SU442746A1 - Method of obtaining radiactive isotopes with short half-life period - Google Patents

Description

one

The invention can find application in those sectors of the national economy where labeled radioactive preparations are used to solve a number of technical problems.

The invention relates to the field of oilfield geophysics and preznaz. Started for the production of radioactive isotopes with a short half-life directly in the conditions of the npoNSJC word-geophysical enterprises.

Methods are known for producing prostate-sensitive materials under conditions of geophysical enterprises by activating the material placed in the chamber with liquid radioactive isotopes (br-95, Fe-59) prepared in nuclear reactors.

However, radioactive isotopes Ig-95, Fe-59, which have a high adsorption capacity, a long half-life and high specific activity, make the work relative and contaminate the object of study for a long time. The use of isotopes with a short half-life and low specific activity is not advisable for large losses of activity.

isotopes during their transportation and preparation of the object for research. Production of radioactive isotopes with a short half-life under the conditions of industrial geophysical enterprises in accordance with the usual procedure requires the production of a series of reactors, which is practically impracticable.

The purpose of the invention is to increase the speed and safety of conducting geophysical surveys of wells.

This is achieved by the fact that according to the proposed method, a highly soluble powder material is used in the quality of the material to be irradiated, which consists of an activated element and hydrogen, in the absence of other elements with a large neutron capture cross section, while the volume and weight of the irradiated material are sufficient for 1-3, the neutron mean free path, and after irradiation, the material is dissolved in water and removed from the activation chamber.

The proposed method allows the use of neutron sources used in the radioactive logging of wells as an irradiation source, which makes it possible to obtain

short-lived radioactive isotopes directly at the site of their use.

The material obtained at the end of the training process has a low specific radioactivity (of the order for Na-24) with the activity of the entire batch sufficient to study the well. This ensures complete safety of staff, even with direct contact with the material.

The essence of the method consists in using a powdered substance as a radiation material at the same time as a moderator of fast neutrons and not having elements with a large cross section for neutron capture (except hydrogen and an activated element, the activation cross-section of which should be extremely large) and also highly soluble in water.

In the preparation of radioactive isotopes of Na-24, sodium carbonate acid satisfies these conditions.

The volume and weight of one portion of the irradiated material and its distribution around the source is chosen from the requirements of maximum neutron use, which occurs when the material is spread in the activation chamber around the source as a sphere with a radius of several neutron paths and a surrounding environment of the hydrogen-containing material.

The optimum ratio of the retarding and absorption properties of the material can be chosen5 by filling the porous space in the material with water.

The activity of the neutron source (neutron yield per second) is chosen based on the recommended number of radioactive Element atoms per portion (Np), taking into account that their number is

eleven:,

Np (l-e

where L is the decay constant;

c - coefficient of use: zlzovani. neutrons (the ratio of the number of neutrons that are overly active in vmmi drami to the entire neutron flux), equal to 15-20% when using Ro-We neutron sources with an activity of 20-25 Ci and irradiation of NaHCOj ,, wetted with water;

q is the neutron yield per second;

t is the time of irradiation.

The drawing shows a scheme for producing radioactive isotopes with a short half-life of the proposed method.

The irradiated material is placed in an activation chamber 1, pre-filled with water, the radius of which is chosen to be 1-3 neutron paths in the irradiated material. In the center of the activation chamber set the source of 2 neutrons. The activation chamber is surrounded by a hydrogen-containing material 3 to repel neutrons and protect the operating personnel. Irradiation is performed for 1-3 periods of half-life of the activated element. After irradiation, the material is removed from the activation chamber through channel 4 and dissolved in water using a circulation system including a water reservoir 5, a pump b, a discharge line 7 and a suction line 8. After dissolution, the solution is pumped into the well.

Under conditions of a geophysical enterprise, the method gives the best results in obtaining radioactive isotopes Na-24 (half-life - 15 hours) when the compound NaHCOj is irradiated with sodium carbonate acid (baking soda).

Claims (1)

Invention Formula A method for producing radioactive isotopes with a short half-life, for example, for researching wells by irradiating neutrons in an activation chamber of a material containing an activatable element, characterized in that, in order to increase the expressiveness and safety of well studies, a highly soluble powder in water is used the material, which includes an activated element and hydrogen, in the absence of other elements with a large neutron capture cross section, while the volume and weight The irradiated material is chosen sufficient for 1-3 neutron paths, and after irradiation the material is dissolved in water and removed from the activation chamber.