JPH05273389A - Decontamination method by use of mixed acid of radioactive waste - Google Patents
Decontamination method by use of mixed acid of radioactive wasteInfo
- Publication number
- JPH05273389A JPH05273389A JP6826592A JP6826592A JPH05273389A JP H05273389 A JPH05273389 A JP H05273389A JP 6826592 A JP6826592 A JP 6826592A JP 6826592 A JP6826592 A JP 6826592A JP H05273389 A JPH05273389 A JP H05273389A
- Authority
- JP
- Japan
- Prior art keywords
- acid
- tank
- radioactive waste
- mixed
- mixed acid
- 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.)
- Granted
Links
Landscapes
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は原子力発電所等から発生
するステンレス系の放射性廃棄物の混酸による除染法に
関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for decontaminating a radioactive waste of stainless steel generated from a nuclear power plant or the like with mixed acid.
【０００２】[0002]
【従来の技術】原子力発電所等から発生する鉄系の放射
性廃棄物の除染方法として、混酸により放射性廃棄物の
表面層を溶解し、表面に付着した放射性物質を除去する
方法が従来から知られている。しかし効率良くステンレ
ス系の放射性廃棄物を除染するためには、硝酸、塩酸、
フッ酸の混酸を使用することが望ましい。2. Description of the Related Art As a decontamination method for iron-based radioactive waste generated from nuclear power plants, a method of dissolving the surface layer of the radioactive waste with mixed acid and removing the radioactive substances adhering to the surface has been conventionally known. Has been. However, in order to decontaminate stainless steel radioactive waste efficiently, nitric acid, hydrochloric acid,
It is desirable to use a mixed acid of hydrofluoric acid.
【０００３】ところがこの硝酸、塩酸、フッ酸の混酸は
混合後に時間が経過すると、ステンレスに対する溶解性
能が急速に低下してしまう欠点があるため、使用の都度
新しい混酸を調合しなければならないという不便があっ
た。However, this mixed acid of nitric acid, hydrochloric acid, and hydrofluoric acid has a drawback that the dissolution performance in stainless steel rapidly deteriorates with time after mixing, so that it is inconvenient to prepare a new mixed acid each time it is used. was there.
【０００４】[0004]
【発明が解決しようとする課題】本発明は上記した従来
の問題点を解決して、使用の都度新しい混酸を調合する
必要がなく、しかもステンレス系の放射性廃棄物の表面
層を溶解して確実に除染することができる放射性廃棄物
の混酸による除染法を提供するために完成されたもので
ある。SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and eliminates the need for preparing a new mixed acid each time it is used, and also ensures that the surface layer of radioactive waste of stainless steel is dissolved. It has been completed to provide a method for decontaminating radioactive waste that can be decontaminated with mixed acid.
【０００５】[0005]
【課題を解決するための手段】上記の課題を解決するた
めに本発明者等は、硝酸、塩酸、フッ酸の混酸を使用し
た場合、なぜ混合後に急速に溶解性能が低下するのかと
いう点について研究した。その結果、硝酸、塩酸、フッ
酸の混酸は空気と接触すると、水分及び酸（特にフッ
酸）が蒸発することにより混合比の変化を生じ、初期に
設定した混合比からずれてしまうことが分かった。ま
た、上記の混酸は硝酸と塩酸の化学平衡反応により化１
によって例えばNOClのような化合物を生じ、硝酸や塩酸
の活量が減少してしまい、これらの原因によって溶解性
能が低下することが分かった。In order to solve the above-mentioned problems, the inventors of the present invention have pointed out why, when a mixed acid of nitric acid, hydrochloric acid and hydrofluoric acid is used, the dissolution performance is rapidly lowered after mixing. Researched. As a result, it was found that when a mixed acid of nitric acid, hydrochloric acid, and hydrofluoric acid comes into contact with air, the mixing ratio changes due to evaporation of water and acid (particularly hydrofluoric acid), which deviates from the initially set mixing ratio. It was Further, the above mixed acid is formed by a chemical equilibrium reaction between nitric acid and hydrochloric acid.
It was found that, for example, a compound such as NOCl is produced, the activity of nitric acid and hydrochloric acid decreases, and the dissolution performance decreases due to these causes.
【０００６】[0006]
【化１】HNO3+3HCl ⇔NOCl+Cl2+2H2O[Chemical 1] HNO 3 + 3HCl ⇔ NOCl + Cl 2 + 2H 2 O
【０００７】従って、硝酸、塩酸、フッ酸の混酸を密閉
系に置いて空気との接触を絶てば混合比の変化を防止す
ることができ、また混酸を密閉系に置いてCl2 の発生を
抑制すれば、上式の右向きの反応も抑制されてNOClのよ
うな化合物の発生が防止できることとなる。本発明は上
記した知見に基づいて完成されたもので、ステンレス系
の放射性廃棄物を、密閉系のタンクに収納された硝酸、
塩酸、フッ酸の混酸に接触させて除染したのち、除染に
使用した混酸から金属イオン等の不純物を除去し、各酸
の混合比を調整したうえ循環させて再利用することを特
徴とするものである。Therefore, if a mixed acid of nitric acid, hydrochloric acid and hydrofluoric acid is placed in a closed system to prevent contact with air, the change in the mixing ratio can be prevented, and if the mixed acid is placed in a closed system, Cl 2 is generated. By suppressing the above, the reaction in the right direction of the above formula is also suppressed and the generation of compounds such as NOCl can be prevented. The present invention has been completed on the basis of the above-mentioned findings, and stainless steel radioactive waste is stored in a closed tank of nitric acid,
After decontamination by contacting with a mixed acid of hydrochloric acid and hydrofluoric acid, impurities such as metal ions are removed from the mixed acid used for decontamination, the mixing ratio of each acid is adjusted, and recycled for reuse. To do.
【０００８】[0008]
【実施例】以下に本発明を図示の実施例によって更に詳
細に説明する。図１は本発明の方法によりステンレス系
の放射性廃棄物を除染する装置を示すもので、１は除染
室であり、その内部に混酸による表面処理槽２、洗浄槽
３が順次設置され、ステンレス系の放射性廃棄物Ｗはク
レーン６によりこれらの各槽間を順次移動するようにな
っている。The present invention will be described in more detail with reference to the embodiments shown in the drawings. FIG. 1 shows an apparatus for decontaminating a radioactive waste of stainless steel according to the method of the present invention. Reference numeral 1 denotes a decontamination chamber, in which a surface treatment tank 2 with a mixed acid and a cleaning tank 3 are sequentially installed. The stainless-type radioactive waste W is sequentially moved between these tanks by the crane 6.
【０００９】また、７は表面処理槽２からリターンされ
た硝酸、塩酸、フッ酸の混酸が収納される原液タンクで
あり、混酸はポンプ８によりフィルタ９へ送られ、拡散
透析槽10により金属イオンを除去されたうえ、回収酸タ
ンク11に入る。更に混酸は回収酸タンク11からポンプ12
により酸調整タンク13へ送られ、硝酸、塩酸、フッ酸、
水の濃度を調整されたうえ、酸供給タンク14でヒーター
15により加熱され、ポンプ16で混酸による表面処理槽２
へ送られる。Reference numeral 7 is a stock solution tank for storing a mixed acid of nitric acid, hydrochloric acid and hydrofluoric acid returned from the surface treatment tank 2. The mixed acid is sent to a filter 9 by a pump 8 and a metal ion is taken by a diffusion dialysis tank 10. After being removed, it enters the recovered acid tank 11. Furthermore, the mixed acid is pumped from the recovered acid tank 11 to the pump 12
Sent to the acid adjustment tank 13 by nitric acid, hydrochloric acid, hydrofluoric acid,
After adjusting the water concentration, heater in the acid supply tank 14
Surface treatment tank 2 that is heated by 15 and is mixed with pump 16 by mixed acid
Sent to.
【００１０】一般に、このような多数のタンクをパイプ
で連結した配管系統においては、各タンクの液面が自由
に上下できるように、各タンクの上部空間はそれぞれ独
立に大気圧に開放されているのが普通である。しかし本
発明においては、図２に示すように原液タンク７、回収
酸タンク11、酸調整タンク13、酸供給タンク14の各タン
クは密閉されており、これらのタンクの上部空間は互い
に共通のガス配管17に連通させてある。これにより、各
タンクは液面の上下動が可能な密閉系を構成することと
なり、混酸は大気との接触を防止されることとなる。Generally, in such a piping system in which a large number of tanks are connected by pipes, the upper space of each tank is independently opened to atmospheric pressure so that the liquid level of each tank can be freely raised and lowered. Is normal. However, in the present invention, as shown in FIG. 2, the stock solution tank 7, the recovered acid tank 11, the acid adjustment tank 13, and the acid supply tank 14 are hermetically sealed, and the upper spaces of these tanks share the same gas. It is connected to the pipe 17. As a result, each tank constitutes a closed system in which the liquid surface can move up and down, and the mixed acid is prevented from contacting with the atmosphere.
【００１１】なお硝酸：塩酸：フッ酸の混合比は特に限
定されるものではないが、重量比で20：２：３の付近が
最も好ましい除染効果を得ることができる。The mixing ratio of nitric acid: hydrochloric acid: hydrofluoric acid is not particularly limited, but the most preferable decontamination effect can be obtained when the weight ratio is around 20: 2: 3.
【００１２】[0012]
【作用】このような装置によりステンレス系の放射性廃
棄物Ｗの除染を行うには、酸供給タンク14から混酸を表
面処理槽２に供給しておき、ステンレス系の放射性廃棄
物Ｗをクレーン６により表面処理槽２内に浸漬させてそ
の表面を溶解する。そして表面処理槽２から流出した混
酸は原液タンク７を介してフィルタ９でろ過され、更に
拡散透析槽10により金属イオン等の不純物を除去された
うえ、酸調整タンク13で各酸の混合比を調整されて再び
酸供給タンク14へ戻り、再利用されることとなる。In order to decontaminate the stainless type radioactive waste W with such an apparatus, the mixed acid is supplied from the acid supply tank 14 to the surface treatment tank 2, and the stainless type radioactive waste W is transferred to the crane 6 Is immersed in the surface treatment tank 2 to dissolve the surface. The mixed acid flowing out from the surface treatment tank 2 is filtered by a filter 9 through a stock solution tank 7, impurities such as metal ions are further removed by a diffusion dialysis tank 10, and a mixing ratio of each acid is adjusted by an acid adjusting tank 13. It will be adjusted and returned to the acid supply tank 14 again for reuse.
【００１３】このように混酸は各タンク内を循環しつつ
放射性廃棄物Ｗの除染を行うのであるが、本発明では各
タンクは密閉系とされて内部の混酸と大気との接触が遮
断されているので、硝酸、塩酸、フッ酸の混酸は蒸発が
抑制され、混合後に時間が経過しても混合比が変化しに
くく、またステンレス系の放射性廃棄物Ｗを除染した結
果生じた混合比の変化は、拡散透析槽10と酸調整タンク
13を通過する間に補正されるので、混合比を一定に保つ
ことができる。また本発明では各タンクを密閉系とした
ためにNOClのような化合物の発生が防止され、硝酸や塩
酸の活量が減少することがない。As described above, the mixed acid circulates in each tank to decontaminate the radioactive waste W. In the present invention, each tank is a closed system so that the contact between the mixed acid inside and the atmosphere is blocked. Therefore, the mixed acid of nitric acid, hydrochloric acid, and hydrofluoric acid is suppressed from evaporating, and the mixing ratio does not easily change even after a lapse of time after mixing. In addition, the mixing ratio generated as a result of decontaminating the stainless radioactive waste W Changes in the diffusion dialysis tank 10 and acid adjustment tank
Since it is corrected while passing through 13, the mixing ratio can be kept constant. Further, in the present invention, since each tank is a closed system, generation of compounds such as NOCl is prevented, and the activities of nitric acid and hydrochloric acid do not decrease.
【００１４】図３は本発明の効果を従来の開放系と比較
して示したものであり、黒く塗った印で示した本発明の
場合には保存時間が48時間を越えてもステンレス表面を
溶解する能力が低下することがない。これに対して白い
印で示した従来の開放系の場合には、保存時間が長くな
るとステンレス表面を溶解する能力が急速に低下するこ
とが分かる。FIG. 3 shows the effect of the present invention in comparison with the conventional open system. In the case of the present invention shown by a black-painted mark, the stainless steel surface is protected even when the storage time exceeds 48 hours. The ability to dissolve does not decrease. On the other hand, in the case of the conventional open system shown by the white mark, it is found that the ability to dissolve the stainless steel surface is rapidly reduced as the storage time becomes longer.
【００１５】[0015]
【発明の効果】以上に説明したように、本発明の放射性
廃棄物の混酸による除染法によれば、ステンレス系の放
射性廃棄物を、密閉系のタンクに収納された硝酸、塩
酸、フッ酸の混酸に接触させて除染したのち、除染に使
用した混酸から金属イオン等の不純物を除去し、各酸の
混合比を調整したうえ循環させて再利用するようにした
ので、使用の都度新しい混酸を調合することなく、ステ
ンレス系の放射性廃棄物の表面層を溶解して確実にかつ
経済的に除染することができる。よって本発明は従来の
問題点を解決したものとして、産業の発展に寄与すると
ころは極めて大である。As described above, according to the method for decontaminating radioactive waste by mixed acid according to the present invention, stainless radioactive waste is treated with nitric acid, hydrochloric acid or hydrofluoric acid stored in a closed tank. After decontaminating it by contacting it with the mixed acid, the impurities such as metal ions were removed from the mixed acid used for decontamination, and the mixed ratio of each acid was adjusted and circulated for reuse. The surface layer of stainless radioactive waste can be dissolved and reliably and economically decontaminated without preparing new mixed acid. Therefore, the present invention is extremely large in that it contributes to the development of industry by solving the conventional problems.
【図１】本発明の実施例を示す配管系統図である。FIG. 1 is a piping system diagram showing an embodiment of the present invention.
【図２】本発明の実施例の要部を示す配管系統図であ
る。FIG. 2 is a piping system diagram showing a main part of an embodiment of the present invention.
【図３】時間の経過による混酸の溶解性能の変化を示す
グラフである。FIG. 3 is a graph showing a change in dissolution performance of mixed acid over time.
１ 除染室 ２ 混酸による表面処理槽 ７ 原液タンク 11 回収酸タンク 13 酸調整タンク 14 酸供給タンク 1 Decontamination room 2 Surface treatment tank with mixed acid 7 Stock solution tank 11 Recovery acid tank 13 Acid adjustment tank 14 Acid supply tank
Claims (1)
のタンクに収納された硝酸、塩酸、フッ酸の混酸に接触
させて除染したのち、除染に使用した混酸から金属イオ
ン等の不純物を除去し、各酸の混合比を調整したうえ循
環させて再利用することを特徴とする放射性廃棄物の混
酸による除染法。1. A stainless radioactive waste is contacted with a mixed acid of nitric acid, hydrochloric acid and hydrofluoric acid stored in a closed tank for decontamination, and the mixed acid used for decontamination contains impurities such as metal ions. A method for decontaminating radioactive waste with a mixed acid, which comprises recycling the recycled acid after removing it and adjusting the mixing ratio of each acid.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP04068265A JP3088826B2 (en) | 1992-03-26 | 1992-03-26 | Decontamination method of radioactive waste by mixed acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP04068265A JP3088826B2 (en) | 1992-03-26 | 1992-03-26 | Decontamination method of radioactive waste by mixed acid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05273389A true JPH05273389A (en) | 1993-10-22 |
| JP3088826B2 JP3088826B2 (en) | 2000-09-18 |
Family
ID=13368752
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP04068265A Expired - Fee Related JP3088826B2 (en) | 1992-03-26 | 1992-03-26 | Decontamination method of radioactive waste by mixed acid |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3088826B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012185097A (en) * | 2011-03-07 | 2012-09-27 | Mitsubishi Heavy Ind Ltd | Radioactive waste decontamination method |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6057868B2 (en) * | 2013-09-20 | 2017-01-11 | 本田技研工業株式会社 | Welding gun |
-
1992
- 1992-03-26 JP JP04068265A patent/JP3088826B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012185097A (en) * | 2011-03-07 | 2012-09-27 | Mitsubishi Heavy Ind Ltd | Radioactive waste decontamination method |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3088826B2 (en) | 2000-09-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP2819125B1 (en) | Radioactive organic waste treatment method and system | |
| US6147274A (en) | Method for decontamination of nuclear plant components | |
| EP0859671B1 (en) | Method for decontamination of nuclear plant components | |
| JP2004170278A (en) | Chemical decontamination method and system for radioactive chemical | |
| MXPA00010614A (en) | Method for reducing the level of radioactivity of a metal part. | |
| JPH05273389A (en) | Decontamination method by use of mixed acid of radioactive waste | |
| WO1997017146A9 (en) | Method for decontamination of nuclear plant components | |
| US8115045B2 (en) | Nuclear waste removal system and method using wet oxidation | |
| JP4309324B2 (en) | Chemical decontamination method and chemical decontamination apparatus | |
| US20200013519A1 (en) | Chemical decontamination method | |
| KR102256404B1 (en) | Method for treating decontamination liquid waste | |
| JP2004340769A (en) | Disposing method and device of organic acid decontamination waste liquid | |
| JP3511244B2 (en) | Method for recovering hydrochloric acid with good purity | |
| US6716402B2 (en) | Dissolution and decontamination process | |
| JP2002365397A (en) | Decontamination method of radioactive member | |
| JP3495904B2 (en) | Supercritical water oxidation treatment of TMAH waste liquid | |
| US20230182116A1 (en) | Regenerating agent for radionuclide adsorbent, method for regenerating spent radionuclide adsorbent using same, and method for treating spent regenerating agent | |
| JPS6263898A (en) | Method and device for processing chemical decontaminated waste liquor | |
| US20220139587A1 (en) | Iodine trapping apparatus and nuclear power structure | |
| JP2009162687A (en) | Method for removing radioactive contaminant | |
| JPH01287286A (en) | Method and device for preventing corrosion in highly corrosive liquid | |
| JP5096652B2 (en) | Treatment agent and treatment method for aluminum member surface | |
| JP2003033653A (en) | Organic acid decomposing catalyst and chemical decontamination method | |
| JP2000065989A (en) | Method for chemical decontamination of radioactive contaminant | |
| JPS6055596B2 (en) | Corrosion protection equipment for power plants |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20000630 |
|
| LAPS | Cancellation because of no payment of annual fees |