JPH0329899A - Apparatus for manufacturing radioactive isotope, particularly cobalt 60 - Google Patents

Abstract

PURPOSE: To produce a radioactive isotope continuously and economically using a simple means by disposing a production unit representatively at a protective assembly around a nuclear core and making a central channel for receiving a capsule containing a sample. CONSTITUTION: The body 1 of the production unit has the outside dimensions and the profile similar to those of one protective assembly interposed between the fuel parent substance bracket and a containment on the outside of a fast neutron reactor and disposed in place thereof. A holder holding a capsule 7 containing a sample comprises a tubular sleeve moderator 9 having a central channel 11 for temporarily receiving the capsule 7 during irradiation. The acting part of the unit is present at the longitudinal parts AB matching the arrangement of the irradiation 9 and a material rod 13 to be irradiated is encapsulated in the removable capsule 7. Upon finishing irradiation, the body 1 is taken out and the fast neutron reactor is filled again with a body 1 having a new capsule 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the industrial production of artificial radioisotopes in which a sample of natural material to be irradiated is converted by an (n, γ) reaction in a fast neutron reactor.

More specifically, the present invention is particularly aimed at producing cobalt-60 from cobalt-59, but its scope is as follows:
It also extends to the production of other radioactive isotopes, such as iridium-192, gadolinium-153, and chromium-51.

Kobal l.60, which is well known to be a strong γ emitter, is
In the medical field, it is used to treat tumors, and in the food industry, γ
Its consumption has increased over the past few years as it has come to be used in large quantities for food sterilization and preservation using wires.

The conventional conventional industrial production method for cobalt-60 uses natural cobalt-59 as a starting material, and activates this natural cobalt-59 by an (n, gamma) reaction of neutron flux.

As the neutron flux, the neutron flux of a nuclear reactor is generally used. The efficiency of the activation reaction of natural cobalt depends on both the neutron flux acting on the cobalt and the energy of the neutrons constituting the neutron flux. For various reasons well known to those skilled in the art, liquid metal cooled fast neutron reactors are well suited for this industrial process, but in order to produce cobalt-60 at a profitable cost and in a reasonable turnaround time, It is clear that there is a need to significantly improve the production efficiency of desired radioisotopes by slowing down fast neutrons.

At a symposium held in Jackson, Wyoming, USA in September 1988, an experimental industrial manufacturing method was proposed, which was developed for IIIHc-S^-0262E.
Published as l'. However, this test was conducted in an FFTF furnace under conditions that are economically disadvantageous and difficult to put into practical use on an industrial scale. In this test, the moderator and the material rods to be irradiated were mixed around the reactor core, and the core was irradiated. The moderator was yttrium hydride.

Under these experimental conditions, an improvement in the theoretical neutron efficiency is certainly possible, but as a result of the almost homogeneous mixing of the moderator and the material rods to be irradiated, its industrial application is difficult, if not entirely impossible. It turned out to be (cost l~ is too high).

The object of the present invention is to provide an apparatus for the production of radioisotopes, which makes it possible to produce radioisotopes using easily available means and in an industrially viable and economical continuous process.

The device of the present invention is used in a fast neutron reactor cooled by liquid metal contained in a reactor vessel to generate radioactive isotopes, especially cobalt 6, by the (n, γ) reaction of a sample to be irradiated.
Manufacture 0. The core of the nuclear reactor is surrounded by an outer fuel parent material blanket and a neutron protection assembly. The present invention is characterized in that the device has the external dimensions and shape of the protective assembly along the outer blanket and is placed in place of the protective assembly; In the center of the height is a cylindrical sleeve of neutron moderator material, said sleeve having a central channel adapted to receive a removable capsule containing a sample to be irradiated.

As a result, it will be clear that the essential feature of the invention lies in the geometry of the moderator and the geometry of the device used as sample holder.

The device is inserted into the center of the production equipment itself in the form of a removable capsule.

The manufacturing device of the invention, having external dimensions and shape matching the protective assembly of the core of a nuclear reactor, can be placed very easily around the core without any disturbance to the core operation, especially with respect to neutrons. A part of the device serves as a holder in the form of a cylindrical sleeve incorporating a moderator, said sleeve being provided with a central channel for inserting a capsule containing a rod of material to be irradiated. In such systems, the capsule is the only consumable part that must be replaced at the end of each process. On the contrary, a holder with a moderator coating on the inside is reusable and can be used several times in succession to fill the capsule containing the sample to be irradiated.

According to another feature of the invention which is also important, the neutron moderator used is from calcium hydride LCa. actual,
Although its quality as a moderator is far inferior to water, calcium hydride is still an excellent moderator.
It has several advantages. Advantages that may be cited include, for example, inexpensive materials, ease of use, and good temperature stability.

The present invention will be more fully understood from the following description based on the embodiment of the radioisotope production apparatus shown in FIGS. 1 to 3 in Attachment 1.

FIG. 1 shows a main body 1 of a radioisotope production apparatus, which is the object of the present invention. As mentioned above, this body 1 has the same external dimensions and shape as one of the protective assemblies provided in all fast neutron nuclear reactors between the outer fuel parent material blanket and the reactor vessel. As a result, the device has a leg 3 inserted into the lower plate and an upper opening 5 for assembling and accessing a removable capsule 7 serving as a sample holder as desired.

In FIGS. 1 and 2, the capsule 7 is shown in a position where it has been introduced into the interior of a holder of a radioisotope production device. More particularly, the holder consists of a cylindrical sleeve 9 of calcium hydride used as a moderator, which sleeve has a central channel oval forming a temporary receptacle for a detachable capsule 7 during the irradiation period. 11.

As shown in FIG. 1, the active part of the device that is the object of the invention is located in the longitudinal section 8B of the device.

This part matches exactly where the moderator 9 is placed,
The removable capsule 7 contains a rod 13 of the material to be irradiated, in this non-limiting example a rod of natural cobalt 59. These rods 13 are distributed into several sections 15, 17 as shown in FIG. The division of the sections is shown in FIG.

Of course, as mentioned above, when the production apparatus is taken out from the reactor to extract the capsule after irradiation, the main body 1 of the radioisotope production apparatus is removed by a gripping means (not shown).
The removable capsule 7 may be extracted from the holder. A new capsule filled with rods of natural cobalt 59 of the same arrangement is introduced into the holder part of the device 1 and placed inside the channel l1. The assembly of devices filled in this way is refilled into the fast neutron reactor. The collection of devices can easily be placed in place of the protective assembly. The filling of the capsule can be adjusted according to the substance to be irradiated and the desired specific activity for a given time.

Examples of industrial-scale utilization of the above-mentioned apparatus of the present invention are shown below. The mass of cobalt to be irradiated in the capsule is approximately 3
kg. After 2 years of irradiation, the average activity of this cobalt is 50 Curie h. This is Marcou1e
This corresponds to a total radioactivity of 150,000 Curie-h from an assembly of this kind that can be sufficiently placed around a fast neutron reactor of the Phenix reactor type installed at Sai-1. Twenty assemblies of this kind of construction can therefore produce 1.5 million Curies per year. This is roughly equivalent to France's current consumption.

The radioisotope production apparatus according to the present invention can of course be used in all types of fast nuclear reactors. The device may be placed directly around the reactor core, or more preferably around the periphery 8 if the reactor has a radial blanket. The latter arrangement is extremely important. This is because in this case no neutron interaction occurs between the reactor core and the irradiation device (the reaction efficiency is not affected even in the event of an operational accident). Neutrons captured by cobalt are leakage neutrons with almost zero probability of returning to the core.

[Brief explanation of drawings]

Figure 1 is a four axial sectional view of the device of the present invention incorporating a capsule containing a sample to be irradiated, Figure 2 is a horizontal sectional view taken along the XX line in Figure 1, and Figure 3 is a sample holder. FIG. 2 is an enlarged cross-sectional view showing a collection of material rods to be irradiated in a functioning capsule; 1... Device body, 7... Capsule, 9
...Deceleration control, 13...Material rod. JP-A-3 29899 (4)

Claims (2)

[Claims] (1) In a fast neutron reactor cooled by liquid metal contained in the reactor vessel and whose core is surrounded by an outer fuel parent material blanket and a neutron protection assembly, ) Apparatus for producing a radioactive isotope, in particular cobalt-60, by reaction, the apparatus having the external dimensions and shape of, and being placed in place of, a protective assembly between the outer blanket and the container. and the device has a cylindrical sleeve made of a neutron moderator in the central part of the device in the height direction, and the sleeve is arranged to receive a removable capsule containing a sample to be irradiated. Apparatus for the production of radioactive isotopes, in particular cobalt-60, characterized in that it comprises a central channel with a central channel. (2) The device according to claim 1, wherein the neutron moderator is calcium hydride H_2Ca.