FR2762709A1 - FLEXIBLE SYSTEM FOR THE ABSORPTION OF IONIZING RADIATIONS, FOR THE COVERAGE OF EMISSION AREAS OF SUCH RADIATIONS - Google Patents

Abstract

The flexible system for absorbing ionizing radiation comprises at least one sheet 1 of a material made of mineral compounds of high atomic weight, embedded in a flexible polymer matrix and having good qualities of absorbing ionizing radiation. The flexible sheet 1 can be placed astride a pipe 3 to be protected, and can have a cutout 2 in the form of a buttonhole for the passage of a valve 4 carried by the pipe 3. The invention provides a protection system having a good temperature resistance, quick installation and easy conformation.

Description

-1 The present invention relates to protection at the emission of

  ionizing radiation and, more particularly, the production and use of absorption systems of ionizing radiation making it possible to cover emission zones of such radiation. According to the invention, the flexible protection system is made of a material based on one or more vulcanized elastomers with high flexibility, the formulation of which is particularly suitable for absorbing ionizing radiation, and more

  particularly Gamma radiation.

  The flexible system is designed to cover very quickly containers receiving radioactive fluids, such as pipes and valves, by limiting Gamma radiation in the environment of the intervention areas and, consequently, , reducing

doses received by staff.

  The system according to the invention can be configured in advance to the device which it must cover, or it can be easily and quickly configured on site. Finally, the flexible system according to the invention is provided to meet the requirements (concerning its fireproofing, its aging, its location, etc.)

  which are linked to its use in a nuclear environment.

  To clearly understand the flexible protection system according to the present invention, there will be described below, by way of example without limitation, a preferred embodiment with reference to the appended schematic drawing in which: FIG. 1 is a view in elevation of a flexible protective element intended to equip a valve; and Figure 2 is a perspective view showing the protection device of Figure 1 in

  place on a pipe fitted with a valve.

2 2762709

  The formulation of the material constituting the flexible protective element according to the invention uses mineral compounds with high atomic weight, which are embedded in a flexible polymer matrix having the characteristics of a rubber for reasons of handling. , that is to say showing good flexibility in order to position itself by its own weight (according to a "drape" phenomenon) on curved or flat surfaces (such as pipes,

valves or others) to be covered.

  The material has mechanical properties which allow it to be manipulated, suspended or folded without causing tearing or appreciable reduction in its thickness and density

can be between 1 and 10.

  The material absorbs radiation (on a Cobalt 60 source) with an efficiency between i and 4% 0 of absorption per mm of thickness and this absorption increases as a function of the thickness of the material,

which can vary from 1 to 200mm.

  For example, the composition of the material according to the invention may comprise the following elements: - a rubber base, natural or synthetic, in a proportion of 10 to 55%, - mineral compounds with atomic weight greater than or equal to 56, in a proportion of 10 to 90%, - a crosslinking system in proportion of 0.1 to 1% giving the material its infusible character, - a protection system against aging in proportion of 0.01 to 3%, and - a system fireproofing in the proportion of 0.1

at 50%.

  FIG. 1 shows a flexible sheet i of the above material according to the invention and, in a suitable location of the sheet 1, a cutout 2 is made in the form of a buttonhole intended to allow the positioning and the maintenance of sheet 1 without other accessories (such as straps, clips,

staples, etc ...).

  In Figure 2, there is shown the establishment of the flexible sheet 1 on a pipe 3 at the place of a valve 4, which is carried out with great speed. For this purpose, it suffices simply to introduce the valve 4 into the slot 2, and to drop the sheet 1 straddling the piping 3. In the case where the piping to be covered does not include a valve, the slot 2 is unnecessary and the sheet is simply placed astride the piping, where its weight is sufficient to hold it in place. The length of the sheet is

  then adapted to that of the piping to be covered.

  We can of course multiply the layers of material, and cross them, depending on the desired attenuation. It will be understood that, for the establishment of the sheet of material, the operator will advantageously hold it in front of him during his approach to the radioactive source, so as to be thus protected. The positioning on vertical or strongly inclined supports calls for fast strapping systems. It will also be noted that the isotropy of the properties of the material and the homogeneity of its composition guarantee an absorption of ionizing radiation whatever its orientation and the dimensions of implementation. It is also possible to cut the material, to conform it to the area to be protected, without altering its local properties or generating

  particles or undecontaminated areas.

  As the material according to the invention is not fusible, since it is not thermoplastic, it can be used on materials brought to high temperature, with however a maximum of 300 C during

a short time.

  The flexible material according to the invention does not have hard or sharp points, it advantageously reduces the risk of human or material accidents in the event of careless handling or falling. It will be noted that the material has good aging properties in a weak radioactive medium, thus ensuring the maintenance of its

properties over time.

  Finally, the material according to the invention is advantageously obtained with light colors allowing its easy location on a site by

example.

Claims (8)

  1. Flexible system for absorbing ionizing radiation, characterized in that it comprises at least one sheet (1) of a material made of mineral compounds of high atomic weight, embedded in a flexible polymer matrix, and having good   qualities of absorption of ionizing radiation.   2. Flexible system according to claim 1, characterized in that said material has a density between 1 and 10.   3. Flexible system according to claim 1 or claim 2, characterized in that the material has mechanical properties making it possible to handle, suspend and fold the material without causing tearing or appreciable reduction in its thickness. 4. Flexible system according to any one of   claims 1 to 3, characterized in that the material   has a thickness between 1 and 200mm.   5. Flexible system according to any one of   previous claims, for the cover of   piping, characterized in that said sheet (1) is simply arranged astride the piping, in   being held in place by its weight.   6. Flexible system according to any one of   claims 1 to 4, for the cover of valves (4),   characterized in that said sheet (1) has a cutout (2) in the form of a buttonhole intended to allow the passage of the valve.   7. Flexible system according to any one of   Claims 1 to 6, characterized in that it comprises   several said flexible sheets (1) superimposed.   8. Flexible system according to claim 7, characterized in that said flexible sheets (1) are crossed between them.