JP5880851B2 - Radionuclide decontamination system and radionuclide decontamination method - Google Patents

Description

  The present invention relates to a radionuclide decontamination system and a radionuclide decontamination method for decontaminating radionuclides from radioactively contaminated water.

  Radioactive contaminated water is not limited to fresh water that does not contain salt, but may contain groundwater, seawater, or sea salt components (NaCl, Ca, Mg, etc.) at high concentrations. In order to release sewage into the environment such as sewage, rivers, and oceans, it is necessary to decontaminate until all of the contained radionuclides are at or below their respective concentrations stipulated by law.

  Methods for decontaminating radionuclides can be broadly divided into precipitation methods and adsorption methods. The precipitation method is desirable due to the fact that the system is large and costly, and that primary and secondary wastes are generated in large quantities due to the addition of co-precipitating agents, and that disposal is cumbersome. That's not true.

  The adsorption method, on the other hand, is intended to decontaminate by passing radioactive contaminated water through the adsorption tower packed with adsorbent, that is, there is a possibility that the decontamination system can be simplified. Benefits that can be reduced can be expected.

  Patent Document 1 describes a treatment method and apparatus for radioactive substance-containing wastewater, in which filtered water is passed through activated carbon and then passed through an ion exchanger or a reverse osmosis membrane.

  Patent Document 2 describes that a water-soluble metal ion is adsorbed by an adsorbent as an unnecessary oxide in water.

  Non-Patent Document 1 describes a circulating water cooling and a contaminated water treatment system.

JP 2008-64703 A JP-A-7-260997

Journal of the Atomic Energy Society of Japan Vol. 3 (2012)

  When the containment of the reactor pressure vessel or the containment vessel is lost due to the occurrence of a nuclear accident, the radioactive materials present in the vessel are released or leaked, and many kinds of radionuclides are contained. A large amount of radioactive polluted water will be generated. When radioactive water containing radioactive cesium, strontium, and many other radionuclides is released into the environment, it is required to thoroughly decontaminate many types of radionuclides in the radioactively contaminated water. Only after such decontamination, strict radioactivity checks, and confirmation that the concentration is below the level stipulated by law is allowed to be released into the environment such as sewage, rivers or oceans. Become.

  As shown in the patent literature, many methods and means have been proposed for methods and devices for removing and decontaminating radionuclides normally produced during operation in nuclear power plants. No method or means for decontaminating radioactive contaminated water containing many types of radionuclides that accompany it has been proposed.

  Non-Patent Document 1 describes a circulating water cooling and contaminated water treatment system as shown in FIG.

  The present invention has been made in view of the above points, and can be easily decontaminated from many types of radionuclide radioactive contaminated water released or leaked due to the occurrence of a nuclear accident, and without cost. The purpose is to facilitate the disposal of secondary waste.

The present invention relates to a radionuclide decontamination system for decontamination by removing these radionuclides from radioactively contaminated water containing various types of radionuclides.
When the Ca alginate membrane is used in an aqueous solution, the surface of the adsorbing member solidified with an inorganic material having the property of allowing Ca or Ca and Mg to coexist and selectively allowing Sr and Ba to permeate. A first means on which Sr and Ba selective adsorbent is formed, in which a layer is formed and the adsorbing member adsorbs selectively permeated Sr and Ba in an impermeable state of Ca or Ca and Mg;
A second means formed of ferrocyanated Co or ferrocyanated Fe-supported activated carbon or a TiO ₂ inorganic material and loaded with a Cs adsorbent;
A third means equipped with a multi-nuclide decontamination adsorbent which is formed from activated carbon and activated alumina and performs multi-nuclide decontamination;
A fourth means equipped with iodine and a super-uranium element decontamination adsorbent, formed from iodine-supporting activated carbon and chelating agent-supported or added activated carbon, and decontaminating iodine containing super-uranium element;
The present invention provides a radionuclide decontamination system characterized in that a radioactive contamination water is passed through an adsorbent decontamination means formed in combination with and a variety of radionuclides are decontaminated.

  The present invention also provides a radionuclide decontamination system characterized in that the zeolite powder is spherically solidified with the above-mentioned alginic acid or binder to form an adsorption member.

  In the present invention, the adsorbent decontamination means described above is formed from DDTC-supported or added activated carbon, or Al-containing inorganic carbon-based material, and oxine-supported activated carbon, DTPA-supported activated carbon, or cuperon-supported activated carbon, Provided is a radionuclide decontamination system including an adsorption means on which a multi-nuclide decontamination adsorbent is mounted.

  The present invention also provides a radionuclide decontamination system, wherein the decontamination means for contaminating nuclides includes a decontamination means equipped with a decarboxylation tower for C-14 decontamination.

  The present invention also includes a reverse osmosis membrane mounting means for generating desalted water and concentrated salt water by separating salt from the radioactively contaminated water described above, and the adsorbent decontamination means is provided in the line of desalted water or concentrated salt water. Or a radionuclide decontamination system, characterized in that it is provided in both lines.

  The present invention also includes reverse osmosis membrane mounting means for generating desalted water and concentrated salt water by separating salt from the above-mentioned radioactive contaminated water, and the radioactive contaminated water line on the upstream side of the osmotic membrane mounting means A radionuclide decontamination system is provided, wherein a means is provided.

  The present invention also provides a radionuclide decontamination system characterized in that the first means is arranged on the downstream side of the second means in the above-described fresh water line of the desalted water.

  The present invention also provides a radionuclide decontamination system, characterized in that a first means is arranged on the downstream side of the third means and the second means in the above-mentioned salt water system line of concentrated brine.

The present invention relates to a radionuclide decontamination method using a radionuclide decontamination system that decontaminates by removing these radionuclides from radioactively contaminated water containing various types of radionuclides.
When the Ca alginate film is used in an aqueous solution, the surface layer of the adsorbing member solidified with an inorganic material having a property of making the coexisting Ca or Ca and Mg impermeable and selectively allowing Sr and Ba to permeate. The adsorbing member is loaded with Sr and Ba selective adsorbent that adsorbs selectively permeated Sr and Ba in the impervious state of Ca or Ca and Mg to form a first means,
Loading ferrocyanated Co or ferrocyanated Fe-supported activated carbon or TiO ₂ inorganic material Cs adsorbent to form a second means,
A multi-nuclide decontamination adsorbent that is formed from activated carbon and activated alumina and performs multi-nuclide decontamination is mounted to form a third means,
Formed from iodine-supported activated carbon and chelating agent-supported or added activated carbon, and the fourth means is formed by loading iodine and a super-uranium element decontamination adsorbent that performs decontamination of super-uranium element containing iodine,
The present invention provides a radionuclide decontamination method characterized by combining these means to form an adsorbent decontamination means and decontaminating various types of radionuclides by passing through radioactive contaminated water.

  The present invention also provides a radionuclide decontamination method characterized in that an adsorbent member is formed by solidifying zeolite powder into a spherical shape with the above-mentioned alginic acid or binder.

  In the present invention, the adsorbent decontamination means described above is formed from DDTC-supported or added activated carbon, or Al-containing inorganic carbon-based material and oxine-supported activated carbon, DTDA-supported activated carbon or cuperon-supported activated carbon, and performs multi-nuclide decontamination. Provided is a radionuclide decontamination method characterized by comprising an adsorption means equipped with a multi-nuclide decontamination adsorbent.

  The present invention also provides a radionuclide decontamination method characterized in that the above-mentioned decarboxylation tower is attached to perform C-14 decontamination.

  The present invention also uses a reverse osmosis membrane mounting means for generating desalted water and concentrated salt water by separating salt from the radioactively contaminated water described above, and the adsorbent decontamination means is connected to the desalted water or concentrated salt water line. Or a radionuclide decontamination method characterized in that it is provided on both lines.

  The present invention also uses reverse osmosis membrane mounting means for producing desalted water and concentrated salt water by separating salt from the above-mentioned radioactive contaminated water, and in the radioactive contaminated water line upstream of the osmotic membrane mounting means, A radionuclide decontamination method characterized by providing a first means is provided.

  The present invention also provides a radionuclide decontamination method characterized in that the first means is arranged on the downstream side of the second means in the desalted water line described above.

  The present invention also provides a radionuclide decontamination method characterized in that the first means is arranged on the downstream side of the third means and the second means in the above-described concentrated salt water line.

  According to the present invention, it is possible to easily decontaminate many types of radionuclides in radioactively contaminated water that leaks to the outside due to the occurrence of a nuclear reactor accident including radioactive cesium and strontium. Moreover, since the secondary waste generated in connection with the treatment is activated carbon, the incineration treatment can be performed and the treatment can be facilitated.

The figure which shows the basic composition of the radionuclide decontamination system of this invention Example. The figure which shows the adsorption | suction concept of Sr and Ba selective adsorption agent employ | adopted by a present Example. The figure which shows a manufacturing method. The figure which shows the structure of a dripping nozzle. The figure which shows the relationship between the seawater flow volume obtained by filling the column with the Sr and Ba selective adsorption agent employ | adopted by a present Example, and an element adsorption removal rate when seawater is used. The figure which shows the result of having investigated the influence which it has on the adsorption | suction characteristic of Sr and Ba of a present Example in case the chelating agent for RO membrane scale prevention coexists in seawater. The figure which shows the result of having investigated the influence which seawater salt concentration change (seawater ratio 1-5 times concentration) has on the adsorption | suction characteristic of Sr and Ba of a present Example. The figure which shows the adsorption tower arrangement | positioning basic composition of a freshwater and saltwater corresponding | compatible decontamination system. The figure which shows the detailed structure of the freshwater type | system | group decontamination processing line and salt-water type | system | group decontamination processing line which are employ | adopted by this invention Example. The figure which shows the nuclide decontaminated by the adsorption tower adsorbent arrange | positioned. The figure which shows the list of the radionuclides decontaminated by a present Example in a periodic table.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention is included in radioactive contaminated water composed of salt water such as seawater and the like, and is effective for decontaminating radioactive Sr, which has been difficult to decontaminate in the past. By using this Sr selective adsorbent in combination with the use of various adsorbents, various types of radionuclides are decontaminated from the radioactively contaminated water. Such decontamination was only possible with the use of Sr selective adsorbents. Here, since the Sr selective adsorbent is used for removing Sr and Ba, it is hereinafter referred to as the Sr and Ba selective adsorbent, but the function is the same as the adsorbent.

  Is it possible to decontaminate all of these radionuclides as the following types of radionuclides are assumed as radioactive nuclides leaking from the reactor containment pressure vessel or the reactor containment vessel due to a nuclear accident? Is subject to evaluation. The present embodiment is configured to decontaminate these radionuclides as evaluation target nuclides.

  C-14, Rb-86, Sr-89, Y-90, Y-91, Nb-95, Tc-99, Ru-103, Rh-106, Ag-110m, Sn-123, Sb-124, Sb- 125, Te-123m, Te-127, Te-129, Te-129m, I-129, Cs-134, Cs-136, Cs-137, Ba-140, Ce-141, Ce-144, Pr-144, Pm-146, Pm-148m, Eu-152, Eu-154, Tb-160, Pu-241, Am-241, Fe-59, Mn-54, Co-58, Co-60, Ni-63, Zn- 65, Sr-90, Ru-106, Rh-103m, Cd-113m, Cd-115m, Sn-119m, Sn-126, Te-125m, Te-127m, Cs-135, Ba-137m, Pr-144m, Pm-147, Pm-148, Sm-151, Eu- 55, Gd-153, Pu-238, Pu-239, Pu-240, Am-242m, Cm-242, Cm-244, uranium, neptunium

FIG. 1 is a diagram showing a basic configuration of a radionuclide decontamination system that is an embodiment of the present invention.
In FIG. 1, a radionuclide decontamination system 100 according to the present embodiment separates salinity from the treatment line 1 of stagnant contaminated water leaked to the outside due to the occurrence of a nuclear accident, and the radioactive polluted water as stagnant contaminated water. It is formed from a freshwater system decontamination treatment line 2 that is demineralized water and a saltwater system decontamination process line 3 that is a concentrated brine.

  The freshwater decontamination processing line 2 constitutes a [freshwater] ocean discharge system, and the saltwater decontamination treatment line 3 constitutes a [saltwater] ocean discharge system.

  In the processing line 1 for staying contaminated water in FIG. 1, 11 indicates a nuclear reactor, and in accordance with the accident of this nuclear reactor, water is injected into the nuclear reactor, for example, underground or seawater or a mixed water 12 thereof. Suppose. It is assumed that a large amount of groundwater 12 is injected into the reactor 11 and discharged from the reactor 11 together with various types of radionuclides. In FIG. 1, RO represents a reverse osmosis membrane.

  The discharged radioactive contaminated water is subjected to oil removal 13 by an oil removal device, Cs removal 14 is performed by the Cs removal device, Sr and Ba removal 15 is performed by the Sr and Ba removal device, and salt removal 16 is performed by the salt removal device. Made. The radioactive polluted water that has been made fresh water by removing the salt is temporarily stored in the treated water temporary storage tank 17, and a part of the buffer 18 is added from the buffer line, and is injected again into the reactor 11 through the return pipe 19.

  The fresh water 21 temporarily stored in the treated water temporary storage tank 17 is led from the fresh water line 22 to the fresh water system decontamination processing line 2.

The concentrated salt water from which the salt content has been removed 16 is primarily stored in a primary concentrated salt water storage tank 25 and further evaporated and concentrated by an evaporator (EVAPO) 26. The evaporated and cooled water is stored in the EVAPO treated water storage tank 27 and returned to the evaporator 26 via the line 30 via the desalting tower, the RO device 28 and the makeup water supply equipment 29. The evaporator functions as a salt removal device.

  Fresh water stored in the EVAPO treated water storage tank 27 and desalinated by heating evaporation and cooling is led to the line 22 through the line 31 and led to the fresh water decontamination processing line 2.

The concentrated salt water further concentrated by the evaporator 26 is stored in the secondary concentrated salt water storage tank 32 and temporarily stored. The concentrated salt water 33 is partially from water line 34 is returned to primary concentration brine storage tank 25, a part is introduced via line 3 5 salt water system decontamination process line 3.

  An RO device may be employed as the salt removal device for the salt water removal 16. Therefore, it displays as salt removal (RO) here.

Here Sr and lean removed by be that Sr and Ba removing device Ba will be described.

  A Sr and Ba removal device equipped with a Sr and Ba selective adsorbent is employed.

  FIG. 2 shows the concept of adsorption of the Sr and Ba selective adsorbent 79.

  In FIG. 2, the Sr and Ba selective adsorbent 79 is formed of an Sr and Ba adsorbing member 78 as an inner filling material and a Ca alginate film 77 formed on the surface. In this example, the Ca alginate film is integrally formed on the surface of the Sr and Ba adsorbing member in a mixed state with the Sr and Ba adsorbing member. Further, it is possible to mix a substance involved in selective adsorption into the Ca alginate film 77 and the inside.

  FIG. 3 is a diagram showing a production method for producing an Sr adsorbent according to an embodiment of the present invention.

  In FIG. 3, the Sr adsorbent manufacturing apparatus 200 includes a dropping nozzle apparatus 201 and a gelling apparatus 202.

  The dripping nozzle device 201 includes a raw material feeding pipe 203, multiple (six in FIG. 3) dropping nozzles 204 connected to the pipe, and an air blowing pipe 205 connected to the dropping nozzle 204.

  The raw material solution is sent from the raw material feed pipe 203 to the dropping nozzle 204, and the air controlled so as to be intermittently blown is sent from the air blowing pipe 205 to the dropping nozzle 204.

  The raw material solution is a solution in which an Sr adsorbing member and alginic acid (Algi) are mixed. In this embodiment, A-type zeolite is preferably used as the Sr adsorbing member.

  FIG. 4 shows details of the dripping nozzle 204.

  In FIG. 4, the dripping nozzle 204 has a double nozzle configuration, and the raw material solution is passed through the inner flow path 212 in the inner pipe 211, and the outer flow formed by the outer pipe 213 and the inner pipe 211. Air that is intermittently controlled in the path 214 flows. The outer flow path 214 is narrowed at the outlet end, and the air flow with increased flow is blown out inward.

When the raw material solution that has flowed through the inner flow path 212 is discharged from the outlet end 215, it is cut into small particles by the air flow of intermittent air that has flowed through the outer flow path 214. The cut grains of the raw material solution are spheroidized by the surface tension. Figure in illustrates an enlarged droplet 206 shown in FIG. 3 as a drop 2 1 6 grains were spheroidized.

  In this example, a double nozzle configuration is used, but as a triple nozzle configuration, zeolite may be input from the inner flow region and Algi may be input from the outer flow region. If it does in this way, a zeolite and Algi will be thrown in separately, and will be in a separate composition state.

Returning to FIG. 3, the gelling apparatus 202 includes a container 201 and a gelling solution 220 stored in the container 201 . In this example, the gelling solution 220 is CaCl ₂ . The upper surface of the gelling solution 220 is disposed opposite to the multiple dripping nozzles 204. That is, the droplet 206 falls in the vertical direction.

With such an arrangement, the dropped droplet 206 is received in the gelling solution, and the alginic acid on the surface of the droplet 206 is gelled with CaCl ₂ to form a Ca alginate film. As a result, a gel sphere whose surface is gelled is formed.

FIG. 3 shows the generated gel sphere 207. The generated gel sphere 207 is collected from the container 201 . FIG. 3 shows the gel sphere collection 208.

  The recovered gel spheroids are in the form of particles, dried by a drier (not shown), and solidified with an inorganic material, and provided with a Ca alginate film that selectively permeates Sr, thereby selectively selecting Sr. It becomes a granular Sr selective adsorbent adsorbed on the surface.

FIG. 2 shows a case where the Sr and Ba selective adsorbent 79 having such a form is taken out from the container 69 and placed in seawater salt component-mixed water 70 as an environment, for example, RO concentrated water.

  As shown in FIG. 2, the thickness of the Ca alginate film 77 is considerably smaller than the particle size (for example, 1 to 2 mmΦ). That is, a thin film layer is formed.

The seawater salt component-mixed water ^{70, Sr 2+, 90 Sr 2+} , strontium containing radioactive strontium as radionuclides 89 ^{Sr 2+,} Ba ^2+, there is barium containing radioactive barium as radionuclides 140 ^{Ba 2+} .

On the other hand, Ca ²⁺ , Mg ²⁺ , Na ⁺ , Cl ⁻ , SO ₄ ²⁻ and HCO ₃ ⁻ are present. As is clear from these, Sr, Ca, and Mg coexist in the concentrated salt water 33 that is seawater salt component mixed water.
Example of seawater salt mixed water that was tried:
1) Kd value of Sr and Ba selective adsorbent (this example)
Add 2.5g of Sr and Ba selective adsorbent to 500ml of test solution and stir for 2h Seawater: Kd (Sr) 292
Fresh water: Kd (Sr)> 9.3e + 4
2) Kd value of the Sr and Ba selective adsorbent consisting of only Sr and Ba selective adsorbing members 1 g of Sr and Ba selective adsorbent is added to 100,500 ml of the test solution, and stirred for 14 hours Seawater: Kd (Sr) 645-857, Kd (Ca) 94-135, Kd (Mg) 4
. 8 to 7.6
Fresh water: Kd (Sr) 6.9e + 3 to 1.0e + 4
An Sr and Ba adsorption zone is formed in the Sr and Ba adsorption member 78 inside the Sr and Ba selective adsorbent 79. This zone is also an adsorption zone for Sr or Sr and Ba. The Ca alginate film 77 formed outside the Sr and Ba selective adsorbent 79 has a Ca impermeability function. This film also has an impervious function of Ca or Ca and Mg. In FIG. 2 , functions are displayed as an Sr adsorption zone, a Ba adsorption zone, and a Ca impermeable film. The reason why the Mg impermeable film is not used is that Mg may be adsorbed in the initial stage of the adsorption operation. After this initial stage, the film becomes an Mg impervious film in the initial state of the adsorption operation. Therefore, in this state, both Ca and Mg are impervious.

  The Ca alginate film 77 selectively transmits Sr and Ba when Sr, Ba, and Ca coexist. Although a larger amount of Ca than the amount of Sr coexists in seawater or seawater salt mixed water, the Ca alginate film 77 selectively permeates Sr and Ba in the presence of Ca as an inhibitory element. This Ca alginate film 77 is used in an aqueous solution containing seawater or seawater salt components, and has a property of making Ca non-permeable and selectively allowing Sr and Ba to permeate. This was obtained by the inventors. This is a new finding.

  Thus, the Ca alginate film 77 selectively transmits Ba in addition to Sr. In FIG. 2, this phenomenon is displayed as Sr, Ba selective transmission.

  As described above, the Ca alginate film 77 prevents Ca from permeating and reaching the internal Sr and Ba adsorbing members 78. In addition, the Ca alginate film 77 excludes Ca and Mg from reaching the internal Sr and Ba adsorbing member 78 in addition to Ca. In this state, the selectively transmitted Sr and Ba reach the Sr and Ba adsorbing members and are adsorbed here. In the figure, this phenomenon is indicated as Ca and Mg exclusion. Sr and Ba from which Ca or Ca and Mg are excluded reach the adsorption zone of the Sr and Ba adsorption member. Exclusion of Ca and Mg means that Ca and Mg are not adsorbed and remain in seawater or seawater salt mixed water, and these non-radioactive substances Ca and Mg are radioactive wastes. It means that it must not be, and has great significance in the processing process.

Na ⁺ , Cl ⁻ , SO ₄ ²⁻ , HCO ₃ ⁻ present in seawater or seawater salt component-containing water do not participate in the adsorption of Sr or Ba.

  Here, as described above and as will be described later, the phenomenon that Ca is impermeable does not mean that Ca is not transmitted at all. In a practical process, at the start of trial, Ca is a Ca alginate film. It is said to be impervious, including the case where it does not permeate in a situation where it is not substantially adsorbed on the surface. According to the experiments by the present inventors, the Ca alginate film does not substantially adsorb Ca.

  In this way, Sr and Ba that selectively permeate the Ca alginate film 77 are adsorbed in the Sr and Ba adsorption zone formed by the Sr and Ba adsorption member 78. Further, Ba that selectively permeates the Ca alginate film 82 is adsorbed by the Ba adsorption capability of the Sr and Ba adsorption member 78.

  The Sr and Ba selective adsorbent 79 of this example was immersed in tetramethoxysilane, tetraethoxysilane, titanium tetraisopropoxide or titanium tetrabutoxide, and reacted with the hydroxyl group of alginic acid present on the surface of the Ca alginate film, By forming a three-dimensional structure by crosslinking with silica or titania on the surface of the Ca alginate film, the strength of the Sr and Ba adsorbents can be increased. As a result, a three-dimensional structure is formed on the surface of the Ca alginate film 77 in which silica or titania is cross-linked to the hydroxyl group of alginic acid.

  FIG. 5 shows the relationship between the amount of seawater flow obtained by filling the column with the Sr and Ba selective adsorbent employed in this example and the element adsorption removal rate when seawater is used. The Sr and Ba adsorbing members used in this example are A-type zeolite. Similar results are obtained using X-type zeolite. Similar results can be obtained by the action of the Ca alginate film even with other Sr and Ba adsorbing members. Various types of Sr and Ba adsorbing members can be used, and many have been announced. It is also well known that Sr and Ba adsorbing members adsorb Ba.

  A comparative example shows the case where the Sr and Ba adsorbents which are composed only of the Sr and Ba adsorbents of the Sr and Ba selective adsorbents of this embodiment and do not form a Ca alginate film are used.

  From FIG. 5, it can be seen that there are two major membrane effects resulting from the formation of the Ca alginate membrane.

  Membrane effect (1): According to this example, the removal rate of Sr shows a high value even when seawater flow increases. Moreover, according to the present Example, the removal rate of Ba shows a high value even if seawater flow increases. On the other hand, in the comparative example, the Sr removal rate decreases with Ca adsorption.

  Film effect (2): According to this example, no Ca adsorption on the Sr and Ba selective adsorbents was observed. Mg adsorption was slight at the beginning of operation. Even in this example, Mg adsorption was slightly observed, which was the same as the comparative example. This slight Mg adsorption does not affect Sr selective adsorption or Ba selective adsorption, or even if given. Further, when this operation initial stage is passed and the operation state is reached, Mg is also not adsorbed and becomes impermeable.

  As can be seen from FIG. 5, the Ca alginate film formed on the surface of the Sr and Ba adsorbing members is used in an aqueous solution containing seawater or seawater salt components to make Ca impervious and select coexisting Sr and Ba. It has the characteristic of having a property to transmit. And the Sr and Ba selective adsorption agent of a present Example is equipped with Ca alginate film | membrane which has such a characteristic, It is characterized by the above-mentioned. This characteristic state has important implications due to Sr and Ba selective adsorption.

  FIG. 6 shows the results of examining the influence of the RO membrane scale prevention chelating agent on the adsorption characteristics of Sr and Ba in this example when coexisting with seawater.

  From FIG. 6, it is determined that the coexistence of HEDP and EDTA has no influence on the Sr and Ba removal rate of this embodiment.

  FIG. 7 shows the results of examining the influence of seawater salt component concentration change (seawater ratio 1 to 5 times the concentration) on the adsorption characteristics of Sr and Ba in this example.

  FIG. 6 shows that the Sr and Ba removal rates tend to decrease slightly at high salt concentrations, but a high Sr and Ba removal rate can be maintained.

  Conventionally, it is difficult to separate Ca and Sr, Ba, which coexist in an aqueous solution containing seawater or seawater salt components, because both elements belong to the Group 2A alkaline earth metal in the periodic table. In order to achieve this, pretreatment such as precipitating Ca was required. However, according to this example, the action of Ca as an inhibitory element can be eliminated without performing pretreatment or the like. It became possible to selectively separate Sr and Ba. There is no accumulation of Ca that has been eliminated because it is not necessary to perform pretreatment.

Returning to FIG. 1, the freshwater decontamination treatment line 2 is composed of a FW-contaminated water receiving tank 85 for temporarily storing freshwater-contaminated water, activated charcoal or TiO ₂ system carrying cobalt ferrocyanide or ferrocyanide as a (main) component. Adsorption tower (column) 86 equipped with Cs adsorbent, alumina Al ₂ O ₃ and titania TiO ₂ (main) components, adsorbent adsorbing Sr or adsorption tower 87 equipped with FW-KAZLS (for KAZLS, In FIG. 2, it is indicated by 79. Here, it is indicated by 87.) Adsorption tower 88 equipped with an adsorbent containing AC-Al and CeO ₂ as (main) components, adsorbing I ₂ / AC-tannin / AC adsorbent Adsorption tower 89, adsorption tower 90 equipped with DDTC / AC-aluminum-containing carbon-based adsorbent, adsorption tower 9 equipped with DDTC + oxine + DTPA + cuperon / AC adsorbent And becomes the AC-Al adsorbent from the adsorbent tower 92 mounted constituted further processed water tank 93, it is supplementary released for storage tank 94 and discharge 95.

In FIG. 1, these indicate that the adsorption towers with the adsorbent arrangement are arranged in the displayed arrangement order. In the following description, the adsorbing tower is omitted and the adsorbent is sometimes given a number. Each adsorption tower is good at any time not a single be two by two sequences may be intended to secure the safety of the process. Cs containing cobalt ferrocyanide or iron ferrocyanide as the (main) component upstream of the adsorption tower 87 equipped with Sr adsorbent or FW-KAZLS containing (main) components of alumina Al ₂ O ₃ and titania TiO ₂ An adsorption tower 86 equipped with an adsorbent is arranged. It is desirable that an AC-Al adsorbent is provided on the upstream side of the adsorption tower 86 equipped with this Cs adsorbent containing cobalt ferrocyanide or iron ferrocyanide as a (main) component. The freshwater FW decontamination treated water receiving tank 93 is also connected to a backup line as a backup system. The adsorption tower used for each adsorption means has the same configuration, and a valve switching operation is performed in order to enable parallel processing in a parallel or series configuration. In the case of a series configuration, one adsorption tower is used as the upstream side and the other adsorption tower is used as the downstream side by switching the valves provided above and below the adsorption tower. When the outlet concentration from the upstream adsorption tower exceeds a predetermined value, the valve is switched to switch the upstream side and the downstream side. According to such switching, since the downstream adsorption tower serves as a backup, the predetermined value of the outlet concentration can be made higher than that in the parallel configuration, and the utilization rate of the adsorbent can be made higher than that in the parallel configuration.

On the other hand, the concentrated salt water-based decontamination treatment line 3 includes an SW contamination receiving tank 96 for storing concentrated salt water (SW contaminated water), an adsorption tower 88 equipped with an AC-Al adsorbent, cobalt ferrocyanide or iron ferrocyanide ( main) and the adsorption tower 86 equipped with loaded with activated carbon, TiO ₂ based Cs adsorbent, SW-KAZLS adsorption tower 87 was attached, the AC-Al and CeO ₂ (main) adsorbing the adsorbent to components mounted Tower 88, adsorption tower 89 equipped with I ₂ / AC-tannin / AC adsorbent , adsorption tower 90 equipped with reduced iron / AC-aluminum-containing carbon-based adsorbent, adsorption equipped with DDTC + oxine + DTPA + cuperon / AC adsorbent It comprises an adsorbent tower comprising a tower 91 and an adsorption tower 92 equipped with AC-Al, a salt water SW decontamination treated water receiving tank 97, a discharge storage tank 98 and a discharge 99. In FIG. 1, these are arranged in the arrangement order shown.

  FIG. 8 shows a treatment line that can be commonly used for a freshwater marine release system and a saltwater decontamination treatment line using a freshwater decontamination treatment line. In addition, a decarboxylation tower and a C-14 absorption tower are added to this treatment line.

The processing line shown in FIG. 8 is very similar to the saltwater-based decontamination processing line, but 87FW-KAZLS and 87FW-KAZLS are juxtaposed as adsorption towers equipped with KAZLS indicated by 87.

  When the salinity concentration EC in the contaminated water receiving tank 96 is measured and the salinity concentration EC is a predetermined value (for example, 0.25 S / m) or less, 87FW-KAZLS is used by switching the valve, and when it is less than the predetermined value 87SW-KAZLS is used.

In addition, as shown in the figure, desorption is performed between the adsorption tower 89 equipped with the I ₂ / AC-tannin / AC adsorbent and the adsorption tower 90 equipped with the reduced iron (rFe) / AC-aluminum-containing carbon-based adsorbent. The carbonic acid tower 101 is inserted. On the upstream side, Scavenger (CO ₃ ²⁻ ) is attached as a carbon-based decarburizing agent. H ₂ SO ₄ is injected into this as a pH adjuster, and Air is injected from below.

The generated gas is led to the C-14 absorption tower 102, and C-14 is removed by the action of the Ca (OH) ₂ solution.

  FIG. 9 shows a processing line composed of a service line and an emergency backup line. The arrangement configuration of each processing line of the regular line and the emergency backup line is the same as the processing line shown in FIG. 8, and two adsorption towers are juxtaposed.

  The series of treatment systems shown in FIG. 9 can be mounted on a trailer and moved to a place where radioactive polluted water is accumulated as a trailer-mounted mobile multi-nuclide decontamination system.

  In the above configuration, the radionuclide decontamination system of the present embodiment is configured to include the following means. The salt water SW decontamination treated water receiving tank 87 is connected to a backup line as a backup system.

Ca alginate membranes, when used in aqueous solution, coexisting Ca, or Ca and Mg and opaque, have a property of selectively transmitting the Sr and Ba, were solidified with an inorganic material of the Ca alginate film A first means in which a surface layer of an adsorbing member is formed, and the adsorbing member is mounted with Sr and Ba selective adsorbent that adsorbs selectively permeated Sr and Ba in an impermeable state of Ca or Ca and Mg;
A second means formed of ferrocyanated Co or ferrocyanated Fe-supported activated carbon or a TiO ₂ inorganic material and loaded with a Cs adsorbent;
A third means equipped with a multi-nuclide decontamination adsorbent which is formed from activated carbon and activated alumina and performs multi-nuclide decontamination;
Firstly, an iodine-supported activated carbon and a chelating agent-supported or added activated carbon, for example, tannin-supported activated carbon or DDTC-supported or added activated carbon, which is equipped with iodine and a super-uranium element decontamination adsorbent for decontamination of super-uranium element containing iodine. Four means,
The adsorbent decontamination means 80 formed in combination with the radioactive contamination water is passed through to decontaminate many types of radionuclides.

  The adsorbent decontamination means 80 is formed of DDTC-supported activated carbon, or Al-containing inorganic carbon-based material, and oxine-supported activated carbon or DTPA-supported activated carbon, and is equipped with a multi-nuclide decontamination adsorbent that performs multi-nuclide decontamination. Including means.

  The adsorbent decontamination means 80 includes sixth means on which a multi-nuclide decontamination adsorbent is formed which is formed from cuperon-supported activated carbon and performs multi-nuclide decontamination.

  A reverse osmosis membrane mounting means for generating desalted water and concentrated salt water by separating salt from radioactive contaminated water is provided, and the adsorbent decontamination means is provided in the desalted water or concentrated salt water line, or in both lines. .

  A reverse osmosis membrane mounting means for generating desalted water and concentrated salt water by separating salt from the radioactive contaminated water is provided, and a first means is provided in the radioactive contaminated water line upstream of the osmotic membrane mounting means.

  In this example, many types of radionuclides contained in radioactively contaminated water, for example, 62 types of radionuclides, are adsorbed according to their functions corresponding to the radionuclides, thereby reducing the number of adsorption towers and enabling thorough decontamination. It is characterized by that.

As described above, in the first means, Sr and Ba are removed by radioactive Sr and Ba selective adsorbent to form an Sr and Ba adsorption tower,
In the second means, radioactive Cs is removed to form a Cs adsorption tower,
The third means removes multi-nuclide species (multi-elements) to form a multi-element adsorption tower,
In the fourth means, a super uranium element containing iodine is removed to form a super uranium element adsorption tower. The fourth means A can be an iodine removing means, and the fourth means B can be another transuranium element adsorption means.

  And when C-14 is contained in the evaluation decontamination nuclide, the seventh means is adopted to remove C-14. The first means and the seventh means may be functionally combined means.

  A radionuclide decontamination system and a radionuclide decontamination method are configured by including the first stage to the fourth stage, or the seventh stage.

  In these radionuclide decontamination systems and radionuclide decontamination methods, fifth and sixth means are added for decontamination of the remaining radionuclides even through the above means.

  Multi-nuclide removal is performed by the fifth and sixth means. According to the aluminum-containing carbon-based material, it is effectively removed to remove Sb, Se, Te, and Tc among multiple elements.

  In the salt water-based decontamination system, an AC-Al adsorption tower is placed at the first stage of the system to remove multielements in advance and lower the decontamination rate. Finally, an AC-Al adsorption tower can be provided as a final treatment.

As will be described later, according to SW-KAZLS, which is a decontamination agent, Y is removed in addition to Sr and Ba in salt water. In addition to radioactive Cs in salt water, Rb is removed by the Cs adsorbent containing cobalt ferrocyanide or iron ferrocyanide as the (main) component. Here, Cs adsorbent by ferrocyanated Co or ferrocyanated Fe-supported TiO ₂ inorganic material, Sr adsorbent having alumina Al ₂ O ₃ and titania TiO ₂ as main components, adsorption of aluminum-containing carbon The agent is a commercially available adsorbent.

DDTC is sodium diethyldithiocarbamate and is represented by the molecular formula C ₅ H ₁₀ NS ₂ Na, and is manufactured and sold by many manufacturers as a general reagent.

  AC means activated carbon.

  In the fresh water-based decontamination treatment line for desalted water, the first means is arranged on the downstream side of the second means, and the second means, the first means, the third means, the fourth means, the fifth means, and the sixth means. , An array of seventh means.

For the freshwater decontamination processing line 2, a decontamination agent composed of an Sr adsorbent containing alumina Al ₂ O ₃ and titanium TiO ₂ (main components) is used instead of the Sr and Ba adsorbents of the first means. Can do. The adsorbent that adsorbs Sr with alumina (Al ₂ O ₃₎ and titania (TiO ₂ ) as the main components is a decontamination agent composed of an Al ₂ O ₃ + TiO ₂ inorganic material, and the introduction of a fresh water decontamination treatment line 2 It is used for fresh water previously decontaminated by using Sr and Ba adsorbents in the first stage, and used for decontamination when Sr and Ba remain in fresh water.

  In the salt water-based decontamination treatment line of concentrated salt water, the first means is arranged on the downstream side of the third means and the second means, and the fifth means, the second means, the first means, the third means, and the fourth means. The sixth means and the seventh means are arranged.

  If two suction means are included in the first to seventh means, it does not mean that the two suction means must be used in combination. It only indicates that it is desirable to place the adsorbent separately or mixed in one column.

For example, the fourth means is composed of an adsorbent on which I ₂ / AC-supported activated carbon and Tan / AC-charged activated carbon are mounted. These are the fourth means (A) in which the I ₂ / AC-supported activated carbon adsorbent is used. The fourth means (B) is a tannin / AC-supported activated carbon adsorbent.

  In FIGS. 1, 8, and 9, it is possible to input a drug to assist adsorption. In these figures, Scavenger (Scav, difficult to remove ion multi-element) and DDTC solution are added to the contaminated water.

  The adsorbent decontamination means 80 is configured by combining the adsorption means. The adsorbent decontamination means 80 passes radioactive contaminated water in one direction, that is, through. Here, one-time through is referred to as one-through.

  In this way, a one-through adsorption decontamination method is formed. Radioactive contaminated water exists in three systems as shown in FIG.

  FIG. 10 shows decontamination target nuclides that can be decontaminated by each means. Co-decontamination nuclides are removed together with the decontamination target nuclides. The decontamination target nuclide is a main decontamination target nuclide, and the co-decontamination nuclide is a nuclide that is auxiliaryly removed when the decontamination target nuclide is removed.

  Tables 1 and 2 show the decontamination system and the decontamination agent having the method configuration.

  Here, multi-elements: Ag, Cd, Eu, Mn, Co, Y, Ru, Ce, Te, Ni, Zn, Rh, Nd, Sn, Sb, Tc, Pr, Sm, Gd, V + TRU (U, Np, Pu, Am, Cm) or a part thereof.

  The adsorbent decontamination means 80 is required to include each means from the first means to the fourth means when decontaminating various types of radionuclides. Among these, whether or not the fourth means needs to have a C-14 decontamination function formed from a decarboxylation tower can be determined by the nuclide to be evaluated as described above. When C-14 is not wrapped in the radioactively contaminated water introduced into the treatment line, it is not necessary to provide a treatment means equipped with a C-14 decontamination function in this line. However, when C-14 is contained in the contaminated water, it is necessary to provide a processing means equipped with a C-14 decontamination function in this line. In the case of a nuclear accident, C-14 is contained in the radioactive polluted water that becomes the stagnant water. Therefore, any of the entire lines should be equipped with a processing means equipped with a C-14 decontamination function. Provide.

  Each means of the adsorption means by the cuperone-supported activated carbon of the fifth means to the seventh means is a guard processing means provided for thorough the decontamination processing from the first means to the fourth means described above to ensure decontamination. It is.

  For these guard treatment means, an adsorbent formed from activated carbon supporting DDTC, activated carbon supporting oxine and activated carbon supporting cuperon is used. By using these supported activated carbons, the remaining multi-nuclide decontamination is performed, and the treated water can be reduced to a radioactive concentration or less stipulated by law.

  In order to enhance the decontamination function in each means, a chelating agent is preferably added as appropriate.

  There are a great many types of chelating agents that can be supported on activated carbon and can adsorb heavy metal ions and radioactive substances, and typical examples include Oxine, DTPA, cuperone, tannic acid, and DDTC. In order to use for decontamination, there is a method in which a chelating agent is supported on activated carbon, or a method in which a chelating agent is added as a solution like DDTC and added to radioactive contaminated water to chelate a radioactive substance and then adsorbed on activated carbon. As other chelating agents, there are NTA (Nitriotropic acid), PAN (Pyrylozone Naphthol), AA (Acetylacetone), TOPO (Tri-octylphosphine), HFA (Hexafluoropentanedione), Nitto, etc.

  In FIG. 1, FIG. 8, and FIG. 9, in each adsorption tower, the dose is measured at the outlet of the adsorption tower, and in the case of the parallel arrangement of the adsorption tower, switching between the upstream adsorption tower and the downstream adsorption tower is performed. Dose measurement can be easily performed by performing γ-ray measurement. The measurement result is digitized, and the adsorbent conversion time is appropriately determined by computer control. In this way, the treated water is checked, and if it is determined that the residual radioactivity has not reached the predetermined numerical value, the treated water is guided to the backup system. The backup system is configured as a processing line having the same configuration as the processing line described above, and is juxtaposed.

  Each means from the first means to the fourth means may be arranged in any combination order, and may be configured such that the arrangement can be changed during operation. In FIG. 1, the Sr and Ba selective adsorbent of the first means is formed of an inorganic material, and the other means is formed of a porous carbon material that is activated carbon. Therefore, the porous carbon material is left on the upstream side. It is preferable to construct a system of a sequence that removes the target nuclide as much as possible at the site.

  Since the volume of activated carbon can be reduced by incineration, high-concentration nuclides can be treated with activated carbon on the upstream side and treated with an inorganic material downstream to replace or reduce the volume when saturation is reached. Total secondary waste should be reduced. However, it is preferable to provide an AC-Al adsorption tower as a spare in the final stage.

  In FIG. 1, the 2nd means, the 3rd means, and the 2nd means are installed in the upstream of the 1st means carrying Sr and Ba selective adsorption agent. That is, the second means, the first means, the third means, and the fourth means are arranged in this order in the desalinated water freshwater decontamination treatment line 2. Further, in the salt water-based decontamination processing line 3 of the concentrated salt water, the number of means before the first means is increased, and the third means, second means, first means, and fourth means are arranged. 8 and 9 show the arrangement of each means.

  Thereby, as described above, the porous carbon material is installed on the upstream side, the target nuclide is removed as much as possible at the site, and as the lifetime of the porous carbon material is shortened, the contaminant concentration is high, Processing to arrive at adsorption saturation is performed, the amount of waste of the porous carbon material is increased and incinerated and dissolved, and the amount of waste of the inorganic material on the downstream side is reduced.

  FIG. 11 shows, in the periodic table, nuclides (elements) that can be decontaminated by a solid line frame and test confirmation nuclides (elements) by a hatched frame by the radionuclide decontamination method by the radionuclide decontamination system 100 of the present embodiment. Other non-target elements are indicated by thin line frames. Therefore, according to the method of the present embodiment, all evaluation target nuclides shown on page 5 can be decontaminated.

  DESCRIPTION OF SYMBOLS 1 ... Retained contaminated water processing line, 2 ... Fresh water system decontamination processing line, 3 ... Salt water system decontamination processing line, 11 ... Reactor, 21 ... Fresh water, 22 ... Fresh water line, 33 ... Salt water, 34 ... Salt water line.

Claims (9)

In many kinds of these radionuclides remove radionuclides decontamination system from a radioactive contaminated water containing radioactive nuclides,
The Ca alginate film has the property of being impermeable to coexisting Ca or Ca and Mg and selectively permeable to Sr and Ba, impermeable to Ca or Ca and Mg, and capable of adsorbing Sr and Ba . An adsorbent comprising an adsorbing member in which an inorganic material is solidified, and the Ca alginate film formed on the surface of the adsorbing member, wherein the adsorbent is mounted;
A second means formed of ferrocyanated Co or ferrocyanated Fe-supported activated carbon or a TiO ₂ inorganic material and loaded with a Cs adsorbent;
A third means loaded with a multi-nuclide decontamination adsorbent formed from activated carbon or activated alumina or mixtures thereof;
A fourth means that is formed from iodine-supporting activated carbon and chelating agent-supported or additive activated carbon, and is equipped with iodine and a super-uranium element decontamination adsorbent that performs decontamination of transuranium element containing iodine;
A radionuclide decontamination system characterized by comprising adsorbent decontamination means formed in combination with.   The radionuclide decontamination system according to claim 1, wherein the zeolite powder is spherically hardened with alginic acid or a binder to form an adsorption member.   2. The adsorbent decontamination means according to claim 1, wherein the adsorbent decontamination means is formed from DDTC-supported or added activated carbon, or Al-containing inorganic carbon-based material, and oxine-supported activated carbon, DTPA-supported activated carbon or cuperone-supported activated carbon, A radionuclide decontamination system comprising an on-board adsorption means.   The radionuclide decontamination system according to claim 1, further comprising a decarboxylation tower attached to perform C-14 decontamination.   The method according to any one of claims 1 to 3, further comprising means for producing demineralized water and concentrated salt water for separating salt from radioactive polluted water, wherein the adsorbent decontamination means is in the line of demineralized water or concentrated salt water, or both. A radionuclide decontamination system characterized by being provided in a line.   The method according to any one of claims 1 to 3, further comprising means for generating demineralized water and concentrated salt water for separating salt from the radioactive contaminated water, wherein the first means is provided in the radioactive contaminated water line upstream of the means. A featured radionuclide decontamination system.   6. The radionuclide decontamination system according to claim 5, wherein the first means is arranged on the downstream side of the second means in the fresh water line of the desalted water.   8. The radionuclide decontamination system according to claim 5, wherein a first means is arranged on the downstream side of the third means and the second means in the salt water system line of the concentrated salt water. In a radionuclide decontamination method using a radionuclide decontamination system that decontaminates by removing these radionuclides from radioactive contaminated water containing multiple types of radionuclides,
When a Ca alginate membrane is used in an aqueous solution, it has the property of making Ca or Ca and Mg coexisting and selectively permeating Sr and Ba, and impervious to Ca or Ca and Mg. and the adsorbent which enables adsorption of Ba is, the inorganic material is from the Ca alginate film formed on the surface of the solidified adsorptive member and adsorbing member, mounted the adsorbent,
Equipped with ferrocyanated Co or ferrocyanated Fe-supported activated carbon or TiO ₂ inorganic material Cs adsorbent,
A multi-nuclide decontamination adsorbent that is formed from activated carbon and / or activated alumina or a mixture thereof and performs multi-nuclide decontamination,
Formed from iodine-supported activated carbon and chelating agent-supported or added activated carbon, and equipped with iodine and super-uranium element decontamination adsorbent that performs decontamination of super-uranium element containing iodine, forming an adsorbent decontamination means, and radioactive A radionuclide decontamination method characterized by decontaminating various types of radionuclides by passing through contaminated water.

Images