily controlled and secreted. Furthermore, because of the known health risks associated with radioactive materials, it is important to identify and inventory such materials to comply with government regulations.

Following the second step, in which the process of substantially tamper-proof sealing of the containers has been completed, the third step is to transport the containers to a storage area, i.e., station 14, for further inventory purposes. It becomes more. Food machinery can also be used advantageously for transporting containers. However, other methods for transporting containers are known in the art and are equally advantageous for this stage of the invention.

If large amounts of radioactive material need to be processed, it is more cost effective to transport this material automatically, where it is sealed in a container. Again, by using standard food industry equipment consisting of automatic or manual feeders, such conveyance can be accomplished in a relatively inexpensive manner.

According to the fourth stage, the sealed containers are transported to a transport/inventory stage 16, where all of the cans, 12, are inventoried and verified to be intact. Additionally, in the fourth stage, storage areas are beneficial for inventory operations, which require government regulations to provide extensive documentation of the material being processed or buried to prevent theft. Container identification and marking can also be included, as the requirements for preserving the container include container identification and marking.

The means for conveying the sealed cans described above may be either a conduit and feed system or a belt conveyor. Such systems are typical of those used in the food industry to transport containers from storage and transfer areas to other areas where the containers are packed, prepared for shipment, etc. It is something.

After each container is transported to the storage area for inventory,
It can be automatically transported to a station where it is melted. This area is shown as stage 5 in the drawings. The invention includes the use of a dissolver 18, which is advantageously a tank 2o containing an acid solution or solvent 22, in which the sealed container is immersed for processing. The radioactive material is at this stage contained in a completely sealed can 12 and thus not exposed to the atmosphere. Therefore, there is less risk to health from inhaling the released dangerous powder substances.

In particular, in the fifth step, the sealed can 12 is added directly to the melter 18, without the need to handle the powder. The dissolver described above may consist of a tank 20 having a predetermined capacity and predetermined dimensions and containing a solution 22. One useful solution is nitric acid, but it should be understood that other acids are also advantageous for dissolving containers containing radioactive powder material. The temperature of the tank containing nitric acid is approximately 0℃~
It is heated to a temperature in the range of about 60°C. It has been discovered that a temperature of about 50'C should be used to give the best results. Similarly, it has been discovered that for dissolving containers containing radioactive material in a tank containing acid, the best results are obtained by heating the acid. That is, the container, and its contents, are consumed more quickly in a tank with heated acid than if the acid were not heated. However, it should be understood, and will be appreciated by those skilled in the art, that similar results are achieved with this method whether the acid is heated or remains at room temperature.

Although the present invention discloses a method by which radioactive materials can be treated in a manner that promotes safety, other hazardous materials, such as poisonous organisms that are not necessarily radioactive, can also easily be substituted into the present invention, thus making it a critical problem. can be avoided. One such toxic substance is beryllium, which is known to cause serious health problems when exposed for long periods of time.

The present invention has inadequate flow characteristics in the dissolver environment.
It should also be understood that this includes the use of all dissolvable powders. Powders that do not dissolve will also be dispersed in the dissolver by the method of the invention, especially if the powder has poor flow properties in the dissolver environment. Such powders may contain anti-caking agents (body feeds) which enhance the subsequent filterability of the melt, or thickeners which enhance the flow properties of the melt.

More particularly, in the fifth step, the sealed container 12 is placed in a dissolver configured as a tank 20 containing a predetermined concentration of nitric acid of at least 5 molar and heated in a predetermined manner. It will be destroyed. Furthermore, to ensure that nuclear material criticality problems are avoided, No.1. No, 2
Alternatively, the tank is sized or dimensioned according to the size of the N013 can. Thus, according to the present invention, the size of tank 20 is 254 mm < 10 inches) or smaller. In this way, the tank 20 can contain any concentration of uranium oxide, e.g.
NO,1,No with content of L103 up to % concentration
, 2 or No. 3 is made critically safe to accept cans of human size. Conversely, if the diameter of tank 20 is increased above 250 am (10 inches), the contents of tank 20 will become critical, thus preventing it from sustaining its own chain reaction.
The size of the container must be correspondingly reduced.

Even if the container dissolves quickly and completely in the acid, its contribution to the insoluble residue in the solvent, ie nitric acid, will be extremely small. Thus, because the powder is contained in a hermetically sealed container, and because the container is immersed in a tank of acid, and further because the container and its contents are completely consumed, the powder 10 is free of air. Don't come inside.

The elements that make up the can 12 used to practice this invention have extremely high C decontamination factors when used in solvent extraction machines.
tor). Since the weight of the can 12 is small compared to the weight of the powder (approximately 1:60), the can contributes little to the waste generated. Furthermore, according to the present invention,
Then, the physical characteristics of the substance placed in the dissolver 18 are
Due to the properties of loose and difficult to handle powders, 1
discrete quantity
The fact that the substance changes into
And it can be operated safely.

From the above, the steps and advantages of the present invention can be understood. However, the person skilled in the art will necessarily have various other features and advantages not specifically listed. Similarly, various modifications and variations of the illustrated embodiments may occur. All of this may be accomplished without departing from the spirit and scope of the claims.

[Brief explanation of the drawing]

The drawings are flow sheets showing each step of the invention. The first stage is container filling, the second stage is sealing, the third stage is transport and storage, the fourth stage is transport and inventory, and Figure 5 shows melting. 10...Powder, 12...Can (container), 14...Storage area, Item 16...Transportation, Memories of death, 18... ...dissolver, 20...tank, 22...solvent. patent applicant

Claims (1)

[Claims] (1) A method for treating hazardous substances, comprising the following steps: (a) placing a hazardous substance in a dissolvable container; (b) sealing the container; (C,) containing a solvent for both the material of the container and the contents of the container; (d) transporting said container to a dissolution station formed by a tank; and (d) applying a solvent to dissolve both said container and the contents therein, without escaping the hazardous substance into the atmosphere. Completely immerse the container into the tank containing the (2) The tank containing the solvent at the dissolution station comprises an acid solution of a predetermined concentration sufficient to dissolve the container and its contents. The method described in. (3) Claim 2 characterized by a tank containing an acid solution to facilitate dissolution of the container and its contents.
The method described in section. (4) The hazardous substance contains uranium oxide, and the fusible container in which the hazardous substance is placed is standard No. The diameter of the tank having a capacity and dimensions less than or equal to the capacity and dimensions of three size cans, and in which the solvent in which the container is submerged, is less than or equal to 245+ m (10 inches); 2. The method of claim 1, which is critically safe for any uranium oxide concentration up to 5% enrichment. - (5) The method according to claim 4, wherein the solvent consists of nitric acid. (6) The method of claim 5, wherein the nitric acid is heated to at least 30°C. (7) A method for processing powdered radioactive materials, consisting of the following steps: (a) filling the metal can with the substance; (b) sealing the nucleation with the substance (completely filled); (C) identifying and marking the sealed can containing the substance; (d) transporting sealed cans containing the substance to a storage area; (e) inventorying the sealed cans containing the substance; and (f) heated solvent. immersing the nucleation in a container containing a heated solvent for a predetermined period of time effective to dissolve the can and its contents below the surface of the can. (8) In a method for processing powdered radioactive material,
The method consists of the following steps: (a) placing powdered radioactive material in a dissolvable container; (b) 1) weighing the radioactive material; and 2-) marking the container for IE identification; (C) sealing the container containing the radioactive material; (d) transporting the container containing the radioactive material to a storage area; (e) subsequent inventory. (f) Subsequently inventorying such containers containing radioactive material; and ((+) ensuring that radioactive material does not escape into the atmosphere. hand,
consisting of completely immersing the container in a tank containing suitably heated nitric acid for a predetermined period of time effective to dissolve the container and the radioactive material therein. (9) The method according to claim 8, wherein the dissolvable container containing the powdered radioactive material has a predetermined volume and predetermined internal dimensions. (10) The method according to claim 8, wherein the tank containing nitric acid has a predetermined concentration. 11. The method of claim 10, wherein the predetermined concentration of M is at least 5 molar. (12) The method according to claim 8, wherein the container is a metal can. (13) Process 5 according to claim 12, wherein the can has a capacity sufficient to contain at least 1.2 kg of U 03. 14. The method of claim 9, wherein the Q amount is between about 296 cc (10 fluid ounces) and about 947.2 cc (32 fluid ounces). (15)! A method for processing powdered radioactive waste containing uranium monide, comprising the following steps: (a) At least 1.2k with specified internal dimensions no thicker than a standard N003 size can. (b) 1) weighing the waste material; and 2) marking the waste material for identification; (C) sealing the nucleation in which the waste material is contained; (d') an area awaiting subsequent inventory; (e) Subsequently inventorying the nuclearization containing waste material; (f) Transporting the nuclearization containing waste to a dissolution station and dissolving the The station consists of a tank having a diameter not greater than 254 mm (10 inches), so that the tank is critically safe for any concentration of uranium oxide in the can up to a concentration of 5%, and (g) having a nitric acid solution having a concentration of at least 5 molar and heated to at least 30°C; complete immersion of the nucleation in said tank containing nitric acid for a predetermined period of time effective to dissolve both the nitric acid and its contents; (76) lysis having poor flow characteristics in the environment of the dissolver; In a method for processing a powdered material, the following steps include: (a) placing the material in a dissolvable container; (b)
) sealing the container; (C) transporting the container to a dissolution station consisting of a tank containing a solvent for both the material of the container and its contents; and (d) the container and its contents. Completely immerse the container in the tank containing the solvent to easily dissolve both. (17) The method of claim 16, wherein the solvent comprises an acid solution of a predetermined concentration sufficient to dissolve the container and its contents. (18) A method according to claim 17, characterized by an acid solution to promote dissolution of the container and its contents. (19) The method of claim 16, wherein the powder is not dissolvable for the purpose of modifying the properties of the solute. 20. The method of claim 19, wherein the solvent comprises an acid solution of a predetermined concentration sufficient to dissolve the container and disperse its contents. (21) The method according to claim 20, characterized by an acid solution to promote dissolution of the container.