JP6783155B2 - Waste resin treatment method and waste resin treatment system - Google Patents

Description

The present invention relates to a waste resin treatment method and a waste resin treatment system.

The system water of a nuclear plant contains multiple types of radionuclides. Ion exchange resins are used to adsorb these and purify system water. Among the radionuclides, cationic metal ions having high radioactivity such as cobalt, cesium, strontium, iron, and nickel are eluted from the ion exchange resin into an aqueous solution containing sulfuric acid in an eluent.

The eluent containing the radionuclide and sulfuric acid eluted from the ion exchange resin is separated into the radionuclide and sulfuric acid by the diffusion dialysis membrane. The separated sulfuric acid is sent to the eluent again for reuse. As a method for reusing the eluent, for example, in Patent Document 1, the eluent containing metal ions is separated into metal ions and acid by electrodialysis, and the separated acid is reused to recycle the amount of waste liquid. Techniques for reducing the amount of

On the other hand, the eluent waste liquid, which is the eluent from which sulfuric acid is separated by the diffusion dialysis membrane, is neutralized and then sent to the evaporation concentrator. The elution waste liquid concentrated here is finally cemented. By performing the concentration treatment in the evaporation concentrator, the final amount of radioactive waste is reduced.

Japanese Unexamined Patent Publication No. 2014-210235

However, when concentrating the eluent waste liquid, it is necessary to suppress the concentration reduction rate to the solubility of sodium sulfate or less in order to suppress the precipitation of sodium sulfate which is the main component in the neutralized eluent waste liquid. As a result, if the amount of elution waste liquid increases as the amount of radionuclides to be treated increases, the amount of high-dose radioactive waste after cement solidification increases. Therefore, there is a desire to reduce the amount of high-dose radioactive waste.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a waste resin treatment method and a waste resin treatment system capable of reducing the amount of high-dose radioactive waste generated by cement solidification. To do.

The present invention employs the following means in order to solve the above problems.
The waste resin treatment method according to the first aspect of the present invention is an elution step in which a sulfuric acid solution is supplied to an ion exchange resin adsorbing a radionuclide and the radionuclide is eluted from the ion exchange resin, and an elution step is performed. A recovery step of recovering at least a part of sulfuric acid from the eluent which is the sulfuric acid solution containing the radionuclide via a diffusion dialysis membrane, and a first of the eluents in which the sulfuric acid is recovered in the recovery step. A removal step of passing the elution waste liquid through an inorganic adsorbent to remove the radionuclide from the first elution waste liquid and a second elution waste liquid which is the first elution waste liquid from which the radionuclide was removed in the removal step are performed. The waste liquid treatment step to be treated, the inorganic adsorbent solidification step of cement-solidifying the inorganic adsorbent through which the first elution waste liquid was passed in the removal step, and the ion concentration of the radionuclide in the first elution waste liquid It includes a determination step of determining whether or not the value is below the predetermined reference value, and when it is determined that the value is below the reference value, the removal step is performed.

According to such a configuration, by passing the first elution waste liquid through the inorganic adsorbent, the radionuclides contained in the first elution waste liquid are adsorbed on the inorganic adsorbent and removed from the first elution waste liquid. As a result, radionuclides can be removed from the first elution waste liquid with high accuracy, and the dose of the second elution waste liquid can be reduced. Therefore, the second elution waste liquid can be treated in the waste liquid treatment step without solidifying with cement.
Further, depending on the state of the first elution waste liquid, it can be determined whether or not it is inefficient to use the inorganic adsorbent for removing the radionuclide, and the inorganic adsorbent can be used efficiently.

Further, in the waste resin treatment method according to the second aspect of the present invention, in the first aspect, in the determination step, when the elapsed time after performing the recovery step exceeds a predetermined predetermined time, the ion concentration May be determined to be below the reference value.

With such a configuration, it is possible to easily identify the case where it is inefficient to use the inorganic adsorbent only by measuring the elapsed time.

Further, in the waste resin treatment method according to the third aspect of the present invention, when it is determined in the first aspect or the third aspect that the value exceeds the reference value in the determination step, the first elution waste liquid is concentrated. It may include a waste liquid solidification step of cement solidification.

With such a configuration, when it is determined that the value exceeds the standard value, the first elution waste liquid is concentrated and cement-solidified, so that only the first elution waste liquid having a high ion concentration of radionuclides is cement-solidified. However, only the first elution waste liquid having a low ion concentration of the radionuclide can be treated with an inorganic adsorbent. This makes it possible to efficiently treat radionuclides and reduce the amount of high-dose radioactive waste.

Further, in the waste resin treatment method according to the fourth aspect of the present invention, in the third aspect, the waste liquid solidification step is carried out at the same time as the inorganic adsorbent solidification step, and the inorganic adsorbent and the first elution waste liquid are combined. After mixing, the cement may be solidified.

With such a configuration, the amount of waste after cement solidification can be reduced by mixing the inorganic adsorbent to be cement solidified and the first elution waste liquid.

Further, in the waste resin treatment system according to the fifth aspect of the present invention, an elution unit that elutes the radionuclide from an ion exchange resin to which a sulfuric acid solution is supplied and the radionuclide is adsorbed, and the elution unit that is eluted by the elution unit. A recovery unit having a diffusion dialysis membrane to which an eluent containing the radionuclide-containing sulfuric acid solution is supplied and recovering at least a part of sulfuric acid from the eluent, and the eluent from which the sulfuric acid is recovered by the recovery unit. A removal unit having an inorganic adsorbent that removes the radionuclide from the first elution waste liquid by supplying a first elution waste liquid and passing water through the first elution waste liquid, and the radionuclide in the removal unit. A waste liquid treatment unit for treating the removed second elution waste liquid, which is the first elution waste liquid, and an inorganic adsorbent solidification unit for cement solidifying the inorganic adsorbent through which the first elution waste liquid is passed through the removal unit. And, a determination unit for determining whether or not the ion concentration of the radionuclide in the first elution waste liquid has fallen below a predetermined reference value, and when it is determined that the ion concentration has fallen below the reference value, the removal unit has the first unit. (1) A switching unit for supplying an elution waste liquid is provided.

With such a configuration, by passing the first elution waste liquid through the inorganic adsorbent, the radionuclides contained in the first elution waste liquid are adsorbed by the inorganic adsorbent and removed from the first elution waste liquid. .. As a result, radionuclides can be removed from the first elution waste liquid with high accuracy, and the dose of the second elution waste liquid can be reduced. Therefore, the second elution waste liquid can be treated in the waste liquid treatment unit without solidifying with cement.
Further, depending on the state of the first elution waste liquid, it can be determined whether or not it is inefficient to use the inorganic adsorbent for removing the radionuclide, and the inorganic adsorbent can be used efficiently.

Further, in the waste resin treatment system according to the sixth aspect of the present invention, in the fifth aspect, the determination unit sets a predetermined elapsed time, which is the time during which the eluent is supplied to the recovery unit. If it exceeds, it may be determined that the ion concentration is below the reference value.

With such a configuration, it is possible to easily identify the case where it is inefficient to use the inorganic adsorbent only by measuring the elapsed time.

Further, in the waste resin treatment system according to the seventh aspect of the present invention, when the determination unit determines in the fifth or sixth aspect that the value exceeds the reference value, the first elution waste liquid is supplied. The first elution waste liquid may be provided with a concentrating part for concentrating the first elution waste liquid and a waste liquid solidifying part for cementing the first elution waste liquid concentrated in the concentrating part.

With such a configuration, when it is determined that the value exceeds the standard value, the first elution waste liquid is concentrated and cement-solidified, so that only the first elution waste liquid having a high ion concentration of radionuclides is cement-solidified. However, only the first elution waste liquid having a low ion concentration of the radionuclide can be treated with an inorganic adsorbent. This makes it possible to efficiently treat radionuclides and reduce the amount of high-dose radioactive waste.

Further, in the waste resin treatment system according to the eighth aspect of the present invention, in the seventh aspect, the waste liquid solidifying portion is provided integrally with the inorganic adsorbent solidifying portion, and the inorganic adsorbent and the first elution waste liquid are used. The mixture may be cement-solidified.

With such a configuration, the amount of waste after cement solidification can be reduced by mixing the inorganic adsorbent to be cement solidified and the first elution waste liquid.

According to the present invention, it is possible to reduce the amount of high-dose radioactive waste generated by cement solidification.

It is a block diagram which shows schematic the waste resin treatment system which concerns on embodiment of this invention. It is a flow figure which shows the waste resin processing method which concerns on embodiment of this invention. In the embodiment of the present invention, it is a graph which shows the relationship between the ion concentration of a radionuclide in the first eluent, and the elapsed time.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.
As shown in FIG. 1, the waste resin treatment system 100 of the present embodiment is a system that disposes of an ion exchange resin adsorbing radionuclides generated by the operation of a nuclear power plant. Examples of the radionuclide adsorbed on the ion exchange resin include cationic metal ions such as cobalt, cesium, strontium, iron and nickel.

The waste resin treatment system 100 of the present embodiment includes a waste resin tank 2, an eluent (eluent) 3, an incinerator 4, a recovery device (recovery) 5, a pure water supply section 6, and a sulfuric acid supply section. 7 and a sulfuric acid mixer 8 are provided. Further, the waste resin treatment system 100 includes a switching unit 9, a control unit 10, a removal unit 11, a waste liquid treatment unit 12, a neutralization tank 13, a neutralizer supply unit 14, and a concentrator (concentrator) 15. A concentrated waste liquid tank 16 and a solidifying unit 17 are provided.

The waste resin tank 2 stores ion exchange resins that have adsorbed various types of radioactivity used in nuclear power plants and the like. The waste resin tank 2 sends the ion exchange resin to the eluent 3 via the waste resin delivery line 201. The waste resin delivery line 201 connects the waste resin tank 2 and the eluent 3.

The eluent 3 receives the ion exchange resin and elutes the radionuclide. The eluent 3 is supplied with a sulfuric acid solution which is an aqueous solution containing sulfuric acid. The eluent 3 elutes the radionuclide from the ion exchange resin on which the radionuclide is adsorbed by the sulfuric acid solution. In the eluent 3 of the present embodiment, the ion exchange resin is introduced from the waste resin tank 2 via the waste resin delivery line 201. The eluent 3 sends an eluent, which is a sulfuric acid solution containing the eluted radionuclides, to the recovery device 5 via the receiving chamber introduction line 203. The eluent 3 sends the elution-treated ion exchange resin to the incinerator 4 via the elution-treated resin delivery line 202. The elution-treated resin delivery line 202 connects the eluent 3 and the incinerator 4. The incinerator 4 incinerates the ion exchange resin after the radionuclides have been eluted.

The collector 5 is supplied with an eluent from the eluent 3. The recovery device 5 has a diffusion dialysis membrane 53 that recovers at least a part of sulfuric acid from the eluent. In the collector 5, the receiving chamber 51 and the collecting chamber 52 are partitioned by the diffusion dialysis membrane 53.

The receiving room 51 is connected to the receiving room introduction line 203 and the receiving room sending line 204. The receiving chamber introduction line 203 introduces the eluent sent out from the eluent 3 into the receiving chamber 51 of the recovery device 5. The reception chamber introduction line 203 connects the reception chamber 51 and the eluent 3. The receiving chamber sending line 204 sends out the first elution waste liquid described later from the receiving chamber 51. The receiving chamber sending line 204 connects the receiving chamber 51 and the switching unit 9.

The collection chamber 52 is connected to the collection chamber introduction line 205 and the collection chamber delivery line 206. The recovery chamber introduction line 205 introduces pure water into the recovery chamber 52. The recovery chamber introduction line 205 connects the recovery chamber 52 and the pure water supply unit 6. The recovery chamber delivery line 206 sends out an eluent (sulfuric acid solution) from the recovery chamber 52 from which most of the radionuclides and a part of sulfuric acid have been removed to the eluent 3. The recovery chamber delivery line 206 connects the recovery chamber 52 and the eluent 3.

In FIG. 1, one receiving chamber 51 and one collecting chamber 52 are separated by a diffusion dialysis membrane 53 for simplification of illustration, but the collecting device 5 has many such structural parts. It is provided. The reception room introduction line 203 is divided and communicates with a large number of reception rooms 51. In addition, the collection chamber introduction line 205 is also divided and communicated with a large number of collection chambers 52. In addition, a large number of receiving chambers 51 merge and communicate with the receiving chamber sending line 204. In addition, a large number of collection chambers 52 merge and communicate with the collection chamber delivery line 206.

The diffusion dialysis membrane 53 selectively dialyzes sulfuric acid from the eluent of the receiving chamber 51 toward the recovery chamber 52. The specific material of the diffusion dialysis membrane 53 is, for example, a copolymer in which styrene, chloromethylstyrene, vinylpyridine, and divinylbenzene are combined. The diffusion dialysis membrane 53 of the present embodiment allows sulfate ions and hydrogen ions to permeate from the eluent of the receiving chamber 51 to the recovery chamber 52 side. As a result, the first elution waste liquid remains in the receiving chamber 51. The first elution waste liquid is an eluent after sulfuric acid is recovered to the recovery chamber 52 side by the diffusion dialysis membrane 53, and is an elution waste liquid containing radionuclides and a part of sulfuric acid.

The pure water supply unit 6 supplies pure water to the recovery chamber 52 via the recovery chamber introduction line 205. The pure water supply unit 6 supplies pure water at a constant flow rate.

The sulfuric acid supply unit 7 supplies sulfuric acid to the recovery chamber delivery line 206 via the sulfuric acid supply line 207. The sulfuric acid supply line 207 connects the sulfuric acid supply unit 7 and the recovery chamber delivery line 206. A sulfuric acid supply pump 208 for delivering sulfuric acid is provided in the middle of the sulfuric acid supply line 207. A sulfuric acid mixer 8 is connected to the recovery chamber delivery line 206 on the downstream side (eluent 3 side) of the connection position with the sulfuric acid supply line 207. The sulfuric acid mixer 8 mixes the low-concentration sulfuric acid solution sent out from the recovery chamber 52 with the sulfuric acid supplied from the sulfuric acid supply unit 7. As a result, the sulfuric acid solution in which a part of the sulfuric acid is recovered by the recovery device 5 and the concentration is lowered is replenished with the sulfuric acid. The sulfuric acid solution replenished with sulfuric acid is sent to the eluent 3 again. As a result, a sulfuric acid solution having a constant concentration and a constant flow rate is supplied to the eluent 3.

The switching unit 9 is connected to the receiving chamber sending line 204. The switching unit 9 is capable of switching the delivery destination of the supplied first elution waste liquid. The switching unit 9 of the present embodiment is, for example, a three-way valve. The switching unit 9 of the present embodiment is connected to the removal unit introduction line 209 and the neutralization tank introduction line 210. The switching unit 9 is capable of switching the delivery destination of the first elution waste liquid supplied from the receiving chamber delivery line 204 to either the removal unit introduction line 209 or the neutralization tank introduction line 210.

The control unit 10 controls the switching of the switching unit 9. The control unit 10 of the present embodiment opens the neutralization tank introduction line 210 to the switching unit 9 when the removal unit introduction line 209 is closed. The control unit 10 closes the neutralization tank introduction line 210 when the removal unit introduction line 209 is opened to the switching unit 9. The control unit 10 of the present embodiment includes a determination unit 101 and an output unit 102.

The determination unit 101 determines whether or not the ion concentration of the radionuclide in the first elution waste liquid is below a predetermined reference value Ik. When the ion concentration falls below the reference value Ik, the determination unit 101 sends a signal to the output unit 102 to send an instruction to the switching unit 9 to supply the second elution waste liquid to the removal unit introduction line 209. When the ion concentration exceeds the reference value Ik, the determination unit 101 sends a signal to the output unit 102 to send an instruction to the switching unit 9 to supply the second elution waste liquid to the neutralization tank introduction line 210. Here, the reference value Ik of the present embodiment is a value that can be regarded as a sufficiently low ion concentration of the radionuclide in the first elution waste liquid. Therefore, the reference value Ik is a value that can be regarded as more efficient for removing radionuclides by using an inorganic adsorbent than by cementing the first elution waste liquid.

The determination unit 101 of the present embodiment determines that the ion concentration has fallen below the reference value Ik when the elapsed time exceeds a predetermined predetermined time Ts. The elapsed time is the time during which the eluent is being supplied to the recovery device 5, and is the working time during which the recovery device 5 is removing radionuclides from the eluent. The elapsed time of the present embodiment is the time elapsed from the start of the eluent flowing from the receiving chamber introduction line 203 into the receiving chamber 51. The specified time Ts is the time when the ion concentration of the radionuclide in the first elution waste liquid rises once and then becomes the reference value Ik or less.

The determination unit 101 may acquire the elapsed time based on the bed volume of the first elution waste liquid acquired by a sensor (not shown). Further, the elapsed time may be acquired by inputting from the outside or measuring with a timer linked to the device.

The output unit 102 sends an instruction to the switching unit 9 to switch the delivery destination of the first elution waste liquid based on the signal from the determination unit 101. As a result, the switching unit 9 switches the delivery destination of the first elution waste liquid between the removal unit introduction line 209 and the neutralization tank introduction line 210.

The removal unit 11 is supplied with the first elution waste liquid from the collector 5 via the switching unit 9. The removing unit 11 has an inorganic adsorbent that removes radionuclides from the first elution waste liquid by passing water through the first elution waste liquid. The removal unit 11 of the present embodiment is connected to the removal unit introduction line 209 and the second elution waste liquid delivery line 211. The removal unit 11 is supplied with the first elution waste liquid from the removal unit introduction line 209 via the switching unit 9. The removing unit 11 passes the supplied first elution waste liquid through the inorganic adsorbent to adsorb the radionuclides in the first elution waste liquid to the inorganic adsorbent. The removal unit 11 sends out the second elution waste liquid, which is the first elution waste liquid from which the radionuclides have been removed, to the waste liquid treatment unit 12 via the second elution waste liquid delivery line 211. Examples of the inorganic adsorbent include zeolite-based, ferrocyanide-based, crystallized silicotitanate-based, and antimonate-based.

The waste liquid treatment unit 12 treats the second elution waste liquid from which the radionuclides have been removed by the removal unit 11. The waste liquid treatment unit 12 is connected to the second elution waste liquid delivery line 211. The waste liquid treatment unit 12 is a radioactive waste treatment system (WDS) that treats various low-dose radioactive liquids. Specifically, the wastewater treatment unit 12 stores a low-dose radioactive liquid such as drain water in a drain tank, and then evaporates and concentrates the stored radioactive wastewater. After that, the radioactive liquid waste containing almost no radioactive substances and having a very low dose is treated by desalination and reused in the plant. In addition, radioactive liquid waste whose dose is not so low is treated by asphalt solidification after concentration. The waste liquid treatment unit 12 of the present embodiment treats the second elution waste liquid supplied via the second elution waste liquid delivery line 211 together with such other radioactive liquid waste.

The neutralization tank 13 is supplied with the first elution waste liquid from the recovery device 5 via the switching unit 9. The neutralization tank 13 neutralizes the stored first elution waste liquid. The neutralization tank 13 of the present embodiment is connected to the neutralization tank introduction line 210. The neutralization tank 13 is supplied with the first elution waste liquid from the neutralization tank introduction line 210 via the switching unit 9. Therefore, the neutralization tank 13 is supplied with the first elution waste liquid that has not been supplied to the removal unit 11. The neutralization tank 13 neutralizes the neutralizing agent supplied from the neutralizing agent supply unit 14 by mixing the first elution waste liquid. The neutralizing agent supply unit 14 supplies caustic soda (natrim hydroxide) to the neutralizing tank 13 as a neutralizing agent for sulfuric acid via the neutralizing agent supply line 215. The neutralizing agent supply line 215 is provided with a neutralizing agent pump 216 that pumps the neutralizing agent toward the neutralizing tank 13 in the middle of the line. The neutralized waste liquid, which is the neutralized first elution waste liquid, is introduced into the concentrator 15 via the neutralization waste liquid introduction line 213 and concentrated by heating. The neutralization waste liquid introduction line 213 is provided with a neutralization waste liquid pump 214 for pumping the neutralization waste liquid toward the concentrator 15 on the way.

The neutralized waste liquid is concentrated in the concentrator 15 while containing the radionuclides. The concentrated waste liquid, which is a concentrated neutralized waste liquid, is stored in the concentrated waste liquid tank 16 via the concentrated waste liquid introduction line 217. The concentrated waste liquid introduction line 217 is provided with a concentrated waste liquid pump 218 that pumps the concentrated waste liquid toward the concentrated waste liquid tank 16 on the way. The concentrated waste liquid stored in the concentrated waste liquid tank 16 is sent to the solidifying unit 17 via the solidifying unit introduction line 219.

The solidification unit 17 treats and stores a high dose of radioactive waste by cement solidification. The solidifying section 17 of the present embodiment includes a waste liquid solidifying section 171 and an inorganic adsorbent solidifying section 172.

The waste liquid solidification unit 171 cements the concentrated waste liquid which is the first elution waste liquid concentrated by the concentrator 15. The waste liquid solidifying section 171 is connected to the solidifying section introduction line 219. The waste liquid solidification unit 171 cements the concentrated waste liquid supplied via the solidification unit introduction line 219.

The inorganic adsorbent solidifying unit 172 cements the inorganic adsorbent through which the second elution waste liquid is passed through the removing unit 11. The inorganic adsorbent solidifying unit 172 is connected to the inorganic adsorbent delivery line 212. The inorganic adsorbent solidifying section 172 supplies the inorganic adsorbent to which the radionuclide is adsorbed via the inorganic adsorbent delivery line 212. The inorganic adsorbent solidifying unit 172 cements the inorganic adsorbent adsorbed by the radionuclide.

In the present embodiment, the waste liquid solidifying unit 171 is provided integrally with the inorganic adsorbent solidifying unit 172. Therefore, in the solidification section 17, a mixture of the inorganic adsorbent and the concentrated waste liquid which is the neutralized and concentrated first elution waste liquid is cement-solidified.

Next, the waste resin treatment method S100 using the waste resin treatment system 100 will be described with reference to FIGS. 1 and 2. The waste resin treatment method S100 of the present embodiment is a method of discarding an ion exchange resin adsorbing a radionuclide.

The waste resin treatment method S100 of the present embodiment includes an elution step S1, an incineration step S2, a recovery step S3, a determination step S4, a removal step S5, a waste liquid treatment step S6, and a solidification step S7.

In the elution step S1, a sulfuric acid solution is supplied to the ion exchange resin adsorbing the radionuclide, and the radionuclide is eluted from the ion exchange resin. Specifically, in the elution step S1 of the present embodiment, the ion exchange resin is introduced into the eluent 3 from the waste resin tank 2 via the waste resin delivery line 201. Then, the radionuclide is eluted from the ion exchange resin by performing an elution treatment with a sulfuric acid solution in the eluent 3. The eluent containing the eluted radionuclides is supplied to the receiving chamber 51 of the collector 5 via the receiving chamber introduction line 203.

The incineration step S2 is carried out after the elution step S1. The incineration step S2 incinerates the ion exchange resin from which the radionuclides have been removed in the elution step S1. In the incineration step S2 of the present embodiment, the ion exchange resin supplied from the eluent 3 is incinerated via the elution-treated resin delivery line 202.

The recovery step S3 is performed after the elution step S1. In the recovery step S3, at least a part of sulfuric acid is recovered from the eluent eluted in the elution step S1 via the diffusion dialysis membrane 53. In the recovery step S3 of the present embodiment, the eluent supplied from the eluent 3 via the receiving chamber introduction line 203 is introduced into the plurality of receiving chambers 51. Sulfuric acid is dialyzed by the diffusion dialysis membrane 53 of the eluent introduced into the plurality of receiving chambers 51. As a result, the sulfate ion and the hydrogen ion in the eluent of the receiving chamber 51 are permeated into the recovery chamber 52. As a result, most of the sulfuric acid is recovered from the receiving chamber 51 to the recovery chamber 52 side, and the first elution waste liquid containing radionuclides and a part of sulfuric acid remains in the receiving chamber 51.

The determination step S4 is carried out after the recovery step S3. The determination step S4 determines whether or not the ion concentration of the radionuclide in the first elution waste liquid has fallen below a predetermined reference value Ik. If it is determined in the determination step S4 that the value is below the reference value Ik, the removal step S5 is performed. If it is determined in the determination step S4 that the reference value Ik is exceeded, the waste liquid solidification step S71 described later is carried out. In the determination step S4 of the present embodiment, it is determined that the ion concentration has fallen below the reference value Ik when the elapsed time after the recovery step S3 is performed exceeds a predetermined predetermined time Ts. Specifically, in the determination step S4, the determination unit 101 of the control unit 10 makes a determination based on the elapsed time, which is the time during which the recovery step S3 is being executed. In the determination step S4, the delivery destination of the first elution waste liquid in the switching unit 9 is switched based on the determination result. More specifically, in the determination step S4, the switching unit 9 is switched so as to supply the second elution waste liquid to the removal unit introduction line 209 when the fixed time Ts is exceeded. In the determination step S4, the switching unit 9 is switched so as to supply the second elution waste liquid to the neutralization tank introduction line 210 when the specified time Ts is not exceeded.

The removal step S5 is carried out after the determination step S4. In the removal step S5, the first elution waste liquid is passed through an inorganic adsorbent to remove radionuclides from the first elution waste liquid. The removal step S5 is performed when it is determined in the determination step S4 that the ion concentration is below the reference value Ik. In the removal step S5 of the present embodiment, the first elution waste liquid supplied from the removal unit introduction line 209 via the switching unit 9 is passed through the inorganic adsorbent. As a result, the radionuclide is adsorbed on the inorganic adsorbent and removed from the first elution waste liquid. The second elution waste liquid, which is the first elution waste liquid from which the radionuclides have been removed, is sent out to the waste liquid treatment unit 12.

The waste liquid treatment step S6 is carried out after the removal step S5. The waste liquid treatment step S6 treats the second elution waste liquid. In the waste liquid treatment step S6 of the present embodiment, the second elution waste liquid is introduced from the removal unit 11 to the waste liquid treatment unit 12 via the second elution waste liquid delivery line 211. The second elution effluent is then treated with other radioactive effluents by desalting or asphalt solidification.

In the solidification step S7, a high dose of radioactive waste is treated and stored by cement solidification. The solidification step S7 of the present embodiment includes a waste liquid solidification step S71 and an inorganic adsorbent solidification step S72.

The waste liquid solidification step S71 is carried out after the determination step S4. In the waste liquid solidification step S71, when it is determined in the determination step S4 that the ion concentration exceeds the reference value Ik, the first elution waste liquid is concentrated and cemented. In the waste liquid solidification step S71 of the present embodiment, when it is determined in the determination step S4 that the ion concentration exceeds the reference value Ik, the neutralization tank 13 supplies the first elution waste liquid supplied from the neutralization tank introduction line 210. Neutralize. In the neutralization treatment, caustic soda (Natrim hydroxide) is supplied to the first elution waste liquid as a neutralizer via the neutralizer supply line 215, so that the sulfuric acid in the first elution waste liquid is converted to sodium sulfate. As a result, the neutralized waste liquid, which is the neutralized first elution waste liquid, is introduced into the concentrator 15 via the neutralization waste liquid introduction line 213 and concentrated by heating. The concentrated waste liquid produced by heating and concentrating is stored in the concentrated waste liquid tank 16 via the concentrated waste liquid introduction line 217, and then sent to the waste liquid solidifying unit 171 via the solidifying unit introduction line 219. In the waste liquid solidification unit 171, the supplied concentrated waste liquid is cement-solidified.

The inorganic adsorbent solidification step S72 is carried out after the removal step S5. In the inorganic adsorbent solidification step S72, the inorganic adsorbent through which the first elution waste liquid is passed in the removal step S5 is cement-solidified. In the inorganic adsorbent solidification step S72 of the present embodiment, the inorganic adsorbent adsorbed by the radionuclide is supplied to the inorganic adsorbent solidification unit 172 via the inorganic adsorbent delivery line 212. In the inorganic adsorbent solidifying section 172, the inorganic adsorbent adsorbed by the radionuclide is cement-solidified.

In the present embodiment, the waste liquid solidification step S71 is carried out at the same time as the inorganic adsorbent solidification step S72. Therefore, in the solidification step S7, the inorganic adsorbent and the concentrated waste liquid which is the neutralized and concentrated first elution waste liquid are mixed to form an integral mixture, and then cement solidification is performed.

According to the waste resin treatment system 100 and the waste resin treatment method S100 as described above, in the removal step S5, the first elution waste liquid treated by the collector 5 is passed through an inorganic adsorbent to pass the first elution waste liquid. The radionuclides contained in the above are adsorbed on the inorganic adsorbent and removed from the first elution waste liquid. As a result, radionuclides can be removed from the first elution waste liquid with high accuracy, and the dose of the second elution waste liquid can be reduced. Therefore, the second elution waste liquid can be treated together with other low-dose waste liquid in the waste liquid treatment unit 12 in the waste liquid treatment step S6 without solidifying the second elution waste liquid with cement. Therefore, it is possible to reduce the amount of liquid that requires cement solidification and reduce the amount of high-dose radioactive waste.

Further, in the determination step S4, when the determination unit 101 determines that the ion concentration of the radioactive concentration in the first elution waste liquid is lower than the reference value Ik, the switching unit 9 is made to supply the first elution waste liquid to the removal unit 11. The removal step S5 is carried out. High ion concentrations of radionuclides in the first elution effluent increase the amount of inorganic adsorbent required to treat all radionuclides. Therefore, when the ion concentration of the radionuclide in the first elution waste liquid is high, it is difficult to significantly reduce the amount of high-dose radioactive waste even if an inorganic adsorbent is used. Therefore, depending on the state of the first elution waste liquid, it is possible to determine whether or not it is inefficient to use the inorganic adsorbent for removing the radionuclide, and the inorganic adsorbent can be used efficiently.

Further, the determination unit 101 determines that the ion concentration has fallen below the reference value Ik when the elapsed time exceeds a predetermined predetermined time Ts. This is because, as shown in FIG. 3, the ion concentration of the radionuclide in the first elution waste liquid sent out through the eluent 3 and the recovery device 5 increases once after the start of the treatment and then decreases significantly. .. Therefore, it is possible to easily determine the case where it is inefficient to use the inorganic adsorbent only by setting the specified time Ts to a time during which the ion concentration of the radionuclide greatly decreases and measuring the elapsed time.

Further, as shown in FIG. 3 described above, the ion concentration of the radionuclide in the first elution waste liquid is high for a certain period of time after the start of the treatment. That is, radionuclides occupy more in the first elution waste liquid than sulfuric acid. On the other hand, when the ion concentration of the radionuclide becomes low after the specified time Ts, sulfuric acid occupies a large amount in the first elution waste liquid as compared with the radionuclide. That is, the amount of the first elution waste liquid itself does not change, but the amount of radionuclides changes significantly.

When such a first elution waste liquid is treated by cement solidification, it is necessary to concentrate the neutralized waste liquid neutralized by the concentrator 15 before cement solidification. However, in order to suppress the precipitation of sodium sulfate, which is the main component of the neutralized waste liquid, the concentration reduction rate must be suppressed to below the solubility of sodium sulfate. As a result, when the waste liquid solidification unit 171 is treated by cement solidification, the amount of radioactive waste after cement solidification is determined by the amount of the first elution waste liquid regardless of the ion concentration of the radionuclide. Therefore, many primary elution effluents must be treated as high dose waste, even if the radionuclide ion concentration is low. Therefore, when it is determined that the value exceeds the reference value Ik, the first elution waste liquid is concentrated in the waste liquid solidification unit 171 and cemented to solidify only the first elution waste liquid having a high ion concentration of the radionuclide. , Only the first elution waste liquid with low ion concentration of radionuclides can be treated with an inorganic adsorbent. This makes it possible to efficiently treat radionuclides and reduce the amount of high-dose radioactive waste.

Further, in the solidification step S7, the solidification unit 17 mixes the inorganic adsorbent and the concentrated waste liquid to be cement solidified. By mixing the solid inorganic adsorbent and the liquid concentrated waste liquid, the volume of the entire mixture is reduced. As a result, the amount of high-dose radioactive waste after cement solidification is reduced.

(Other variants of the embodiment)
Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations thereof in the respective embodiments are examples, and the configurations are added or omitted within a range not deviating from the gist of the present invention. , Replacement, and other changes are possible. Further, the present invention is not limited to the embodiments, but only to the scope of claims.

In the determination step S4 of the present embodiment, the determination unit 101 of the control unit 10 is used, but the present invention is not limited to such a configuration. The determination step S4 may determine whether or not the ion concentration of the radionuclide in the first elution waste liquid has fallen below the reference value Ik. For example, the determination step S4 may be determined by an operator.

Further, in the present embodiment, the switching unit 9 is provided, but the structure is not limited to such a structure. For example, the waste resin treatment system 100 may not have the switching unit 9, and the first elution waste liquid may be directly supplied from the collector 5 to the removal unit 11.

Further, examples of the radionuclide whose ion concentration is determined by the determination unit 101 include cesium, cobalt, strontium, iron, nickel and the like.

100 ... Waste resin treatment system 2 ... Waste resin tank 3 ... Eluent 4 ... Incinerator 5 ... Recovery device 51 ... Receiving room 52 ... Recovery room 53 ... Diffusion dialysis membrane 6 ... Pure water supply section 7 ... Sulfur supply section 8 ... Sulfuric acid Mixer 9 ... Switching unit 10 ... Control unit 101 ... Judgment unit 102 ... Output unit 11 ... Removal unit 12 ... Waste liquid treatment unit 13 ... Neutralization tank 14 ... Neutralizer supply unit 15 ... Concentrator 16 ... Concentrated waste liquid tank 17 ... Solidification section 171 ... Waste liquid solidification section 172 ... Inorganic adsorbent solidification section 201 ... Waste resin delivery line 202 ... Elution-treated resin delivery line 203 ... Receiving room introduction line 204 ... Receiving room delivery line 205 ... Recovery room introduction line 206 ... Recovery room Delivery line 207 ... Sulfur supply line 208 ... Sulfur supply pump 209 ... Removal part introduction line 210 ... Neutralization tank introduction line 211 ... Second elution waste liquid delivery line 212 ... Inorganic adsorbent delivery line 213 ... Neutralization waste liquid introduction line 214 ... Medium Japanese waste liquid pump 215 ... Neutralizer supply line 216 ... Neutralizer pump 217 ... Concentrated waste liquid introduction line 218 ... Concentrated waste liquid pump 219 ... Solidified part introduction line S100 ... Waste resin treatment method S1 ... Elution process S2 ... Incineration process S3 ... Recovery Process S4 ... Judgment process S5 ... Removal process S6 ... Waste liquid treatment process S7 ... Solidification process S71 ... Waste liquid solidification process S72 ... Inorganic adsorbent solidification process Ts ... Specified time

Claims (8)

An elution step in which a sulfuric acid solution is supplied to an ion exchange resin adsorbed with a radionuclide and the radionuclide is eluted from the ion exchange resin.
A recovery step of recovering at least a part of sulfuric acid from the eluent, which is a sulfuric acid solution containing the radionuclide eluted in the elution step, via a diffusion dialysis membrane.
A removal step of passing the first elution waste liquid, which is the eluent from which the sulfuric acid was recovered in the recovery step, through an inorganic adsorbent to remove the radionuclide from the first elution waste liquid.
A waste liquid treatment step of treating the second elution waste liquid which is the first elution waste liquid from which the radionuclides have been removed in the removal step, and a waste liquid treatment step.
An inorganic adsorbent solidification step of cementing the inorganic adsorbent through which the first elution waste liquid was passed in the removal step ,
A determination step of determining whether or not the ion concentration of the radionuclide in the first elution waste liquid has fallen below a predetermined reference value is included.
A waste resin treatment method for carrying out the removal step when it is determined that the value is below the reference value . The waste resin treatment method according to claim 1 , wherein in the determination step, when the elapsed time after performing the recovery step exceeds a predetermined predetermined time, it is determined that the ion concentration has fallen below the reference value. The waste resin treatment method according to claim 1 or 2 , further comprising a waste liquid solidification step of concentrating and cement solidifying the first elution waste liquid when it is determined in the determination step that the value exceeds the reference value. The waste resin treatment method according to claim 3 , wherein the waste liquid solidification step is carried out at the same time as the inorganic adsorbent solidification step, and the inorganic adsorbent and the first elution waste liquid are mixed and then cement solidified. An elution part that elutes the radionuclide from the ion exchange resin to which the sulfuric acid solution is supplied and the radionuclide is adsorbed.
A recovery unit having a diffusion dialysis membrane to which an eluent, which is a sulfuric acid solution containing the radionuclide eluted in the elution unit, is supplied and recovers at least a part of sulfuric acid from the eluent,
An inorganic adsorbent that removes the radionuclide from the first elution waste liquid by supplying the first elution waste liquid which is the eluent from which the sulfuric acid is recovered in the recovery unit and passing water through the first elution waste liquid. With a removal part that has
A waste liquid treatment unit in which the second elution waste liquid, which is the first elution waste liquid from which the radionuclide has been removed, is treated in the removal unit, and a waste liquid treatment unit.
An inorganic adsorbent solidifying section that cements the inorganic adsorbent through which the first elution waste liquid is passed through the removing section ,
A determination unit for determining whether or not the ion concentration of the radionuclide in the first elution waste liquid has fallen below a predetermined reference value, and
A waste resin treatment system including a switching unit for supplying the first elution waste liquid to the removal unit when it is determined that the value is below the reference value . According to claim 5 , the determination unit determines that the ion concentration has fallen below the reference value when the elapsed time, which is the time during which the eluent is supplied to the recovery unit, exceeds a predetermined predetermined time. The waste resin treatment system described. When the determination unit determines that the value exceeds the reference value, the first elution waste liquid is supplied and the concentration unit that concentrates the first elution waste liquid.
The waste resin treatment system according to claim 5 or 6 , further comprising a waste liquid solidifying unit for cementing the first elution waste liquid concentrated in the concentrating unit. The waste resin treatment system according to claim 7 , wherein the waste liquid solidifying unit is provided integrally with the inorganic adsorbent solidifying unit, and cement solidifies a mixture of the inorganic adsorbent and the first elution waste liquid.

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