JP2013148364A - Radioactive waste liquid processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radioactive waste liquid processor capable of achieving reduced costs for disposal by reducing the volume of secondary waste.SOLUTION: A radioactive waste liquid processor 1 includes: two-staged evaporative concentrators 2A, 2B sequentially concentrating a radioactive waste liquid W by evaporation; an oil remover 3 and a filtration device 4 which are followed by the first and second evaporative concentrators 2A, 2B in such a manner that the four devices are connected together in this order from an upper stream to a lower stream in the flow of a process of converting the radioactive waste liquid W into concentrated liquid waste; a condensed water lead-out path 21 leading a first condensed water G1 generated from the first evaporative concentrator 2A in the foremost stage out of the radioactive waste liquid processor 1; and a condensed water circulation path 22 leading a second condensed water G2 generated from the second evaporative concentrator 2B in the subsequent stage into the first evaporative concentrator 2A.

Description

  The present invention relates to a radioactive liquid waste treatment apparatus that can be applied to the entire waste liquid treatment containing a high level of radioactive material.

Conventionally, urgent treatment is performed on contaminated water (radioactive waste liquid) in which high-level radioactive substances generated in nuclear power plants are dissolved (see, for example, Patent Document 1).
Specifically, it is a method of reducing the dose in the waste liquid by removing radioactive substances by adsorption or precipitation, and then further purifying by desalting. In this case, the purified treated water can be reused as fuel cooling water to suppress an increase in the total amount of high-level waste liquid.

  By the way, as a general processing flow of general radioactive waste liquid, first, the radioactive waste liquid is sent to the oil separation device, and after removing the oil, the cesium adsorption device uses an adsorbent such as zeolite to adsorb cesium, In the decontamination equipment, nuclides other than cesium are adsorbed and coagulated. In addition, when seawater is mixed with radioactive waste liquid, the chlorine is removed by reverse osmosis membrane (RO) treatment in the desalination unit, reused as cooling water through the treated water receiving tank, and the removed chlorine is The amount is reduced by evaporation.

Special table 2009-189798

However, the conventional waste liquid treatment method has the following problems.
That is, in each processing step described above, a large amount of secondary waste contaminated with radioactivity is generated. Specifically, waste adsorbent (zeolite or the like) that adsorbs radioactive substances in the cesium adsorption device, sludge concentrated by precipitation treatment, concentrated water separated by desalting treatment, and the like are generated. These secondary wastes are further processed appropriately and moved to the final disposal site. Until the final disposal method is determined, they are stored in a predetermined temporary storage site for a long time. May be required. In other words, it is necessary to store high-level waste in the long term, and these secondary wastes are in various forms such as solid, slurry, and liquid, and their storage methods and management are difficult, and there is room for improvement in that respect. was there.

  The present invention has been made in view of the above-described problems, and provides a radioactive liquid waste treatment apparatus that can reduce the cost of disposal by minimizing the amount of secondary waste generated. Objective.

  In order to achieve the above object, in the radioactive liquid waste processing apparatus according to the present invention, the radioactive liquid waste processing apparatus includes a plurality of stages of evaporation and concentration units for sequentially evaporating and condensing the radioactive liquid waste, and is generated from the front-stage evaporation and concentration unit. A condensed water lead-out path for leading the condensed water to the outside, and a condensed water reflux path for introducing condensed water generated from the evaporating and condensing part other than the first evaporating and concentrating part to the evaporating and condensing part upstream of the evaporating and concentrating part. It is characterized by providing.

In the present invention, the first stage evaporative concentration section (hereinafter referred to as the first evaporative concentration section) can be separated into concentrated water (high radiation, high salt concentration) and condensed water (low radiation, low salt concentration). Only the condensed water generated from the first evaporating and concentrating part is led out to the outside as water that can be discharged through the condensed water outlet, and the concentrated water having high radioactive and high salt concentration evaporated and concentrated in the first evaporating and concentrating part is It is introduced into an evaporation concentration unit (hereinafter referred to as a second evaporation concentration unit) other than the one evaporation concentration unit. Then, in the second evaporating and concentrating part, the treated condensed water is not led out to the outside but is introduced into the first evaporating and concentrating part via the condensed water reflux path, and again processed in the first evaporating and concentrating part, and further evaporated. Concentrated concentrated water can be disposed of as concentrated waste liquid (secondary waste).
As described above, in the present radioactive waste liquid treatment apparatus, it is possible to concentrate at a high salt concentration and a high radiation dose in the evaporative concentration treatment, compared to the reverse osmosis membrane treatment, and therefore, the high radioactivity finally generated by the multi-stage evaporative concentration unit. Therefore, the amount of concentrated waste liquid having a high salt concentration can be reduced and the volume can be reduced.

Further, by providing a plurality of stages of evaporation and concentration units, the concentration rate of the evaporation and concentration process in the first stage of evaporation and concentration unit can be suppressed, and brought in from the splash of condensed water derived from the first evaporation and concentration unit. The amount of impurities mixed in can be suppressed. For example, since the concentration of impurities contained in the droplets at the time of evaporation is suppressed to about 10 times by suppressing the concentration rate by the first evaporative concentration unit to about 10 times, the amount of radioactivity transferred to the concentrated water by the droplets is low. Can be suppressed.
Even if radioactivity is mixed in the condensed water generated in the first evaporating and concentrating portion, the condensed water has low radioactivity and low salt concentration. For example, after removing radioactive substances with an adsorption facility, It can be discharged out of the system, and the amount of adsorbent used for reducing to a level capable of water discharge generated at this time can be reduced.

  Moreover, in the radioactive waste liquid processing apparatus which concerns on this invention, it is also possible to introduce a condensed water recirculation path into the evaporative concentration part of the 1st stage.

  In this case, even if a plurality of evaporation / concentration units (second evaporation / concentration unit) other than the first stage are provided, all of the condensed water is introduced into the first-stage evaporation / concentration unit (first evaporation / concentration unit). Therefore, the amount of processing in the first evaporating and concentrating unit can be suppressed.

  Moreover, in the radioactive waste liquid processing apparatus which concerns on this invention, the 1st adsorption part which adsorb | sucks a cesium and strontium, the 2nd adsorption part adsorb | sucking using an inorganic ion exchanger, and an ion exchange resin are provided in a condensed water extraction path. An adsorbing facility having a third adsorbing unit that adsorbs the adsorbing unit, and an appropriate adsorbing tower among the first adsorbing unit, the second adsorbing unit, and the third adsorbing unit according to the radiation dose and electrical conductivity of the condensed water. It is preferable to selectively switch a plurality of adsorption processing methods for passing the water.

  In this case, the condensed water led out from the condensed water lead-out path is freed of radioactive substances by the adsorption facility, and then discharged out of the system as discharged water. And in the adsorption facility, it becomes possible to select and process a suitable adsorption treatment method according to the radiation amount and electric conductivity of the condensed water, so that the adsorbent used can be managed to the minimum necessary. And secondary waste can be reduced. Further, depending on the water quality condition of the condensed water, for example, the treatment cost can be reduced by positively treating the third adsorbing portion that adsorbs using an inexpensive ion exchange resin.

  Moreover, in the radioactive waste liquid processing apparatus which concerns on this invention, the measurement part which detects a radiation dose and electrical conductivity may be provided in the entrance of adsorption equipment.

  In this case, since the radiation amount and electric conductivity of the condensed water immediately before being introduced into the adsorption facility can be detected by the measurement unit, a more appropriate and reliable adsorption treatment method can be selected. It is also possible to control the detection value of the measurement unit in real time and automatically select the adsorption processing method based on the detection value.

  Further, in the radioactive liquid waste treatment apparatus according to the present invention, an adsorption tower for adsorbing a radioactive substance may be provided on the rear stage side of the evaporation and concentration unit.

  By adopting such a configuration, the radioactive material of the concentrated water generated in the evaporation and concentration unit can be adsorbed by the adsorption tower, and the radiation dose of the concentrated water introduced from the adsorption tower to the next evaporation and concentration unit can be reduced. Can do.

  Moreover, in the radioactive waste liquid processing apparatus which concerns on this invention, the dechlorination part which removes a chlorine ion from the high concentration radioactive waste liquid concentrated by the evaporation concentration part may be provided in the back | latter stage side of the evaporation concentration part.

  According to the radioactive liquid waste treatment apparatus according to the present invention, it is possible to reduce the chlorine ion concentration in the concentrated waste liquid or in the condensed water derived from the condensed water outlet, and to increase the durability of the material due to corrosion, Since it is possible to reduce the expensive material (metal) used for the equipment, secondary waste can be stored for a long period of time, and overall processing costs can be reduced.

  Further, in the radioactive liquid waste treatment apparatus according to the present invention, the dechlorination unit includes an electrolytic treatment unit that generates chlorine by electrolysis and removes it in the gas phase, and a precipitation treatment that generates a silver chloride precipitate and removes it as a solid phase. And at least one of the parts.

  In the present invention, in the case where the electrolytic treatment unit is provided, the chlorine ion concentration in the concentrated water is discharged out of the system as chlorine gas in the concentrated waste liquid by electrolysis or in the condensed water derived from the condensed water outlet passage. Can be lowered. Moreover, when it has a precipitation process part, since the solubility of silver chloride is very low, it can reduce to the chloride ion density | concentration of several mg / L.

  In the radioactive liquid waste treatment apparatus according to the present invention, the electrolytic treatment unit may be provided with a cation exchange membrane or a sodium permselective ion exchange membrane.

In the present invention, by introducing concentrated water generated from the evaporating and concentrating portion to the anode side of the cation exchange membrane or the sodium permselective ion exchange membrane, chlorine ions in the concentrated water are removed as chlorine gas and remain. The cation mainly composed of sodium moves to the cathode side through the ion exchange membrane selectively permeable to sodium cation exchange membrane. At this time, since metal ions decrease on the anode side, an increase in the pH of the concentrated water is suppressed, so that the amount of pH adjusting agent (acid) added can be reduced. At the cathode, water is decomposed to generate hydrogen, and hydroxide ions remain. Furthermore, sodium hydroxide water can be generated at the cathode from sodium ions that have passed through a cation exchange membrane or a sodium permselective ion exchange membrane and electrolytically generated ion ions, which can be used for chlorine recovery. The amount of sodium hydroxide reagent used for chlorine recovery can be reduced.
Moreover, since the cation concentration of sodium in the electrolytic treatment liquid discharged toward the precipitation treatment unit is lowered, the final disposal amount of the waste liquid can be reduced.

  According to the radioactive liquid waste treatment apparatus of the present invention, by providing a plurality of stages of evaporation and concentration sections, it is possible to reduce the amount of concentrated waste liquid generated by using only the highly radioactive and high salt concentration concentrated waste liquid that is finally generated. Secondary waste can be reduced in volume, and the cost for disposal can be reduced.

It is a flowchart which shows typically the process of the radioactive waste liquid processing apparatus by the 1st Embodiment of this invention. It is a flowchart which shows the processing process of adsorption equipment typically. It is a schematic diagram which shows the adsorption | suction system of the adsorption | suction processing system in the adsorption | suction installation of FIG. It is a flowchart which shows typically the process of the radioactive liquid waste processing apparatus by 2nd Embodiment. It is a flowchart which shows typically the process of a chlorine gas collection | recovery part. It is a flowchart which shows typically the process of the dechlorination apparatus by 3rd Embodiment. It is a figure which shows the structure of the electrolytic treatment part of the dechlorination apparatus by 4th Embodiment. It is a flowchart which shows typically the process of the radioactive waste liquid processing apparatus by 5th Embodiment.

  Hereinafter, a radioactive liquid waste processing apparatus according to an embodiment of the present invention will be described with reference to the drawings. This embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention.

(First embodiment)
As shown in FIG. 1, the radioactive liquid waste treatment apparatus 1 according to the present embodiment includes a radioactive substance from a waste liquid containing a radioactive substance such as cesium or a cleaning liquid generated by washing contaminated soil containing a radioactive substance such as cesium. It is related with the method of isolate | separating and removing.

  That is, the radioactive liquid waste treatment apparatus 1 includes a plurality of (in this case, two stages) evaporative concentration apparatus 2 (2A, 2B) (evaporation concentration section) for sequentially evaporating and condensing the radioactive liquid waste W. In the process of becoming concentrated waste liquid, the oil removal equipment 3, the filtration equipment 4, the first evaporative concentration apparatus 2A, and the second evaporative concentration apparatus 2B are connected and arranged in that order from the upstream side toward the downstream side. It has become. The radioactive liquid waste treatment apparatus 1 includes a condensed water lead-out path 21 that guides the first condensed water G1 generated from the first stage first evaporative concentration apparatus 2A to the outside of the radioactive liquid waste treatment apparatus 1, and a second stage second evaporative concentration apparatus. A condensed water reflux path 22 for introducing the second condensed water G2 generated from 2B (evaporating and concentrating apparatus other than the first evaporating and concentrating apparatus 2A) to the first evaporating and concentrating apparatus 2A.

The oil removal equipment 3 has a general configuration in which oil and dust (floating suspension) are separated from the supplied radioactive waste liquid W and recovered and removed. Hereinafter, the separated oil and the like are simply referred to as “oil K”. That is, the oil K that has floated is removed, and water (the radioactive waste liquid W from which the oil K has been removed) is extracted from the tank bottom and sent to the filtration equipment 4. In addition, the oil component K separated and recovered here becomes a secondary waste containing a radioactive substance.
Specific examples of the oil removal equipment 3 include a CIP separator and a pressure levitation separator.

  The filtration equipment 4 can adopt, for example, a membrane separation type or a sand filtration type, and separates and removes sand and dust (garbage that cannot be removed by the oil removal equipment 3), and water (filtered radioactive waste liquid). W) is sent to the first evaporative concentration apparatus 2A. Note that the solid matter M (sand, dust, etc.) recovered by filtration becomes secondary waste containing radioactive substances.

The evaporative concentrator 2 (2A, 2B) can employ, for example, a vacuum vapor compression type, concentrates the radioactive waste liquid W, concentrates the concentrated water N (highly radioactive, high salt concentration) and condensed water G (low radioactive, low Salt concentration).
In the first evaporative concentration apparatus 2A arranged in the preceding stage, the first concentrated water N1 is sent to the second evaporative concentration apparatus 2B, and the first condensed water G1 passes through the condensed water outlet path 21 and is used as cooling water. Or they are released. On the other hand, in the second evaporative concentration apparatus 2B arranged in the subsequent stage, the second concentrated water N2 is extracted as the concentrated waste water, and the second condensed water G2 passes through the condensed water reflux path 22 as described above and is concentrated in the first evaporation. Returned to device 2A. The second condensed water G2 returned to the first evaporating and concentrating device 2A is mixed with the radioactive waste liquid W before concentration, and is again subjected to the concentrating step by the first evaporating and concentrating device 2A.

  The condensed water outlet 21 for extracting the first condensed water G1 generated by the first evaporative concentrator 2A includes a first conduit 23 that is reused as cooling water, and a second conduit 24 that is discharged as a surplus. , Have been branched. The second conduit 24 adsorbs radioactive material contained in the first condensed water G1 to reduce the radiation dose to a set discharge standard value or less (approximately 0.01 to 0.001 or less). Equipment 5 is provided.

Next, the configuration of the adsorption facility 5 will be specifically described with reference to FIG.
As shown in FIG. 2, the adsorption facility 5 includes a first adsorption tower 51 (first adsorption section) having a cesium adsorption tower and a strontium adsorption tower, and a second adsorption tower 52 (first adsorption) that uses an inorganic ion exchanger. 2 adsorption section), the third adsorption tower 53 (third adsorption section) that adsorbs using an ion exchange resin, and the radiation amount and electric conductivity of the first condensed water G1 obtained by the first evaporating and concentrating device 2A as appropriate. And a measurement unit 54 that performs measurement at a frequent frequency.
Then, as shown in FIG. 3, a plurality of (the appropriate number of adsorbing towers that pass among the first adsorbing tower 51, the second adsorbing tower 52, and the third adsorbing tower 53, depending on the detection value in the measurement unit 54 ( The seven adsorption processing methods (first adsorption system 5A to seventh adsorption system 5G) can be selectively switched. As shown in FIG. 2, the adsorption processing method is switched by opening and closing switching valves 55, 56, and 57 provided in pipes connecting the first adsorption tower 51, the second adsorption tower 52, and the third adsorption tower 53. Is done by.
In addition, when radioactivity is not mixed in the 1st condensed water G1 detected by the measurement part 54, it is also possible to discharge directly, without letting the said adsorption towers 51, 52, and 53 pass.

  The first adsorption tower 51 employs zeolite or the like, and adsorbs and removes cesium and strontium. The second adsorption tower 52 adsorbs the remaining cesium, strontium and other nuclides by the inorganic ion exchanger, and reduces the radioactivity. The third adsorption tower 53 adsorbs all ions with an ion exchange resin having a large adsorption capacity, thereby reducing the amount of secondary waste generated.

As shown in FIG. 3, the first adsorption system 5 </ b> A is a route through which three adsorption towers of a first adsorption tower 51, a second adsorption tower 52, and a third adsorption tower 53 are passed. The second adsorption system 5B is a route through which the two adsorption towers of the first adsorption tower 51 and the third adsorption tower 53 are passed. The third adsorption system 5C is a route through which the two adsorption towers of the first adsorption tower 51 and the second adsorption tower 52 are passed. The fourth adsorption system 5 </ b> D is a route through which the two adsorption towers of the second adsorption tower 52 and the third adsorption tower 53 are passed. The fifth adsorption system 5E is a route through which only the first adsorption tower 51 passes, the sixth adsorption system 5F through only the second adsorption tower 52, and the seventh adsorption system G through only the third adsorption tower 53.
By appropriately selecting these adsorption systems 5A to 5G, the salt concentration and the radiation dose in the first condensed water G1 can be reduced to the level of discharged water with the minimum amount of secondary waste generated.

Here, the determination method of the switching of the adsorption processing method based on the detection value of the first condensed water G1 detected by the measurement unit 54 will be described.
When the radiation amount of cesium or strontium is high and the electrical conductivity is high in the first condensed water G1, for example, the first adsorption system 5A is selected, and the first adsorption tower 51 adsorbs cesium or strontium having a high radiation dose. Then, what cannot be removed by the first adsorption tower 51 is removed by the inorganic ion exchanger of the second adsorption tower 52, and other miscellaneous radioactivity is removed by the ion exchange resin of the third adsorption tower 53. In this case, the generation amount of the waste ion exchange resin corresponding to the high level radioactive waste can be reduced. That is, since the ion-exchange resin has a high ion adsorption capacity, if the first condensed water G1 having a high radioactivity is directly input to the third adsorption tower 53, the radioactivity accumulated in the ion-exchange resin becomes high and disposal is difficult. Such waste. The amount of radioactivity accumulated in the ion exchange resin can be kept low by lowering the amount of radioactivity in the first condensed water G1 by passing the first adsorption tower 51 and the second adsorption tower 52 first.

Further, when the radiation amount of cesium or strontium is not high (higher than the level that can be discharged) and the electrical conductivity is low in the first condensed water G1, for example, the fourth adsorption system 5D or the seventh adsorption system 5G Select and remove all ions by adsorption.
Furthermore, when the radiation dose is high despite the low concentration of cesium and strontium, other nuclides are present, so that the adsorption system that does not pass through the first adsorption tower 51, that is, in FIG. The fourth adsorption system 5D and the sixth adsorption system 5F can be selected.
Furthermore, if there is no miscellaneous radioactivity in the first condensed water G1, for example, the third adsorption system 5C can be selected.

  Here, as a criterion for determining the first condensate G1 detected by the measurement unit 54, the cesium radiation concentration is set to, for example, 1 to 100 becquerels / ml or more, and the electric conductivity is, for example, 100 μSiemens / cm or less. To do.

  Moreover, since the radiation amount and electrical conductivity of the condensed water immediately before being introduced into the adsorption facility 3 can be detected by the measurement unit 54, a more appropriate and reliable adsorption treatment method can be selected. It is also possible to control the detection value of the measurement unit 54 in real time and automatically select the adsorption processing method based on the detection value.

Next, the operation of the radioactive liquid waste treatment apparatus 1 will be specifically described based on the drawings.
As shown in FIG. 1, in the radioactive liquid waste treatment apparatus 1 of the present embodiment, the first concentrated water N1 (high radiation, high salt concentration) and the first condensed water G1 (low radiation, low concentration) in the first evaporative concentration apparatus 2A. Salt concentration), and only the first condensed water G1 generated from the first evaporating and concentrating device 2A passes through the condensed water deriving channel 21 and is discharged to the outside as the first evaporating and concentrating device. The first radioactive water N1 having a low radioactive concentration and a low salt concentration evaporated by 2A is introduced into the second evaporation concentrator 2B. Then, in the second evaporative concentration apparatus 2B, the treated second condensed water G2 is not led out to the outside, but is introduced into the first evaporative concentration apparatus 2A via the condensed water recirculation path 22, and again the first evaporative concentration apparatus 2B. The second concentrated water N2 treated with 2A and further evaporated and concentrated can be disposed of as a concentrated waste liquid (secondary waste).
As described above, in the radioactive liquid waste treatment apparatus 1, since it is possible to concentrate at a high salt concentration and a high radiation dose in the evaporation concentration treatment compared to the reverse osmosis membrane treatment, the evaporation concentration portions 2 </ b> A and 2 </ b> B in a plurality of stages (two stages). As a result, it is possible to reduce the amount of concentrated waste liquid (second concentrated water N2) that is finally generated with high radioactivity and high salt concentration, and to reduce the volume.

Further, by providing the two-stage evaporative concentration apparatus 2A, 2B, the concentration rate of the evaporative concentration process in the first evaporative concentration apparatus 2A can be suppressed, and the first condensation derived from the first evaporative concentration apparatus 2A. It is possible to prevent impurities mixed with radioactivity from being mixed into the water G1. For example, by suppressing the concentration rate by the first evaporative concentration apparatus 2A to about 10 times, the concentration of impurities contained in the droplets at the time of evaporation can be suppressed to about 10 times. It can be kept low.
If radioactivity is mixed in the first condensate G1 generated in the first evaporative concentrator 2A, the first condensate G1 has a low radioactivity and a low salt concentration. After that, it can be discharged out of the system as effluent water, and the amount of adsorbent used for reducing to a level that can be discharged at this time can be reduced.

  Then, as shown in FIG. 3, in the adsorption facility 5, a suitable adsorption treatment method (first to seventh adsorption systems 5A to 5G) is selected according to the radiation amount and electric conductivity of the first condensed water G1. Since it becomes possible to process, the adsorbent to be used can be managed to the minimum necessary, and the secondary waste can be reduced. Further, depending on the water quality condition of the first condensed water G1, for example, the treatment cost can be reduced by positively treating the third condensed tower 53 that adsorbs using an inexpensive ion exchange resin.

  In the radioactive liquid waste treatment apparatus according to the first embodiment described above, by providing the two-stage evaporative concentration apparatus 2A, 2B, only the concentrated radioactive liquid with high radioactive and high salt concentration that is finally generated is obtained. Since the generated amount can be reduced, the volume of secondary waste can be reduced, and the cost for disposal can be reduced.

  Next, another embodiment of the radioactive liquid waste treatment apparatus of the present invention will be described with reference to the accompanying drawings. The same reference numerals are used for members and parts that are the same as or similar to those of the first embodiment described above. The description is omitted, and a configuration different from the embodiment will be described.

(Second Embodiment)
In the radioactive liquid waste treatment apparatus 1 according to the second embodiment shown in FIG. 4, the dechlorination apparatus 6 (desorption) is provided between the first evaporative concentration apparatus 2A and the second evaporative concentration apparatus 2B of the first embodiment described above. Chlorine part) is interposed to reduce the chloride ion concentration in the concentrated waste liquid. The dechlorination apparatus 6 removes chlorine ions from the high-concentration radioactive waste liquid concentrated by the first evaporative concentration unit 2A that evaporates and condenses the radioactive waste liquid W containing chlorine ions. The dechlorination apparatus 6 includes an electrolytic processing unit 61 that generates chlorine by electrolysis and removes it in the gas phase, and a precipitation processing unit 62 that generates a silver chloride precipitate and removes it as a solid phase. The chlorine ion removal process is performed in the order of an electrolysis process and a precipitation process.

In the electrolytic treatment unit 61, chlorine is generated by electrolysis and removed in the gas phase by supplying a pH adjuster to the first concentrated water N <b> 1 output from the first evaporative concentration 2 </ b> A. The generated chlorine ions (chlorine gas) are recovered by the chlorine gas recovery unit 60 shown in FIG. 5 and absorbed by an alkaline material such as sodium hydroxide (NaOH) to be rendered harmless.
In the precipitation processing unit 62, silver nitrate or silver sulfate is supplied and reacted with the concentrated water from which the chlorine ions have been removed by the electrolytic processing unit 61 by a precipitation method, thereby generating a silver chloride precipitate and removing it as a solid phase. To do.

In the present dechlorination apparatus 6, chlorine ions in the first concentrated water N1 are discharged as chlorine gas to the outside of the system (outside the radioactive waste liquid treatment apparatus 1) by electrolysis in the electrolytic treatment unit 61. Chlorine ion concentration can be lowered. Moreover, in the precipitation process part 62, since the solubility of silver chloride is very low, it can reduce to the chloride ion density | concentration of several mg / L.
In general, the electrolytic method requires a chlorine concentration of about 5000 ppm or more as a condition for effective electrolysis. On the other hand, in the second embodiment, the first concentrated water N1 is evaporated and concentrated, and the chlorine concentration of the first concentrated water N1 can be increased to 5000 ppm or more. On the other hand, a step of efficiently reducing chlorine ions can be performed by an electrolytic method. As a result, the chlorine ion concentration in the concentrated waste liquid can be lowered, the durability of the material due to corrosion can be increased, and the expensive material (metal) used in the equipment can be reduced. Secondary waste can be stored for a long period of time, and overall processing costs can be reduced.

(Third embodiment)
As shown in FIG. 6, the radioactive liquid waste treatment apparatus 1 according to the third embodiment regenerates silver chloride generated in the precipitation treatment unit 62 with ammonia or the like in the dechlorination apparatus 6 of the second embodiment described above. After dissolution, a silver recovery part 63 that recovers silver by electrolytic treatment is provided, and chloride ions are removed by electrolytic treatment of the silver recovery part 63. Chlorine gas generated in the silver recovery unit 63 is detoxified in the chlorine recovery unit 60. And in the silver collection | recovery part 63, after re-dissolving the silver precipitated by electrolysis in nitric acid etc., it sends to a precipitation process and is reused.

In the third embodiment, by recovering and reusing expensive silver, the amount of chemicals such as silver nitrate can be reduced, and the running cost can be reduced.
And what is generated with this dechlorination apparatus 6 is only chlorine gas, and since it can discharge | release outside the system after collection | recovery, there exists an advantage that a new secondary waste does not generate | occur | produce.
Moreover, since the chlorine gas generated in the silver recovery unit 63 can be processed in the existing chlorine recovery process, there is an advantage that additional equipment for chlorination becomes unnecessary.

(Fourth embodiment)
The fourth embodiment shown in FIG. 7 has a configuration in which a cation exchange membrane 65 is attached inside the electrolytic treatment section 61 of the dechlorination apparatus 6 of the third embodiment described above.
In this case, by introducing the first concentrated water N1 generated from the first evaporative concentration device 2A to the anode 65a side of the cation exchange membrane 65, the chlorine ions in the first concentrated water N1 are removed as chlorine gas and remain. The cation mainly composed of sodium (Na +) passes through the cation exchange membrane 65 and moves to the cathode 65b side. At this time, since metal ions decrease on the anode 65a side, an increase in the pH of the first concentrated water N1 is suppressed, so that the amount of pH adjusting agent (acid) added can be reduced. In the cathode 65b, water is decomposed to generate hydrogen, and hydroxide ions (OH-) remain. Further, sodium hydroxide (NaOH) water is generated at the cathode 65b from sodium (Na +) that has passed through the cation exchange membrane 65 and hydroxide ions (OH−) generated by electrolysis.

Thus, in the fourth embodiment, the NaOH water generated at the cathode 65b can be used as NaOH in the chlorine recovery unit 60, and the sodium hydroxide reagent used in the chlorine recovery unit 60 (see FIG. 6). The amount added can be reduced.
Moreover, since the cation concentration of sodium (Na +) of the electrolytic treatment liquid discharged toward the precipitation treatment unit 62 is reduced, the final disposal amount of the waste liquid can be reduced.

  In the fourth embodiment, a sodium permselective ion exchange membrane may be provided instead of the cation exchange membrane 65. Also in this case, chlorine ions in the first concentrated water N1 are removed as chlorine gas, and Na + selectively passes through a sodium selective permeable ion exchange membrane among the remaining cations mainly composed of sodium (Na +). And move to the cathode side. At this time, since metal ions decrease on the anode 65a side, an increase in the pH of the first concentrated water N1 is suppressed, so that the amount of pH adjusting agent (acid) added can be reduced. Since Na + ions decrease on the anode side, the increase in the liquid pH is suppressed.

  In this case, the same operation and effect as in the fourth embodiment can be obtained, and only Na + can be transmitted from the anode, so that radioactive substances (cations such as cesium Cs and strontium Sr) can flow out to the cathode side. Can be suppressed. And the cathode side liquid can maintain the amount of radioactivity low.

(Fifth embodiment)
In the radioactive liquid waste treatment apparatus 1 according to the fifth embodiment shown in FIG. 8, the cesium adsorption tower 7 (and between the first evaporative concentration apparatus 2A and the second evaporative concentration apparatus 2B of the first embodiment described above). (Or strontium adsorption tower).
In this case, the radiation concentration of the radioactive waste liquid is reduced by lowering the radiation dose in the cesium adsorption tower 7 with respect to the first concentrated water N1 discharged from the first evaporative concentration apparatus 2A and then further evaporating and concentrating with the second evaporative concentration apparatus 2B. The salt concentration can be concentrated while the amount remains below a certain level. That is, since the first concentrated water N1 having a high concentration rate that has passed through the first evaporative concentration apparatus 2A has an increased chloride ion concentration, the chloride ion in the dechlorination apparatus 6 of the second to fourth embodiments described above. The removal rate can be improved.
Moreover, since more chloride ions are removed by electrolytic treatment, the amount of silver (silver nitrate or the like) used in the precipitation treatment of the second to fourth embodiments can be reduced.

As mentioned above, although embodiment of the radioactive waste liquid processing apparatus by this invention was described, this invention is not limited to said embodiment, In the range which does not deviate from the meaning, it can change suitably.
For example, in the present embodiment, the number of stages of the evaporation concentrators 2A and 2B is two, but the number is not limited to this number, and a configuration in which three or more stages are provided is also possible. In the case of providing three or more stages of the evaporative concentrator, the condensed water reflux path 22 of the second and subsequent stages of the evaporative concentrator 2 is connected to the first evaporative concentrator 2A in the foremost stage, You may make it return to 1A evaporative concentration apparatus 2A, and you may make it return the condensed water recirculation path 22 of the evaporative concentration apparatus 2 of the 2nd stage or later to the evaporative concentration apparatus of the 1st previous stage.

  Moreover, although the dechlorination apparatus 6 by 2nd-4th embodiment mentioned above is provided between the 1st stage | paragraph and the 2nd stage | paragraph evaporative concentration apparatus 2A, 2B, the position is not limited. . For example, in the case where three or more multi-stage evaporative concentration apparatuses 2 are provided, the dechlorination apparatus 6 can be disposed between, for example, the second and third evaporative concentration apparatuses.

  Further, the evaporation concentrating device is not limited to the vacuum vapor compression type, and may be a decompression type or a scooping type concentrating device.

  In the present embodiment, the dechlorination device 6 includes an electrolytic treatment unit 61 and a precipitation treatment unit 62, but is not limited thereto, and only one of the electrolytic treatment unit 61 and the precipitation treatment unit 62 is used. It may be configured to.

  In the fifth embodiment, the cesium adsorption tower is provided after the first evaporative concentration apparatus 2A. However, the present invention is not limited to this position. For example, the cesium adsorption tower 7 (and / or the strontium adsorption tower) is installed in the front stage of the first evaporative concentration apparatus 2A to reduce the radiation dose, and then evaporate and concentrate to maintain the radioactivity level of the condensed water. , Can increase the concentration rate. And if the concentration rate increases, the recovery rate of treated water also increases, so the amount of concentrated waste liquid can be reduced.

  In addition, it is possible to appropriately replace the constituent elements in the above-described embodiments with well-known constituent elements without departing from the spirit of the present invention, and the above-described embodiments may be appropriately combined.

1 Radioactive waste liquid treatment device 2 Evaporation concentration device (evaporation concentration unit)
2A 1st evaporation concentration apparatus (evaporation concentration part)
2B 1st evaporation concentration apparatus (evaporation concentration part)
3 Oil removal equipment 4 Filtration equipment 5 Adsorption equipment 5A-5G 1st-7th adsorption system 6 Dechlorination equipment (dechlorination part)
7 Cesium adsorption tower 21 Condensed water outlet path 22 Condensed water reflux path 23 First water path 24 Second water path 51 First adsorption tower (first adsorption section)
52 2nd adsorption tower (2nd adsorption part)
53 3rd adsorption tower (3rd adsorption part)
54 Measuring unit 54
55, 56, 57 Switching valve 60 Chlorine recovery unit 61 Electrolytic processing unit 62 Precipitation processing unit 63 Silver recovery unit 65 Cation exchange membrane

Claims (8)

A radioactive waste liquid treatment apparatus comprising a plurality of stages of evaporation and concentration units for sequentially evaporating and condensing radioactive waste liquid,
A condensed water lead-out path for guiding condensed water generated from the evaporating and concentrating part at the front stage to the outside;
A condensed water reflux path for introducing condensed water generated from the evaporative concentration unit other than the evaporative concentration unit in the front stage to the evaporative concentration unit upstream of the evaporative concentration unit;
A radioactive liquid waste treatment apparatus comprising:   The radioactive liquid waste treatment apparatus according to claim 1, wherein the condensed water recirculation path is introduced into the evaporating and concentrating unit preceding one stage. The condensed water lead-out path has a first adsorption part that adsorbs cesium and strontium, a second adsorption part that adsorbs using an inorganic ion exchanger, and a third adsorption part that adsorbs using an ion exchange resin. Adsorption equipment is provided,
Selectively switching a plurality of adsorption processing methods for passing an appropriate adsorption tower among the first adsorption unit, the second adsorption unit, and the third adsorption unit according to the radiation amount and electric conductivity of the condensed water. The radioactive liquid waste treatment apparatus according to claim 1 or 2, characterized by the above.   The radioactive waste liquid treatment apparatus according to claim 3, wherein a measurement unit that detects the radiation dose and electrical conductivity is provided at an entrance of the adsorption facility.   The radioactive waste liquid treatment apparatus according to any one of claims 1 to 4, wherein an adsorption tower for adsorbing a radioactive substance is provided on a rear stage side of the evaporative concentration unit.   The dechlorination part which removes a chlorine ion from the high concentration radioactive waste liquid concentrated by this evaporation concentration part is provided in the back | latter stage side of the said evaporation concentration part, The any one of Claim 1 thru | or 5 characterized by the above-mentioned. The radioactive waste liquid processing apparatus as described in the paragraph. The dechlorination part is
An electrolytic treatment section for generating chlorine by electrolysis and removing it in the gas phase;
A precipitation processing section for generating a silver chloride precipitate and removing it as a solid phase;
It has at least one of these, The radioactive waste liquid processing apparatus of Claim 6 characterized by the above-mentioned.   8. The radioactive liquid waste treatment apparatus according to claim 7, wherein the electrolytic treatment unit is provided with a cation exchange membrane or a sodium permselective ion exchange membrane.

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