JP6319622B2 - Fly ash cleaning device and fly ash cleaning method - Google Patents

Description

  The present invention relates to a fly ash cleaning apparatus and a fly ash cleaning method for cleaning fly ash generated when a waste contaminated with a radioactive substance is incinerated.

  The fly ash generated when incinerating waste contaminated with radioactive substances (such as radioactive cesium) contains the radioactive substances. If the fly ash containing the radioactive material is in a low pollution state below the specified value, it can be landfilled at an existing final disposal site. It cannot be landfilled directly at the final disposal site, and fly ash is solidified in cement or contained in a container to prevent radioactive substances from eluting, and then landfilled at a managed landfill site. ing.

  However, in reality, disposal to prevent elution has not progressed, and fly ash containing radioactive materials has been stored without being disposed of, resulting in a huge amount (volume). . Therefore, in order to make it possible to landfill fly ash containing radioactive substances in an existing final disposal site, for example, as in Non-Patent Document 1, fly ash is brought to a level that allows landfill disposal at the final disposal site. Techniques for cleaning and decontamination so as to reduce the concentration of radioactive substances are being studied.

  FIG. 3 shows an outline of the configuration of the fly ash cleaning apparatus for performing the fly ash cleaning described in Non-Patent Document 1. As shown in FIG. 3, this fly ash cleaning apparatus is connected to a cleaning apparatus 11 that generates fly ash slurry by cleaning fly ash containing radioactive substances (such as cesium) with cleaning water. The slurry is dehydrated and the radioactive substance contained in the interstitial water between the fly ash particles is dissolved in the rinsing water and transferred to the dehydration rinsing apparatus 12, the washing apparatus 11 and the dehydration rinsing apparatus 12, and the washing apparatus 11, an adsorbing device 13 that adsorbs and removes radioactive substances contained in the washing drain from 11 and the rinse drain from the dehydrating rinse device 12 by an adsorbent, and is included in the adsorbed water from the adsorbing device 13 connected to the adsorbing device 13. And a solidification processing device 14 for solidifying the radioactive substance.

  The solidification processing device 14 has a reverse osmosis membrane processing device 15 to be described later, and the solidified water separated from the radioactive substance by the reverse osmosis membrane processing device 15 is returned for use as washing water and rinsing water. . Specifically, the solidified water is supplied to the cleaning device 11 as cleaning water together with makeup water from the outside, and is supplied to the dehydration rinsing device 12 as rinsing water.

  The cleaning device 11 has a cleaning tank (not shown) that receives and stores fly ash and receives injection of cleaning water for cleaning the fly ash. The radioactive material contained is dissolved in the washing water and the fly ash slurry is generated.

  The dehydration rinsing apparatus 12 has a dehydrator (not shown) such as a belt filter and a filter press for dehydrating the slurry. When the dehydration rinsing device 12 receives the slurry from the cleaning device 11 and dehydrates the slurry with the dehydrator, the dehydrator sprays the rinsing water into the slurry, and the radioactive water contained in the interstitial water between the fly ash particles of the slurry. The substance is dissolved and transferred in rinsing water.

  The adsorption device 13 is filled with an adsorbent for adsorbing a radioactive substance, receives the washing waste water from the washing device 11 and the rinse waste water from the dehydrating rinse device 12, and is included in the washing waste water and the rinse waste water. The radioactive substance is adsorbed and removed by the adsorbent.

  The solidification processing device 14 uses the reverse osmosis membrane (the reverse osmosis membrane (the radioactive material contained in the washing waste water and the rinse waste water in which the radioactive material is adsorbed by the adsorption device 13 and the concentration of the radioactive material is reduced). RO membrane (not shown) for separating and removing radioactive substances by a radioactive osmosis membrane treatment device 15 and a heater (not shown) for concentrated water containing the radioactive material separated and removed by the reverse osmosis membrane treatment device 15 And an evaporative solidification processing device 16 for evaporating moisture and solidifying the radioactive substance.

  Further, as shown in FIG. 3, the transfer pipe for transferring the waste water (solidified water) that has been subjected to the reverse osmosis membrane treatment of the reverse osmosis membrane treatment device 15 and discharged to the outside of the solidification treatment device 14 is made up of makeup water. Connected to the supply pipe. As a result, the returned solidified water is replenished with replenishing water and supplied to the cleaning device 11 or the dehydration rinsing device 12 as cleaning water or rinsing water, respectively.

  The fly ash is processed in the following manner by the fly ash cleaning apparatus having such a configuration. First, fly ash containing a radioactive substance is supplied to the cleaning tank of the cleaning device 11 and cleaning water is injected. In the above washing tank, the fly ash is immersed in the wash water with the liquid-solid ratio of the wash water and fly ash being about 3 to 5 to produce a slurry of the fly ash, A radioactive substance is dissolved in the washing water from the fly ash. The radioactive water is contained in the pore water between the fly ash particles of the slurry thus generated.

  The slurry generated by the cleaning device 11 is sent to the dehydration rinse device 12 and dehydrated by the dehydrator. During the dehydration treatment, the rinsing water is sprinkled into the slurry, and the radioactive substances contained in the interstitial water between the fly ash particles of the slurry dissolve in the rinsing water and migrate. The fly ash (dehydrated ash) after the slurry is dehydrated has a sufficiently reduced concentration of radioactive material, and is landfilled at an existing landfill site.

  The washing waste water from the washing device 11 and the rinse waste water from the dehydration rinsing device 12 are sent to the adsorption device 13, and the radioactive substances contained in the washing waste water and the rinse waste water are adsorbed and removed by the adsorbent. Waste water from the adsorber 13, that is, the adsorbed treated water in which the concentration of radioactive substances is reduced, is sent to the solidification treatment device 14 and included in the adsorbed treated water by the reverse osmosis membrane treatment device 15 of the solidification treatment device 14. Radioactive material is separated. The concentrated water containing the separated radioactive substance is heated by the evaporative solidification processing device 16, and as a result, the water is evaporated and the radioactive substance is solidified. The solidified product is concentrated and reduced in volume compared to the original fly ash and stored in a container.

  On the other hand, the wastewater from which the reverse osmosis membrane treatment device 15 has been subjected to the reverse osmosis membrane treatment and from which the radioactive substances have been separated and removed is discharged from the solidification treatment device 14 as solidified treatment water. This solidified treated water is sufficiently free of radioactive materials to the extent that it can be used as washing water or rinsing water, and is returned as shown in FIG. 3 to be used as washing water or rinsing water along with makeup water. 11 or dehydration rinsing apparatus 12.

“Study on cleaning and separation of cesium in fly ash”, Proceedings of the 23rd Annual Meeting of the Waste Recycling Society of Japan Waste Resource Recycling Society October 22, 2012, E2-2, p.573

  In Non-Patent Document 1, as described above, the dehydration rinsing device 12 sprinkles rinsing water in order to remove radioactive substances contained in the interstitial water between the fly ash particles when dehydrating the fly ash slurry. While dehydrating. However, a large amount of rinsing water is required to sufficiently reduce the residual concentration of radioactive substances in dehydrated ash (dehydrated fly ash) by rinsing, and the amount of rinsing waste water from the dewatering rinsing device 12 correspondingly. Will also be large. Further, in Non-Patent Document 1, in order to reuse the cleaning waste water from the cleaning device 11 and the rinse waste water from the dehydrating rinse device 12 as cleaning water and rinsing water, the concentration of radioactive substances in the cleaning waste water and the rinse waste water should be reduced. The radioactive substances contained in the washing waste water and the rinse waste water are removed by adsorption treatment or reverse osmosis membrane treatment. However, as described above, as a result of an increase in the amount of rinse drainage, it is necessary to increase the scales of the adsorption device 13 and the reverse osmosis membrane treatment device 15, and there is a problem that equipment costs and operating costs increase.

  In view of such circumstances, it is an object of the present invention to provide a fly ash cleaning apparatus and a fly ash cleaning method that can efficiently remove radioactive substances from fly ash while keeping facility costs and operation costs low.

<First invention>
The fly ash cleaning apparatus according to the first invention cleans the fly ash generated when the waste contaminated with the radioactive material is incinerated.

  In such a fly ash cleaning apparatus, in the first invention, the fly ash containing a radioactive substance is accommodated and a cleaning tank that receives cleaning water, a coagulant, and a flocculant is contained. The radioactive material in the fly ash is washed and dissolved in the wash water, and the fly ash suspended or suspended in the wash water is condensed by a coagulant, and the condensed fly ash is aggregated by a flocculant to settle ash And a washing device that settles in the lower part of the tank, drains the supernatant in which the radioactive substance is dissolved, and discharges the settled ash, and receives the supernatant from the washing device, and the flying liquid contained in the supernatant. The ash is captured and removed by a filter medium, and the supernatant from which the fly ash has been removed is drained as filtered water, and the captured fly ash is discharged as a filtration residue, and the filtration from the filter Radioactive substances contained in treated water Adsorbed and removed by an adsorbent packed bed that adsorbs, or supplies the separation and removal agent and flocculant to separate and remove the separation / removal agent particles that have adsorbed the radioactive material by coagulation / precipitation separation, and Included in the dewatered water, a removal device that drains as treated water, a dewatering device that receives the precipitated ash from the cleaning device and dehydrates the precipitated ash, and receives the dewatered water from the dewatering device And a solidification processing device for solidifying the radioactive substance.

  In the fly ash washing apparatus according to the first invention, the supernatant produced by the washing apparatus has a high concentration of radioactive substances and contains fly ash that has not settled and is sent to the filtration apparatus. It is done. And, the fly ash contained in the supernatant is captured and removed by the filtration device and sent to the removal device as filtered water, and the radioactive material is efficiently removed by the removal device. .

  In the cleaning device, a large amount of rinsing water is not sprinkled as in the conventional dehydration rinsing device, but it is only necessary to supply an amount of cleaning water that can float or suspend fly ash in the cleaning tank. That is, in the first invention, the amount of washing water used for washing fly ash is smaller than the amount of rinsing water that has been conventionally required. Accordingly, the amount of filtered water to be removed by the removal device is reduced accordingly, so that the scale of the removal device can be reduced, and the equipment cost and operation cost of the removal device can be suppressed.

  In the first invention, the dehydration apparatus does not receive the rinsing water supply as in the prior art when dewatering the settled ash. Therefore, the dewatered water discharged from the dewatering device is only the water contained in the settled ash, and is a small amount compared to the conventional case where the rinsing water is sprinkled with the dewatering rinsing device. As a result, the amount of dewatered water to be solidified by the solidification processing device is also reduced accordingly, so the scale of the solidification processing device can be reduced, and the equipment cost and operating cost of the solidification processing device can be suppressed. it can.

  Furthermore, using a coagulant and a flocculant with a washing device, the fly ash suspended or suspended in the wash water is condensed and agglomerated to settle as precipitated ash. While it is necessary to leave it for a period of time, the precipitated ash can be settled in a short time, and the working time required for the fly ash cleaning can be greatly shortened.

  Further, since the fly ash is condensed, aggregated and settled by the coagulant and the flocculant in the washing device, the fly ash can be sufficiently separated from the supernatant as the precipitated ash. Accordingly, since the fly ash floating or suspended in the supernatant is reduced by that amount, the filter medium of the filter device is not easily clogged when the fly ash is filtered by the filter device. Moreover, since the frequency which performs the operation | work which removes the fly ash clogged with the filter medium can be decreased, the operation efficiency of the whole fly ash washing | cleaning apparatus can be improved.

  In the first invention, the cleaning device has a stirrer for stirring the inside of the cleaning tank, and the fly ash cleaning device is a measuring means for measuring the radioactive concentration of the removal treated water from the removing device or the concentration of the radioactive substance. And the agitator is controlled so that the agitator agitates the inside of the washing tank when the change rate with time of the radioactive concentration or the concentration of the radioactive substance measured by the measuring means is smaller than a predetermined change rate with time. You may have a stirring control apparatus.

  In such a configuration, when the rate of change with time of the concentration of radioactive water or the concentration of radioactive material removed from the removal device becomes smaller than the predetermined rate of change with time, in other words, it is contained in the supernatant. When it can be determined that some of the radioactive material has been removed, the inside of the washing tank is stirred with a stirrer, and the precipitated ash is dispersed or suspended in the supernatant. As a result, the transfer (dissolution) of the radioactive substance remaining in the water in the gap between the settled ash is promoted, so that the amount of the radioactive substance contained in the water in the gap between the settled ash is reduced. . Accordingly, since the amount of radioactive material contained in the dewatered water discharged from the dewatering device that dehydrates the settled ash can be reduced, the scale of the solidifying device can be reduced, and the equipment cost and operation of the solidifying device can be reduced. Costs can be reduced.

  In the first invention, the solidification processing device separates and removes the radioactive material contained in the dehydrated water from the dehydration processing device with a reverse osmosis membrane, and drains the dehydrated water from which the radioactive material has been removed as membrane treated water. A membrane treatment device, and an evaporative solidification treatment device that evaporates the water of the concentrated water containing the radioactive material separated and removed by the reverse osmosis membrane treatment device to solidify the radioactive material, and the cleaning device removes from the removal device The treatment water and the membrane treatment water from the reverse osmosis membrane treatment apparatus may be received in the washing tank as washing water together with makeup water supplied from the outside.

  In such a configuration, the removal treated water from the removal device and the membrane treated water from the reverse osmosis membrane treatment device are returned to the washing tank of the washing device and reused as washing water. Since this removal treatment water and membrane treatment water can cover the washing water, only a small amount of replenishing water is newly supplied to the washing tank from the outside, and the fly ash can be efficiently washed with the washing water. .

<Second invention>
The fly ash cleaning method according to the second invention cleans fly ash generated when incinerated waste contaminated with radioactive substances.

  In such a fly ash cleaning method, in the second invention, the fly ash containing a radioactive substance is accommodated in a washing tank, and the fly ash is washed in the washing tank with washing water to wash the radioactive substance in the fly ash. In addition to being dissolved in water, the fly ash suspended or suspended in the wash water is condensed with a coagulant, and the condensed fly ash is aggregated with the coagulant and settled to the bottom of the tank as precipitated ash, so that the radioactive substance is dissolved. The washing step of draining the supernatant liquid that is discharged and discharging the precipitated ash, and the fly ash contained in the supernatant liquid drained in the washing step is captured and removed with a filter medium, The removed supernatant is drained as filtered water, and a filtration process for discharging the fly ash as a filtration residue, and a radioactive substance contained in the filtered water drained in the filtration process are adsorbed to the radioactive substance. Adsorbed and removed by adsorbent packed bed Alternatively, the separation and removal agent and the flocculant are supplied and the separation / removal agent particles adsorbed with the radioactive substance are removed by agglomeration and precipitation, and the filtered treated water from which the radioactive substance has been removed is drained as removed treated water, and A dehydration process for dehydrating the sedimented ash discharged in the washing process and a solidification process for solidifying the radioactive material contained in the dewatered water drained in the dehydration process are provided.

  In the second invention, the stirring step of stirring the inside of the washing tank with a stirrer, the measurement step of measuring the radioactive concentration or concentration of the radioactive substance of the removal treated water drained in the removal step, and the above measurement step A stirring control step of controlling the stirrer so that the stirrer stirs the inside of the washing tank when the change rate with time of the radioactive concentration or the concentration of the radioactive substance is smaller than a predetermined change rate with time. Also good.

  In the second invention, the solidification treatment step separates and removes the radioactive substances contained in the dehydrated water drained in the dehydration treatment step with a reverse osmosis membrane, and drains the dehydrated water from which the radioactive substances have been removed as membrane treated water. A reverse osmosis membrane treatment step, and an evaporation and solidification treatment step for evaporating the water of the concentrated water containing the radioactive material separated and removed in the reverse osmosis membrane treatment step to solidify the radioactive material. The removal treated water drained in step 1 and the membrane treated water drained in the reverse osmosis membrane treatment step may be received in a washing tank as washing water together with makeup water supplied from the outside.

  As described above, in the present invention, the supernatant liquid generated by the cleaning apparatus has a high concentration of radioactive substances and contains fly ash that has not settled. In the supernatant, fly ash contained in the supernatant is captured and removed by a filter medium, and is sent to a removal device as filtered water. In the removing device, the radioactive substance contained in the filtered water is efficiently removed by removing the radioactive substance from the filtered water by the adsorption process using the adsorbent or the coagulating sediment separation using the separating and removing agent and the coagulant. In addition, the filtered treated water from which radioactive materials have been removed is drained as removed treated water and returned to the washing tank of the washing device as washing water, so that the supply of external makeup water is reduced as much as possible to wash fly ash. be able to. In addition, the amount of washing water used for washing fly ash is small compared to the amount of rinsing water conventionally required, and the amount of filtered water removed by the removal device is reduced. The scale of the removal device can be reduced, and the equipment cost and operation cost of the removal device can be suppressed.

  Further, the dehydration apparatus does not receive rinsing water when dewatering the settled ash. Therefore, the dewatered water discharged from the dewatering apparatus is only the water contained in the settled ash, which is a small amount compared to the conventional case where the rinsing water is sprayed. As a result, the amount of dewatered water to be solidified by the solidification processing apparatus is also reduced accordingly, so that the scale of the solidification processing apparatus can be reduced. Accordingly, it is possible to reduce the equipment cost and operation cost of the solidification processing apparatus.

  Furthermore, since the fly ash suspended or suspended in the wash water is condensed and aggregated using the coagulant and coagulant in the cleaning device and settled as precipitated ash, the precipitated ash can be settled in a short time. The work time required for fly ash cleaning can be greatly reduced. In addition, by using a coagulant and a flocculant in the washing device, the precipitated ash and the supernatant can be sufficiently separated, and the amount of fly ash floating or suspended in the supernatant can be reduced. When the ash is filtered by the filtering device, the filter medium of the filtering device is not easily clogged. Moreover, since the frequency which performs the operation | work which removes the fly ash clogged with the filter medium can be decreased, the operation efficiency of the whole fly ash washing | cleaning apparatus can be improved.

It is a schematic block diagram which shows the fly ash washing apparatus which concerns on embodiment of this invention. It is a graph which shows the time-dependent change of the radioactive density | concentration of the adsorption process water from an adsorption | suction apparatus. It is a schematic block diagram which shows the conventional fly ash washing | cleaning apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing a fly ash cleaning apparatus according to an embodiment of the present invention. The fly ash cleaning apparatus according to this embodiment is configured to reduce the concentration of the radioactive substance in the fly ash containing radioactive substances (cesium, etc.) to such an extent that it can be disposed at an existing landfill site. Wash the ash. The radioactive material in the waste water containing high concentration of the washed radioactive material is adsorbed and removed by the adsorbent, and the radioactive material in the waste water from which the washed fly ash has been dehydrated is concentrated by reverse osmosis membrane treatment. Store the solidified product containing radioactive material after moisture solidification.

  As seen in FIG. 1, the fly ash cleaning device is connected to the cleaning device 1 for cleaning fly ash containing radioactive substances with cleaning water and separating it into supernatant and precipitated ash, and the cleaning device 1. A filtration device 2 that receives the supernatant from the cleaning device 1 and captures and removes fly ash contained in the supernatant by a filter medium, and adsorbs radioactive substances contained in the filtered water from the filtration device 2 An adsorbing device 3 as a removing device that adsorbs and removes with an agent, a dehydration processing device 4 that dehydrates the precipitated ash from the cleaning device 1, and a solidification that solidifies a radioactive substance contained in the dehydrated water from the dehydration processing device 4. And a processing device 5. In addition, the fly ash cleaning device corresponds to a radioactivity concentration meter 9 that measures the radioactivity concentration of the adsorbed treated water from the adsorption device 3 and a rate of change with time of the radioactivity concentration measured by the radioactivity concentration meter 9. And a stirring control device 10 for controlling the operation of a stirrer 1B described later provided in the cleaning device 1.

  The cleaning apparatus 1 includes a cleaning tank 1A that receives and contains fly ash containing radioactive substances and receives cleaning water, a coagulant, and a flocculant, and a stirrer 1B for stirring the inside of the cleaning tank 1A. The cleaning device 1 cleans fly ash in the cleaning tank 1A with cleaning water, dissolves most of the radioactive substances in the fly ash in the cleaning water, and condenses fly ash suspended or suspended in the cleaning water. The agglomerates are aggregated by a flocculant, and the aggregates of the condensed fly ash are agglomerated by a flocculant to form flock ash, which is settled in the lower part of the tank as precipitated ash. As a result, in the washing tank 1A, the settled ash forms a slurry and forms a lower layer, and the wash water in which the radioactive substance is dissolved forms an upper layer as a supernatant. The supernatant is drained from the washing tank 1A and sent to the filtration device 2, and the settled ash is discharged from the bottom of the tank and sent to the dehydration processing device 4.

  In the present embodiment, for example, an inorganic coagulant such as polyaluminum chloride (PAC), iron chloride or a sulfuric acid band is used as the coagulant. As the coagulant, for example, an anionic polymer coagulant (acrylamide / acrylic acid), Polymer flocculants such as nonionic polymer flocculants are used.

  In the present embodiment, when the fly ash is naturally settled by using the coagulant and the flocculant, the fly ash suspended or suspended in the wash water is condensed and aggregated to settle as the precipitated ash. While it is necessary to stand for a long time, the fly ash can be settled in a short time, and the working time required for the fly ash cleaning can be greatly shortened.

  The stirrer 1B is suspended in the cleaning tank, and the inside of the cleaning tank 1A is stirred by a stirring blade provided at the lower end. When the agitator 1B agitates the inside of the washing tank 1A, the transfer (dissolution) of the radioactive substance contained in the fly ash to the washing water is promoted. As will be described later, when the stirrer 1B stirs the cleaning tank 1A after the supernatant liquid layer (upper layer) and the precipitated ash layer (lower layer) are formed in the cleaning tank 1A, the precipitated ash is It is dispersed or suspended or suspended in the liquid, and the transfer (dissolution) of the radioactive material remaining in the water in the gap between the precipitated ash to the supernatant is promoted. As will be described later, the operation of the stirrer 1B is controlled by the stirring control device 10.

  A washing water supply pipe 8 is connected to the washing tank 1 </ b> A of the washing apparatus 1, and washing water is supplied from the washing water supply pipe 8. In the present embodiment, the cleaning water is supplied by adsorption treatment water as removal treatment water from the adsorption device 3, membrane treatment water described later from the solidification treatment device 5, and further by adsorption treatment water and membrane treatment water. Replenishment water replenished from the outside by an amount that compensates for a deficiency with respect to the amount of water (for example, the amount evaporated by the evaporative solidification processing device 7 described later) is supplied to the cleaning tank 1A through the cleaning water supply pipe 8.

  The filtration device 2 is connected to the upper portion of the cleaning tank 1A of the cleaning device 1 via a pipe, and receives the supernatant liquid drained from the cleaning tank 1A. The filtration device 2 has a filter medium (not shown) for capturing fly ash (fly ash particles and small aggregates of the fly ash particles) mixed in the supernatant. The filter medium is constituted by, for example, a filter cloth filter. The filter cloth filter preferably has a mesh size of 0.1 to 100 μm and is made of plastic such as polypropylene. The filtration device 2 has a blocking prevention mechanism (not shown) that prevents blocking by fly ash adhering to the filter medium. The blocking prevention mechanism includes, for example, a backwashing mechanism that removes fly ash adhering to the filter medium by flowing back the filtered water that has passed through the filter medium, a mechanism that applies mechanical vibration to the filter medium, Further, it can be configured by a mechanism that blows compressed air to give vibration to the filter medium to remove fly ash. The supernatant liquid from which fly ash has been removed by the filter medium is drained as filtered water.

  Moreover, in this embodiment, the fly ash which is the filtration residue captured and removed by the filtration device 2 is returned to the supernatant liquid in the washing tank 1A together with the supernatant liquid backflowed by the backwashing mechanism. Yes. The returned fly ash is washed again in the washing tank 1A, condensates and aggregates, and settles in the lower part of the tank as precipitated ash. Thus, the structure which returns a filtration residue to a supernatant liquid can further remove the radioactive substance which remains in a filtration residue.

  Moreover, in this embodiment, since fly ash is condensed and aggregated with a coagulant and a flocculant, it settles, and it can fully isolate | separate with a supernatant liquid as a fly ash. Accordingly, since the fly ash floating or suspended in the supernatant is reduced by that amount, when the fly ash is filtered by the filter device 2, the filter medium of the filter device 2 is hardly clogged. Moreover, since the frequency which performs the operation | work which removes the fly ash clogged with the filter medium can be decreased, the operation efficiency of the whole fly ash washing | cleaning apparatus can be improved.

  The adsorption device 3 is connected to the filtration device 2 and receives the filtered water from the filtration device 2. The adsorbing device 3 has a packed bed filled with an adsorbent for adsorbing the radioactive substance, and the radioactive substance contained in the filtered water is adsorbed and removed by the adsorbent. In the present embodiment, for example, zeolite or the like is used as the adsorbent. Further, the adsorption device 3 is connected to the above-described washing water supply pipe 8, and the adsorption treated water discharged from the adsorption device 3 is sent to the washing water supply pipe 8. As shown in FIG. 1, in the pipe connecting the adsorbing device 3 and the washing water supply pipe 8, the radioactivity concentration of the adsorbed treated water from the adsorbing device 3 is measured at a position near the drain outlet of the adsorbing device 3. A radioactive densitometer 9 is provided.

  In the present embodiment, the adsorption device 3 described above is provided as a removal device for removing radioactive substances contained in the filtered water, but instead, it is included in the filtered water as the removal device. You may provide the coagulation sedimentation separation apparatus which removes a radioactive substance by coagulation sedimentation separation. The coagulation sedimentation separation apparatus has a coagulation sedimentation tank that receives the injection of filtered treated water, adds separation / removal agent particles to the filtration treated water, adsorbs radioactive substances to the separation / removal agent particles, and further adds a coagulant. It is added to agglomerate and settle the suspended separation and removal agent particles, and the radioactive material is removed by extracting the precipitate. As the separation and removal agent particles, for example, ferrocyanide complex salts such as nickel ferrocyanide complex and Prussian blue (iron ferrocyanide complex) are used, and as the flocculant, for example, ferric sulfate is used. Etc. are used.

  The dehydration processing device 4 is connected to the lower portion of the cleaning tank 1A of the cleaning device 1 and the filtration device 2 via pipes, and receives sedimented ash that has settled in the lower portion of the cleaning tank 1A. Yes. The dehydration apparatus 4 includes a dehydrator (not shown) such as a belt filter or a filter press, and dehydrates the precipitated ash with the dehydrator. Further, in this embodiment, the filtration residue captured and removed by the filtration device 2 is returned to the cleaning tank 1A of the cleaning device 1, but instead, as indicated by a one-dot chain line in FIG. The filtration residue may be sent to the dehydration apparatus 4 and dehydrated together with the precipitated ash.

  The solidification processing device 5 is connected to the dehydration processing device 4 so as to receive dehydrated processing water containing a radioactive substance drained from the dehydration processing device 4. The solidification processing device 5 separates and removes the radioactive substance contained in the dehydrated treated water with a reverse osmosis membrane (RO membrane; not shown), and reverse osmosis for draining the dehydrated treated water from which the radioactive substance has been removed as membrane treated water. The radioactive substance is concentrated and solidified by heating the membrane treatment apparatus 6 and the concentrated water containing the radioactive substance separated and removed by the reverse osmosis membrane treatment apparatus 6 with a heater (not shown) to evaporate the moisture. And an evaporative solidification processing device 7.

  The reverse osmosis membrane treatment apparatus 6 is connected to the above-described washing water supply pipe 8, and the membrane treated water subjected to the reverse osmosis membrane treatment and drained by the reverse osmosis membrane treatment apparatus 6 is the washing water supply pipe. 8 to be sent.

  The agitation controller 10 has a rate of change over time in the radioactivity concentration of the adsorbed treated water from the adsorber 3 measured by the radioactivity meter 9 after the separation of the precipitated ash and the supernatant from the predetermined rate of change over time. When it is small, the stirrer 1B of the cleaning apparatus 1 is controlled so that the inside of the cleaning tank 1A is stirred. The control by the stirring control device 10 will be described in detail later.

  With the fly ash cleaning apparatus of this embodiment having such a configuration, fly ash containing radioactive substances is processed in the following manner. First, after supplying cleaning water to the cleaning tank 1 </ b> A of the cleaning apparatus 1 and storing it, fly ash containing a radioactive substance is put into the cleaning water. And the inside of washing tank 1A is stirred with stirrer 1B, and fly ash particles are suspended or suspended in clean water, and dissolution of a radioactive substance in washing water is promoted. Next, by supplying an acid agent or an alkali agent, the washing water in which the radioactive substance is dissolved is adjusted to have a pH suitable for agglomeration with the aggregating agent, for example, about pH 7-9.

  Next, by adding a coagulant to the washing tank 1A and eliminating the repulsive force of ions acting on the fly ash particles (colloid particles) suspended or suspended in the wash water, a small aggregate of fly ash particles To form and condense. Further, a flocculant is introduced into the washing tank 1A, and the aggregated small aggregates are agglomerated by electrical neutralization with ions and the long-chain polymer of the flocculant to form large flocs, thereby generating floc ash. Stirring by the stirrer 1B is continued even after charging the flocculant, and as a result, most of the radioactive substances contained in the fly ash are dissolved in the washing water.

  Next, the operation of the stirrer 1B is stopped, and the floc ash is settled in the tank lower part of the washing tank 1A as precipitated ash. The flock ash settles in the lower part of the tank in about 3 minutes to form a lower layer. On the other hand, the wash water in which the radioactive substance is dissolved forms an upper layer as a supernatant.

  The supernatant liquid in the washing tank 1A is drained from the washing tank 1A and sent to the filtration device 2. The supernatant liquid sent to the filtration device 2 was trapped and removed by fly ash (fly ash particles and fly ash small aggregates) mixed in the supernatant liquid, and passed through the filter medium. The washing waste water is sent to the adsorption device 3 as filtered water. Since most of the radioactive substances contained in the fly ash are dissolved in the supernatant by washing with the washing apparatus 1, the concentration of radioactive substances in the fly ash captured by the filter medium is sufficiently high. Has been reduced. The fly ash (filtration residue) removed by the filtration device 2 is returned to the supernatant in the washing tank 1A as described above. The settled ash that has settled in the lower part of the washing tank 1A is sent to the dehydration apparatus 4 and dehydrated by the dehydrator.

  The filtered water sent to the adsorption device 3 permeates the packed bed of adsorbent, so that the radioactive substances contained in the filtered processed water are adsorbed and removed by the adsorbent in the packed bed. As a result, after the radioactive substance is adsorbed and removed by the adsorbent to the extent that it can be reused as washing water, the filtered water is drained from the adsorption device 3 as adsorbed water. The adsorption treated water is sent to the cleaning water supply pipe 8, supplied to the cleaning tank 1A of the cleaning device 1 as cleaning water, and reused. Further, the adsorbent that has adsorbed the radioactive substance by repeating the above-described adsorption treatment is appropriately taken out from the adsorption device 3 and stored. Further, the adsorbing device 3 is filled with a new adsorbent.

  In the present embodiment, the radioactivity concentration of the adsorption treated water from the adsorption device 3 is measured by the radioactivity concentration meter 9. The operation of the agitator 1B of the cleaning device 1 is controlled by the agitation control device 10 based on the change with time of the radioactivity concentration measured by the activity concentration meter 9. This control operation will be described later with reference to FIG. Further, instead of the radioactive concentration of the adsorption treated water, the concentration of the radioactive substance contained in the adsorption treated water is measured so that the operation of the stirrer 1B is controlled based on the change over time of the concentration of the radioactive substance. Good.

  Moreover, the settled ash discharged | emitted from the washing | cleaning apparatus 1 is sent to the dehydration processing apparatus 4, and is dehydrated with a dehydrator. The fly ash (dehydrated ash) after the settled ash has been dehydrated has a sufficiently reduced concentration of radioactive material, and is landfilled at an existing landfill site.

  The dehydrated water from the dehydration processing device 4 is sent to the reverse osmosis membrane treatment device 6 of the solidification treatment device 5 and subjected to reverse osmosis membrane treatment in the reverse osmosis membrane treatment device 6 to separate and remove radioactive substances. The concentrated water containing the separated and removed radioactive substance is sent to the evaporative solidification processing device 7 and heated by a heater, and the radioactive substance is solidified by evaporating the water. The radioactive substance solidified product is stored in a container.

  After the dehydrated water is subjected to the reverse osmosis membrane treatment by the reverse osmosis membrane treatment device 6, the radioactive substance is removed to such a degree that it can be reused as washing water, and is discharged from the solidification treatment device 5 as membrane treated water. The The membrane treated water is sent to the cleaning water supply pipe 8 and supplied as cleaning water to the cleaning tank 1A of the cleaning apparatus 1.

  In the fly ash cleaning apparatus according to the present embodiment, the supernatant liquid generated by the cleaning apparatus 1 has a high radioactive substance content concentration, and fly ash is mixed and sent to the filtration device 2. Then, the fly ash mixed in the supernatant is captured and removed by the filtration device 2 and sent to the adsorption device 3 as filtered water, and the radioactive material is efficiently used by the adsorption device 3. Removed well. Further, the filtered treated water from which the radioactive substances have been removed is drained as adsorption treated water and returned to the washing tank 1A of the washing apparatus 1 as washing water, so that the supply of external makeup water can be reduced as much as possible to wash fly ash. It can be performed.

  The cleaning apparatus 1 does not sprinkle a large amount of rinsing water as in the conventional dehydration rinsing apparatus, but supplies an amount of cleaning water that can agitate the inside of the cleaning tank 1A to clean the fly ash. That is, in the present embodiment, the amount of washing water used for washing fly ash is smaller than the amount of rinsing water that has been conventionally required. Accordingly, the amount of filtered water to be adsorbed by the adsorbing device 3 is also reduced accordingly, so the scale of the adsorbing device 3 can be reduced, and the equipment cost and operating cost of the adsorbing device 3 can be suppressed. .

  In this embodiment, the dehydration apparatus 4 does not receive the rinsing water supply as in the prior art when dewatering the settled ash. Therefore, the dewatered water discharged from the dewatering device 4 is only water contained in the settled ash, and is a small amount compared to the conventional case where the rinsing water is sprinkled with the dewatering rinsing device. As a result, the amount of waste water to be solidified by the solidification processing device 5 is also reduced accordingly, so that the scale of the solidification processing device 5 can be reduced and the equipment cost and operation cost of the solidification processing device 5 can be suppressed. it can.

  Further, the adsorption treated water from the adsorption device 3 and the membrane treated water from the solidification treatment device 5 are returned to the washing tank 1A of the washing device 1 and reused as washing water. Since this adsorption treated water and membrane treated water can cover the washing water, only a small amount of replenishing water is newly supplied to the washing tank 1A from the outside, and the fly ash can be efficiently washed with the washing water. it can.

  In the present embodiment, the solidification processing device 5 solidifies the radioactive substance separated and removed by the reverse osmosis membrane processing device 6 by heating it with a heater of the evaporation solidification processing device 7 to evaporate water. However, instead of the evaporative solidification processing device 7, for example, a cement solidification processing device may be provided to solidify the radioactive substance with cement. The solidified product solidified with cement may be stored as it is, or may be stored in a container.

  Next, control of the stirrer 1B of the cleaning device 1 by the stirring control device 10 will be described with reference to FIG. In the fly ash cleaning apparatus according to the present embodiment, an operation of returning the supernatant from the cleaning apparatus 1 to the cleaning apparatus 1 as cleaning water through the filtration apparatus 2 and the adsorption apparatus 3 (hereinafter referred to as “supernatant circulation operation”). And an operation in which the stirrer 1B of the cleaning device 1 stirs the inside of the cleaning tank 1A (hereinafter referred to as “stirring operation”) are alternately performed. This supernatant circulation operation and stirring operation are repeated until the radioactivity concentration (radioactivity concentration measurement value) of the adsorption treated water from the adsorption device 3 measured by the radioactivity concentration meter 9 reaches a predetermined target value. Done.

  FIG. 2 is a graph showing the change with time of the radioactivity concentration of the adsorbed treated water from the adsorption device 3 measured by the radioactivity concentration meter 9 during the supernatant circulation operation. In FIG. 2, the horizontal axis indicates the time during which the supernatant liquid is passed through the adsorption device 3, and the vertical axis indicates the radioactivity concentration measurement value of the adsorption treated water. In FIG. 2, the time during the stirring operation, that is, the time during which the water flow to the adsorption device 3 is stopped is not shown in the “water flow time” on the horizontal axis of the graph.

  Supernatant circulation operation of the first (◆), second (■) and third (●) in the time periods of 0 to 10 minutes, 10 to 20 minutes, and 20 to 30 minutes shown in FIG. Is performed, and the supernatant circulation operation is not performed, that is, at the time of “0 minute”, “10 minutes”, and “20 minutes” on the horizontal axis in FIG. The stirring operation is performed. When the supernatant circulation operation is performed, the radioactive substance measurement value gradually decreases as shown in FIG. 2 as the radioactive substance contained in the supernatant is adsorbed and removed by the adsorption device 3. FIG. 2 shows an example in which the measured radioactivity concentration reaches a predetermined target value (10 Bq / l) in the third circulation operation.

  As shown in FIG. 2, after the first stirring operation (stirring operation performed when the fly ash, the coagulant and the flocculant are added to the cleaning device 1) is stopped, the first supernatant circulation operation is started. Then, the radioactivity concentration of the adsorption treated water measured by the radioactivity concentration meter 9 decreases from the concentration at the beginning of the supernatant circulation operation (water flow time 0 minutes). Then, after the start of the first supernatant circulation operation, when the change in the radioactivity concentration measurement value decreases gradually, that is, the change rate with time of the radioactivity concentration measurement value becomes smaller than the predetermined change rate with time. The supernatant circulation operation is stopped (water flow time 10 minutes). Then, the stirring control device 10 operates the stirrer 1B, and the second stirring operation is started. By this agitation operation, the precipitated ash (floc ash) that has settled at the bottom of the washing tank 1A is dispersed and suspended or suspended in the supernatant, and the supernatant of the radioactive material is removed from the water in the gap of the precipitated ash. Transition (dissolution) to is promoted. As a result, the concentration of the radioactive substance contained in the supernatant increases. After the second agitation operation is performed for a predetermined time, the agitator 1B is stopped by the agitation control device 10, that is, the agitation operation is stopped, and the floc ash is again settled in the lower part of the tank.

  Next, the second supernatant circulation operation is started. Since the radioactive material in the supernatant has been removed to some extent in the first supernatant circulation operation, the measured radioactivity concentration at the beginning of the second supernatant circulation operation (water flow time 10 minutes) is As seen in FIG. 2, it is lower than the beginning of the first supernatant circulation operation (water flow time 0 minutes). After the start of the second supernatant circulation operation, the supernatant circulation operation is stopped when the rate of change with time of the radioactivity concentration measurement value becomes smaller than a predetermined rate of change with time (water flow time of 20 minutes). Then, the stirring control device 10 operates the stirrer 1B again, and the third stirring operation is performed in the same manner as the second stirring operation described above.

  After the third stirring operation is performed for a predetermined time, the floc ash is again settled in the lower part of the tank, and then the third supernatant liquid circulation operation is started. As shown in FIG. 2, the radioactivity concentration measurement value at the beginning of the third supernatant circulation operation (water flow time 20 minutes) is the beginning of the second supernatant circulation operation (water flow time 10). Min). Then, after the start of the third supernatant circulation operation, when the measured radioactivity concentration reaches a predetermined target value (water passage time 30 minutes), the supernatant circulation operation is stopped. Then, after the floc ash has sufficiently settled as precipitated ash in the cleaning tank 1 </ b> A, the precipitated ash is discharged from the cleaning tank 1 </ b> A and supplied to the dehydration apparatus 4. Thus, in this embodiment, the amount of radioactive material contained in the water in the gaps between the settled ash can be sufficiently reduced by repeatedly performing the supernatant circulation operation and the stirring operation alternately. Accordingly, since the amount of radioactive material contained in the dehydrated water from the dehydration processing device 4 can be reduced, the scale of the solidification processing device 5 can be reduced, and the equipment cost and operation cost of the solidification processing device 5 can be suppressed. Can do.

DESCRIPTION OF SYMBOLS 1 Cleaning apparatus 1A Cleaning tank 1B Stirrer 2 Filtration apparatus 3 Adsorption apparatus (removal apparatus)
4 Dehydration treatment device 5 Solidification treatment device 9 Radioactivity concentration meter 10 Stirring control device

Claims (8)

In a fly ash cleaning device that cleans fly ash generated when incinerated waste contaminated with radioactive materials,
It has a washing tank that contains the above-mentioned fly ash containing radioactive substances and receives washing water, a coagulant and a flocculant, and the above-mentioned fly ash is washed with washing water in the washing tank to wash the radioactive substances in the fly ash. In addition to dissolving in water, the fly ash suspended or suspended in the wash water is condensed with a coagulant, and the condensed fly ash is aggregated with a coagulant and settled as sedimentation ash at the bottom of the tank, and the radioactive material is dissolved. A washing device for draining the supernatant liquid and discharging the sedimented ash,
The supernatant liquid from the washing device is received and fly ash contained in the supernatant liquid is captured and removed by a filter medium, and the supernatant liquid from which the fly ash has been removed is drained as filtered water and captured. A filtration device that discharges fly ash as filtration residue and returns it to the supernatant in the washing tank ;
The radioactive substance contained in the filtered water from the filtration device is adsorbed and removed by the adsorbent packed bed that adsorbs the radioactive substance, or the separation / removal agent particles that adsorb the radioactive substance by aggregating the separation / removal agent particles are aggregated It was removed by precipitation separation, a removing device for draining the filtered treated water radioactive material has been removed as a removal process water,
The dewatering process which receives the settling ash from the cleaning device , dehydrates the settled ash, discharges the dehydrated settled ash as dehydrated ash with reduced radioactive substance content, and drains the dehydrated water Equipment,
A solidification treatment device that receives the dehydration treatment water from the dehydration treatment device and solidifies the radioactive substance contained in the dehydration treatment water ,
Cleaning apparatus, the removal process water from removing device, fly ash cleaning device according to claim Rukoto received in the cleaning tank as the cleaning water together with the supplementary water supplied externally. In a fly ash cleaning device that cleans fly ash generated when incinerated waste contaminated with radioactive materials,
It has a washing tank that contains the above-mentioned fly ash containing radioactive substances and receives washing water, a coagulant and a flocculant, and the above-mentioned fly ash is washed with washing water in the washing tank to wash the radioactive substances in the fly ash. In addition to dissolving in water, the fly ash suspended or suspended in the wash water is condensed with a coagulant, and the condensed fly ash is aggregated with a coagulant and settled as sedimentation ash at the bottom of the tank, and the radioactive material is dissolved. A washing device for draining the supernatant liquid and discharging the sedimented ash,
The supernatant liquid from the washing device is received and fly ash contained in the supernatant liquid is captured and removed by a filter medium, and the supernatant liquid from which the fly ash has been removed is drained as filtered water and captured. A filtration device for discharging fly ash as a filtration residue;
The radioactive substance contained in the filtered water from the filtration device is adsorbed and removed by the adsorbent packed bed that adsorbs the radioactive substance, or the separation / removal agent particles that adsorb the radioactive substance are aggregated by supplying the separation / removal agent and the flocculant. A removal device that drains the filtered treated water from which radioactive materials have been removed by precipitation separation as drained treated water;
The precipitated ash from the washing device and the filtration residue from the filtration device are received, the precipitated ash and the filtration residue are dehydrated, and the dehydrated precipitated ash and the filtration residue are mixed with a radioactive substance having a concentration of radioactive material. A dewatering device that discharges the dewatered ash as reduced and drains the dewatered water,
A solidification treatment device that receives the dehydration treatment water from the dehydration treatment device and solidifies the radioactive substance contained in the dehydration treatment water,
The washing apparatus receives the removal treated water from the removing apparatus in a washing tank as washing water together with makeup water supplied from the outside. The cleaning device has a stirrer that stirs the inside of the cleaning tank,
The fly ash cleaning apparatus has a measuring means for measuring the concentration of radioactive water or radioactive substance removed from the removing apparatus, and the rate of change with time of the concentration of radioactive substance or radioactive substance measured by the measuring means is predetermined. when smaller than aging rate, Fei of claim 1 or claim 2, to have a stirring controller for controlling the agitator so that the agitator agitates the cleaning tank Ash cleaning equipment. The solidification treatment device is a reverse osmosis membrane treatment device that separates and removes the radioactive substance contained in the dehydrated treatment water from the dehydration treatment apparatus and drains the dehydrated treatment water from which the radioactive substance has been removed as membrane treated water; An evaporative solidification treatment device that evaporates the water of the concentrated water containing the radioactive material separated and removed by the reverse osmosis membrane treatment device and solidifies the radioactive material,
Cleaning apparatus, a membrane treated water from said reverse osmosis membrane treatment apparatus, according to claim 1 to claim 3 and to receive the cleaning tank as washing water together with removal process water from the makeup water removal device supplied from the outside The fly ash cleaning apparatus according to one of the above. In the fly ash cleaning method for cleaning fly ash generated when incinerated waste contaminated with radioactive materials,
The fly ash containing radioactive material is stored in a washing tank, the fly ash is washed in the washing tank with washing water to dissolve the radioactive substance in the fly ash in the washing water, and suspended or suspended in the washing water. The clouded fly ash is condensed with a coagulant, and the condensed fly ash is aggregated with a coagulant and settled as precipitated ash at the bottom of the tank, and the supernatant solution in which the radioactive substance is dissolved is drained and the precipitated ash Cleaning process for discharging
With the fly ash contained in the supernatant which has been drained by the cleaning step to catch and removed by filtering material, draining supernatant captured fly ash has been removed as a filtration treatment water, it captured the flight A filtration step of discharging ash as a filtration residue and returning it to the supernatant in the washing tank;
Separation / removal agent particles that adsorb and remove radioactive substances contained in the filtered water drained in the filtration step by adsorbent packed bed that adsorbs radioactive substances, or supply separation / aggregation agent and flocculant to adsorb radioactive substances Removing by coagulating sediment separation, and draining the filtered treated water from which radioactive substances have been removed as removed treated water;
The settling ash discharged in the washing process is received, the settling ash is dehydrated, the settling ash that has been dehydrated is discharged as dehydrated ash with a reduced concentration of radioactive material, and dewatered water is drained. A dehydration process;
A solidification treatment step for solidifying a radioactive substance contained in the dehydration treatment water drained in the dehydration treatment step,
In the washing step, the fly ash washing method is characterized in that the removal treated water from the removing device is received in the washing tank as washing water together with makeup water supplied from the outside.
In the fly ash cleaning method for cleaning fly ash generated when incinerated waste contaminated with radioactive materials,
The fly ash containing radioactive material is stored in a washing tank, the fly ash is washed in the washing tank with washing water to dissolve the radioactive substance in the fly ash in the washing water, and suspended or suspended in the washing water. The clouded fly ash is condensed with a coagulant, and the condensed fly ash is aggregated with a coagulant and settled as precipitated ash at the bottom of the tank, and the supernatant solution in which the radioactive substance is dissolved is drained and the precipitated ash Cleaning process for discharging
The fly ash contained in the supernatant drained in the washing step is captured and removed with a filter medium, and the supernatant from which the trapped fly ash has been removed is drained as filtered water, and the trapped fly ash is removed. A filtration step for discharging ash as a filtration residue;
Separation / removal agent particles that adsorb and remove radioactive substances contained in the filtered water drained in the filtration step by adsorbent packed bed that adsorbs radioactive substances, or supply separation / aggregation agent and flocculant to adsorb radioactive substances Removing by coagulating sediment separation, and draining the filtered treated water from which radioactive substances have been removed as removed treated water;
The sedimented ash discharged in the washing step and the filtration residue from the filtration device are received and the sedimented ash and filtration residue are dehydrated, and the dehydrated sedimentation ash and filtration residue have a radioactive substance content concentration. A dehydration process that discharges dehydrated ash while reducing the amount of dehydrated ash ;
A solidification treatment step for solidifying a radioactive substance contained in the dehydration treatment water drained in the dehydration treatment step,
In the washing step, the fly ash washing method is characterized in that the removal treated water from the removing device is received in the washing tank as washing water together with makeup water supplied from the outside. A stirring step of stirring the inside of the washing tank with a stirrer;
A measurement process for measuring the radioactive concentration or concentration of radioactive material in the removal treated water drained in the removal process;
Stirring control for controlling the stirrer so that the stirrer stirs the inside of the washing tank when the time-dependent change rate of the radioactive concentration or the concentration of the radioactive substance measured in the measurement step is smaller than a predetermined time-change rate. The fly ash cleaning method according to claim 5 , further comprising a step. The solidification treatment step is a reverse osmosis membrane treatment step of separating and removing radioactive substances contained in the dehydrated treatment water drained in the dehydration treatment step and draining the dehydrated treatment water from which the radioactive substances have been removed as membrane treatment water. And evaporative solidification treatment step of evaporating the water of the concentrated water containing the radioactive material separated and removed in the reverse osmosis membrane treatment step to solidify the radioactive material,
At the washing step, the claims of the membrane treated water is drained by the reverse osmosis membrane treatment step, as both the wash water and removal treated water from the makeup water removal device supplied from the outside, and to receive the cleaning tank The fly ash cleaning method according to claim 5 or claim 7 .

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