EP1105357A2

EP1105357A2 - Radiation protective concrete and radiation protective casing

Info

Publication number: EP1105357A2
Application number: EP99952354A
Authority: EP
Inventors: Dieter Vanvor
Original assignee: Siemens AG; Framatome ANP GmbH
Current assignee: Areva GmbH
Priority date: 1998-08-21
Filing date: 1999-08-11
Publication date: 2001-06-13
Also published as: CZ2001618A3; CA2341206C; CA2341206A1; CN1314874A; WO2000010935A2; BR9913188A; AR021779A1; AU6463499A; KR20010079675A; US20020134951A1; US6630683B2; WO2000010935A3; JP2002526746A; TW464878B; AU756455B2; JP3699650B2

Abstract

In order to obtain maximum shielding from heat and radiation, a radiation protective casing (2) is provided with a wall area (2a-2z) that is made of radiation protective concrete (22a-22z) that includes a first aggregate containing boron with a particle size of up to 1 mm, in addition to a second metal aggregate with a particle size of up to 7 mm. In a first embodiment, the amount of the first aggregate containing boron included in the radiation protective concrete is at least 5.0 wt. % and more particularly at least 7.8 %. In a second embodiment, the proportion of the second metal aggregate in the radiation protective concrete (22b) is 80-90 wt. %, more particularly 85-90 %. In the gap, the proportion of the first aggregate containing boron can range from 1.0 to1.5 wt. %.

Description

description

Radiation protection concrete and radiation protection jacket

The invention relates to a radiation protection concrete and a radiation protection jacket for shielding radiation from a radiation source, in particular for / shielding neutron and gamma radiation.

To shield a radiation source from which ionizing radiation and / or neutron beams are emitted, e.g. B. the radiation in the area of a beam channel of a reactor system, a spallation neutron source or the radiation from a medical device, steel, cast materials, polyethylene layers, lead, lead alloys and combinations of these materials are usually used as shielding materials. By doping these materials with so-called neutron poisons, e.g. Boron, in particular Borisotop 10, or cadmium, shielding materials of this type are particularly suitable for shielding neutrons. The neutrons are dependent on the selected neutron poison concentration, e.g. Boron concentration, and the neutron energy is absorbed to a greater or lesser extent.

The type, size and power of the radiation source largely determine the design, the material selection and the material arrangement of the shield. The required total thickness of the shield is usually determined by the intensity of the radiation at the entrance to the shield and the desired weakening of the intensity via the thickness of the shield and the specific shielding effectiveness of the selected shielding materials.

To with a particularly strong radiation source, e.g. B. a beam channel of a reactor plant to be able to achieve an effective protective jacket against the heat, neuron and gamma radiation that occurs, the shielding then exhibits them required high overall thickness usually has a particularly large volume. In addition, in the case of reactor plants or spallation neutron sources, the protective jacket or the protective barrier is divided into several areas or layers of different materials. For example, the reactor core is cooled and shielded by continuously cooled water as the first layer of the protective jacket. This first layer is usually followed by a second layer of solids, preferably concrete with a comparatively high density. As a result, the individual layers of the protective sheath formed from solids must be corrosion-resistant both to liquid and to vaporous water. For this purpose, the solid material selected as the shielding material is predominantly coated or encapsulated with refined metals. This is particularly complex in terms of design and assembly.

Another disadvantage is that cavities caused by a complex structure of the radiation source cannot be used, or cannot be used completely, for shielding due to the solid shielding materials. This leads to the fact that the dimensions are particularly large due to the shielding effect to be achieved and prescribed by regulations, and such a protective jacket is particularly expensive.

From a technical article from the magazine "Beton '10/78, pages 368 to 371, with the title" Radiation protection concrete - leaflet for the design, manufacture and testing of concretes of structural radiation protection *, it is known to add boron-containing substances to concrete as additives. Such boron-containing substances are, for example, colemanite, boron calcite, boron putty and boron carbide. In addition, heavy metal surcharges such as e.g. Iron granules or steel sand.

So far it was assumed that the boron-containing additives on the one hand and the heavy metal additives on the other hand, only a very small proportion can be added to the concrete without, for example, adversely affecting the setting of the concrete. With the radiation protection concretes described in the above-mentioned technical article, a radiation protection jacket could likewise only be produced with large dimensions, to the knowledge of the specialist knowledge to date.

The invention is therefore based on the object of specifying a radiation protection concrete with which a radiation protection jacket with a particularly small volume can be produced, taking into account the highest possible radiation-absorbing shielding effect. This should be achievable with a particularly high level of installation flexibility combined with a particularly low purchase and production effort. A radiation protection jacket should also be specified for this purpose.

In a first embodiment, this object is achieved according to the invention by a radiation protection concrete which, with a content of at least 5.0% by weight, in particular at least 7.8% by weight, contains a first boron-containing additive with a grain size contains up to 1 mm, and which contains a second, metallic aggregate with a grain size of up to 7 mm.

The radiation protection concrete of the first embodiment is particularly suitable for shielding strong neutron radiation.

The stated object is achieved in a second embodiment according to the invention by a radiation protection concrete which contains a first boron-containing aggregate with a grain size of up to 1 m and which contains between 80 and 90% by weight a second metallic aggregate with a Contains grain size up to 7 mm.

In radiation protection concrete of the second embodiment of the first, boron-containing additive is preferably present in a proportion or content of between 1.0 and 1.5 by weight. ^"The proportion of the second metallic aggregate is preferably in the interval from 85 to 89% by weight.

The radiation protection concrete of the second embodiment is particularly suitable for shielding against strong gamma radiation.

Contrary to expectations and to the astonishment of the experts, tests have shown that the radiation protection concrete of both embodiments can be produced and used technically despite the high content of the first boron-containing additive or the high content of the second metallic additive.

The radiation protection concrete according to the invention is particularly suitable for producing radiation protection antels, in which a wall area is formed from the radiation protection concrete at least one of the two embodiments.

The invention is based on the consideration that in order to achieve a particularly large shielding effect with a minimal volume, such a shielding material or radiation protection material should be used which can also be emptied into complicated cavities and thus achieves a shielding effect in the immediate vicinity of the radiation source. The composition of the shielding material should be designed in such a way that direct exposure to radiation can be achieved. In other words: the shielding should be particularly temperature and radiation-resistant, which means that it can also be used directly at the radiation source and thus under extreme environmental conditions. In addition, the potential for self-activation determined by the composition of the shielding material must be taken into account. In other words, due to the high gamma radiation, constituents of the additives can be activated with correspondingly long irradiation periods and even substances to be emitted can be emitted. Based on this, the radiation protection jacket is made of a concrete, which achieves the desired high shielding effect and low potential for self-activation due to its chemical composition and the grain size of the chemicals used. With regard to the desired shielding effect, the ratio of the gamma to the neutron radiation component with the total radiation intensity of the radiation source is decisive. The higher the proportion of cooking radiation, the higher the bulk density of the concrete to be selected in the set state according to DIN 1045. In the second embodiment, this is achieved by a high proportion of the second, metallic aggregate, which influences the density of the concrete used as a shielding material. In contrast, for a high proportion of neutron radiation in the first embodiment, the proportion of the first boron-containing additive which acts as a neutron poison is chosen to be particularly high. A minimum bulk density of about 3000 kg / m can also advantageously be set, since otherwise secondary gamma radiation can arise when neutron radiation is absorbed.

The radiation protection concretes of the first and second embodiment are advantageously concrete mixtures which contain as a base elements a cement with a high crystal water content and water (so-called / mixing water), the first boron-containing additive as a so-called neutron poison and the second metallic additive to achieve the desired bulk density.

A third, metallic or a fourth, mineral additive is preferably used in the radiation protection concretes according to the invention to further increase the bulk density or to increase the water content. In addition, a flow agent and / or a retarder are expediently provided as an auxiliary. The addition of flow and retarding agents improves the processability of the Concrete mix, especially from a bulk density of approx. 4000 kg / m ³ .

This concrete absorbs almost no water, so that there is almost no corrosion of the metallic aggregates. By adding the fourth mineral additive, preferably serpentine, it is also achieved that the water supplied during the production of the concrete is not removed even at higher temperatures. Rather, a large part of the water is bound in the form of crystal water in the concrete mix. Serpentine is characterized by its particularly good binding properties of a particularly large amount of water in the form of crystal water. This results in an improved corrosion resistance compared to standard concrete with at the same time particularly good properties for workability and producibility. These in turn enable shielding bodies of any shape to be produced. These shielding bodies or concrete blocks form the desired number and layering of the radiation protection jacket.

Because of its high capture cross section for neutrons (especially thermal neutrons), the boron mainly serves as a neutron absorber and heats up accordingly. However, boron is very light, less thermally conductive and less resistant to gamma radiation than many other materials. However, metals are used as the second additive, which often have a reflective effect on neutron radiation. Therefore, the quantity ratios of the aggregates allow absorption, moderation and reflection of the neutron radiation to be set according to the respective requirements, the density, heat dissipation and gamma absorption being achieved at the same time.

A suitable bulk density is achieved by combining the selected additives and a suitable one

Choice of their grain size causes. The respective grain size of the aggregates can be chosen so that the concrete visually the processing and the properties to be achieved, such as. B. moderation and absorption, the highest possible installation flexibility or the most effective shielding effect. For this purpose, the additives preferably have both fine and coarse particles. It has proven to be particularly advantageous that the first, boron-containing additive is more fine-grained than the second, metallic additive, the fine-grained first additive having an average grain diameter of approx. 1 mm and the coarse-grained second additive having an average grain diameter of approx. 7 mm exhibit.

For various applications of the radiation protection jacket according to the invention, it has been found to consider two borderline cases with regard to the type of radiation: a) predominantly neutron radiation with a residual portion of gamma radiation and taking into account the secondary gamma radiation which arises, and b) predominantly gamma radiation with residual portions of neutron radiation radiation.

In case a), the desired shielding effect is preferably achieved with the highest possible proportion of neutron poison in the shielding concrete, which should have a minimum density for shielding the secondary gamma radiation. For case a), the radiation protection concrete of the first embodiment is particularly suitable.

In case b), the desired shielding of gamma radiation is preferably achieved by the highest possible bulk density of the concrete (/ shielding concrete), this AD shielding concrete should have a minimal amount of a neutron poison to shield the residual neutron radiation. For this purpose, the radiation protection concrete of the second embodiment is preferred. The corresponding wall area formed from one of the concretes can be combined in the manner of a layer structure with other shielding layers of the radiation protection jacket each comprising a different concrete mixture. The individual shielding layers differ depending on their composition in the shielding effect achieved. For example, shielding layers can be provided with a lower bulk density and an increased boron content compared to the wall area, in order to obtain a higher protection against neutrons with a longer range.

To shield, in particular to absorb, the neutron radiation emanating from the radiation source, the boron in the first additive is advantageously used in the form of a boron-containing mineral, in particular colemanite containing boron oxide. The boron content in the first additive is at least 20% by weight, preferably between 30 and 50% by weight (calculated as boron oxide). The admixture of cole anit (naturally occurring mineral) with a boron oxide content of up to 41% by weight consequently makes it particularly high

Absorption property for thermal neutrons of the radiation protection jacket achieved.

To achieve a particularly high bulk density of the concrete, iron granules or steel granules are expediently provided as the second metallic additive. The use of steel granulate with a bulk density of up to 7850 kg / m as a coarse-grained material with a grain size of 0.3 mm to 7 mm determines the bulk density of the concrete produced. In addition, the selected grain size makes the concrete particularly easy to manufacture and process, even for smaller dimensions of the radiation protection jacket.

In order to achieve particularly good binding of the iron or steel granules in the concrete and, in addition, to achieve particularly high compressive and splitting tensile strength, a third additive, in particular barite sand, is preferably used. seen, which preferably has a grain size of up to 1 mm and is therefore particularly fine-grained. Through the targeted admixture of barite sand, the required compressive and splitting tensile strength can be set, which allows the concrete to be used both in load-bearing areas of concrete structures and in statically loaded concrete blocks.

For borderline case a), i.e. For a particularly high shielding of neutron beams, the wall area of the radiation protection jacket is preferably formed from the radiation protection concrete of the first embodiment. This radiation protection concrete is in particular a first concrete that has a minimum cement content between 8 and 9% by weight, a minimum water content (mixing water) between 4.5 and 6.5% by weight, a minimum residual content of the first aggregate ( Colemanite) of at least 7.8% by weight up to the same proportion as the selected proportion of cement, a minimum content of the second aggregate (iron or steel granules) between 30 and 35% by weight and a minimum content of the fourth mineral-containing aggregate ( Serpentine) between 40 and 50 wt .-%. Auxiliaries are not necessary for this first concrete mix. The percentages by weight relate to the sample weight minus the water which can be expelled at 80 ° C.

The particularly high proportion of water in the first concrete causes - due to the binding of the mixing water in the form of crystal water - a particularly high deceleration of neutron radiation. This is also reinforced by the colemanite content. In other words, the higher the colemanite and water content, the better this first one will be

Concrete its shielding property against neutron radiation.

This first concrete or the radiation protection concrete of one of the two embodiments advantageously has a bulk density of approximately 3000 kg / m ³ . In particular through the use of iron or steel granules with a certain grain size as the second additive, the specified mm minimum density achieved. The bulk density achieved additionally provides a sufficient shielding effect from the gamma radiation. By adding the fourth aggregate - serpentine, the crystal water content of the concrete mixture is increased significantly and the bond within the concrete is improved so that it is particularly pressure and splitting tensile. Due to the particularly high proportion of serpentine, the first concrete is referred to below as "serpentine concrete".

In order to keep the water content of the aggregates for the Serpentm concrete low, the third aggregate preferably has a grain size of up to 7 mm. It has proven to be particularly advantageous if the third additive is mixed with two different grain sizes. The minimum content of the third aggregate with a first grain size of up to 3 mm is advantageously between 12 and 16% by weight. With a second grain size between 3 and 7 mm, the minimum content is between 28 and 34% by weight. The specification of the grain size refers to the geometric mean value as it occurs when minerals are crushed or during the corresponding manufacturing process in the bulk material. In particular, however, the specified upper limit can be set by the mesh size of a corresponding sieve.

For borderline case b), i.e. for a high absorption of the

Gamma radiation of the radiation protection jacket, the wall area is preferably formed from the radiation protection concrete of the second embodiment. This radiation protection concrete is in particular a second concrete that has a minimum cement content between 4 and 4.5% by weight, a minimum water content between 1.5 and 2.5% by weight, and a minimum content of the first aggregate (colemanite) between 1 and 1.5% by weight, a minimum content of the second additive (iron or steel granulate) between 85 and 89% by weight, a minimum content of the third additive (barite sand) between 4.5 and 5% by weight and one Has a minimum content of at least one auxiliary from 0.1 to 0.15% by weight. The weight percentages are given on the weight minus the concrete's water which can be expelled at 80 ° C.

This second concrete or the radiation protection concrete of one of the two embodiments advantageously has a bulk density of approximately 6000 kg / m ³ . A particularly high bulk density is achieved in particular by using steel granulate with a certain grain size as the second additive, which forms the main component of the concrete. The high bulk density in turn causes a particularly high shielding of the resulting gamma radiation. By binding the water (mixing water) m form z. B. Kπstallwasser as well as the crystal water already contained in the raw materials, in serpentine, furthermore a braking (moderation) of the neutron radiation is also achieved in this case. In addition, the concrete has a good absorption property of neutron radiation due to the Colemamt component. By adding the third additive (barite sand), the bond within the concrete is improved so that it achieves particularly good compressive and splitting tensile strengths. For particularly quick and easy processing of the concrete, a flow agent and / or a delaying agent are preferably provided as auxiliary substances. The addition of these auxiliaries depends on the amount of colεmanite added, which has a particularly strong influence on the workability of the second concrete. This second concrete, which has iron or steel granules as the main constituent for borderline case b), is referred to as "steel granulate concrete".

When choosing the concrete with regard to the minimum content of its components, a variety of different properties to be achieved with different influences must be taken into account, e.g. B. Type of radiation to be shielded, dose rate in front of unα nacn αer shielding or the radiation protection jacket, neutron radiation component and its energy level, long-term corrosion under the conditions of a particularly strong radiation source, etc. To, for example, a To combine particularly high shielding of neutron beams with good protection against gamma rays, several different compositions of the concrete, in particular several shielding layers, each consisting of a different amount of the concrete containing aggregates, can be combined.

In a particularly advantageous embodiment, at least part of the radiation protection jacket comprises a first layer provided with the first concrete (serpentine concrete) and a second layer provided with the second concrete (steel granulate concrete). Such a two-layer radiation protection jacket ensures that minimum and maximum limits for the remaining radiation after these layers are met by an appropriately selected thickness of the respective layer or by a certain number of layers. This enables safety requirements with regard to the radiation exposure of man and machine to be met.

A radiation protection jacket constructed of concrete in this way is particularly advantageously suitable for indirect and / or direct shielding of a radiation source, X-ray prediction, a room having a radiation source or a radiation channel in a reactor system. For example, the radiation protection jacket is suitable both for the direct shielding of a radiation source in the form of a formwork and for the indirect shielding of a radiation source in a room in the form of a wall or a floor.

Exemplary embodiments of the invention are explained in more detail with reference to a drawing. Darm shows the figure a schematic representation of a radiation protection jacket for the direct shielding of a radiation source.

The radiation protection jacket 2 shown in the exemplary embodiment according to the figure and arranged around two beam channels 1 is Part of a radiation source, not shown in detail, for example a reactor core of a nuclear power plant. The two jet channels 1 are, for example, part of a measuring arrangement in the control area of a reactor plant or nuclear power plant. A tank 4 is arranged to shield the reactor core (radiation source), which is not shown. The design of the tank 4 depends on the construction of the system. The reactor basin 6 connects to the tank 4. Depending on the type of system, the tank 4 and the reactor basin 6 can also form a unit. The reactor pool 6 is delimited by a reactor pool wall 8.

The two beam channels 1 are arranged in the radiation protection jacket 2 for the controlled removal and guidance of the radiation emanating from the reactor core. The radiation protection jacket 2 is arranged between the tank 4 and the outer wall of the reactor pool wall 8, a casing tube 12, comprising a casing tube 12A, a formwork tube 12B and a compensator tube 12C. The cavity to be filled by the radiation protection jacket 2 is limited by the respective inner wall of the casing tube 12A, the formwork tube 12B, the compensator tube 12C and the inside of a jet tube nose 10 guided in the tank 4. The components or components mentioned are attached to the respective connection piece 16 with fastening elements 14 attached, e.g. screwed.

To avoid continuous gaps, the hollow tube 12 is stepped several times in the axial direction. For this purpose, the tubes forming the casing tube 12 - the casing tube 12A, the switching tube 12B, the compensator tube 12C - have a correspondingly increasing diameter. The casing tube 12, also called the formwork tube, can consist of one element, e.g. Casting element, or consist of several tubes or sub-elements.

After installation of the radiation protection jacket 2 m, the outer tube 12 is closed on the side of the lining case 12A by means of an / end plate 18. To shield the (laterally scattering) neutron and gamma radiation emerging from the two beam channels 1, the two beam channels 1 are completely enveloped by a metal jacket 19 in cross section. The metal jacket 19 is preferably formed from a rustproof ferritic material and causes the least possible self-activation of the radiation protection jacket 2 arranged subsequently in cross section. In addition, the thickness of the metal jacket 19 is determined by the static and dynamic loading of the radiation protection jacket 2.

In order to achieve different shielding properties of the radiation protection jacket 2, this is divided into a number of wall areas 2a to 2z, each of which completely surrounds the two radiation channels 1 and each of which consists of a radiation protection concrete or concrete 22a to which contains different amounts of additives and thus has different raw densities 22z are formed.

The thickness of the wall area 2a to 2z is determined by the respective diameter of the individual elements of the hollow tube 12. Both the number and the respective thickness as well as the respective chemical composition and the respective bulk density of the wall areas 2a to 2z is determined by pre-dimensioning as required. The concretes 22a to 22z forming the wall regions 2a to 2z can thus vary.

Depending on the desired requirement, the concrete 22a to 22z belonging to a wall area 2a to 2z has corresponding proportions of a first boron-containing aggregate with a grain size of up to 1 mm and a second metallic aggregate with a grain size of up to 7 mm. The first fine-grain aggregate is a boron-containing mineral, e.g. B. colemanite. The second aggregate, known as coarse-grained because of its grain size, is preferably iron granulate or steel granulate. The proportions of the first and second aggregate for the concrete 22a to 22z are largely determined by the shielding properties to be achieved, in particular gamma absorption and absorption and moderation of neutrons, of the radiation protection jacket 2 in the associated wall area 2a to 2z. For a particularly high absorption and moderation of neutrons, the concrete 22a primary that forms the wall region 2a closest to the radiation source, the reactor core, is suitable for absorbing neutron radiation due to its high proportion of the first mineral-containing additive - colemanite.

For this purpose, the first concrete 22a has a minimum cement content between 8 and 9% by weight, a minimum water content (mixing water) between 4.5 and 6.5% by weight, a minimum content of the first aggregate (colemanite) of 7. 8% by weight up to the weight fraction of cement, a minimum content of the second aggregate (iron or steel granulate) between 30 and 35% by weight and a minimum content of a fourth mineral-containing aggregate (serpentine) between 40 and 50% by weight . Due to the low proportion of the second aggregate - iron or steel granulate - this concrete 22a is only suitable for absorbing the gamma radiation. When set, the first concrete 22a has a minimum bulk density of up to 3000 kg / m.

In order to improve the bond within the first concrete 22a and to substantially increase the crystal water content, serpentine is used as the fourth, mineral-containing additive. For an advantageous mixture of the first concrete 22a, it has been found that the minimum serpentine content for a first grain size up to 3 mm is between 12 and 16% by weight. For the second grain size between 3 and 7 mm, the minimum content is between 28 and 34% by weight. This first concrete 22a, which has serpentine as its main component, is called Serpentine concrete, and is particularly pressure and splitting tensile.

For a particularly good shielding of a considerable part of the gamma radiation which is produced, the wall region 2b, which is seen as a second layer from the radiation source, is formed from a second concrete 22b having a different chemical composition than the first concrete 22a.

The second concrete 22b forming the second wall region 2b preferably has a minimum content of cement between 4 and 4.5% by weight, a minimum content of water (mixing water) between 1.5 and 2.5% by weight, a minimum content of the first Aggregate (colemanite) between 1 and 1.5 wt .-%, a minimum content of the second aggregate (iron or steel granules) between 85 and 89 wt .-%, a minimum content of a third, in particular metallic, aggregate (barite sand) between 4 , 5 and 5 wt .-% and a minimum content of at least one auxiliary from 0.1 to 0.15 wt .-%. Due to this composition of the second concrete 22b, it is preferably suitable for a particularly high shielding of the gamma radiation and, due to the colemanite portion, for a lower absorption and moderation of the neutron radiation emanating from the radiation source than the first concrete 22a.

Due to the grain structure of the first and second aggregate, for a particularly good binding of the second concrete 22b as the third aggregate, it is expedient to provide bar sand with a grain size of up to 1 mm. In order to improve and accelerate the setting process and thus the producibility of the second concrete 22b, a flow agent or a delaying agent is provided as an auxiliary. Such a second concrete 22b formed from the above-mentioned proportions of cement, water, aggregates and auxiliary materials has a bulk density in the set state of up to 6000 kg / m ". This bulk density largely determines the particularly high shielding of the gamma radiation.

In order to achieve a particularly high binding of the water content as crystal water in the second concrete 22b, alumina cement based on calcium alumates is used in particular as cement. The crystal water effects a particularly good deceleration of the neutron radiation. The addition of colemanite with a boron oxide content of up to 41 mass * also achieves a particularly high absorption of thermal neutrons.

The two-layer arrangement has proven to be particularly advantageous, since in the first wall area 2a of the radiation protection jacket 2 the fast neutrons emerging from the radiation source and not the two beam channels 1 are moderated particularly well by the high proportion of colemanite in the first concrete 22a be absorbed. In addition, in accordance with the bulk density characterizing the first concrete 22a, a shielding of a considerable proportion of gamma radiation is already achieved. In the second wall area 2b, mainly gamma radiation is shielded due to the larger proportion of steel or iron granulate compared to the first concrete 22a, the neutrons emerging laterally from the beam channels 1 due to scattered radiation due to the proportion of the first aggregate (colemanite) analogously to first concrete 22a are moderated and absorbed.

Depending on the type and intensity of the radiation source, further wall areas 2c to 2z can be filled with further suitably chosen concrete 22c to 22z. Depending on the selected proportions of the raw materials of the concrete 22a to 22z belonging to the respective wall area 2a to 2z, this has special shielding properties or effects. For example, the bulk density of the concrete 22a can be changed by changing the proportion of the iron or steel granulate can be set to 22z. Furthermore, the boron content of the respective concrete 22a to 22z can be adjusted by changing the content of colemanite.

Furthermore, the use of concrete 22a to 22z for certain layers or wall areas 2a to 2z of the radiation protection jacket 2 enables the radiation source to be completely enveloped and thus a particularly high shielding effect of the radiation source even with difficult and complex geometries or constructions. In particular, the concrete 22a to 22z enables formwork, e.g. m the hollow tube 12 that cavities are also closed. Alternatively, the wall area 2a of the radiation protection jacket 2 can be designed as a formwork, a wall or em floor of a room or a building. B. is an X-ray device or another radiation source.

The table on the description page 20 shows the components which are important for the two limit cases a) and b) described above and for the shielding properties of the first concrete 22a (serpentine concrete) and the second concrete 22b (steel granulate concrete) to be achieved, particularly advantageous minimum and maximum limits. The minimum and maximum limits for the particular grain size of the granulated constituents, which are determined to be particularly advantageous for a particularly simple production and processing of the two concretes 22a and 22b, are also specified. Further mixing ratios between the two concrete mixtures are also possible.

Due to the highly effective radiation shielding provided by the respective composition of the concretes 22a and 22b to 22z, the radiation protection jacket 2 em has particularly good behavior both with regard to self-activation and thermal influences and with regard to absorption and moderation of neutrons and shielding of gamma radiation. The radiation protection jacket 2 is therefore particularly suitable for direct use in radiation sources, for. B. in radiation pipes from research facilities, on the Pπmarkkreislauf a reactor system, etc. In addition, the radiation protection jacket 2 can be carried out on the one hand over a large area and in one layer, for example in the form of walls, floors and ceilings. On the other hand, the radiation protection jacket 2 can be constructed from a plurality of layers or wall regions 2a to 2z, each of which has different shielding properties. The radiation shielding structure of the radiation protection jacket 2, which is particularly radiation-shielding, also excludes any significant radiation exposure of the operating personnel.

table

Claims

claims

1. Radiation protection concrete (22a), which contains at least 5.0% by weight, in particular at least 7.8% by weight, of a first boron-containing aggregate with a grain size of up to 1 mm, and the second , metallic aggregate with a grain size up to 7 mm.

2. Radiation protection concrete (22b), which contains a first, boron-containing aggregate with a grain size up to 1 mm, and with a content between 80 and 90% by weight, contains a second, metallic aggregate with a grain size up to 7 mm.

3. Radiation protection concrete (22b) according to claim 2, which contains the first boron-containing additive with a content between 1.0 and 1.5% by weight.

4. Radiation protection concrete (22b) according to claim 2 or 3, wherein the content of the second metallic aggregate is between 85 and 89% by weight.

5. Radiation protection concrete (22a, 22b) according to one of claims 1

the first boron-containing additive being a boron-containing mineral, in particular colemanite.

6. Radiation protection concrete (22a, 22b) according to one of claims 1 to 5, wherein iron granulate or steel granulate is provided as the second metallic additive.

7. Radiation protection concrete (22a, 22b) according to one of claims 1 to 6, which has a minimum bulk density of about 3000 kg / m '.

8. radiation protection concrete (22a, 22b) according to one of claims 1

which has a bulk density of about 6000 kg / m ³ .

9. radiation protection concrete (22a, 22b) according to one of claims 1

which comprises a third, metallic aggregate, in particular barite sand, with a grain size of up to 1 mm.

10. radiation protection concrete (22a, 22b) according to one of claims 1 to 9, wherein em fourth, mineral-containing aggregate, in particular serpentine, is provided with a grain size of up to 7 mm.

11. Radiation protection jacket (2) with a wall area (2a to 2z) made of a radiation protection concrete (22a, 22b, 22c to 22z) according to one of claims 1 to 10.

12. Use of a radiation protection jacket (2) according to claim 11 for shielding a radiation source, an X-ray device, a room having a radiation source or a radiation pipe (1) in a reactor system.