Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F3/00—Shielding characterised by its physical form, e.g. granules, or shape of the material
  • G21F3/04—Bricks; Shields made up therefrom
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F1/00—Shielding characterised by the composition of the materials
  • G21F1/12—Laminated shielding materials
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F3/00—Shielding characterised by its physical form, e.g. granules, or shape of the material
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F7/00—Shielded cells or rooms

Definitions

• the invention relates to a multilayer radiation protection wall for shielding gamma and / or particle radiation, in particular for radiation shielding of a reaction site on a high-energy accelerator array and a radiation protection chamber with the radiation protection wall.
• High-energy accelerators for particle beams are being used more and more frequently worldwide. Here are the
• accelerators are not only planned for basic research as a neutron source, but are also discussed as nuclear facilities for power generation, with which subcritical arrangements with an additional neutron flux can be brought into a critical state. Furthermore, these systems can also be used for so-called in-cineration, in which durable radioactive material can be transformed into short-lived.
• a problem in the operation of high energy accelerators is the production of high energy secondary radiation in the target areas (target of the particle beam in which it is deposited) or in beam losses during transport on the path of the beamlines of the high energy or primary beam towards the target.
• the generated neutron and gamma radiation has a high permeability even by meter-thick shields.
• pions are also generated, among others, which break down into muons. The latter also have very long ranges and must be stopped in special jet killers.
• Walls and ceilings can be assembled as individual parts to form an overall shield.
• the shield can in addition to normal concrete with typical densities in the range of 2.3 g / cm 3 and heavy concrete types with appropriate surcharges such.
• the production of the radiation depends on the radiation quality, the energy, the intensity and the loss rate.
• the shielding thickness also depends on the limits to be observed by the national legislation to be observed.
• the limit values are defined as annual dose limits or related to the dose rate in ⁇ Sv / h.
• the level of radioactivity generated must be below certain limits in order to comply with national legislation. So z. B. for the unrestricted release of substances in accordance with German radiation protection law, a nuclide-specific release value Ai in Bq / g should be undercut. For multiple radionuclides, the total exhaustion must be determined by applying the sum rule be less than one.
• the total exhaustion G is defined as:
• Fi is the actual activity per mass and radionuclide summed over all radionuclides (i).
• High-energy accelerator systems with regard to the radioactive activation of the materials and their Abkling in need of improvement, based on the operation of several years or decades of high beam energies and intensities and the subsequent ' disposal. This aspect is particularly true on the one hand be of particular importance when natural shielding • use after use of the plant as radioactive activated and but on the other hand are present little experience in dealing with large amounts of these substances.
• the invention is therefore based on the object to provide a multi-layer radiation protection wall, in particular for shielding high-energy gamma and / or particle radiation from high energy and / or nuclear reactions for a radiation protection chamber, which even after a long period of operation and high beam energies and intensities with respect to the subsequent disposal of the materials used has good manageable ' radioactive activation and whose components are at least partially recyclable. It is still a task, such a task
• Radiation protection wall for a high-energy accelerator system to provide, in which when decommissioning as little as possible to be disposed of contaminated material and as much material is below the predetermined limits and can be reused.
• a further object is to provide such a radiation protection wall and radiation protection chamber which avoids or at least reduces the disadvantages of known shields.
• a multilayer radiation protection wall for shielding high-energy gamma and / or
• Particle radiation in particular from high energy and / or nuclear reactions, generated by primary radiation in the range above 1 GeV, in particular over 10 GeV or even higher provided.
• the radiation is shielded or attenuated from a reaction site at a high energy particle accelerator facility.
• the radiation to be shielded is in most cases secondary radiation, which results from a reaction of the primary beam with a target, but may also be a remainder or part of the primary beam itself.
• the radiation protection wall has a sandwich-type construction of at least one first and second layer arrangement, wherein the first layer arrangement comprises at least one primary shielding layer and the second layer arrangement comprises at least one secondary shielding layer, which in particular consists of different materials and is functionally different.
• the primary shield layer is preferably formed as a spallation layer and the secondary shield shield layer is preferably formed as a moderation layer.
• Layer arrangement particularly preferably both, multiple parts ⁇ formed or subdivided into a plurality of adjacent and already pre-defined in the construction subsections, so that a simple, separate dismantling and a separate and ' selected recycling or disposal of the sections are possible.
• the subdivision into subsections can be realized by division into a plurality of adjacent separate moderation layers and / or spallation layers and / or by lateral (transversely to the layer plane) division of the moderation layer (s) and / or the spallation layer (s). '
• the subsections which experience a high activation by the operation are separated from the subsections which, although having a shielding effect and, to a lesser extent, a deactivation, ie lower in their activity level.
• These layers, the z. B. contain natural substances and are only slightly activated, are soon after the end of use again without restriction or at least released for release and are then available for natural use again.
• the invention is not limited to the satisfaction of any national limit regulations.
• the first layer arrangement comprises a plurality of 2, 3 or more spallation layers and / or the second layer arrangement comprises a plurality of 2, 3 or more moderation layers in order to achieve a separability along the layer normal in addition to the lateral separability.
• the deconstruction planning can be adapted in two dimensions - in polar coordinates azimuthally and radially - to the expected radiation exposure during the design, so that a two-dimensional modular or differentiated dismantling is possible.
• moderation layer (s) and / or the spallation layer (s) are formed as bulk material layer (s), since a separate deconstruction is particularly easy to accomplish here.
• Radiation protection wall on both sides of the spallation layer (s) and the moderation layer (s) a solid static concrete support layer. Furthermore, between the spallation and moderation layers or bulk layers (thin) partitions, z. B. concrete, intended to ensure separate disposal. Front side ⁇ laterally adjacent sections of bulk material layers are separated by separating elements. In other words, the separating layers and separating elements form adjacent containers or filling spaces in the
• Spallation material or the moderation material is filled so as to form the two-dimensionally sectioned radiation protection wall.
• the invention has the radiation protection wall at least one lateral position, in particular in a central region at least following layer structure downstream of the beam in the following order: a first solid (concrete) base layer,
• the moderation layers or sections contain (more than 50%) mainly elements with an atomic number less than 30 or consist of such. These elements are particularly suitable for the moderation of light core fragments and nucleons.
• moderation layers of gypsum or other materials with bound water have proven to be particularly suitable. But also liquid sections or layers, z. B. from water are conceivable.
• ordinary earth excavation, sand, gravel, feldspar, lime feldspar, potash feldspar or similar natural raw materials can also be used as moderation layer (s).
• an iron-containing material or a raw ore, in particular iron ore or barite has proven particularly useful. This material is inexpensive to procure and advantageous to dispose of or recycle if necessary.
• the moderation layer (s) have a density of less than or equal to 3, 5 g / cm 3 and the
• Spallation layer (s) has a density of greater than or equal to 3, 0 g / cm 3 .
• the radiation protection wall according to the invention forms, in particular, the downstream wall of the radiation protection chamber a primary high energy beam from a particle accelerator is directed at a reaction site or target.
• the radiation protection chamber points. that is to say at least the following components: a first radiation protection wall positioned downstream with the above-described sectioned structure, a second positioned upstream of the radiation
• the first radiation protection wall thus has a central area for attenuating the of the
• the lateral radiation protection walls may have a different layer structure.
• Beamdump ⁇ is arranged in the forward direction of the primary high-energy beam or downstream of the reaction place.
• the jet destroyer preferably adjoins the first radiation protection wall downstream of the radiation protection chamber, or is at least partially integrated in the latter.
• Fig. 1 shows a schematic cross section through a radiation protection chamber according to a first embodiment of the invention from above
• FIG. 2 shows the detail A from FIG. , 1
• FIG. 3 shows a calculated dose profile at the radiation protection chamber according to FIG. 1 ,
• Fig. 4 shows a calculated radioactivity divided into isotopes of section 8 in FIG. 1 ,
• Fig. 5 shows a schematic cross section through a radiation protection chamber according to a second
• Fig. Fig. 1 shows this radiation protection chamber 1 constructed of a first (forward) radiation protection wall 110 positioned downstream, a second radiation shield 210 positioned rearwardly, and two lateral radiation shields 310, 410 which, together with the floor and ceiling, not shown, form a substantially closed cage as a reaction cavity one .
• the chamber 1 has a labyrinth-shaped entrance area 60.
• the high-energy primary beam 70 enters the chamber 1 through a jet entry region 80 and strikes. 'To the target 50.
• the primary beam 70 in this example 10 12 protons / sec at an energy of 30 GeV secondary radiation 90, which is indeed emitted in all directions, but still has a maximum in the forward direction generated.
• this secondary radiation 90 should be effectively shielded.
• the radiation protection walls 110, 210, 310, 410 have, j in each case _, .. an inner solid base layer or supporting concrete layer 140, 240, 340, 440 and j each case an outer solid base layer or supporting concrete layer 150, "250, 350, 450
• the front and side outer concrete layers 150, 350 and 450 are in turn formed in two layers in layers 152, 154, 352, 354 and 452, 454.
• the radiation protection walls 110, 210, 310, 410 also each have an inner layer arrangement 120, 2.20, 320, 420 of a spallation material such.
• the front spallation layer arrangement 120 is in turn constructed in two layers in spallation layers 122, 124.
• the lateral spallation layer arrangements 320, 420 each have only one spallation layer 322, 422.
• moderation layer arrangements 130, 230, 330, 430 are made of earth.
• the front moderation layer arrangement 130 is in turn constructed in three layers in moderation layers 132, 134, 136.
• the lateral moderation layer arrangements 330, 430 each have two moderation layers 332, 334 ' and 432, 434, respectively.
• the concrete layers 140, 152 serve as inner and outer bearing wall to fill with bulk material ore for the spallation or pourable 'earth for the moderation layers.
• the earth has a composition that is common at the location of the research facility.
• Intermediate layers and tie rods (not shown in FIG. 1) are incorporated to meet the static requirements.
• the spallation layers are made of materials with a higher atomic number than the moderation layers.
• spallation reactions are triggered mainly by high-energy neutrons, the u. a. result in the production of evaporation neutrons.
• the evaporation neutrons have smaller energies than the neutrons of the secondary radiation, the generation of further radionuclides is done with less
• the layer thickness is sufficiently large, then a large part of the neutrons of the secondary radiation is converted into neutrons of the evaporation cores. If this layer thickness is adapted to the primary beam (ion type, energy, intensity) and the target (element, thickness) so that the secondary radiation generated in the target is strongly scattered and weakened, they are downstream following weakly activated layers, the level of radioactivity generated is low.
• the front radiation protection wall 110 or. their layers are on the one hand lateral, d. H . transverse to the respective layer plane and on the other hand by dividing the layer arrangements 120, 130 into further separate layers 122, 124, resp. 132, 134, 136 divided into sections.
• the . Subdivision is in this example as seen from the inside out as follows:
• the inner layer of concrete • 140 has a central part portion 21 and two peripheral sections 20th
• the first spallation layer 122 has a central partial section 15 and two peripheral partial sections 13. • ' . '
• the second 'spallation layer 124 has a central part portion 16 and two peripheral sections fourteenth
• the first moderation layer 132 has a central partial section 10 and two peripheral partial sections 7.
• the second moderation layer 134 has a central partial section 11 and two peripheral partial sections 8.
• the third moderation layer 136 has a central one
• the outer concrete layers 152, 154 are each formed in one piece.
• the lateral radiation protection walls -310 and 410 ' are also subdivided as follows:
• the inner concrete layer 340 has a first partial section 22 and a second partial section 23.
• the single spallation layer 322 has a first partial section 17 and a second partial section 18.
• the first moderation layer 332 has a first partial section 2 and a second partial section 4.
• the second moderation layer 334 has only one section 3.
• the inner concrete layer 440 has only one section 441.
• the spallation layer 422 has only one section 443.
• the first moderation layer 432 has a first partial section 6 and a second partial section 433.
• the second moderation layer 434 has only one section 5.
• the inner rear concrete layer 240 is integrally formed (section 24). • . • • The spallation layer 222 includes only a portion of the nineteenth
• the moderation layer 232 has only a section 1.
• the outer concrete layer 250 is formed in one piece.
• FIG. 1 Between the spallation layers and moderation layers are shown in FIG. 1 dividing walls, not shown provided. Furthermore, frontally adjacent sections, z. B. the sections 13 and 15, separated at the end faces by separating elements from each other.
• FIG. 2 shows a section enlargement of the subsections 15, 16 of the spallation layer and FIGS. 10, 11, 12 of FIG Moderation layer as well as the outer supporting concrete layers 152, 154 and the portion 21 of the inner supporting concrete layer 140.
• the sections of the spallation layer and the moderation layer are bounded by partitions 92 and separating elements 94 and the adjacent supporting concrete layers. This creates closed frames or containers in which the loose or compacted Spallations- or. Moderation material to form the present section.
• the front radiation protection wall is adapted to the anisotropy of the secondary radiation 90.
• the inside, d. H . the target . 50 facing, central layer sections 21, 15 and 16 have the strongest • shielding effect and therefore have the strongest activations.
• the remaining sections are less activated due to their peripheral location or their outermost position. Most of the remaining sections are therefore fully unlockable immediately after use of the system or after a short waiting time.
• so little material with the necessary layer thickness and unavoidable increased activation and on the other hand, as much natural material as necessary to be installed to receive the dose rate outside the chamber 1 or the building below a certain value.
• the invention described herein optimizes two quantities: 1. The distribution of radioactivity within the various sections 1-24 of the radiation protection wall 110, 210, 310, 410 and 2. the dose rate to be undershot outside the chamber 1.
• the spallation layers 122, 124 are separated from the moderation layers 132, 134, 136,
• the spallation layers 122, 124 and the moderation layers 132, 134, 136 are in each case laterally into, subsections 13-16, resp. 7-12 divided. 5
• the various layers can be provided as solid layers (concrete support layers) or as bulk material layers (spallation layers, moderation layers) or even as liquid layers (moderation layers). 0 More precisely, the moderation layers contain bulk material as
• Fig. 3 shows a calculated dose profile for operation with proton beam 70 of energy 30 GeV 'and intensity 10 12 protons / sec.
• the dose rate is given in the unit ⁇ Sv / h. 0
• the irradiation chamber has been optimized in two ways:
• Fig. 3 it can be seen that using natural shielding materials, in this example , iron ore as spallation material . and earth as moderation material, the generated radiation is effectively weakened.
• the dose rate is very high (1 Sv / h and higher), outside the radiation protection chamber 1 (except immediately in the forward direction) it is at a level between 0, 1 and 1 ⁇ Sv / h. The requirements of the national legal limits can thus be met. '''
• the activation in the various sections 1 to 24 is calculated for a beam time of 30 years and a mean intensity of 1.00E + 12 protons / sec at 30 GeV.
• the target causes a reaction rate of the protons of approx. 1% . It generates an intense high-energy secondary radiation (neutrons, protons, pions, muons). This in turn generates radioactivity in the shielding layers as follows.
• the sections 1 to 12 consist of earth, the sections 13 to 19 of iron ore and the sections 20 to 24 made of concrete. Activation is in units of Total exhaustion for unrestricted release for three different cooldowns, namely 5 years, 1 year and 1 month. ' Values less than 1 mean unrestricted release.
• the concrete and iron ore layer sections are partly strongly activated.
• the iron ore sections 15 and 16 are most activated with a value of the exhaustion activity of 275 (section 15) after a 1 month decay phase.
• the preceding concrete layer is also heavily activated (Section 21) with a value of 142. Even a 5-year waiting period is not sufficient to bring the exhaustion levels below one.
• These materials are not fully releasable, i. H . they can be used again as shielding material in other installations or, according to national radiation protection regulations, can also be disposed of in landfills.
• Fig. 4 shows by way of example the distribution of the generated
• FIG. 5 shows a radiation protection chamber 1 corresponding to that shown in FIG. 1, but with an additional beam destroyer 95 made of iron with a concrete sheathing 96.
• the jet destroyer 95 is centrally located in the
• An inlet channel 98 is provided in the layers arranged upstream of the jet destructor and preferably in the inlet region of the jet destructor 95. '
• the separation of weak and more activated layers represents an optimization with regard to radiation protection, since the total mass of the substances to be disposed of (or reused) is reduced and thus the disposal is simplified.
• the invention is not only applicable to high-energy accelerators. B. also applicable to installations where neutrons with lower energies or thermalized neutrons are released, such as B. Nuclear reactors for power generation or research reactors (activation by neutron capture with n, ⁇ reactions) or spallation neutron sources. In general, the invention is applicable to types of radiation that cause activation in the radioactive sense of substances and materials. ,

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Particle Accelerators (AREA)
• Buildings Adapted To Withstand Abnormal External Influences (AREA)
• Fire-Detection Mechanisms (AREA)

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• 2004
  • 2004-12-29 DE DE102004063732A patent/DE102004063732B4/de not_active Expired - Fee Related
• 2005
  • 2005-11-19 US US11/794,190 patent/US7820993B2/en not_active Expired - Fee Related
  • 2005-11-19 EP EP10003355A patent/EP2204820B1/fr not_active Not-in-force
  • 2005-11-19 EP EP05819499A patent/EP1831896B1/fr not_active Not-in-force
  • 2005-11-19 DE DE502005010568T patent/DE502005010568D1/de active Active
  • 2005-11-19 JP JP2007548707A patent/JP5284647B2/ja not_active Expired - Fee Related
  • 2005-11-19 WO PCT/EP2005/012404 patent/WO2006072279A1/fr active Application Filing
  • 2005-11-19 AT AT05819499T patent/ATE488843T1/de active
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