A multi-permeable reagent barrier for the uptake of cesium and strontium radionuclides

Abstract

The invention relates to a multi-permeable reactive barrier developed for use in nuclear power plants, which provides the uptake of cesium and strontium radionuclides, and contains at least one upper cover (1) providing fixation, through which the liquid enters; at least one lower cover (2) providing fixation, through which the liquid exists (drainage); at least one sealing element (3) positioned to separate each component from each other; at least one liquid permeable filter (4); and at least one body (5) containing zeolite, diatomite, clay and sepiolite components, respectively from top to bottom.

Description

[0001] A MULTI-PERMEABLE REAGENT BARRIER FOR THE UPTAKE OF CESIUM AND STRONTIUM RADIONUCLIDES

[0002] Technical Field

[0003] The invention relates to a multi-permeable reactive barrier developed for use in nuclear power plants, which provides the uptake of cesium and strontium radionuclides and contains at least four body parts containing the components zeolite, diatomite, clay and sepiolite, respectively, from top to bottom.

[0004] State of the Art

[0005] Sepiolite is a raw material, the resources in the world of which are extremely limited compared to the other industrial minerals and the economic deposits of which are limited only to Spain and Turkey. Natural zeolite reserves in Turkey are approximately 50 billion tons (DPT, 2001). The natural zeolite reserve in Gbrdes, Manisa is 1.1 billion tons, and the resource contains high quality clinoptilolite. According to the inventory prepared by MTA, Turkey is considered very rich in terms of diatomite reserves. The current total potential bentonite (clay) reserves of Turkey are known as 250,543,000 tons.

[0006] Cesium 137 and Strontium 90 are mainly used in the nuclear industry, and it is very dangerous for them to contaminate clean environments during a nuclear accident. Permeable reactive barrier (PRB) systems are used in the state of the art to prevent the emission of these substances into clean environments. However, for cooling systems of a nuclear power plant, these barriers should be water-permeable, so these PRBs are developed accordingly.

[0007] In the state of the art, Mallants et al. (2001 ) investigated iron oxyhydroxides, coarse and fine-phase FeO, Al-Fe oxides and zeolites in the permeable reactive barrier system for uranium removal from groundwater.

[0008] In another state of the art, a study conducted by Nikashinaa et al. (2017) used the PRB system based on natural zeolites (Kazakhstan) and performed a mathematical model and simulation, in order to solve ecological problems. Considering the ecological problems caused by the leakage of liquid radioactive wastes (LRW) into reservoirs and the groundwater contamination with radioactive Cs+ and Sr2+, the physicochemical properties (including sorption) of the clinoptilolite-bearing tuff taken from the Chankanai deposit were evaluated. The chemical and phase composition, total cation exchange capacity and equilibrium (exchange isotherms) and kinetic (diffusion coefficients) characteristics of zeolite were analyzed, and the uptake of radioactive Cs+ and Sr2+ ions from CaCI2 solution was investigated. The protection life of the clinoptilolite-based geochemical barrier was evaluated.

[0009] In another state of the art, a study conducted by Mason et al. (2000) investigated the, characterization, transport and remediation options of radioactive Sr (Strontium) and Cs (cesium) from the contaminated areas. In this study, an area contaminated with Cs- 137 and Sr-90 at Los Alamos National Laboratory was investigated. Experimental results show that the distribution coefficients for Cs are much bigger than those for Sr. This causes Sr to spread faster than waterborne transport routes. The additional Sr is transported by sorption onto colloids, which provides an additional transport mechanism.

[0010] Moore et al. (2016) successfully used the hydroxyapatite PRB system to prevent and remove uranium contamination from the ore processing facility in the Old Rifle from entering the groundwater.

[0011] A study conducted by Vermeul et al. (2014) has developed an injectable permeable reactive barrier (PRB) technology to isolate Sr-90 in groundwater through in situ formation. This injectable barrier technology has extended the application of the PRB concept to sites where groundwater contaminants are very deep, or where site conditions would not interfere with the application.

[0012] In the studies in the above-mentioned literature in the state of the art, iron oxyhydroxides are required to be separated from Fe-containing minerals or the synthesis of PRB materials such as FeO and Al-Fe oxides in a thin phase. Although either natural materials or synthesis products have been used as PRB materials in the studies conducted in the literature, there has not been a study in which the effects of all experimental parameters have been examined together and the materials that Turkey is rich in reserves have been designed (ranked) according to these experimental results. Therefore, there is a need to develop PRBs that contain components for which natural minerals are used and which are properly ranked without being subjected to any synthesis process.

[0013] Summary of the Invention

[0014] An object of the invention is to develop a barrier system containing zeolite, diatomite, clay and sepiolite components, respectively, with a box model configuration. The uptake efficiency of strontium 90 and cesium 137 of each material used in the invention is examined individually, and a layout is provided according to the results obtained. However, in the invention, a ranking is made by using natural minerals without any synthesis and according to the sorption capacities of the natural materials used. In order to see the effects of some experimental parameters that will affect the PRB system, the effectiveness of the PRB design in the uptake of Cs and Sr from the contaminated solutions was investigated for the first time as a result of the characterization studies of natural barrier materials by applying and using the full factorial experimental design method.

[0015] The invention has been developed as a solution to the problem of the spread of important radionuclides (strontium and cesium) from environmentally contaminated environments (cooling water from the contaminated reactor, and the contaminated water in the turbine building, tank storage water and leakage water) to clean environments, which may arise as a result of any possible nuclear accident.

[0016] The permeable reactive barrier of the invention has an advantage of being used horizontally or vertically depending on the requirements. Due to a high capacity of all barrier materials used in the invention to uptake Sr and Cs ions, it becomes possible to use the multi-barrier system as a horizontal and / or vertical modular system. However, each component is separated from each other by a permeable membrane tissue.

[0017] The invention has allowed optimum conditions to have been determined in the uptake of Sr and Cs elements of four different components, and thus a modular configuration which may change according to needs to be achieved. The barrier of the invention has a capacity to produce different solutions to different problems. A permeable reactive barrier, or a "PRB", is a wall created underground to clean the contaminated groundwater. The capacity to produce different solutions to the different problems mentioned here is that this wall can produce solutions not only for Sr and Cs ions, but also for the removal of uranium, chlorinated aliphatics, or heavy metals.

[0018] Due to its barrier structure, it has been developed to prevent both underground and aboveground contamination.

[0019] Description of the Drawings

[0020] Fig. 1 is a representative view of a multi-permeable reactive barrier of the invention.

[0021] Description of the References in the Drawings

[0022] 1. Upper cover

[0023] 2. Lower cover

[0024] 3. Sealing element

[0025] 4. Filter

[0026] 5. Body

[0027] K. Cage

[0028] Detailed Description of the Invention

[0029] The invention relates to a multi-permeable reactive barrier (PRB) of a permeable, reactive and modular structure for the uptake of radionuclides of cesium (Cs) and strontium (Sr) with long half-lives in the event of a nuclear accident.

[0030] The multi-permeable reactive barrier of the invention contains at least one upper cover (1) providing fixation, through which the liquid enters; at least one lower cover (2) providing fixation, through which the liquid exists (drainage); at least one sealing element (3) positioned to separate each component from each other; at least one liquid permeable filter (4); and at least one body (5) (a column) containing zeolite, diatomite, clay and sepiolite components, respectively from top to bottom. A preferred embodiment of the invention includes an upper cover (1 ), a lower cover (2), five sealing elements (3), four filters (4), and a body (5).

[0031] Said body (5) contains four different materials in the specified order, and said filter (4) is placed between each material. Thus, a cage (K) system is formed within the body (5). As there is sepiolite material in the lowest fraction, the solution exits the PRB system by its own flow rate.

[0032] Said sealing element (3) is an o-ring gasket in the preferred embodiment of the invention. Said liquid permeable filter (4) is a permeable membrane tissue. A polyamide-based synthetic membrane is preferably used in the invention. In addition, it is also suitable to use synthetic membranes such as Polyethylene, or Polypropylene, or Polyvinyl chloride (PVC), which can be used as geomembranes.

[0033] The multi-permeable reactive barrier of the invention may be manufactured in appropriate sizes according to the needs and can be used modularly.

[0034] The invention has provided a designing method in which the ranking of the materials is determined according to the hydraulic conductivity, the particle size, and the adsorption capacities of natural materials determined with each barrier material.

[0035] The designing method of said multi-permeable reactive barrier includes the following steps:

[0036] - Preparing and carrying out characterization studies of the barrier materials Performing uptake studies of strontium and cesium in a single box with natural barrier materials

[0037] - Performing optimization studies for a permeable reactive barrier using a Full Factorial Experiment Design method

[0038] - Determining the structure of the permeable reactive barrier system

[0039] - Conducting dialysis cell trials

[0040] - Conducting uptake studies of the radioactive Cs137 and Sr90 isotopes and carrying out a dose evaluation

[0041] - Evaluating the data obtained, carrying out scaling calculations, processing the data and carrying out a statistical evaluation - Determining the barrier structure as zeolite, diatomite, clay and sepiolite, respectively, with each PRB material with a particle diameter of 0.5 mm having a permeability value of 10-3and smaller, and producing a permeable reactive barrier accordingly

[0042] The process of preparing and carrying out characterization studies of said barrier materials includes the following steps:

[0043] - Determining the specific gravity of the barrier materials

[0044] - Analyzing the elemental compositions of the barrier materials (SEM-EDX and XRF analyses)

[0045] - Determining the particle size distribution of the barrier materials (laser particle analysis)

[0046] - Measuring the BET surface area, pore volume and pore diameter of the barrier materials

[0047] Determining the swelling volume and dynamic weight change of the barrier materials

[0048] - Determining the permeability by a constant head permeameter under laboratory conditions

[0049] - Creating the diffusion equations.

[0050] The detailed explanations of the processes mentioned at the stage of preparing and carrying out characterization studies of the barrier materials are as follows:

[0051] In the invention, samples were obtained from clay (bentonite) deposits in Buca, which offers large reserves especially around Izmir and Manisa, zeolite (clinoptilolite) deposits found and operated in the Manisa-Gdrdes region, sepiolite deposits found and operated in Eski§ehir region, and diatomite deposits found in Erzurum-§enkaya region. Crushing, grinding and sieving processes were carried out taking into account the original particle sizes of the supplied barrier materials. After the samples were crushed in the mortar, they were pulverized in a grinder and sieved using sieves of 18, 35 and 60 mesh in a sequential sieve system, and the particles of 1 mm and 0.5 mm were used. The materials were dried at 100±5 °C for 24 hours. The particle size distribution was determined by a laser particle size analyzer (Bettersiz BT-9300H) using Mie theory and data processing mode. The specific gravity values (g / cm3) of natural materials were determined by a pycnometer. The swelling volume was found by calculation. The permeability thereof was determined by a constant head permeameter under laboratory conditions.

[0052] FT-IR Analyses of the components used in the invention were performed, and the devices used are as follows:

[0053] - A PERKIN ELMER SPECTRUM TWO model FTIR-ATR instrument was used.

[0054] - XRD analysis was performed with a Panalytical Empyrean instrument. EDXRF Analysis was performed with a RIGAKU EDXRF spectrometer.

[0055] - The BET was performed in a Surface Area Laboratory using a BET Micrometrics 3 Flex Brand instrument.

[0056] Considering the difficulty and economic cost of working with radioactive materials in the step of uptake studies of strontium and cesium in a single box with natural barrier materials, 137Cs and 90Sr radioactive isotopes were simulated with their nonradioactive natural isotopes 133Cs and 88Sr. Compared to a square section column, a cylindrical body (5) (column) was designed and obtained by a 3D printer, in order to provide better wetting of the barrier materials. Thanks to the conical structure of the base, an improvement was observed in water discharge compared to the square section column. Therefore, a cylindrical body (5) structure was preferred in the invention. For the cylindrical body (5), which is designed instead of the square section column, the radius is 2 cm, the height is 15 cm, and the base od the body (5) is: 4.55 cm*4.55 cm.

[0057] A peristaltic pump and the necessary test system were prepared for column tests. After weighing certain quantities, the barrier materials were soaked with distilled water for at least 24 hours.

[0058] Column tests were carried out with a peristaltic pump at 5 different flow stages by determining two separate bed volumes. In column studies, two different liquid feedings were provided in the form of single-point drip and multi-point drip. As a result of the preliminary experiments, a single-point solution feeding mode was chosen. Particle sizes of 1 mm and 0.5 mm were used for Zeolite, Diatomite, Sepiolite, and Clay for column experiments. Strontium analysis was performed by ICP-OES (Inductively coupled plasma atomic emission spectroscopy), and cesium analysis was performed by ICP-MS (Inductively coupled plasma mass spectrometry). Full Factorial Experimental Design Method was used for the experiments. Experiments were performed at specific level intervals by determining the initial pH, particle size, bed volume, flow rate and concentration parameters to examine strontium and cesium uptake with each barrier material (Tables 1 and 2).

[0059] Table 1. Levels and intervals of the independent variables used in the adsorption of strontium on zeolite, diatomite, clay and sepiolite Table 2. Levels and Intervals of the Independent Variables Used in the Adsorption of Cesium on Zeolite, Diatomite, Clay and Sepiolite

[0060] As a result of the experiments, surface response graphs were plotted for both elements (Sr and Cs), statistical data were obtained, and the effects of the parameters were examined individually and in combination. Optimum conditions were determined, and the conditions to be applied in the experiments to be carried out with radioactive isotopes were determined.

[0061] Solid samples with high Sr and Cs uptake were selected, and an EDXRF (Energy Dispersive X-Ray Fluorescence Spectroscopy) analysis was performed.

[0062] Hydraulic conductivity values, which are an important parameter for optimization studies for a permeable reactive barrier (PRB), have been designed for the quadruple PRB system. Hydraulic conductivity (Permeability) used in optimization studies may vary depending on the amount, chemical composition, particle shape and particle size distribution, water content and contact time of the material used. Under the effect of gravity, groundwater moves downwards from higher elevations through the PRB system. It is known that for the structure of the PRB, the permeability of the reactive material to be used in the barrier should be greater than that of the aquifer (Kacimov et al., 2011).

[0063] Table 3. Permeability Values of Natural Barrier Materials

[0064] According to the k values obtained as seen in Table 3, the hydraulic conductivity value of sepiolite is lower than other barrier materials according to both different particle sizes. According to the comparison of the numerical results obtained, the permeability increases according to the ranking of sepiolite-clay-diatomite-zeolite. As a result of the literature review, the hydraulic conductivity value of the materials may vary according to the experimental conditions (Gavaskar et aL, 2000; Kacimov et aL, 2011 ; Puls et aL, 1999; Tohumcu, 2001).

[0065] In the step of determining the structure of the permeable reactive barrier system, experiments were carried out by taking into account the hydraulic conductivity values of the natural barrier materials and keeping the flow rate (7.5 mL / min) and particle size (0.5 mm) of the system constant according to the results obtained with the single system. Other conditions are as follows:

[0066] • Body (5) (column) Volume: 36 cm3(A constant parameter) • Cross-sectional area of the material in each box: TT(2.25cm)2

[0067] • Thickness of the material in each box: 3 cm

[0068] • Volume of Boxes: TT.(2,25cm)2.17cm

[0069] In the quadruple PRB experiments, the variables for Sr and Cs were examined in different level intervals by applying zeolite-diatomite-clay and sepiolite ranking from top to bottom with a multi-box model (Tables 4 and 5).

[0070] Table 4. Levels and Intervals of the Independent Variables Used in the Adsorption of Strontium on Quadruple PRB (Zeolite, Diatomite, Clay and Sepiolite Ranking)

[0071] Table 5. Levels and Intervals of the Independent Variables Used in the Adsorption of Cesium on Quadruple PRB (Zeolite, Diatomite, Clay and Sepiolite Ranking) The ANOVA (analysis of variance) analysis of the applied model within the 95% confidence interval was examined, and the compatibility of the model and experimental findings was investigated.

[0072] In the step of conducting dialysis cell experiments, dialysis cell experiments were carried out for both elements and the following conclusions were reached:

[0073] When the release amounts of each of the Sr and Cs loaded barrier materials used in the quadruple PRB system were examined, the concentrations of Sr and Cs were determined to passed into the solution as a result of the dialysis process were negligible (pg / l, ppb). However, it shows that the natural materials used strongly bind Sr and Cs ions and do not release them in a pure water environment for a period of 72 hours.

[0074] In the uptake studies using a radioactive Cs-137 (cesium-137) standard solution, a radioactive Cs-137 solution with a code SRM 4233E which was prepared in 5 mL HCI with an activity of 298 kBq / g was used. Activity correction was performed for the radioactive Cs-137 intermediate standard solution, and the activity was calculated as 203.832 kBq / g. Cesium-137 decays into barium-137m by beta particle emission. During the decay process, X-rays and gamma rays with energies from about 3 keV to 662 keV are emitted.

[0075] In the adsorption experiments, 1 mL of the mother standard solution was taken and diluted to 100 mL to prepare Standard 1 Cs-137 working solution (2038 Bq / mL). 50 mL of Standard 1 solution was passed through the column through the quadruple barrier system at a rate of 5 ml / min with a peristaltic pump. Each barrier material through which the Cs-137 standard solution was passed was dried at 45°C for 24 hours in an incubator and placed in plastic storage containers the tares of which were determined, and Cs-137 activities were measured by a Na I (Tl) gamma spectrometry device.

[0076] Cs-137 measurements of each barrier material loaded with Cs-137 were carried out by a Gamma Spectrometer consisting of a 3-inch Nal(TI) scintillation detector, a Canberra MCA and an Ortec Amplifier at Ege University Institute of Nuclear Sciences. The spectrum of gamma rays of each barrier fraction was obtained and evaluated. In the results of the uptake studies carried out using the radioactive Cs-137 standard solution, the adsorption values in the multi-barrier system were calculated as 88% for Zeolite, 67% for Diatomite, 36% for Clay and 62% for Sepiolite as a result of gamma spectrometric measurement. In other words, the Cs-137 input activity concentration was 51860 ±Bq / kg and the Cs-137 output activity concentration in this system was 51393 ±Bq / kg. Consequently, Cs-137 activity was determined to be eliminated with 99.09% efficiency by means of the PRB system consisting of four natural barriers.

[0077] In the uptake studies using radioactive Sr-90 (strontium-90) standard solution, 5 mL of radioactive Sr-90 standard solution with a code SRM 49191 at an activity concentration of 4.261 ± 0.020 kBq / g was used. Activity correction was performed for the radioactive Sr-90 standard solution, and the activity was calculated as 2.93 kBq / g. Strontium-90 is a radioactive isotope of strontium produced by nuclear fission, with a half-life of 28.8 years. It has a decay energy of 0.546 MeV and decays into yttrium-90 with p~ decay. A certain mass of a Sr-90 source also contains Y-90 radionuclides over time. Therefore, the resource mass has a mixed spectrum during the times after its production / extraction. This is taken into account in the Monte Carlo simulation.

[0078] In the adsorption experiments, 4.5 mL of the mother standard solution was taken and diluted to 50 mL to prepare a Standard Sr-90 working solution (263.7 Bq / mL). Radioactive Sr-90 solution was passed through the column through each barrier material at a rate of 5 ml / min with a peristaltic pump, and the liquid fractions were collected. The mother solution entered and the solutions leaving the barriers were counted and analyzed individually in the LSC system. During the analysis of the solutions containing Sr-90, 3 mL of sample was taken and 7 mL ((Optiphase hisafe) scintillation cocktail) was added, and counting processes were performed. Sr-90 measurements were carried out by means of the Packard Tri-Carb 2100 TR liquid scintillation counter (LSC) at Ege University Institute of Nuclear Sciences.

[0079] In the results of the uptake studies using radioactive Sr-90 Standard solution and as a result of measurement with LSC device, the adsorption values in the multi-barrier system were calculated as 74% for Zeolite, 77% for Diatomite, 70% for Clay and 45% for Sepiolite. Considering the Sr-90 input and output activity concentrations, Sr-90 was determined to be eliminated with 81.8% efficiency by means of the PRB system consisting of a quadruple natural barrier. The following studies were carried out at the stage of evaluating the data obtained, carrying out scaling calculations, processing the data and carrying out statistical evaluation:

[0080] EGSnrc (software toolkit) code was used in the Monte Carlo Simulation study. This code provides dosimetric calculation of radiation-matter interactions for electromagnetic radiation, electrons and positrons by the Monte Carlo method. The simulation is basically built from a geometry design and the management of input / output data. For this, it is necessary to know the elemental content of the matters used. Element ratios were calculated in order to calculate the simulation path of the doses (output data) provided to the external environment by the radioactive elements uptaken by the absorbents used in the study. The experimental setup has a cylindrical symmetry. This has been adhered to in the simulation design. The dose distribution around the cylinder axis was considered symmetrical due to the radioactive source, which was assumed to be homogeneously distributed to the absorber.

[0081] In the simulation, the parameter of interest is set for an optimum value (MC number of events, number of particles). Almost no electrons (betas) can reach distant regions around the radioactively determined volume. Betas have a very short range. In these regions, the doses emitted by secondary electromagnetic radiation (formed as a result of beta-matter interaction) are effective.

[0082] Initial studies were conducted in the form of a generalization as doses per particle. These data were multiplied by the actual activities measured experimentally and the actual doses in the air were calculated.

[0083] This study is characterized by how much radiation dose will be emitted to the outside of the container if the designed system works actively. Although doses need to be recalculated when large-scale systems are used, the dose distribution profiles will be predicted to be suitable for this study.

[0084] An ERICA Dose Assessment was performed for the dose risk assessment to which non-human reference organisms will be exposed, and the adsorption data obtained from single and multiple systems were calculated by the ERICA 2.0.185 Tool Assessment Simulation program, and the doses to be passed to non-human biota in case of a leak that may occur in the waste area due to any accident. The doses to which freshwater biota as non-human biota, such as crustaceans, phytoplankton, vascular plants, may be exposed have been calculated. When the activity to which the freshwater biota will be exposed due to the Cs and Sr, which cannot be uptaken in multi-systems, was compared, the amount of dose to which the freshwater reference biota would be exposed from radioactivity due to Sr leakage is seen to be lower than that of Cs. The total dose interval to which the freshwater reference organisms from Sr wastes will be exposed is 1 .83E+06 - 9.21 E+08 pGy IT1. For Cs wastes, this interval is 4.39E+06 - 3.17E+10 pGy h-1 .

[0085] The experimental results of the quadruple PRB configuration of the invention for Stransium and Cesium were obtained by the Design Expert program in the case of using four natural materials together as a single PRB system are as follows:

[0086] Optimum conditions for Sr are: pH 4.49, c: 147.08 mg / L, v (bed volume): 30 cm3, ionic strength: 0.1 M KNO3,

[0087] Optimum conditions for Cs are: pH: 3.25, c: 1433.72 mg / L, v: 19.69 cm3, ionic strength: 0,08 M KNO3.

[0088] The reusability of the quadruple PRB system was also studied. The protective life of the barriers was provided by a quadruple system depending on the thickness of the sorbent / barrier material under optimum conditions, the filtration rate and the Sr concentration, and as a result of the experiments carried out with Sr solution and Cs solution which were freshly fed 5 times, the system was determined to work with 99.44% efficiency at the end of the 5 cycles upon the experiments with the Cs solution. In such a case, it is envisaged that the system will be able to operate with high efficiency and without any deformation for more than 15 cycles.

[0089] Experiments were carried out for the calculation of diffusion coefficients in the quadruple PRB system for both elements (Cs and Sr), and the following conclusions were reached:

[0090] The diffusion coefficient in the quadruple PRB system for Sr was found to be 0.0192, and the reason for a large diffusion coefficient in the quadruple PRB system for Sr is that when a feed such as 150 ppm enters, very low values such as 11 ppm are reached as a result of adsorption and an adsorption of 92.86% occurs.

[0091] The diffusion coefficient in the quadruple PRB system for Cs was found to be 0.0137, and the reason for a large diffusion coefficient in the quadruple PRB system for Cs is that when a feed such as 2050 ppm enters, very low values such as 1 ppm are reached as a result of adsorption and an adsorption of 99.85% occurs.

[0092] In order to test the radiation and thermal resistance of the barrier materials, a long-term radiation exposure of the materials was assessed, and the damage to their structures was observed to occur. Radiation resistance tests were carried out to determine the damages that may occur in case of a long-term exposure of the barrier materials to radiation in radioactive waste storage areas. Radiation resistance tests were carried out using a Cs-134 gamma source of 1 .08E+07 Bq.

[0093] Samples to be taken from the barrier materials irradiated by gamma welding at regular intervals were analyzed with FTIR and changes that could occur in the structure were observed. The results obtained from the study of the effects of Cs-134 on zeolite, diatomite, clay and sepiolite (PRB system) irradiated showed that the material did not undergo a phase change at the tested irradiation doses. A thermal analysis is one of the most widely accepted methods for evaluating the structural properties of a material and determining the amount of moisture and volatile compounds present the structures thereof. A thermogravimetric analysis (TGA) was performed to evaluate the thermal stability of the quadruple barrier system. The thermogravimetric analysis was performed with a Shimadzu / DTG60H by heating from 25°C to 500°C under a N2 atmosphere. The results for the effects of temperature show that the material is thermostable at the tested temperatures. Thus, it is possible to state that the PRB system of the invention does not deteriorate due to thermal fields and gamma radiation which can be expected at a radioactive waste disposal site, thanks to the evidence presented. Industrial Applicability of the Invention

[0094] The invention relates to a multi-permeable reactive barrier developed for use in nuclear power plants, which provides the uptake of cesium and strontium radionuclides, and is suitable for industrial applications.

[0095] The invention is not limited to the foregoing explanations, and one person skilled in the art may easily reveal the different embodiments of the invention. These should be considered within the scope of protection of the invention claimed in the claims.

Claims

CLAIMS1. A multi-permeable reactive barrier, characterized in that it contains at least one upper cover (1 ) providing fixation, through which the liquid enters; at least one lower cover (2) providing fixation, through which the liquid exists; at least one sealing element (3) positioned to separate each component from each other; at least one liquid permeable filter (4); and at least one body (5) containing zeolite, diatomite, clay and sepiolite components, respectively from top to bottom.

2. A multi-permeable reactive barrier according to claim 1 , characterized in that the filter (4) is a membrane tissue.

3. A multi-permeable reactive barrier according to claim 2, characterized in that the filter (4) is a polyamide-based synthetic membrane, or Polyethylene, or Polypropylene, or Polyvinyl chloride (PVC).

4. A designing method of the multi-permeable reactive barrier according to claim 1 , characterized in that it comprises following steps:- Preparing and carrying out characterization studies of the barrier materials Performing uptake studies of strontium and cesium in a single box with natural barrier materials- Performing optimization studies for a permeable reactive barrier using a Full Factorial Experiment Design method- Determining the structure of the permeable reactive barrier system- Conducting dialysis cell trials- Conducting uptake studies of the radioactive Cs137 and Sr90 isotopes and carrying out a dose evaluation- Evaluating the data obtained, carrying out scaling calculations, processing the data and carrying out a statistical evaluation- Determining the barrier structure as zeolite, diatomite, clay and sepiolite, respectively, with each PRB material with a particle diameter of 0.5 mm having a permeability value of 10-3and smaller, and producing a permeable reactive barrier accordingly5. A designing method of the multi-permeable reactive barrier according to claim 4, characterized in that the process of preparing and carrying out the characterization studies of the barrier materials includes the following steps:- Determining the specific gravity of the barrier materials - Analyzing the elemental compositions of the barrier materials- Determining the particle size distribution of the barrier materials- Measuring the BET surface area, pore volume and pore diameter of the barrier materialsDetermining the swelling volume and dynamic weight change of the barrier materials- Determining the permeability by a constant head permeameter under laboratory conditions- Creating the diffusion equations.