JP3145176B2 - Removal method of radioactive iodine in radioactive waste liquid - Google Patents
Removal method of radioactive iodine in radioactive waste liquidInfo
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- JP3145176B2 JP3145176B2 JP10472992A JP10472992A JP3145176B2 JP 3145176 B2 JP3145176 B2 JP 3145176B2 JP 10472992 A JP10472992 A JP 10472992A JP 10472992 A JP10472992 A JP 10472992A JP 3145176 B2 JP3145176 B2 JP 3145176B2
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- iodine
- radioactive
- concentration
- waste liquid
- radioactive iodine
- Prior art date
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、放射性廃液中の放射性
ヨウ素の除去方法に係り、特に核燃料再処理プラント又
は原子力発電プラントにおける放射性廃液中の放射性ヨ
ウ素の除去効率（除染係数）を高めるための放射性廃液
中の放射性ヨウ素の除去方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to radioactive
Radioactive liquid waste to increase the removal efficiency of radioactive iodine iodine relates to a method of removing the element, especially in put that radioactive waste nuclear fuel reprocessing plants or nuclear power plants (decontamination factor)
The present invention relates to a method for removing radioactive iodine from the inside .
【０００２】[0002]
【従来の技術】従来の低レベル放射性廃液中のヨウ素の
除去方法は、特開昭６２−２７６４９９号及び特開昭５
５−８３８９４号各公報に示すように、放射性ヨウ素を
含む溶液中、或いは放射性ヨウ素を含む雰囲気中に、ヨ
ウ素の沈殿化剤である硝酸銀または硝酸タリウムだけを
注入または噴霧のかたちで添加し、下記の反応により沈
殿を生成させて、放射性ヨウ素を除去するものであっ
た。2. Description of the Related Art Conventional methods for removing iodine from low-level radioactive waste liquid are disclosed in Japanese Patent Application Laid-Open Nos.
As disclosed in JP-A-5-83894, only silver nitrate or thallium nitrate, which is a precipitating agent for iodine, is injected or sprayed into a solution containing radioactive iodine or an atmosphere containing radioactive iodine. A precipitate was formed by the reaction of (1) to remove radioactive iodine.
【０００３】３Ｉ- ＋３ＡｇＮＯ3 →２ＡｇＩ＋ＡｇＩ
Ｏ3 ＋３ＮＯ２ 3I − + 3AgNO 3 → 2AgI + AgI
O 3 + 3NO 2
【０００４】[0004]
【発明が解決しようとする課題】上記の従来方法では、
高い放射性ヨウ素除去効率（除染係数）を得るために
は、沈殿化剤の添加量を増やさねばならない。殊に、沈
殿化剤と反応しやすい陰イオンを生成する共存物質が存
在する場合には、さらに沈殿化剤の添加量を増やさねば
ならない。さらに、ヨウ素濃度が低い場合には、沈殿化
剤の添加量を増やしても放射性ヨウ素除去効率（除染係
数）はある値以上には上がらなくなることが確認されて
いる。これらの事について下記に説明する。In the above conventional method,
In order to obtain high radioiodine removal efficiency (decontamination coefficient), the amount of the precipitating agent added must be increased. In particular, when there is a coexisting substance that generates an anion that easily reacts with the precipitant, the amount of the precipitant must be further increased. Furthermore, it has been confirmed that when the iodine concentration is low, even if the amount of the precipitating agent added is increased, the radioactive iodine removal efficiency (decontamination coefficient) does not exceed a certain value. These are described below.
【０００５】ヨウ素濃度１０００ｐｐｍ，操作ｐＨ１
０，室温，硝酸溶液中という条件での試験データから
は、沈殿化剤（硝酸銀）添加量を０．００８ｍｏｌ／リ
ットルから０．０８ｍｏｌ／リットルに（１０倍に）増
やすことで、ヨウ素除去効率（除染係数）を１．５から
３．５に（２．３倍に）上げられるとの結果が得られて
いる。[0005] Iodine concentration 1000 ppm, operating pH 1
From the test data under the conditions of 0, room temperature, and in a nitric acid solution, increasing the amount of the precipitating agent (silver nitrate) from 0.008 mol / L to 0.08 mol / L (10 times) shows that the iodine removal efficiency ( Decontamination coefficient) can be increased from 1.5 to 3.5 (2.3 times).
【０００６】しかし、上記条件で、沈殿化剤と反応しや
すい陰イオンを生成する共存物質の一つであるリン酸ナ
トリウムを２０ｇ／リットル添加すると、沈殿化剤（硝
酸銀）添加量を０．００１ｍｏｌ／リットルから０．０
７６ｍｏｌ／リットルに（７６倍に）増やしてもヨウ素
除去効率（除染係数）に有意差がみられないとの結果が
得られている。However, under the above conditions, when 20 g / liter of sodium phosphate, which is one of the coexisting substances which generate anions which easily reacts with the precipitating agent, is added, the amount of the precipitating agent (silver nitrate) added becomes 0.001 mol. / Liter to 0.0
The results show that no significant difference was observed in the iodine removal efficiency (decontamination coefficient) even when the concentration was increased to 76 mol / liter (by 76 times).
【０００７】また、上記条件で、ヨウ素濃度が１００ｐ
ｐｍに下がると、沈殿化剤（硝酸銀）添加量を０．００
８ｍｏｌ／リットルから０．０６ｍｏｌ／リットルに
（７．５倍に）増やしてもヨウ素除去効率（除染係数）
に有意差がみられないとの結果が得られている。Under the above conditions, the iodine concentration is 100 p
pm, the amount of the precipitating agent (silver nitrate) added is reduced to 0.00.
Iodine removal efficiency (decontamination coefficient) even when increased from 8 mol / L to 0.06 mol / L (7.5 times)
Has no significant difference in the results.
【０００８】以上のことから、前記の従来方法は下記の
３点の問題点を抱えていることがわかる。 高い放射性ヨウ素除去効率（除染係数）を得るため
には、沈殿化剤の添加量を増やさねばならず、廃棄物発
生量の増大を招く。 沈殿化剤と反応しやすい陰イオンを生成する共存物
質が存在する場合には、さらに沈殿化剤の添加量を増や
さねばならず、さらに廃棄物発生量の増大を招く。 ヨウ素濃度が低い場合には、沈殿化剤を加えても放
射性ヨウ素除去効率（除染係数）がある値以上に上がら
なくなるので、溶液中の放射性ヨウ素濃度によっては、
十分な除染係数が得られないことがある。From the above, it can be understood that the above-mentioned conventional method has the following three problems. In order to obtain a high radioactive iodine removal efficiency (decontamination coefficient), the amount of the precipitant must be increased, which leads to an increase in the amount of waste generated. If there is a coexisting substance that produces an anion that easily reacts with the precipitating agent, the amount of the precipitating agent must be further increased, which further increases the amount of waste generated. When the concentration of iodine is low, the removal efficiency of radioactive iodine (decontamination coefficient) does not increase beyond a certain value even if a precipitating agent is added, so depending on the concentration of radioactive iodine in the solution,
A sufficient decontamination coefficient may not be obtained.
【０００９】本発明は、放射性ヨウ素の除去効率を向上
できる放射性廃液中の放射性ヨウ素の除去方法を提供す
ることを目的とする。The present invention improves the removal efficiency of radioactive iodine.
It is an object of the present invention to provide a method for removing radioactive iodine in a radioactive waste liquid .
【００１０】[0010]
【課題を解決するための手段】本発明による低レベル放
射性廃液中のヨウ素の除去方法は、特許請求の範囲の請
求項１に記載された特徴を有する。Method of removing iodine low level radioactive liquid waste according to the present invention SUMMARY OF] has the features set forth in the 請 <br/> Motomeko 1 the claims.
【００１１】放射性ヨウ素の除去効率を向上できる放射
性廃液中の放射性ヨウ素の除去方法として本発明に先行
する発明（以下「先行発明」という）は、放射性ヨウ素
を含有する放射性廃液中に非放射性ヨウ素を添加し、そ
の後、該廃液にヨウ素沈殿化剤を供給してヨウ素を沈殿
物として除去することを特徴とするものであるが、該先
行発明においては、放射性ヨウ素を含む低レベル放射性
廃液中に非放射性ヨウ素を添加することにより、放射性
ヨウ素の量を増やすことなく、ヨウ素濃度を上げている
（同位体希釈効果）。 Radiation that can improve the removal efficiency of radioactive iodine
Prior to the present invention as a method for removing radioactive iodine from ionic wastewater
(Hereinafter referred to as "prior invention") is radioactive iodine.
Non-radioactive iodine is added to radioactive waste liquid containing
After that, an iodine precipitating agent is supplied to the waste liquid to precipitate iodine.
It is characterized in that it is removed as an object.
In the present invention , the concentration of iodine is increased without increasing the amount of radioactive iodine by adding non-radioactive iodine to a low-level radioactive waste liquid containing radioactive iodine (isotope dilution effect).
【００１２】ヨウ素の除去効率は、処理前の溶液中に存
在するヨウ素濃度と処理後の溶液中の残留ヨウ素濃度の
比として表される。放射性ヨウ素の除去効率、即ち除染
係数は、処理前の溶液中に存在する放射性ヨウ素濃度と
処理後の溶液中の残留放射性ヨウ素濃度の比として表さ
れる。The iodine removal efficiency is expressed as the ratio of the concentration of iodine present in the solution before treatment to the concentration of residual iodine in the solution after treatment. The removal efficiency of radioactive iodine, ie, the decontamination coefficient, is expressed as the ratio of the concentration of radioactive iodine present in the solution before treatment to the concentration of residual radioactive iodine in the solution after treatment.
【００１３】従来プロセスでは、処理前の廃液中に存在
するヨウ素は放射性ヨウ素だけであるので、沈殿反応に
よるヨウ素の除去効率がそのまま放射性ヨウ素の除去効
率となる。In the conventional process, the only iodine present in the waste liquid before the treatment is radioactive iodine. Therefore, the efficiency of removing iodine by the precipitation reaction is the same as the efficiency of removing radioactive iodine.
【００１４】これに対して、前記した先行発明では、沈
殿反応前の廃液中には、該廃液中に元々存在していた放
射性ヨウ素の他に、添加した非放射性ヨウ素が存在する
ので、除染係数は処理前の廃液中に存在する放射性ヨウ
素濃度と共沈反応後の廃液中の残留放射性ヨウ素濃度の
比として表される。On the other hand, in the above-mentioned prior invention , the non-radioactive iodine added in addition to the radioactive iodine originally present in the waste liquid before the precipitation reaction contains decontamination. The coefficient is expressed as the ratio of the concentration of radioactive iodine present in the waste liquid before the treatment to the concentration of the residual radioactive iodine in the waste liquid after the coprecipitation reaction.
【００１５】ここで共沈反応とは、溶質（ここでは放射
性ヨウ素）が低濃度であって沈殿生成反応が活発でない
場合に、溶質と同じ成分（ここでは非放射性ヨウ素）を
添加して溶質濃度を上げ、沈殿生成反応が活発に起こる
状態にすることで、低濃度時の沈殿による除去効率より
も高い除去効率を得るものである。Here, the coprecipitation reaction means that when the solute (here, radioactive iodine) is low in concentration and the precipitation formation reaction is not active, the same component as the solute (here, non-radioactive iodine) is added and the solute concentration is added. By increasing the concentration to a state in which the precipitation generation reaction actively occurs, a higher removal efficiency than the removal efficiency by precipitation at a low concentration is obtained.
【００１６】上記のような作用により、非放射性ヨウ素
を添加して、放射性ヨウ素量を増やすことなくヨウ素濃
度を上げたことによる共沈反応の効果により、放射性ヨ
ウ素の除去効率（除染係数）が向上する。By the above-mentioned action, the non-radioactive iodine is added, and the iodine concentration is increased without increasing the amount of radioactive iodine. improves.
【００１７】本発明の特許請求の範囲の請求項１に記載
の方法では、非放射性ヨウ素の添加を、放射性ヨウ素が
低レベル放射性廃液中から揮発した気体の状態にて行な
い、その結果の放射性ヨウ素と非放射性ヨウ素との混合
気体を、その後、共存物質を含まない硝酸溶液中に再溶
解させている。In the method according to claim 1 of the present invention, the non-radioactive iodine is added in a gaseous state in which radioactive iodine is volatilized from a low-level radioactive waste liquid. The resulting gas mixture of radioactive iodine and non-radioactive iodine is then redissolved in a nitric acid solution that does not contain coexisting substances.
【００１８】一般に複数の成分からなる気体の溶液中へ
の溶解度は、各物質のモル分率と圧力に応じた分圧、及
び溶液自体の飽和度によって決まる。In general, the solubility of a gas composed of a plurality of components in a solution is determined by the molar fraction of each substance, the partial pressure according to the pressure, and the degree of saturation of the solution itself.
【００１９】従って、請求項１に記載の方法では、廃液
中から放射性ヨウ素を揮発させ、非放射性ヨウ素を添加
してヨウ素分圧を上げた状態で、他の共存物質が含まれ
ない飽和度の低い硝酸溶液に再溶解させることによっ
て、硝酸溶液へのヨウ素の溶解度を処理前の廃液中での
溶解度より高くして、ヨウ素濃度を上げることができ
る。この作用と、前記の請求項１について述べた作用の
相乗効果により、廃液中からの放射性ヨウ素の除去効率
（除染係数）が向上する。Accordingly, in the method according to the first aspect, the radioactive iodine is volatilized from the waste liquid, and the non-radioactive iodine is added to increase the iodine partial pressure. By redissolving in a low nitric acid solution, the solubility of iodine in the nitric acid solution can be made higher than that in the waste liquid before the treatment, and the iodine concentration can be increased. By the synergistic effect of this action and the action described in claim 1, the efficiency of removing radioactive iodine from the waste liquid (decontamination coefficient) is improved.
【００２０】[0020]
【実施例】低レベル放射性廃液から放射性ヨウ素を除去
するプロセスの先行発明の実施例を図１により説明す
る。低レベル放射性廃液は低レベル放射性廃液供給ライ
ン１から反応槽２へ供給される。反応槽２の中で、まず
ヨウ化ナトリウム供給ライン３から非放射性ヨウ素イオ
ンを添加するためにヨウ化ナトリウムが供給され、廃液
中のヨウ素濃度を上昇させる。次に硝酸銀供給ライン４
から沈殿化剤として硝酸銀が供給され、廃液中の放射性
ヨウ素及び非放射性ヨウ素との間で沈殿を生成する。こ
のとき、前述の共沈反応の効果により、ヨウ素濃度が低
い状態での沈殿発生によるヨウ素除去効率よりも高いヨ
ウ素除去効率が得られる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the prior invention of a process for removing radioactive iodine from a low-level radioactive liquid waste will be described with reference to FIG. The low-level radioactive liquid waste is supplied from the low-level radioactive liquid supply line 1 to the reaction tank 2. In the reaction tank 2, sodium iodide is first supplied from a sodium iodide supply line 3 for adding non-radioactive iodine ions, and the iodine concentration in the waste liquid is increased. Next, silver nitrate supply line 4
Supplies silver nitrate as a precipitating agent to generate a precipitate between radioactive iodine and non-radioactive iodine in the waste liquid. At this time, due to the effect of the above-mentioned coprecipitation reaction, iodine removal efficiency higher than the iodine removal efficiency due to the occurrence of precipitation at a low iodine concentration is obtained.
【００２１】反応槽２内の沈殿生成物を含む廃液は、供
給槽５、ポンプ６を経てフィルタ７へ送られ、沈殿生成
物と濾過液に分離される。濾過液は濾過液送液ライン８
から次の処理工程に送られ、他方、沈殿生成物は沈殿生
成物再循環ライン９から供給槽５へ戻され、最終的には
沈殿生成物排出ライン１０から廃棄物固化処理工程に送
られる。The waste liquid containing the precipitated product in the reaction tank 2 is sent to the filter 7 via the supply tank 5 and the pump 6, where it is separated into the precipitated product and the filtrate. The filtrate is the filtrate feed line 8
Is sent to the next processing step, while the precipitated product is returned from the precipitated product recirculation line 9 to the supply tank 5 and finally sent from the precipitated product discharge line 10 to the waste solidification processing step.
【００２２】次に、低レベル放射性廃液から放射性ヨウ
素を除去するプロセスの本発明の実施例を図２により説
明する。低レベル放射性廃液は、低レベル放射性廃液供
給ライン１からヨウ素揮発槽２０へ供給される。ｐＨ調
整した該廃液を揮発槽２０内で加熱コイル３０によって
加熱することで、廃液中の放射性ヨウ素は気相側へ移行
する。この状態でヨウ素供給ライン４０から非放射性ヨ
ウ素のガスを槽２０内の気相中に供給し、気相中のヨウ
素濃度を上げ、これを吸収塔５０の下段へ送る。Next, describing the actual施例of the present invention the process of removing radioactive iodine from a low-level radioactive liquid waste by FIG. The low-level radioactive liquid waste is supplied from the low-level radioactive liquid supply line 1 to the iodine volatilization tank 20. By heating the waste liquid whose pH has been adjusted by the heating coil 30 in the volatilization tank 20, the radioactive iodine in the waste liquid moves to the gas phase. In this state, a non-radioactive iodine gas is supplied from the iodine supply line 40 into the gas phase in the tank 20 to increase the iodine concentration in the gas phase and send it to the lower stage of the absorption tower 50.
【００２３】吸収塔５０の頂部の硝酸供給ライン６０か
ら供給された硝酸溶液は塔５０内でヨウ素を吸収し、塔
５０の底部にはヨウ素を含んだ硝酸溶液が溜る。この硝
酸溶液中にはヨウ素の吸収（溶解）を妨げる共存物質が
含まれないので、硝酸溶液へのヨウ素の溶解度を廃液中
での溶解度より高くすることができ、硝酸溶液中のヨウ
素濃度を上げることができる。The nitric acid solution supplied from the nitric acid supply line 60 at the top of the absorption tower 50 absorbs iodine in the tower 50, and the nitric acid solution containing iodine accumulates at the bottom of the tower 50. Since this nitric acid solution does not contain coexisting substances that hinder the absorption (dissolution) of iodine, the solubility of iodine in the nitric acid solution can be higher than that in the waste liquid, and the iodine concentration in the nitric acid solution can be increased. be able to.
【００２４】ヨウ素を含んだ硝酸溶液は吸収塔５０から
反応槽７０へ送られ、ここで硝酸銀供給ライン８０から
沈殿化剤として硝酸銀が供給され、上記硝酸溶液中の放
射性ヨウ素及び非放射性ヨウ素との間で沈殿を生成す
る。この状態での沈殿の生成による放射性ヨウ素除去効
率は、前述の共沈効果の他に、銀イオンと反応してヨウ
化銀の生成を阻害する共存物質が存在しないことによる
効果が加わって、廃液中での低濃度での沈殿発生による
除去効率よりも高い除去効率が得られる。The nitric acid solution containing iodine is sent from the absorption tower 50 to the reaction tank 70, where silver nitrate is supplied as a precipitating agent from the silver nitrate supply line 80, and is combined with the radioactive iodine and the non-radioactive iodine in the nitric acid solution. A precipitate forms between. The removal efficiency of radioactive iodine due to the formation of precipitates in this state, in addition to the above-mentioned coprecipitation effect, the effect of the absence of coexisting substances that react with silver ions and inhibit the formation of silver iodide, The removal efficiency is higher than the removal efficiency due to the generation of a precipitate at a low concentration in the inside.
【００２５】沈殿生成物を含む上記溶液は反応槽７０か
ら供給槽９０、ポンプ１００を経てフィルタ１１０へ送
られ、沈殿生成物と濾過液に分離される。濾過液は濾過
液送液ライン１２０から次の処理工程に送られ、沈殿生
成物は沈殿生成物再循環ライン１３０から供給槽９０へ
戻され、最終的には沈殿生成物排出ライン１４０から廃
棄物固化処理工程に送られる。The above solution containing the precipitate is sent from the reaction tank 70 to the filter 110 via the supply tank 90 and the pump 100, and is separated into the precipitate and the filtrate. The filtrate is sent to the next processing step from the filtrate sending line 120, and the precipitated product is returned from the precipitated product recirculation line 130 to the supply tank 90, and finally to the waste product from the precipitated product discharge line 140. It is sent to the solidification process.
【００２６】核燃料再処理プラントにおいて発生する低
レベル放射性廃液中からの放射性ヨウ素除去について、
従来の方法と本実施例の方法による放射性ヨウ素除去効
率（除染係数）の比較と、除染係数向上によって得られ
る利点を示すことにより、本実施例の効果を説明する。Regarding removal of radioactive iodine from low-level radioactive waste liquid generated in a nuclear fuel reprocessing plant,
The effect of the present embodiment will be described by comparing the radioactive iodine removal efficiency (decontamination coefficient) between the conventional method and the method of the present embodiment and showing the advantages obtained by improving the decontamination coefficient.
【００２７】まず、従来の方法と本実施例の方法によ
る、低レベル放射性廃液中からの放射性ヨウ素除去効率
（除染係数）を比較する。図３に溶液中のヨウ素濃度に
よる除染係数の違いを示す。縦軸にヨウ素除去効率、横
軸にヨウ素イオンと銀イオンのモル量の比をとってい
る。First, the radioactive iodine removal efficiency (decontamination coefficient) from the low-level radioactive waste liquid by the conventional method and the method of the present embodiment will be compared. FIG. 3 shows the difference in the decontamination coefficient depending on the iodine concentration in the solution. The vertical axis indicates the iodine removal efficiency, and the horizontal axis indicates the ratio of the molar amount of iodine ion to silver ion.
【００２８】図３では、ヨウ素濃度として１０００ｐｐ
ｍと１００ｐｐｍの２種類について比較している以外
に、ヨウ素除去の妨害因子であるリン酸（ＰＯ４ ）の
有無による影響、およびヨウ素の化学形態（Ｉ- とＩＯ
3 -）による影響の比較も行なっている。試験溶液として
は、再処理低レベル放射性廃液を模擬して、廃液中に最
も多く含まれるとされているＮａを、ＮａＮＯ3 ，Ｎａ
ＮＯ4 ，Ｎａ2 ＣＯ3 の３つの形態で合計４００ｇ／リ
ットルの濃度で硝酸に添加したものを用いている。な
お、リン酸（ＰＯ4 ）有りの場合には、リン酸をＮａ3
ＰＯ4 という形態で添加しているため、その分だけＮａ
ＮＯ3 濃度を下げ、Ｎａ濃度を揃えている。不溶化剤と
してはＡｇＮＯ3 を使用している。In FIG. 3, the iodine concentration is 1000 pp.
m and 100 ppm, the effect of the presence or absence of phosphoric acid (PO 4 ), which is an inhibitor of iodine removal, and the chemical forms of iodine (I − and IO
3 -) Comparison is also made of the impact of. The test solution simulates a reprocessed low-level radioactive waste liquid, and Na, which is considered to be most contained in the waste liquid, is NaNO 3 , Na
Three types of NO 4 and Na 2 CO 3 which are added to nitric acid at a total concentration of 400 g / liter are used. When phosphoric acid (PO 4 ) is present, the phosphoric acid is changed to Na 3
Since it is added in the form of PO 4, Na
The NO 3 concentration is lowered and the Na concentration is made uniform. AgNO 3 is used as an insolubilizing agent.
【００２９】核燃料再処理プラントにおいて発生する低
レベル放射性廃液中の放射性ヨウ素濃度は、概ね１００
ｐｐｍ（８×１０-4ｍｏｌ／リットル）であるといわれ
ている。The concentration of radioactive iodine in the low-level radioactive liquid waste generated in the nuclear fuel reprocessing plant is approximately 100%.
ppm (8 × 10 −4 mol / l).
【００３０】従来の方法では、このヨウ素濃度において
沈殿化剤である硝酸銀を添加し、ヨウ素を沈殿除去して
いた。この処理において得られる除染係数は、実験の結
果から１０2 程度であることが確認されている。また、
このヨウ素濃度においては、硝酸銀の添加量をヨウ素の
モル量の１０倍から１００倍まで変化させても、除染係
数の向上が見られず、１０2 程度が除染係数の限界値で
あると言える。In the conventional method, silver nitrate as a precipitating agent was added at this iodine concentration to precipitate and remove iodine. Decontamination factor obtained in this process, it has been confirmed from the result of the experiment is 10 2. Also,
At this iodine concentration, even if the addition amount of silver nitrate is changed from 10 times to 100 times the molar amount of iodine, no improvement in the decontamination coefficient is observed, and about 10 2 is the limit value of the decontamination coefficient. I can say.
【００３１】これに対して、ヨウ素濃度を１０００ｐｐ
ｍ（８×１０-3ｍｏｌ／リットル）まで上げた場合に得
られる除染係数は１０3 程度であり約１桁向上すること
が確認された。この除染係数は、硝酸銀の添加量をヨウ
素のモル量と等量とした場合にも得られていることか
ら、元々のヨウ素濃度を１桁上げることにより同じ量の
硝酸銀で１０倍の除染係数を得ることができる。On the other hand, an iodine concentration of 1000 pp
m (8 × 10 −3 mol / liter), the decontamination coefficient obtained was about 10 3 , and it was confirmed that the decontamination coefficient was improved by about one digit. Since this decontamination coefficient was obtained even when the amount of silver nitrate added was equivalent to the molar amount of iodine, decontamination by 10 times with the same amount of silver nitrate by increasing the original iodine concentration by one digit. The coefficients can be obtained.
【００３２】以上のことから、本実施例の方法によれ
ば、同じ量の硝酸銀で従来の方法の１０倍の除染係数が
得られることが判る。From the above, it can be seen that according to the method of this example, a decontamination coefficient 10 times that of the conventional method can be obtained with the same amount of silver nitrate.
【００３３】次に、除染係数の向上によって得られる利
点を説明する。Next, advantages obtained by improving the decontamination coefficient will be described.
【００３４】ＩＡＥＡの放射性固体廃棄物（１８０リッ
トルドラム缶）中の各種放射性元素濃度の上限値の規定
から、低レベル放射性廃液中の放射性ヨウ素の除染係数
の目標値は１０5 と算定される。From the provisions of the upper limits of the concentrations of various radioactive elements in IAEA radioactive solid waste (180-liter drums), the target value for the decontamination coefficient of radioactive iodine in low-level radioactive waste liquid is calculated to be 10 5 .
【００３５】従来の方法によって上記除染係数の目標値
を達成するためには、沈殿生成処理後の廃液中の放射性
ヨウ素濃度を上げるための濃縮反応操作を行ないつつ、
３回の沈殿生成処理を繰り返す必要がある((１０2)3 ＝
１０6)。これに対して本実施例の方法では、非放射性ヨ
ウ素の添加を行ないつつ、２回の沈殿生成処理を行なう
ことで、除染係数の目標値を達成することができる((１
０3)2 ＝１０6)。In order to achieve the above-mentioned target value of the decontamination coefficient by the conventional method, the concentration reaction operation for increasing the concentration of radioactive iodine in the waste liquid after the precipitation treatment is carried out,
It is necessary to repeat the precipitation treatment three times ((10 2 ) 3 =
10 6 ). On the other hand, in the method of the present embodiment, the target value of the decontamination coefficient can be achieved by performing the precipitation generation process twice while adding the non-radioactive iodine ((1
0 3 ) 2 = 10 6 ).
【００３６】濃縮反応操作には専用の反応塔等が必要で
あるが、本実施例の方法では、その様な反応塔等は不要
であり、非放射性ヨウ素の添加用にヨウ素供給ラインを
追加するだけでよいので、設備を大幅に簡略化できる利
点がある。Although a dedicated reaction tower or the like is required for the concentration reaction operation, such a reaction tower or the like is not required in the method of the present embodiment , and an iodine supply line is added for adding non-radioactive iodine. , There is an advantage that the equipment can be greatly simplified.
【００３７】また、１Ｋｍｏｌの放射性ヨウ素を除染係
数１０3 で処理するために、従来の方法では１０Ｋｍｏ
ｌ／回×３回＝３０Ｋｍｏｌの硝酸銀が必要となるが、
本実施例の方法では、１Ｋｍｏｌ／回×２回＝２Ｋｍｏ
ｌの硝酸銀で処理が可能であり、硝酸銀消費量を１／１
５にできる利点がある。図１の実施例でも同様な効果が
得られる。 In order to treat 1 Kmol of radioactive iodine at a decontamination coefficient of 10 3 , the conventional method requires 10 Kmo.
1 / times × 3 times = 30 Kmol of silver nitrate is required,
In the method of this embodiment , 1Kmol / times × 2 times = 2Kmo
1 silver nitrate, and the silver nitrate consumption is reduced to 1/1.
There is an advantage that can be made to 5. Similar effects are obtained in the embodiment of FIG.
can get.
【００３８】[0038]
【発明の効果】【The invention's effect】
本発明によれば、放射性廃液に含まれるAccording to the present invention, contained in radioactive waste liquid
放射性ヨウ素の除去効率を向上できる。The removal efficiency of radioactive iodine can be improved.
【図１】先行発明に基づく実施例のプロセスフローの
図。[1] Figure of a process flow of based KuMinoru施例of prior invention.
【図２】本発明の特許請求の範囲請求項１に基づく実施
例のプロセスフローの図。FIG Process Flow based KuMinoru施例the scope claim 1 of the claims of the invention; FIG.
【図３】本発明の効果の説明のために、溶液中のヨウ素
濃度による除染係数の違いを示す図である。FIG. 3 is a diagram showing a difference in a decontamination coefficient depending on a concentration of iodine in a solution, for explaining an effect of the present invention.
１…低レベル放射性廃液供給ライン ２…反応槽 ３…ヨウ化ナトリウム供給ライン ４…硝酸銀供給ライン ５…供給槽 ７…フィルタ ８…濾過液送液ライン ９…沈殿生成物再循環ライン １０…沈殿生成物排出ライン ２０…ヨウ素揮発槽 ３０…加熱コイル ４０…ヨウ素供給ライン ５０…吸収塔 ６０…硝酸供給ライン ７０…反応槽 ８０…硝酸銀供給ライン ９０…供給槽 １１０…フィルタ １２０…濾過液送液ライン １３０…沈殿生成物再循環ライン １４０…沈殿生成物排出ライン DESCRIPTION OF SYMBOLS 1 ... Low-level radioactive waste liquid supply line 2 ... Reaction tank 3 ... Sodium iodide supply line 4 ... Silver nitrate supply line 5 ... Supply tank 7 ... Filter 8 ... Filtrate liquid sending line 9 ... Precipitation product recycle line 10 ... Precipitation formation Material discharge line 20 ... Iodine volatilization tank 30 ... Heating coil 40 ... Iodine supply line 50 ... Absorption tower 60 ... Nitric acid supply line 70 ... Reaction tank 80 ... Silver nitrate supply line 90 ... Supply tank 110 ... Filter 120 ... Filtrate liquid sending line 130 … Settling product recirculation line 140… settling product discharge line
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) G21F 9/10 G21F 9/02 ──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. 7 , DB name) G21F 9/10 G21F 9/02
Claims (1)
ら放射性ヨウ素を揮発させて気体として取出し、この取
出された放射性ヨウ素の気体に非放射性ヨウ素の気体を
混合して得られたヨウ素混合気体を硝酸溶液中に再溶解
させ、その後、該硝酸溶液にヨウ素沈殿化剤を供給して
ヨウ素を沈殿物として除去することを特徴とする放射性
廃液中の放射性ヨウ素の除去方法。1. A or in radioactive liquid waste containing radioactive iodine
Radioactive iodine is volatilized and extracted as a gas.
Non-radioactive iodine gas is added to the emitted radioactive iodine gas.
Re-dissolve iodine mixed gas obtained by mixing in nitric acid solution
Removing the iodine as a precipitate by supplying an iodine precipitating agent to the nitric acid solution, and thereafter removing the radioactive iodine from the radioactive waste liquid.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10472992A JP3145176B2 (en) | 1992-04-23 | 1992-04-23 | Removal method of radioactive iodine in radioactive waste liquid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10472992A JP3145176B2 (en) | 1992-04-23 | 1992-04-23 | Removal method of radioactive iodine in radioactive waste liquid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05297190A JPH05297190A (en) | 1993-11-12 |
| JP3145176B2 true JP3145176B2 (en) | 2001-03-12 |
Family
ID=14388592
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10472992A Expired - Fee Related JP3145176B2 (en) | 1992-04-23 | 1992-04-23 | Removal method of radioactive iodine in radioactive waste liquid |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3145176B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006084236A (en) * | 2004-09-14 | 2006-03-30 | Chubu Electric Power Co Inc | Disposal method of organic polymer-based low-level radioactive waste |
| JP4436738B2 (en) * | 2004-09-14 | 2010-03-24 | 中部電力株式会社 | Organic polymer-based low-level radioactive waste treatment method and treatment plant |
| CH715104A2 (en) * | 2018-06-18 | 2019-12-30 | Turbobeads Gmbh | Method of removing radioactive iodide from waste water. |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS537600B2 (en) * | 1972-09-26 | 1978-03-18 | ||
| JPS62276499A (en) * | 1986-05-26 | 1987-12-01 | 株式会社東芝 | Reducer for radioactive iodine |
| JPH0337599A (en) * | 1989-07-04 | 1991-02-18 | Hitachi Ltd | Treatment process for reprocessed waste gas of spent nuclear fuel |
-
1992
- 1992-04-23 JP JP10472992A patent/JP3145176B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
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| JPH05297190A (en) | 1993-11-12 |
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