CS258163B1 - A radioactive surface radiator and its method of preparation - Google Patents

Abstract

The essence of the emitter is a membrane to which a radioactive nuclide is bound by a sorption or ion exchange reaction. This membrane is covered with an inactive foil or casing, thus creating a compact unit of a closed emitter.

Description

The object of the invention is a surface radioactive emitter utilizing in the preparation of the properties of plastics, which solves the uniform and constant distribution of the radioactive substance, achievement of high surface activities and a simple method of preparation. A surface emitter with these properties can be used as a secondary standard for testing and testing activity meters and other applications.

So far, for similar purposes, the emitters have been prepared by applying a lacquer with suspended radioactive material to a substrate. To achieve homogeneity of the active layer, the lacquer was applied with a spray gun. The work with radioactive aerosol placed high demands on radiation hygiene and occupational safety.

Other known methods of preparing surface emitters, such as electrolytic deposition, electrospraying vacuum sublimation, powder metallurgy or adsorption from solution to an anodized surface of the substrate, etc. do not meet the requirements of the emitter usable as a secondary standard for verification and testing of activity meters. These requirements include the uniform distribution of activity across the area, the possibility of preparing various shapes and sizes of emitters in a wide range of nominal area activities of various radionuclides, the possibility of simple production in large series with minimal cost, flexibility of emitters, time stability and resistance of the emitter against mechanical and chemical damage.

SUMMARY OF THE INVENTION The present invention is based on a surface radioactive emitter consisting of a membrane having sorption or ion exchange properties on which the radionuclide is firmly and homogeneously retained.

Necessary shapes are cut from or cut out from the radioactive membrane, which are covered with inactive plastic foils, preferably based on polyester or polyimide, or enclosed in a suitable housing. The thickness of the top sheet is 0.05 mm or thinner to minimize the absorption of the transmitted radiation. Thicker foil backing (0.1 to 0.3 mm) imparts good mechanical properties to the emitter. Welding or gluing of foils or sheaths results in a sealed radioactive emitter.

All the materials used are chosen so that their resistance to radioactive radiation guarantees a sufficient life of the formed sealed emitter.

The above emitters can be prepared with various radionuclides in a wide range of area activities up to 1 MBq.cm. The method of preparation is considerably simpler than the method used so far, it significantly reduces the risk of radioactive contamination of the workplace and is not dependent on the individual abilities of the worker. It allows to obtain a wide choice of shape and size of emitters thanks to its flexibility and creation of different radiation fields.

Guarantees resistance to mechanical and chemical environmental damage. It enables the production of large quantities of surface emitters at minimum cost.

Example

Preparation of the strontium 90 radionuclide surface emitter in radioactive equilibrium with yttrium 90 consists in soaking a switched off pre-swollen (1 hour in distilled water at 40 ° C) ion exchange membrane (polyethylene-based foil incorporating the Ostion KS cation exchanged into H cycle) into an aqueous salt solution radionuclides. The temperature of the aqueous solution is 25 ° C. In addition to radionuclides, the solution contains soluble strontium and yttrium salts as a non-radioactive carrier (concentration 20 µg Sr / l, 20 µg Y / l). The amount of carrier affects the resulting surface activity and homogeneity of the surface emitter. Generally, a higher amount of carrier reduces the resulting sheet activity and increases homogeneity and vice versa. After 8 hours exposure, the membrane is removed from the solution, rinsed with distilled water and dried at room temperature. After cutting out the desired melter, it is sandwiched between two non-radioactive polyester films. The thickness of the top overlay foil is 0.05 mm and the backing foil is 0.25 mm. These films overlap the active area by 5 mm. The foils are then welded or glued over the entire surface to form a closed surface radioactive emitter.

After their attestation, these emitters can be used as secondary standards for verification and testing of particle flow meters, activity, event. for other applications.

Claims (4)

SUBJECT OF THE INVENTION 1. An emitter characterized in that it consists of a membrane with sorption or ion exchange properties to which it is bound, a radionuclide. 2. An emitter according to claim 1, characterized in that the radioactive membrane is hermetically covered by an inactive foil or sheath. 3. A process according to claim 1, wherein the radionuclide is bound to the membrane by a sorption or ion exchange reaction from a radionuclide solution. 4. A method according to claim 3, characterized in that after washing and drying, the radioactive membrane is covered with an inactive foil or sheath.