JPH0564320B2 - - Google Patents
Info
- Publication number
- JPH0564320B2 JPH0564320B2 JP3857284A JP3857284A JPH0564320B2 JP H0564320 B2 JPH0564320 B2 JP H0564320B2 JP 3857284 A JP3857284 A JP 3857284A JP 3857284 A JP3857284 A JP 3857284A JP H0564320 B2 JPH0564320 B2 JP H0564320B2
- Authority
- JP
- Japan
- Prior art keywords
- waste liquid
- iodine
- carbon dioxide
- reprocessing
- evaporator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 52
- 239000007788 liquid Substances 0.000 claims description 49
- 239000002699 waste material Substances 0.000 claims description 43
- 229910052740 iodine Inorganic materials 0.000 claims description 35
- 239000011630 iodine Substances 0.000 claims description 35
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 claims description 34
- 238000000034 method Methods 0.000 claims description 27
- 239000001569 carbon dioxide Substances 0.000 claims description 26
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 26
- 238000001704 evaporation Methods 0.000 claims description 14
- 238000012958 reprocessing Methods 0.000 claims description 14
- 239000010409 thin film Substances 0.000 claims description 13
- 230000008020 evaporation Effects 0.000 claims description 11
- 238000011038 discontinuous diafiltration by volume reduction Methods 0.000 claims description 5
- 239000007789 gas Substances 0.000 description 21
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 239000000843 powder Substances 0.000 description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 8
- 230000007423 decrease Effects 0.000 description 8
- 229910052760 oxygen Inorganic materials 0.000 description 8
- 239000001301 oxygen Substances 0.000 description 8
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 8
- 238000009423 ventilation Methods 0.000 description 7
- 239000003758 nuclear fuel Substances 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 238000012546 transfer Methods 0.000 description 6
- 239000010426 asphalt Substances 0.000 description 5
- 238000000605 extraction Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 230000002285 radioactive effect Effects 0.000 description 4
- 239000004317 sodium nitrate Substances 0.000 description 4
- 235000010344 sodium nitrate Nutrition 0.000 description 4
- 238000007711 solidification Methods 0.000 description 4
- 230000008023 solidification Effects 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000002927 high level radioactive waste Substances 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 235000011121 sodium hydroxide Nutrition 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 229910052778 Plutonium Inorganic materials 0.000 description 2
- 229910052770 Uranium Inorganic materials 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 239000003595 mist Substances 0.000 description 2
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 description 2
- 239000002901 radioactive waste Substances 0.000 description 2
- 239000002915 spent fuel radioactive waste Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000010981 drying operation Methods 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 230000004992 fission Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 150000002496 iodine Chemical class 0.000 description 1
- PNDPGZBMCMUPRI-UHFFFAOYSA-N iodine Chemical compound II PNDPGZBMCMUPRI-UHFFFAOYSA-N 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000013022 venting Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
Landscapes
- Treatment Of Water By Oxidation Or Reduction (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Description
【発明の詳細な説明】
〔発明の利用分野〕
本発明は再処理廃液の減容処理方法に係り、特
にヨウ素含有廃液から、ヨウ素が気相へ放出する
ことを防止するのに適した再処理廃液の減容処理
方法に関するものである。[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for reducing the volume of reprocessed waste liquid, and in particular, a reprocessing method suitable for preventing iodine from being released into the gas phase from iodine-containing waste liquid. The present invention relates to a method for reducing the volume of waste liquid.
原子炉で使用した核燃料中に含まれているウラ
ンおよびプルトニウムを分離回収して、ふたたび
核燃料として使用するのが核燃料の再処理であ
り、現在、湿式法の一つであるPurex法が大部分
の再処理設備で採用されていることは周知のこと
である。第１図にPurex法による再処理工程から
発生する放射性廃液についてのブロツク線図で示
す。Purex法では使用済の核燃料を前処理工程で
数cmの長さに切断し、次にこれを溶解工程で硝酸
に溶解後、分離・抽出工程において、この核燃料
溶解液をミキサセトラーによつてリン酸トリブチ
ル（TBP）と向流接触させ、抽出・洗浄および
逆抽出操作を行ない、核分裂生成成（FP）、ウラ
ンおよびプルトニウムに分離するものである。
Nuclear fuel reprocessing involves separating and recovering the uranium and plutonium contained in the nuclear fuel used in a nuclear reactor and reusing it as nuclear fuel.Currently, the Purex method, which is a wet method, is used in most cases. It is well known that it is used in reprocessing facilities. Figure 1 shows a block diagram of the radioactive waste liquid generated from the reprocessing process using the Purex method. In the Purex method, spent nuclear fuel is cut into lengths of several centimeters in a pretreatment process, then dissolved in nitric acid in a dissolution process, and the nuclear fuel solution is rinsed using a mixer settler in a separation and extraction process. It is brought into countercurrent contact with tributyl acid (TBP), performs extraction, cleaning, and back extraction operations to separate fission products (FP), uranium, and plutonium.
さて、抽出・分離工程から高レベルと中レベル
の２つの廃液が主に発生する。高レベル廃液の発
生量は燃料１トン当り約10m3でこの中に106Ciも
の高い放射能が含まれている。これは核燃料中の
99.9％以上のFPがこの廃液に含まれているため
である。高レベル廃液につては放射能が高く、ま
た、固化法が実用化されていないので、蒸発器で
濃縮後高レベル廃液貯蔵タンクに貯蔵されてい
る。抽出・分離工程で使用したTBPなどの溶媒
は放射線損傷を受け、性能が低下するので、苛性
ソーダなどのアルカリを用い洗浄処理を行ない再
使用される。洗浄後の苛性ソーダは硝酸とともに
中レベル廃液に含まれる。苛性ソーダと硝酸の反
応により硝酸ソーダが生成するため中レベル廃液
の主成分は硝酸ソーダとなる。また、この廃液中
には放射性ヨウ素が含まれる。中レベル廃液の発
生量は核燃料１トン当り約50m3であり、この中に
約0.1mol／の硝酸ソーダおよび約102Ciの放射
能が含まれている。中レベル廃液は、例えばアス
フアルト固化法で処理される。こ固化法は約150
℃に加熱したアスフアルトと廃液をそれぞれ混合
し、水分を蒸発させ、アスフアルト固化体をつく
る方法である。廃液中に含まれるヨウ素は揮発性
であるため、蒸発過程で水分とともにガス系へ移
動する。ガス系にはヨウ素除去用フイルターが設
けられているが、多量のヨウ素が混入するためフ
イルターの容量を大きくしたり、あるいはフイル
ター交換頻度を高めている。 Two types of waste liquids, high level and medium level, are mainly generated from the extraction/separation process. The amount of high-level waste liquid generated is approximately 10 m 3 per ton of fuel, and this contains radioactivity as high as 10 6 Ci. This is in nuclear fuel
This is because more than 99.9% of FP is contained in this waste liquid. High-level waste liquid has high radioactivity and solidification methods have not been put to practical use, so it is concentrated in an evaporator and then stored in a high-level waste liquid storage tank. Solvents such as TBP used in the extraction and separation process are damaged by radiation and their performance deteriorates, so they are cleaned with an alkali such as caustic soda and reused. After washing, caustic soda is included in the medium-level waste liquid along with nitric acid. Sodium nitrate is produced by the reaction between caustic soda and nitric acid, so the main component of medium-level wastewater is sodium nitrate. This waste liquid also contains radioactive iodine. The amount of medium-level waste liquid generated is approximately 50 m 3 per ton of nuclear fuel, and this contains approximately 0.1 mol of sodium nitrate and approximately 10 2 Ci of radioactivity. Medium-level waste liquid is treated, for example, by an asphalt solidification method. The solidification method is about 150
This method creates solidified asphalt by mixing asphalt heated to ℃ and waste liquid, evaporating water, and creating solidified asphalt. Since the iodine contained in the waste liquid is volatile, it moves into the gas system along with moisture during the evaporation process. The gas system is equipped with a filter for removing iodine, but because a large amount of iodine gets mixed in, the capacity of the filter must be increased or the filter must be replaced more frequently.
本発明の目的は、上記の従来技術の欠点をなく
し、ヨウ素含有廃液からヨウ素が気相中へ放出す
ることを低減する再処理廃液減容処理方法を提供
することである。
An object of the present invention is to provide a volume reduction treatment method for reprocessing waste liquid that eliminates the above-mentioned drawbacks of the prior art and reduces the release of iodine from the iodine-containing waste liquid into the gas phase.
上記目的を達成するため、本発明は、再処理工
程から排出されるヨウ素含有廃液を蒸発処理する
蒸発設備を用いて行う再処理廃液減容処理方法に
おいて、当該蒸発設備を炭酸ガス濃度が20％以上
とな雰囲気下で操作するものである。
In order to achieve the above object, the present invention provides a method for reducing the volume of reprocessing waste liquid using evaporation equipment that evaporates iodine-containing waste liquid discharged from a reprocessing process, in which the evaporation equipment has a carbon dioxide concentration of 20%. It is operated under the above atmosphere.
本願発明者等の検討によれば、ヨウ素含有廃液
から気相中へ放出するヨウ素放出率は、蒸発設備
内の炭酸ガス濃度の増大に伴い減少し、炭酸ガス
濃度が20％以上になると炭酸ガス濃度が０％のと
きの約0.1とほぼ一定となることが分かつた。し
たがつて、本発明によれば、ヨウ素の気相中への
放出量が従来の約1/10に低減する。 According to studies by the inventors of the present application, the rate of iodine release from iodine-containing waste liquid into the gas phase decreases as the carbon dioxide concentration in the evaporation equipment increases, and when the carbon dioxide concentration exceeds 20%, the rate of iodine release into the gas phase decreases. It was found that the value is approximately constant at about 0.1 when the concentration is 0%. Therefore, according to the present invention, the amount of iodine released into the gas phase is reduced to about 1/10 of the conventional amount.
以下、本発明を図面に基づいて詳細に説明す
る。
Hereinafter, the present invention will be explained in detail based on the drawings.
蒸発器として従来使用されている遠心薄膜蒸発
器を用いて処理する場合について述べる。第２図
は遠心薄膜蒸発器の一部断面図である。遠心薄膜
蒸発器の動作原理について第２図で説明する。放
射性廃液は廃液供給口４から遠心薄膜蒸発器１の
容器内に導入され、デイストリビユータ５によつ
て蒸発器の容量の伝熱面７に一様に配分される。
このデイストリビユータ５は蒸発器の中央に設け
られた回転軸８と、これに取付けられた可動式の
ブレード９と回転軸の駆動モータ２とからなる。
ブレード９は容器壁に近接して回転軸８に取付け
られており、回転にともなう遠心力により外側に
広がつて容器壁に接するようになつている。伝熱
面７上を重力によつて垂直に落下する廃液は、伝
熱面７上に液膜を形成し、容器壁外側の加熱ジヤ
ケツト６からの熱によつて加熱され、蒸発乾燥さ
れる。加熱ジヤケツト６の熱媒としては、例えば
高圧の蒸気が用いられる。上記ブレード９は、回
転とともに容器壁の伝熱面７上に付着したスケー
ルを除去する。廃液は乾燥した粉体にまで濃縮さ
れ、生成した粉体は遠心薄膜蒸発器１下端の粉体
取出口１０から取り出される。また、廃液の蒸発
により発生した蒸気は、遠心薄膜蒸発器１の上部
にある蒸気出口３から排出され、凝縮器に導びか
れる。凝縮器で蒸気は水に戻されて再使用され
る。上述のようにブレード９は、伝熱面７のスケ
ール除去と、伝熱面７での熱交換の促進という２
つの効果を有する。このため、遠心薄膜蒸発器１
はコンパクトで信頼性の高い蒸発器となつてい
る。 A case will be described in which a centrifugal thin film evaporator, which is conventionally used as an evaporator, is used for processing. FIG. 2 is a partial cross-sectional view of a centrifugal thin film evaporator. The operating principle of the centrifugal thin film evaporator will be explained with reference to FIG. The radioactive waste liquid is introduced into the container of the centrifugal thin film evaporator 1 through the waste liquid supply port 4 and is uniformly distributed over the heat transfer surface 7 of the evaporator volume by the distributor 5.
The distributor 5 consists of a rotating shaft 8 provided at the center of the evaporator, a movable blade 9 attached to the rotating shaft 8, and a drive motor 2 for the rotating shaft.
The blade 9 is attached to the rotating shaft 8 in close proximity to the container wall, and is expanded outward by the centrifugal force caused by rotation to come into contact with the container wall. The waste liquid falling vertically on the heat transfer surface 7 by gravity forms a liquid film on the heat transfer surface 7, which is heated by heat from the heating jacket 6 outside the container wall and evaporated to dryness. As the heating medium for the heating jacket 6, for example, high pressure steam is used. The blade 9 removes scale deposited on the heat transfer surface 7 of the container wall as it rotates. The waste liquid is concentrated to a dry powder, and the generated powder is taken out from the powder outlet 10 at the lower end of the centrifugal thin film evaporator 1. Further, the steam generated by the evaporation of the waste liquid is discharged from the steam outlet 3 located at the top of the centrifugal thin film evaporator 1 and guided to the condenser. The steam is converted back to water in the condenser and reused. As mentioned above, the blade 9 serves two purposes: removing scale from the heat transfer surface 7 and promoting heat exchange on the heat transfer surface 7.
It has two effects. For this reason, the centrifugal thin film evaporator 1
is a compact and reliable evaporator.
次に、本発明の一実施例を第３図によつて説明
する。この図において、１１は廃液タンク、１２
は造粒機、１３は炭酸ガスボンベ、１４はミスト
セパレータ、１５は凝縮器、１６はヨウ素フイル
ター、１７はブロア、１８はグローブボツクス、
１９はドラム缶、２０は定量ポンプである。 Next, one embodiment of the present invention will be described with reference to FIG. In this figure, 11 is a waste liquid tank, 12
is a granulator, 13 is a carbon dioxide gas cylinder, 14 is a mist separator, 15 is a condenser, 16 is an iodine filter, 17 is a blower, 18 is a glove box,
19 is a drum, and 20 is a metering pump.
再処理工程から発生する中レベル廃液は廃液タ
ンク１１に送られる。この廃液は硝酸ナトリウム
を主成分（濃度約30Wt％）とし放射性ヨウ素が
約10-3μCi／c.c.含まれている。廃液タンク内の溶
液は定量ポンプ２０により遠心薄膜蒸発器１に注
入され、加熱ジヤケツトから熱を与えられて蒸発
乾燥する。蒸発器内の圧力は放射能のリークを防
ぐためブロア１７で負圧に保たれている。蒸気は
ミストセパレータ１４、凝縮器１５で凝縮水とし
て回収される。凝縮器出口のガスはヨウ素フイル
ターを介し、放出される。薄膜蒸発器１内での蒸
発乾燥の操作は第２図で説明したとおりである。
生成したNaNO3乾燥粉末は自重で粉体取出口１
０から排出される。この粉末は造粒器１２でアー
モンド型のペレツトに固められた後グローブボツ
クス１８に収納されドラム缶に充填される。 Medium level waste liquid generated from the reprocessing process is sent to waste liquid tank 11. This waste liquid mainly consists of sodium nitrate (concentration approximately 30Wt%) and contains approximately 10 -3 μCi/cc of radioactive iodine. The solution in the waste liquid tank is injected into the centrifugal thin film evaporator 1 by the metering pump 20, and is evaporated to dryness by being given heat from the heating jacket. The pressure inside the evaporator is maintained at negative pressure by a blower 17 to prevent leakage of radioactivity. The steam is collected by a mist separator 14 and a condenser 15 as condensed water. The gas at the condenser outlet passes through an iodine filter and is released. The evaporative drying operation in the thin film evaporator 1 is as explained in FIG.
The generated NaNO 3 dry powder flows through the powder outlet 1 under its own weight.
Ejected from 0. This powder is solidified into almond-shaped pellets in a granulator 12, then stored in a glove box 18 and filled into drums.
さて、廃液を約１時間蒸発処理した後、ヨウ素
フイルター１６に捕集された放射性ヨウ素量を
NaIシンチレーダで測定した。その結果、このヨ
ウ素は廃液中に含まれているヨウ素量とほぼ等し
いことがわかつた。すなわち廃液中のヨウ素は器
内で揮発し、換気系へ流出したものである。 Now, after evaporating the waste liquid for about an hour, the amount of radioactive iodine collected in the iodine filter 16 is calculated.
Measured with NaI scintillator. As a result, it was found that this iodine was almost equal to the amount of iodine contained in the waste liquid. In other words, the iodine in the waste liquid was volatilized within the vessel and leaked into the ventilation system.
次に、炭酸ガスボンベ１３から蒸発器内に炭酸
ガスを供給し、系内を炭酸ガスの雰囲気下にして
廃液の蒸発処理を行つた。先と同様にして換気系
へ流出するヨウ素量を測定した。なお、試験には
バルブ２０の開度を調整し、系内の炭酸ガス濃度
を変えて実施した。第４図にその結果を示す。本
図よりヨウ素放出率は蒸発器内の炭酸ガス濃度の
増大にともない減少し、炭酸ガス濃度が20％以上
で約0.1とほぼ一定になることがわかつた。この
理由は次のように考えられる。水溶液中における
ヨウ素の反応平衡は次式で表わされる。 Next, carbon dioxide gas was supplied from the carbon dioxide gas cylinder 13 into the evaporator, and the inside of the system was brought into a carbon dioxide atmosphere to perform evaporation treatment of the waste liquid. The amount of iodine flowing into the ventilation system was measured in the same manner as before. The test was conducted by adjusting the opening degree of the valve 20 and changing the carbon dioxide concentration in the system. Figure 4 shows the results. This figure shows that the iodine release rate decreases as the carbon dioxide concentration in the evaporator increases, and becomes almost constant at approximately 0.1 when the carbon dioxide concentration is 20% or higher. The reason for this is thought to be as follows. The reaction equilibrium of iodine in an aqueous solution is expressed by the following equation.
I2＋H2O2H+＋2I-＋１／２O2 ……(1)
すなわち廃液中にはI2とI-イオンが共存してい
る。廃液中には溶存酸素があるため(1)式の反応は
左に進み、ヨウ素はI2の化学形態が多い。一方、
炭酸ガス雰囲気下になると、炭酸ガスが廃液に溶
け込み溶存酸素量が低下する。即ち、溶液中の溶
存酸素濃度は気相中の酸素濃度と一定の関係にあ
り、気相中の酸素濃度が下がれば溶液中の酸素濃
度も下がる。これはヘンリーの法則として良く知
られている。この法則は、ガスの種類に依存しな
いので、炭酸ガス雰囲気になれば溶液中に炭酸ガ
スが溶け込む。したがつて、炭酸ガスの雰囲気に
なることは気相中の炭酸ガス濃度が増大し酸素濃
度が低下することであり、溶液中の炭酸ガス量が
多くなり酸素量が少なくなる。この場合には(1)式
の反応は右に進みヨウ素はI-の化学形態をとる。
廃液中の主成分はNaNO3であるのでI-イオンは
Na+イオンと反応しNaIとなる。NaIはI2に比し
て揮発しにくい。したがつて、蒸発器内を炭酸ガ
ス雰囲気下にすることにより、ヨウ素は粉体中に
回収され、気相中への放出量が低下すると考えら
れる。粉体の一部が換気系へ流出することはさけ
られない。炭酸ガス濃度が20％以上の領域でヨウ
素除去率が0.1と一定である理由は粉体の一部が
換気系へ流出したものと考えられる。 I 2 +H 2 O2H + +2I - +1/2O 2 ...(1) That is, I 2 and I - ions coexist in the waste liquid. Since there is dissolved oxygen in the waste liquid, the reaction in equation (1) proceeds to the left, and iodine is mostly in the I 2 chemical form. on the other hand,
In a carbon dioxide atmosphere, carbon dioxide dissolves in the waste liquid and the amount of dissolved oxygen decreases. That is, the dissolved oxygen concentration in the solution has a certain relationship with the oxygen concentration in the gas phase, and as the oxygen concentration in the gas phase decreases, the oxygen concentration in the solution also decreases. This is well known as Henry's law. This law does not depend on the type of gas, so if there is a carbon dioxide atmosphere, carbon dioxide will dissolve into the solution. Therefore, creating an atmosphere of carbon dioxide gas means that the carbon dioxide concentration in the gas phase increases and the oxygen concentration decreases, and the amount of carbon dioxide gas in the solution increases and the amount of oxygen decreases. In this case, the reaction in equation (1) proceeds to the right and iodine takes the chemical form I - .
Since the main component in the waste liquid is NaNO 3 , I - ions are
Reacts with Na + ions to form NaI. NaI is less volatile than I2 . Therefore, it is considered that by creating a carbon dioxide atmosphere in the evaporator, iodine is recovered in the powder and the amount released into the gas phase is reduced. It is unavoidable that some of the powder will escape into the ventilation system. The reason why the iodine removal rate remained constant at 0.1 in the area where the carbon dioxide concentration was 20% or more is thought to be that some of the powder leaked into the ventilation system.
以上のことから、蒸発器内濃度20％以上の炭酸
ガス雰囲気下で操作することによりヨウ素の換気
系への放出量を従来法の約1/10に低減できる。し
たがつて、ヨウ素フイルターの容量を小さくでき
るとともにフイルタの交換頻度を少なくできる。 From the above, the amount of iodine released into the ventilation system can be reduced to about 1/10 of the conventional method by operating in a carbon dioxide atmosphere with a concentration of 20% or more in the evaporator. Therefore, the capacity of the iodine filter can be reduced and the frequency of filter replacement can be reduced.
廃液タンクはNaNO3濃度を均一にするため撹
拌が行なわれる。炭酸ガスを廃液タンク下部に通
気してバブリングを行い、その後炭酸ガスを蒸発
器に通気すれば、ヨウ素の撹拌機が不要となる効
果も新たに生ずる。また、本実施例では蒸発設備
として遠心薄膜蒸発器について述べたが、アスフ
アルト固化に用いられる混でい式蒸発器について
も同様に実施できる。 The waste liquid tank is stirred to make the NaNO 3 concentration uniform. By ventilating carbon dioxide gas into the lower part of the waste liquid tank to perform bubbling, and then venting the carbon dioxide gas into the evaporator, a new effect will be created that an iodine stirrer will no longer be necessary. Further, in this embodiment, a centrifugal thin film evaporator was described as the evaporation equipment, but the same method can be applied to a mixed evaporator used for asphalt solidification.
本発明によれば放射性ヨウ素の換気系への放出
量が従来法の約1/10となるため、換気系に設けら
れるヨウ素フイルターの容量が小さくなる。ま
た、フイルターの交換頻度が著しく低下する。
According to the present invention, the amount of radioactive iodine released into the ventilation system is about 1/10 that of the conventional method, so the capacity of the iodine filter provided in the ventilation system is reduced. Additionally, the frequency of filter replacement is significantly reduced.
第１図は使用済燃料再処理の廃液発生工程を示
すブロツク図、第２図は遠心薄膜蒸発器の断面を
示す図、第３図は本発明の一実施例を示す系統
図、第４図は蒸発器内炭酸ガス濃度と気相中への
ヨウ素放出率との関係を示す線図である。
１…遠心薄膜蒸発器、１１…廃液タンク、１３
…炭酸ガスボンベ。
Fig. 1 is a block diagram showing the waste liquid generation process of spent fuel reprocessing, Fig. 2 is a cross-sectional view of a centrifugal thin film evaporator, Fig. 3 is a system diagram showing an embodiment of the present invention, and Fig. 4 is a diagram showing the relationship between the carbon dioxide concentration in the evaporator and the iodine release rate into the gas phase. 1... Centrifugal thin film evaporator, 11... Waste liquid tank, 13
...carbon dioxide cylinder.
Claims (1)
蒸発処理する蒸発設備を用いて行う再処理廃液減
容処理方法において、当該蒸発設備を炭酸ガス濃
度が20％以上となる雰囲気下で操作することを特
徴とする再処理廃液減容処理方法。 ２ 特許請求の範囲第１項に記載の再処理廃液減
容処理方法において、当該ヨウ素含有廃液を炭酸
ガスを用いて攪拌後、これを当該蒸発設備に導入
することを特徴とする再処理廃液減容処理方法。 ３ 特許請求の範囲第２項記載の再処理廃液減容
処理方法において、当該蒸発設備として遠心薄膜
蒸発器を用いることを特徴とする再処理廃液減容
処理方法。[Scope of Claims] 1. In a reprocessing waste liquid volume reduction treatment method performed using evaporation equipment for evaporating iodine-containing waste liquid discharged from a reprocessing process, the evaporation equipment is placed in an atmosphere where the carbon dioxide concentration is 20% or more. A reprocessing waste liquid volume reduction treatment method characterized by operating under 2. The reprocessing waste liquid volume reduction treatment method according to claim 1, characterized in that the iodine-containing waste liquid is stirred using carbon dioxide gas and then introduced into the evaporation equipment. Treatment method. 3. A reprocessing waste liquid volume reduction treatment method according to claim 2, characterized in that a centrifugal thin film evaporator is used as the evaporation equipment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59038572A JPS60183596A (en) | 1984-03-02 | 1984-03-02 | Reprocessing waste liquor volume reducing treating method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59038572A JPS60183596A (en) | 1984-03-02 | 1984-03-02 | Reprocessing waste liquor volume reducing treating method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60183596A JPS60183596A (en) | 1985-09-19 |
| JPH0564320B2 true JPH0564320B2 (en) | 1993-09-14 |
Family
ID=12529002
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59038572A Granted JPS60183596A (en) | 1984-03-02 | 1984-03-02 | Reprocessing waste liquor volume reducing treating method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60183596A (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57110999A (en) * | 1980-12-27 | 1982-07-10 | Nippon Atomic Ind Group Co | Method of solidifying radioactive waste |
-
1984
- 1984-03-02 JP JP59038572A patent/JPS60183596A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57110999A (en) * | 1980-12-27 | 1982-07-10 | Nippon Atomic Ind Group Co | Method of solidifying radioactive waste |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60183596A (en) | 1985-09-19 |
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