WO2015132425A1

WO2015132425A1 - Portable shielded enclosure for applications using ionising radiation

Info

Publication number: WO2015132425A1
Application number: PCT/ES2015/000021
Authority: WO
Inventors: Miguel SUFO PINO
Original assignee: Universidad De Cádiz (Otri)
Priority date: 2014-03-07
Filing date: 2015-02-06
Publication date: 2015-09-11
Also published as: ES2545276A1; ES2545276B2

Abstract

The invention relates to a containment structure formed by standardised hollow and bolted metal profiles which comprise guides facilitating the construction of each modular shielded panel forming the walls of the enclosure, by joining individual plates constructed by means of a sandwich-type structure with a layer of polymer material, another layer of lead of the same proportions and an air chamber as the central core. The portability, modularity and ease of assembly of the invention facilitate the implementation of tests anywhere.

Description

PORTABLE SHIELDED ENCLOSURE FOR APPLICATIONS USING IONIZING RADIATION.

SECTOR OF THE TECHNIQUE

The scientific area is "Environmental technologies".

The technological area is "II. Instruments: CT09- Nuclear engineering".

The branch of industrial activity is "DJ-Metallurgy, Manufacture of metallic products", CNAE Division "28- Manufacture of Products, Metals, except Machinery and Equipment".

The international patent code would be G21F 5/00.

Section G: Physics.

G2: Nuclear Science.

G21: Nuclear Physics; Nuclear technique

G21F: Protection against X-rays, Gamma rays, corpuscular radiation or particle bombardment; treatment of materials contaminated by radioactivity; provisions for decontamination.

G21F 5/00. Portable or transportable armored containers.

STATE OF THE TECHNIQUE

As indicated by the Nuclear Safety Council (CSN), in all applications of ionizing radiation, the exposure dose of users and other persons in the vicinity in addition to the surrounding environment, must implement the ALARA concept (As Low As Reasonably Achievable), that is, reduced to levels as low as reasonably possible and, in any case, not to exceed the internationally agreed threshold as dictated by the Agency International Atomic Energy (IAEA) through its standards for occupational radiation protection (No. RS-G-1.1, 1.2 and, 1.3, 2004).

One of the methods to achieve this objective is to act on the shielding materials that make up the enclosure where the tests will be carried out by means of the radioactive source. Other aspects also related to this purpose are the structural design and wall thicknesses suitable for the armored enclosure.

In Spain, through the practical manual of radiological safety published in April 1996 (IAEA-PRSM-2) and, in particular, within the manual on armored enclosures, the definition of these constructions is collected as "any enclosed space built to contain ionizing radiation and provide sufficient shielding to people in adjoining areas. " The definition is indifferent to the size and design of the enclosure, what varies is the type of radioactive source that will act inside: X-rays, gamma or neutrons, among others. This aspect will imply a design based on suitable materials and thicknesses to ensure that the threshold that defines the radiological alert zone is not exceeded. In this document, therefore, a series of recommendations are made for the selection of the thicknesses of the primary and secondary barriers based on two parameters: The radioactive source and the type of material of the barriers: concrete or lead. This results in a series of standard thicknesses for each source-material configuration. These types of recommendations are established for solid barriers and, only, for these two types of shielding materials but, from them, allow the estimation of the calculation of the dose rate of any person or object located at a certain distance from the outside of the armored enclosure.

In the scientific literature, it is possible to find old records such as those published by the authors Roca and Capdevila, in 1967, where an armored enclosure for the spectrographic analysis of radioisotope solutions is described. Said enclosure was one of the first designs to attenuate the ionizing radiation by estimating the necessary wall thickness in lead, taking iodine-131 as the basis for said study. From the radioactive spectrum and the distance of the operator not less than 45cm from the outer wall of the enclosure, the need to use 10mm thick solid lead plates that provided an adequate safety margin. The dimensions of said container were 1254x800xl000mm. Later, patents US4079257A of the year 1978 and, EP0171256 Bl of 1985, deal with other types of fixed cameras to carry out chemical or photochemical processes with different purposes and, using for this purpose, metal containers where materials and thicknesses of materials are not indicated. barrier. The reference FR2577684A1 of the year 1985, provides an interesting solution by providing a useful container for its application as an instrument for measuring the dose of gamma radiation with the mediation of a set of sensors. Other types of records found in the literature, such as patents EP0513512B1 and EP0513515B1 of 1992 address different types of container ships to house radioactive sources from which, at present, they are already easily commercially available but suffer from armored enclosures to carry out any activity radiological without risk for the people who operate there. Similarly, the reference WO 94/02869 of the year 1994, describes a calibration system of the radiation dose received in two separate containers, this design is widely used in radiodiagnostic activities to compare the dose received in different human organs.

More recently, the utility model U201130221 of the year 2011, deals with the design of a mobile tank for the transport of radiological material, of geometry in the form of a parallelepiped, built using massive walls of concrete and, arranged with lugs on its upper part or , holes in its lower part, for lifting. In this last register, no barrier thicknesses or weight of the complete deposit are provided and, being civil works, it can hardly be used as an itinerant work instrument, easily assembled and disassembled. Finally, in US2013047521 Al, an autonomous portable equipment for radiological activity is described. The device includes an outer container adapted to be portable and self-supporting. The interior of the container has barriers of different thicknesses to reduce the radiation dose and allow the occupation of several people without risk. The walls are designed with metallic and polymeric materials, likewise, the container itself includes a trailer system with wheels. Given the dimensions and, therefore, the weight of this previous referenced deposit, it is estimated that the cost of transporting it can seriously compromise the economic aspect of its use.

DESCRIPTION OF THE INVENTION

The object of the invention consists of a portable armored enclosure oriented towards applications that use ionizing radiation, among others those of the gamma type.

The enclosure has a parallelepiped shape and is composed of an envelope composed of twelve modular panels, which are inserted in a containment structure, composed of bolted standardized metal profiles, which facilitates its assembly and disassembly, without requiring heavy machinery for handling.

The containment structure is prepared so that each side of the enclosure is closed by two panels arranged in parallel, one on the inner side and, next to the first, on the outer face, so that, once the radioactive source is placed and the specimens to be tested inside the enclosure, the dose of external radiation that passes through the two panels on each side is limited to levels allowed to reduce the risk of people and the environment (IAEA Safety Standards, GSR Part 4, of the year 2010).

The profiles that make up the containment structure can be vertical corner, central vertical, lower horizontal, upper horizontal and upper crosshead. Each profile is fixed to the others by removable joints. The vertical corner profiles have guides that facilitate the clamping of the plate structure that will form each of the modular panels. The horizontal profiles have square-shaped plates for joining these with the vertical profiles by means of removable joints. The upper crosshead will be mounted on the structure constructed by the lateral and horizontal profiles, to support the panels that constitute the armored roof of the enclosure.

All the profiles that settle on the ground, that is, the vertical, central and the vertical ones; they have armored inner caps that prevent radiation path escaped from inside the metal profile gap, as illustrated in figures 10 and 11, the design guarantees the tightness of the radiation path to the level specified above.

The lower horizontal profiles have a guide where the plates are inserted and incorporate a U-shaped support (figures 3 and 4), which will be responsible for holding the plates to prevent buckling deformations, motivated by their slenderness.

Each of the modular panels is constructed from various plates, sandwich type, square prismatic geometry, between 14-24mm thick. These plates must be placed next to each other, taking advantage of the guides that contain the containment structure, until each of the panels is formed.

Each plate is formed by a sandwich structure that has a layer of polymeric material, then a layer of lead, followed by a layer of air and, the same configuration is repeated, as shown in Figure 7. The polymeric material It can be pvc, polypropylene, polymethacrylate, etc.

The plates that complete the inner face of the perimeter enclosure are narrower than those located on the outer face, so that their joints never coincide. This geometric aspect prevents any type of radiation leakage through the joint joints of the plates, as shown in Figure 8. Similarly, all plates will have dimensions in height that will cover all faces from top to bottom of the enclosure surface of the enclosure. Any plate located on the side faces could serve as an entry and exit door for people and the material needed to carry out the tests. Gaps have been arranged as handles, on the top of each plate, to improve its handling in the assembly and disassembly, especially for those that are disassembled first, the other plates will be easily disassembled, once have removed the first.

The union of the two panels on each side (interior + exterior), give the assembly a minimum thickness of 14 + 14 = 28mm to each effective wall of the container. With this configuration is achieved a dose attenuation efficiency of more than 97%. The value of the residual radiation determines the scope of the observable zone, within a radiation protection program.

The construction of each panel, from modular plates of low weight, facilitates its transport, which together with its ease of assembly and disassembly of the armored container allows the test to be moved to any place, adapting to the needs of the client.

The design is designed for applications with radioactive sources of artificial origin, whose energy spectrum is less than 300 keV, such as Irl92 and Se75, whose sources are confined or added inside capsules or protective boxes and, by means of an internal guide, pushes them and move until you go outside. These radioactive sources are considered Category 2 by Safety Guide No. RS-G-1.9 of the IAEA of 2009, that is, considered Very Dangerous for people and the environment. Based on them, the thickness of the panels must have been estimated, considering parameters such as the distance from the source to the specimen and the orientation of the source with respect to it.

DESCRIPTION OF THE CONTENT OF THE FIGURES

Fig. 1. Exterior isometric view of the armored enclosure.

Fig. 2. Exploded view of the elements that form the enclosure: side panels, floor panels, roof panels and, the containment structure.

Fig. 3. Isometric view of the vertical structural corner profile from the inside.

Fig. 4. Isometric view of the vertical structural corner profile from the outside.

Fig. 5. Isometric view of the set of vertical profiles on the periphery of the armored panels located on the floor.

Fig. 6. Isometric view of the upper structure, basically composed of a cross-shaped profile, which will support the panels mounted on them, constituting the armored roof of the enclosure. Fig. 7. Geometric and physical configuration of each unit plate that forms each panel.

Fig. 8. Isometric view illustrating the arrangement of armored panels on the lateral surface of the enclosure, by its introduction into the metal guides welded into the structural profiles.

Fig. 9. Perspective view of the lower part of the enclosure where the arrangement of armored baseboards on the edges of the metal profiles is shown.

Fig. 10. Isometric view of the internal shielding elements that line the holes of the corner profiles of the metal structure.

Fig. 11. Isometric view of the exact location of the internal armor elements that line all the holes in the metal structure and the armored floor panels.

EMBODIMENT OF THE INVENTION

The enclosure object of the invention consists of the following components:

- The containment structure, composed of hollow standardized metal profiles that are identified by the location they occupy in each part of the structure.

The modular panels, lateral, inferior and superior, constructed from plates of sandwich type, joined to each other thanks to the guides with which they have the profiles of the structure of containment.

The following describes the way in which the armored enclosure must be assembled.

a) Assembly of the containment structure.

The assembly of the containment structure begins with the corner profiles, as described in Figures 3 and 4. Each corner profile is formed by the union of a vertical profile with two horizontal bottoms that will be made by removable joints. In this way, a corner is geometrically defined by three profiles in a tri-rectangle trihedron configuration.

Once the corner profiles are mounted and joined together, the armored panels located on the floor will be mounted and, subsequently, on the resulting structure, the central vertical profiles will be mounted, as shown in Figure 5.

Once the previous stages are completed, it is possible to mount the upper structure, basically composed of a cross-shaped profile, as shown in figure 6, which will support the panels that are mounted on them, constituting the armored roof of the enclosure.

b) Mounting the side and upper armored panels.

The assembly of the panels begins by covering the entire surrounding side surface of the enclosure. The panels are formed by two levels of plates (interior + exterior), as specified above, which will make each container wall have a minimum thickness of 14 + 14 = 28mm in total. As the plates of each internal and external level of different measures, the joint joints will not coincide, preventing the leakage of radiation through them, as seen in Figure 8. Finally, the panels covering the upper part of the enclosure, by means of two other levels of armored plates.

c) Shielding of lower horizontal profiles

In order to prevent radiation leakage by penetrating the metal profiles, armored sockets located on the inner edges of the lower horizontal profiles have been arranged. This is solved with the arrangement illustrated in Figure 9. To ensure the joining of these panels in the form of sockets to the horizontal metal profiles, it is advisable to use some adhesive or non-slip material that restricts the movement of the elements.

In the section on assembly and disassembly, the assembly has been designed to be comfortably executed by one or two operators, at most. To this end, sizes of plates and metal profiles that are in the range of 15-45kg have been designed. These values are allowed by the Occupational risk prevention regulations, for special cases of lifting loads, assuming that operators are sufficiently trained in this type of practice. Additionally, for the disassembly work mainly, some profiles have been arranged at the top of some plates as handles to facilitate its vertical displacement. The latter is particularly useful in the plates that serve as input and output.

INDUSTRIAL APPLICATION

Historically there have been numerous types of armored enclosures for medical radiodiagnostic applications, many of them highlighted in the background. Likewise, these enclosures have also been used for industrial purposes in fixed non-destructive tests. The problem with this type of fixed installation is that the tests must be limited to those that can be carried out in a specific area. By means of the present invention, due to its ease of transport and assembly, it is possible to carry out tests anywhere.

Claims

1. Portable armored enclosure for applications that use ionizing radiation, comprising: a) A containment structure formed by hollow and bolted standardized metal profiles, which have guides that facilitate the construction of each modular armored panel by joining individual plates its portability

b) Twelve modular armored panels, two on each side (inside + outside) of the parallelepiped that forms the enclosure, arranged two by two, one next to the other in parallel, each formed by the union of various plates of square geometry or rectangular, constructed by a sandwich structure with a layer of polymeric material, another layer of lead in the same proportions and with an air chamber as the central core, which join each other thanks to the guides that have the profiles of the structure of containment.

2. Portable armored enclosure for applications using ionizing radiation, according to claim 1, characterized in that the profiles that make up the containment structure can be vertical corner, central vertical, lower horizontal, upper horizontal and upper crosshead.

3. Portable armored enclosure for applications using ionizing radiation, according to claim 2, characterized in that the vertical corner profiles have guides that facilitate the clamping of the plate structure that will form each of the modular panels.

4. Portable armored enclosure for applications using ionizing radiation, according to claim 2, characterized in that the horizontal profiles have square-shaped plates or tabs, for joining these with the vertical profiles, by means of bolt-type joints.

5. Portable armored enclosure for applications that use ionizing radiation, according to claim 2, characterized in that the lower horizontal profiles have a guide where the plates are inserted and incorporate a U-shaped support, which will be responsible for holding the plates to avoid buckling deformations.

6. Portable armored enclosure for applications using ionizing radiation, according to claim 2, characterized in that the upper crosshead is mounted on the structure constructed by the lateral and horizontal profiles, to support the panels that constitute the armored roof of the enclosure.

7. Portable armored enclosure for applications using ionizing radiation, according to claim 2, characterized in that the vertical profiles have armored inner linings that prevent the passage of leaked radiation into the profile gap.

8. Portable armored enclosure for applications using ionizing radiation, according to claim 2, characterized in that the polymeric material used in the manufacture of each of the plates that form each panel of the enclosure can be pvc, polypropylene, polymethacrylate or, any type of material similar plastic

9. Portable armored enclosure for applications using ionizing radiation, according to claim 2, characterized in that the plates used to form the panels of the interior part of the ceiling and the floor of the enclosure must have different surface geometry than those used to form the exterior panels, so that radiation leakage does not occur through the joint joints of the plates

10. Portable armored enclosure for applications using ionizing radiation, according to claim 2, characterized in that the plates used to form the inner face of the perimeter enclosure are narrower than those located on the outer face so that radiation leakage does not occur through of the joints of joining of the plates, although all will have dimensions in height that will cover from top to bottom the wall of the enclosure,

11. Portable armored enclosure for applications that use ionizing radiation, according to claim 2, characterized in that the plates used to form the panels of the enclosure have a thickness range of between 14-24 mm.

12. Portable armored enclosure for applications that use ionizing radiation, according to claim 2, characterized in that on the top of some plates, profiles are arranged as handles to facilitate its vertical movement in assembly and disassembly work.

13. Construction procedure of the portable armored enclosure for applications using ionizing radiation, according to previous claims comprising the following steps:

a) Mounting the corner profiles, formed by joining a vertical profile with two horizontal bottoms in the form of a tri-rectangular trihedron. Next, another vertical profile is joined with its lower horizontal and, thus, to complete the four identical corners.

b) Mounting the central vertical profiles on the structure mounted in the previous stage.

c) Mounting on two of the sides formed by the structure resulting from the previous stage of two upper horizontal profiles. d) Assembly of the upper structure, composed of a cross-shaped profile on the formed structure resulting from the previous stage. e) Assembly of the plates that will comprise the two roof panels and the two floor panels.

f) Assembly of the plates that will comprise each of the two panels that will form each wall of the enclosure.

g) Shielding of lower horizontal profiles providing two levels of panels in the form of baseboards or corners that line said edges.

14. Use of the portable armored enclosure for applications using ionizing radiation, according to previous claims for applications with radioactive sources of artificial origin, whose energy spectrum is less than 300 keV.

15. Use of the portable armored enclosure for applications that use ionizing radiation, according to previous claims in nuclear medicine in hospital facilities that require a portable enclosure for its location 1 anywhere or simply as a store of radioactive material.