Method for radiostrontium preparation (versions)

FIELD: physics, nuclear physics.

SUBSTANCE: group of inventions is related to the field of nuclear technology and radio chemistry and is intended for preparation and extraction of radioactive isotopes for medical purpose. Method for preparation of radiostrontium includes radiation of target with flow of accelerated charged particles. Inside target shell there is metal rubidium. After target radiation rubidium is melted inside target shell. Extraction of radiostrontium from liquid rubidium is done by surface sorption of different materials that contact with liquid rubidium. Sorption is carried out at the temperature of sorbing surface of 275-350°C. Sorbing surface is internal surface of radiated target shell. After performance of sorption rubidium is removed from target shell. Then radiostrontium is washed from internal surface of target shell by dissolvents.

EFFECT: increased efficiency of radiostrontium preparation and simplification of technology in case of its extraction from large mass of liquid metal rubidium by sorption directly on internal target shell.

8 cl, 5 dwg, 4 tbl

The invention relates to the field of nuclear technology and radiochemistry, namely the acquisition and allocation of radioactive isotopes for medical purposes. In particular, the invention relates to obtaining isotopes Radiostantsiya⁸²Sr and⁸⁵Sr, the first of which is widely used in medicine for diagnosis of diseases using positron emission tomography.

A known method of producing Radiostantsiya [L.F.Mausner, .Prach, S.C.Srivastava, J. Appl. Radiat. Isot. 1987. Vol.38, P.181-184], which includes a radiation flux of accelerated charged particles targets chloride of rubidium and radiochemical separation of radiotrance. The performance of this method is limited due to the low content of the working substance (rubidium) in the material, as well as with the properties of the irradiated material: low thermal conductivity RbCl leads to high temperatures inside the target when it is irradiated by intense particle flux, which causes radiolysis RbCl and the corrosion of the shell of the target formed by chlorine.

Also known is a method of obtaining Radiostantsiya [Blinov, Vmmagic, Vingradinka and others, radiochemistry, 1994, volume 36, s-498; B.L.Zhuikov, V.M.Kokhanyuk, N.A.Konyakhin, A.A.Razbash, J.Vincent, Proc. 6th workshop on targetry and target chemistry, Vancouver, Canada, 1995, TRIUMF, Vancouver, 1996, Ed. J.M.Liuk, T.J.Ruth, p.112; D.R.Phillips, E.J.Peterson, W.A.Taylor et al., J. Radiochim. Acta, 2000, vol.88. p.149-155], which includes a radiation flux of accelerated charged particles Mish is neither metallic rubidium weighing up to ~50 g and radiochemical separation of Radiostantsiya by dissolution of metallic rubidium in alcohol, translation products in an aqueous solution of chlorides and ion exchange. The high conductivity of metallic rubidium allows to irradiate thick targets by intense particle flux, which makes this method effective for producing large amounts of⁸²Sr (unit Key). The disadvantage of this method is that the radiochemical procedure of selection of Radiostantsiya is complicated, time consuming and dangerous. If we consider the possibility of producing a large number of Radiostantsiya of the much more massive targets of metallic rubidium on a wide beam of high intensity, such an approach seems unreal.

Closest to the invention is a method of obtaining Radiostantsiya [Blinov, Vmmagic, Guinet, Patent RU 2102808 C1, 1998], which includes a radiation flux of accelerated charged particles targets of metallic rubidium, melting rubidium after irradiation and extraction of Radiostantsiya adsorption on the surface of various metals or oxides which are submerged in the molten metal is rubidium. The main disadvantage of this method lies in the fact that a significant part of the resulting Radiostantsiya lost Cerberus on the walls of the container in which carry irradiated rubidium, and on the inner surface of the shell of the target, especially when irradiated PU is kOhm high intensity. Thus, when the currents of protons is of the order of 0.5 to 1 µa on the inner surface of the shell of the target sorbed 10-30% of the resulting Radiostantsiya, when increasing the intensity of the current, this proportion is as high as 50-70%.

The technical result of the present invention is to increase the efficiency of obtaining Radiostantsiya and simplification of selecting it from a large mass of liquid metal rubidium by sorption directly on the inner shell of the target or by retrieving Radiostantsiya of circulating rubidium by sorption on a heated surface, or when filtration of liquid rubidium.

The technical result is achieved in that in the method of producing Radiostantsiya, including radiation flux of accelerated charged particles of the target containing the metal rubidium inside the shell of the target, melting rubidium inside the shell of the target after irradiation, extracting Radiostantsiya adsorption on the surface of various materials in contact with liquid rubidium, unlike the prototype radiostrontium removed by sorption from liquid metal rubidium directly on the inner shell surface of the irradiated target (possible materials shell - stainless steel, tantalum, niobium, tungsten, molybdenum, Nickel or noble metals) by keeping sealed micheneri temperature 275-350°C. Then the metal rubidium pumped from the target, while 96±4% of Radiostantsiya remains adsorbed on the inner surface of the shell of the target. Then radiostrontium can be translated into the solution, pouring the target of a variety of solvents, such as organic alcohols, water and/or aqueous solutions of mineral acids, etc. the Most simple and practically feasible to produce a rinse first with water, then mineral acids.

Another option technical solutions is that as the working substance of the target use of liquid rubidium, which during irradiation circulates in a closed circuit with a trap. Radiostrontium remove the two methods. The first method - sorption on the surface of materials, heated up 220-350°C, immersed in liquid rubidium (for example, on the surface of the metal rods in the trap, made of stainless steel, tantalum, niobium, titanium, zirconium, tungsten, molybdenum, Nickel or noble metals), and the temperature of the rubidium circulating in the loop support in the range of 10-220°C, and the oxygen content in rubichi does not exceed 3 wt.%. The second method - retrieves Radiostantsiya, adsorbed on fly ash particles (solid phase)in the liquid rubichi, by using a filter of a porous membrane (for example, made of metal, not interacting with ruby is receiving), moreover, the oxygen content in the circulating rubichi support in the range of 0.1 to 4.0 wt.% by adding oxygen or rubidium. The temperature selected in the range 10-38°C to maintain a certain ratio of solid and liquid phases. Further radiostrontium washed off from the surface of the rods or filter organic alcohols, water and/or aqueous solutions of mineral acids. This option allows you to extract radiostrontium of rubidium mass even in kilograms, conducting at the same time its irradiation by a beam of accelerated protons high intensity (several hundred μa).

In rubichi containing oxygen, oxygen can be (depending on temperature and concentration) in dissolved form or in the form of colloidal particles of oxide of rubidium. Radiostrontium formed during irradiation, is in rubichi in the form of a true solution or adsorbed on the surface of colloidal particles of oxide of rubidium. Depending on the oxygen content with increasing temperature colloidal particles can either be dissolved in rubichi, or to grow in size and fall out.

The essence of the proposed method is illustrated in the following drawings and tables.

In table 1 shows the distribution of Radiostantsiya in rubichi height of a vertically positioned container (glass cylinder with an inner diameter of 25 mm), is that irradiated rubidium was transferred from the membrane of the target. The concentration of Radiostantsiya represented as activity⁸²Sr calculated at the end of irradiation per unit mass of irradiated rubidium. It is seen that a large part of Radiostantsiya deposited together with the particles of the oxide of rubidium (part of Radiostantsiya concentrated near the surface of liquid rubidium in contact with the gas, where the oxygen content is higher). Thus, when a certain content and the size of colloidal particles (determined by device parameters) strontium can be transported with liquid rubidium without significant deposition on the inner surface parts of the path.

Figure 1 shows the shell of the target (volume 35 ml), which was removed metal rubidium after heating 5 h at 275°C (see Example 1).

Legend: 1-8 zone adsorption of strontium; 9 - cavity shell targets, zapomnivshayasya by RB.

Table 2 presents the distribution of Radiostantsiya absorbed on the inner surface of the membrane of the target (Figure 1), the height of the target after the removal of the irradiated rubidium. Radiostrontium was sorbirovtsa on the inner surface of the shell of the target exposed to the rubidium (cavity 9 in figure 1). The table shows that a large part of Radiostantsiya concentrated in the lower part of the target on the surface of particles of the oxide of rubidium deposited in the sediment, the other part is distributed in the it inner surface of the membrane of the target.

Figure 2 presents the dependence of the degree of sorption of Radiostantsiya on the inner shell surface of the irradiated target (Figure 1), with the gradual increase of temperature and duration of heating at each temperature - 3 hours At a relatively low temperature (about 100°C), the adsorption process is reversible, and at 275°C and above is a fairly complete sorption of Radiostantsiya, obviously, as a result of dissolution of colloidal particles of oxide of rubidium.

Figure 3 presents the dependence of the sorption Radiostantsiya from time heating the irradiated targets at a temperature of 275°C. For 3 hours, heating to about 95% of Radiostantsiya sorbed on the internal surfaces of the membranes of the target.

At the end of the sorption liquid metal rubidium removed from the target and cleanse radiostrontium with the inner surface of the shell target with a solvent. Table 3 shows the effectiveness of flushing Radiostantsiya solvents from the surface of the targets of different sizes.

The inventive method of obtaining Radiostantsiya allows you to organize its continuous production. Figure 4 shows a diagram of the installation for continuous receipt and retrieval⁸²Sr of the liquid metal rubidium target. Rubidium here circulates through the circuit which includes continuously irradiated target 1 in stainless shell and the trap 2 and the sorption extraction ⁸²Sr. The circuit is equipped with an induction pump 3 for pumping liquid rubidium, controlled flow 4 and purity 5 rubidium (standard sensor based on solid electrolyte). The temperature of liquid rubidium in the circuit is maintained in the range from 10 to 220°C (the melting point of rubidium 39°C, but at a certain content of dissolved oxygen, it falls). The oxygen content in the liquid metal rubichi should not exceed 3 wt.%, to prevent sedimentation of the oxide of rubidium. The system circuit is provided for feeding 6 metal rubidium with a specific oxygen content. Trap 2 for Radiostantsiya with thermostat 7, located inside the hot cell 8 with an inert atmosphere. Absorbing rods 9 are heated using heat or built-in heaters for the best sorption Radiostantsiya at a temperature of 220-350°C, and it is possible to heat only the Central core, in order to minimize adsorption on the walls of the trap. As sorbing element can also be used vertically positioned filter - thin smooth metal membrane 10 (Figure 5), through which constantly filtered metal rubidium, and ash particles containing radiostrontium linger. In this case, the oxygen content in the circulating rubichi support in the range of 0.1 to 4.0 wt.%. The temperature in different parts of the contour is chosen in the range 10-38°C to maintain a certain ratio of solid and liquid phases. Sorbing elements 9 (Figure 4) and 10 (Figure 5) periodically extract (perhaps even without suspending beam and circulation of rubidium). In related hot cell extracted sorbing element of the wash water and the solution (e.g., HCl), dried and placed back into the trap. The ELUTIONS containing⁸²Sr, sent for further processing and final product.

Further purification of the selected Radiostantsiya from radionuclide and stable impurities is known radiochemical methods [B.L.Zhuikov, V.M.Kokhanyuk, N.A.Konyakhin, A.A.Razbash, J. Vincent, Proc. 6th workshop on targetry and target chemistry, Vancouver, Canada, 1995, TRIUMF, Vancouver, 1996, Ed. J.M.Liuk, T.J.Ruth, p.112; D.R.Phillips, E.J.Peterson, W.A.Taylor et al. // Radiochim. Acta, 2000, vol.88, p.149-155].

The implementation of the declared method of producing Radiostantsiya illustrated by the following examples.

Example 1.

The target containing 53 g of metallic rubidium, irradiated by a current of protons 62 μa for 2 hours in the energy range of protons 100-40 MeV. After exposure for two weeks, the target was heated at 275°C for 5 hours, then cooled and at 46°C in nitrogen atmosphere drew irradiated rubidium from the shell. Found that 97.5% of Radiostantsiya remained on its internal surface. Then p is layer washed radiostrontium with the inner surface of the shell, schematically shown in figure 1, 0.5 M HCl solution. Layered flushing carried out by pouring the solution, increasing each time the volume of fill solution (first to the border of zone 1, then up to the border of zone 2 and so on). After each pour, stood bathed in the solution for one hour, and then the solution was pumped out. The resulting distribution of Radiostantsiya height of a large target (Table 2) shows that a large part of Radiostantsiya concentrated in the lower part of the target on the surface of particles of the oxide of rubidium, precipitated precipitated and then dissolved at elevated temperature, the other part is distributed on the inner surface of the shell of the target. Then combine all portions of a solution. Comparison of radionuclide content in irradiated rubidium target and total 0.5 M HCl solution illustrates the sorption selectivity of Radiostantsiya (Table 4): erases not only from rubidium, but also from isotopes of selenium and arsenic.

Example 2.

50 grams of metallic rubidium put the target in a tight casing of stainless steel and were irradiated by a current of protons of 0.5 µa for one hour in the energy range of protons 100-40 MeV. After soaking in the week target was heated to 47±2°C. in the nitrogen atmosphere was removed irradiated rubidium from the shell and found that 33% of Radiostantsiya remained on its internally the surface. Another target that contains 53 grams of metallic rubidium, were irradiated by a current of protons 70 µa for 5 hours in the energy range of protons 100-40 MeV. After soaking in the week target was heated to 46±2°C. in the nitrogen atmosphere was removed irradiated rubidium from the shell and found that 64% of Radiostantsiya remained on its internal surface. This example shows that at a relatively low temperature (compared to 275°C., as in Example 1) sorption of Radiostantsiya on the inner shell surface of the target is not so effective.

Example 3.

The target contains 52 grams of metallic rubidium, irradiated by a current of 50 µa protons in the energy range of protons 100-40 MeV. The total charge of the protons was 960 μa·h. After aging for three weeks target was placed in a furnace and heated at 300°C for 3 hours. Then cooled target to 80°C. In an argon atmosphere revealed the target and pumped out of her metal is rubidium. Radiostrontium absorbed on the inner surface of the shell of the target, made of stainless steel, pull, filling the target of 0.5 M HCl solution and leaving for 1 hour. Then the solution was drained from the target and the procedure was repeated flushing of Radiostantsiya with the inner surface of the shell of the target. Combined the two portions and further reviewed by the purification of the selected radiotrance. Radionuclide and stable is remesi, such as⁷⁵Se⁷⁴As iron, Nickel, chromium, removed by ion exchange resin Chelex-100, Dowex 1×8 and Dowex 50×8. Total yield⁸²Sr was 98-99%, radionuclide purity of >99.9%.

Example 4.

Rubidium extracted from irradiated targets containing 3.5% oxygen, were analyzed for the content of colloidal particles by measuring the content of Radiostantsiya height of a vertically positioned glass container (Table 1). After this liquid rubidium containing radiostrontium on colloidal particles, mixed (for leveling the concentration of colloidal particles by volume) and put it through a porous filter made of inorganic material is titanium oxide (porous granules with a diameter of 0.2-0.4 mm) at 30°C. was Achieved almost complete (>98%) extract Radiostantsiya of liquid rubidium.

Thus, using the present invention improves the efficiency of obtaining Radiostantsiya and simplify the technology of its allocation through sorption Radiostantsiya of liquid metal rubidium directly on the inner shell surface of the irradiated target. Irradiated metallic rubidium, remote from the target, can be reused for hours radiotrance. In the case of irradiation of rubidium, circulating in a closed loop, the inventive method allows the shock is resolved to radiostrontium or on the surface of the materials, immersed in liquid rubidium, or the filter is a porous membrane.

Table 3
The results for sequential flushing of Radiostantsiya from the surfaces of steel shells targets (sorption was carried out for 3 h).
The composition of the liquid	The processing time of the surface	Washed Radiostantsiya, %
Small target (13 ml)
Butanol	10 min	71±1
Methanol	10 min	3±1
0.1 M HCl	10 min	25±1
ONLY
Small target (13 ml)
Propanol	10 min	65±2
Diest. water	10 min	28±2
ONLY		93±2
Small target (13 ml)
0.1 M HCl	15 min	>99
Large target (35 ml)
0.5 M HCl	30 min	92±2
0.5 M HCl	30 min	7±1
0.5 M HCl	30 min	<0,5
ONLY		>99,5

1. The method of producing Radiostantsiya, including the irradiation of a target containing the metal rubidium inside the shell target with a stream of accelerated charged particles, the melting rubidium inside the shell of the target after irradiation, removing Radiostantsiya of liquid rubidium adsorption on the surface of various materials in contact with liquid rubidium, characterized in that the sorption of producing is at a temperature of sorbing surface 275-350°C, and as a sorbing surface use interior surface of the irradiated target, and after the sorption of RB from the target shell is removed, and then radiostrontium wash with the inner surface of the shell target with a solvent.

2. The method according to claim 1, characterized in that the shell material rubidium target use stainless steel, tantalum, niobium, tungsten, molybdenum, Nickel or noble metals.

3. The method according to claim 1, characterized in that radiostrontium wash with the inner surface of the shell organic alcohols, water and/or aqueous solutions of mineral acids.

4. The method of producing Radiostantsiya, including the irradiation of a target of metallic rubidium flux of accelerated charged particles, the melting rubidium, removing Radiostantsiya of liquid rubidium adsorption on the surface of various materials in contact with liquid rubidium, characterized in that as the working substance of the target use of liquid rubidium, which during irradiation circulates in a closed circuit with the trap, and the temperature of the circuit is maintained in the range of 10-220°C, liquid rubidium contains oxygen of not more than 3 wt.%, and removing Radiostantsiya produce sorption on the surfaces of the trap is heated to 220-350°C, followed by flushing glad astrantia with the surfaces of the trap solvents.

5. The method according to claim 4, characterized in that the material parts of the traps use stainless steel, tantalum, niobium, titanium, zirconium, tungsten, molybdenum, Nickel or noble metals.

6. The method according to claim 4, characterized in that radiostrontium washed off from the surface of the parts of the trap organic alcohols, water and/or aqueous solutions of mineral acids.

7. The method of producing Radiostantsiya, including the irradiation of a target of metallic rubidium flux of accelerated charged particles, the melting rubidium, removing Radiostantsiya of liquid rubidium adsorption on the surface of various materials in contact with liquid rubidium, characterized in that as the working substance of the target use of liquid rubidium, which during irradiation circulates in a closed circuit with the trap, and the temperature of the circuit is maintained in the range 10-38°C, and liquid rubidium contains oxygen in the range of 0.1 to 4.0%, and removing Radiostantsiya produced by filtration and subsequent washing of Radiostantsiya with the surfaces of the filter element solvents, and a filter element is a porous material that is resistant to liquid metal is rubidium.

8. The method according to claim 7, characterized in that radiostrontium washed off from the surface of the filter element, organic alcohols, in the Oh and/or aqueous solutions of mineral acids.