JPH0720291A - Decontamination method for metal waste - Google Patents
Decontamination method for metal wasteInfo
- Publication number
- JPH0720291A JPH0720291A JP16554293A JP16554293A JPH0720291A JP H0720291 A JPH0720291 A JP H0720291A JP 16554293 A JP16554293 A JP 16554293A JP 16554293 A JP16554293 A JP 16554293A JP H0720291 A JPH0720291 A JP H0720291A
- Authority
- JP
- Japan
- Prior art keywords
- metal waste
- decontamination
- paste
- dissolution
- oxide film
- 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
- 239000010814 metallic waste Substances 0.000 title claims abstract description 50
- 238000005202 decontamination Methods 0.000 title claims abstract description 40
- 230000003588 decontaminative effect Effects 0.000 claims abstract description 37
- 238000010438 heat treatment Methods 0.000 claims abstract description 9
- 239000002253 acid Substances 0.000 claims abstract description 5
- 239000011248 coating agent Substances 0.000 claims abstract description 5
- 238000000576 coating method Methods 0.000 claims abstract description 5
- 238000002844 melting Methods 0.000 claims description 14
- 230000008018 melting Effects 0.000 claims description 14
- 230000004927 fusion Effects 0.000 claims description 2
- 238000004090 dissolution Methods 0.000 abstract description 25
- 239000000941 radioactive substance Substances 0.000 abstract description 7
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 abstract description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 abstract description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 abstract description 2
- 238000009413 insulation Methods 0.000 abstract description 2
- 239000000203 mixture Substances 0.000 abstract description 2
- 229910017604 nitric acid Inorganic materials 0.000 abstract description 2
- 230000002285 radioactive effect Effects 0.000 abstract 1
- 238000000034 method Methods 0.000 description 6
- 239000000155 melt Substances 0.000 description 4
- 239000002344 surface layer Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 239000012752 auxiliary agent Substances 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Processing Of Solid Wastes (AREA)
- 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
生する放射性物質により汚染された金属廃棄物の除染方
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 metal waste contaminated with radioactive substances generated from a nuclear power plant or the like.
【０００２】[0002]
【従来の技術】原子力発電所の定期修理等の際には、放
射性物質により汚染されたパイプのような金属廃棄物が
大量に発生するが、従来はこのような金属廃棄物をその
ままドラム缶に詰めて保管していたため、膨大な保管ス
ペースを要するという問題が生じていた。そこで本発明
者等は、放射性物質により汚染されているのは金属廃棄
物の表面部分だけであることに着目し、表面層のみを除
染液により溶解する方法を先に開発し、特願平1-227902
号として特許出願済みである。このように金属廃棄物の
表面層のみを溶解することにより、残りの部分は一般廃
棄物として取り扱うことができる利点がある。2. Description of the Related Art A large amount of metal waste such as pipes contaminated with radioactive substances is generated during periodical repairs of nuclear power plants. Conventionally, such metal waste is directly packed in drums. Since it was stored as a storage device, there was a problem that a huge storage space was required. Therefore, the inventors of the present invention focused on the fact that only the surface portion of the metal waste is contaminated with radioactive substances, and developed a method of dissolving only the surface layer with a decontamination solution in advance. 1-227902
The patent has been applied for as an issue. By dissolving only the surface layer of the metal waste in this manner, there is an advantage that the remaining portion can be handled as general waste.
【０００３】ところが、従来は除染液の性状と好ましい
除染条件との関係が解明されていなかったため、金属廃
棄物の酸化被膜を溶解するために長時間を要し、所望の
溶解厚さを得るには除染液中にきわめて長時間浸漬しな
ければならないという問題があった。また、除染液を加
熱すれば金属廃棄物の溶解速度を増加できることは容易
に予測できることであるが、除染槽の全体を加熱すると
除染槽自体も侵食されるおそれがあるうえ、余分のエネ
ルギーを必要とする等の問題があった。However, since the relationship between the properties of the decontamination solution and the preferable decontamination conditions has not been clarified so far, it takes a long time to dissolve the oxide film of the metal waste, and a desired dissolution thickness is required. There was a problem in that it had to be immersed in the decontamination solution for an extremely long time to obtain it. Moreover, it can be easily predicted that the dissolution rate of the metal waste can be increased by heating the decontamination solution, but if the entire decontamination tank is heated, the decontamination tank itself may be eroded and extra There were problems such as requiring energy.
【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、除染槽の全体を加熱することな
く、酸化皮膜を形成した金属廃棄物の表面層を速やかに
溶解することができる金属廃棄物の除染方法を提供する
ためになされたものである。DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and quickly dissolves the surface layer of metal waste having an oxide film formed thereon without heating the entire decontamination tank. The purpose of the present invention is to provide a decontamination method for metal waste.
【０００５】[0005]
【発明を解決するための手段】上記の課題を解決するた
めになされた本発明は、酸化皮膜を形成した金属廃棄物
の表面に、混酸をペースト助剤と混合した除染ペースト
を塗布し、塗布面の一部を削るか加温することにより金
属廃棄物表面の溶解を開始させ、これにより発生する溶
解熱を利用して塗布面の残部まで溶解を進行させること
を特徴とするものである。The present invention, which has been made to solve the above problems, is to apply a decontamination paste in which a mixed acid is mixed with a paste auxiliary agent to the surface of a metal waste having an oxide film formed thereon, It is characterized in that the melting of the surface of the metal waste is started by shaving or heating a part of the coated surface, and the heat of fusion generated by this is used to proceed to the rest of the coated surface. .
【０００６】[0006]
【作用】本発明の方法により金属廃棄物の除染を行うに
は、まず混酸をペースト助剤と混合した除染ペーストを
金属廃棄物の表面に塗布したうえ、塗布面の一部を削っ
て表面の酸化被膜を除去するか、あるいは塗布面の一部
のみを40℃以上、好ましくは70℃以上に加熱する。これ
により除染ペーストが金属廃棄物の表面を溶解し始め、
同時に溶解熱が発生する。この溶解熱は除染ペーストが
断熱層として作用するために金属廃棄物の隣接する領域
を加熱し、隣接する領域においても金属廃棄物の溶解が
進行する。このようにして金属廃棄物の全表面について
溶解が行われ、表面に付着している放射性物質が除去さ
れる。In order to decontaminate a metal waste by the method of the present invention, first, a decontamination paste prepared by mixing a mixed acid with a paste aid is applied to the surface of the metal waste, and a part of the applied surface is scraped off. The oxide film on the surface is removed, or only a part of the coated surface is heated to 40 ° C or higher, preferably 70 ° C or higher. As a result, the decontamination paste begins to dissolve on the surface of the metal waste,
At the same time, heat of dissolution is generated. The heat of dissolution heats the adjacent area of the metal waste because the decontamination paste acts as a heat insulating layer, and the dissolution of the metal waste proceeds in the adjacent area. In this way, the entire surface of the metal waste is dissolved and the radioactive substances adhering to the surface are removed.
【０００７】[0007]
【実施例】以下に本発明を実施例によって更に詳細に説
明する。まず硝酸20重量部に対して、塩酸２重量部、弗
酸３重量部を混合した混酸を作製し、ペースト助剤と混
合して除染ペーストを作製する。ペースト助剤として
は、例えばBaSO4 粉とポリ塩化ビニル粉とを１：４〜
４：１の比率で混合したものを使用することができる。
この除染ペーストをステンレススチール（SUS304) より
なる金属廃棄物の表面に均一に塗布する。実施例の金属
廃棄物の表面積は150×150mm であり、除染ペーストの
塗布量と地金溶解厚さとの関係は図１の通りである。こ
の関係に基づいて、目的とする溶解厚さに対応した除染
ペーストの塗布量を選択すればよい。また、酸化皮膜を
形成した金属廃棄物の除染温度と皮膜溶解時間との関係
は図２の通りである。この関係より、溶解時間が高いほ
ど皮膜溶解時間が短くて済み、溶解速度が速く溶解熱を
多く発生させる地金溶解に移行することより、この関係
に基づいて皮膜溶解温度と時間を設定すればよい。EXAMPLES The present invention will be described in more detail below with reference to examples. First, a mixed acid prepared by mixing 2 parts by weight of hydrochloric acid and 3 parts by weight of hydrofluoric acid with 20 parts by weight of nitric acid is mixed with a paste aid to prepare a decontamination paste. As the paste aid, for example, BaSO 4 powder and polyvinyl chloride powder are mixed in a ratio of 1: 4 to
A mixture of 4: 1 ratio can be used.
This decontamination paste is evenly applied to the surface of metal waste made of stainless steel (SUS304). The surface area of the metal waste of the example is 150 × 150 mm, and the relationship between the coating amount of the decontamination paste and the molten metal dissolution thickness is as shown in FIG. Based on this relationship, the amount of decontamination paste applied may be selected in accordance with the target dissolution thickness. Further, the relationship between the decontamination temperature of the metal waste having the oxide film and the film dissolution time is as shown in FIG. From this relationship, the higher the melting time is, the shorter the film melting time is, and the melting speed shifts to the ingot melting that generates a large amount of heat of melting. Therefore, if the film melting temperature and time are set based on this relationship, Good.
【０００８】この結果に基づき、酸化皮膜を形成した金
属廃棄物に除染ペーストを塗布し、その塗布面の一部を
例えば80℃程度の温度に加温すれば、加温部から金属廃
棄物の表面の溶解が始まるが、この溶解の際に溶解熱が
発生する。通常の除染液を使用した場合には、この溶解
熱は速やかに金属廃棄物表面から放散してしまうが、本
発明で使用される除染ペーストは優れた断熱性を有する
ために溶解熱の放散が防止され、隣接する金属廃棄物の
表面を加熱する。その結果、最初に加温された位置の隣
接部においても溶解が進行し、その溶解熱が更にその隣
接部を加熱することを繰り返すことによって、金属廃棄
物の全表面が溶解されることとなる。On the basis of this result, the decontamination paste is applied to the metal waste having the oxide film formed thereon, and a part of the applied surface is heated to a temperature of, for example, about 80 ° C. The surface of the melt begins to melt, but heat of dissolution is generated during this melt. When a normal decontamination solution is used, this heat of dissolution is rapidly dissipated from the surface of the metal waste, but the decontamination paste used in the present invention has excellent heat insulation properties, so Emissions are prevented and heat the surface of adjacent metal waste. As a result, the melting progresses even in the adjacent portion of the first heated position, and the heat of dissolution further heats the adjacent portion repeatedly, whereby the entire surface of the metal waste is dissolved. .
【０００９】図３はこの関係を示すもので、除染ペース
トを用いた場合には上記したように溶解熱による加温が
進行するため、溶解開始時の金属廃棄物の温度の高低に
かかわらず溶解厚さはほぼ一定となる。これに対してゲ
ル状の除染液を使用した場合には、溶解開始時の金属廃
棄物の温度によって溶解厚さが大きく変化することが分
かる。このため、本発明によれば溶解開始時の金属廃棄
物全体の温度を高めることなく、金属廃棄物の全表面を
所望の厚さまで溶解することが可能となる。FIG. 3 shows this relationship. When the decontamination paste is used, the heating by the heat of dissolution proceeds as described above, and therefore regardless of the temperature of the metal waste at the start of melting. The melt thickness is almost constant. On the other hand, when a gel-like decontamination solution is used, it can be seen that the dissolution thickness greatly changes depending on the temperature of the metal waste at the start of dissolution. Therefore, according to the present invention, the entire surface of the metal waste can be melted to a desired thickness without increasing the temperature of the entire metal waste at the start of melting.
【００１０】このようにして金属廃棄物の全表面の溶解
を完了させた後、除染ペーストは水の噴射によって洗い
落とされ、表面に付着していた放射性物質も除染ペース
トとともに回収される。また残部の金属廃棄物は放射性
物質を含まないので、放射線量を測定された後に一般廃
棄物として処分することができる。After the dissolution of the entire surface of the metal waste is completed in this way, the decontamination paste is washed off by jetting water, and the radioactive substances adhering to the surface are also collected together with the decontamination paste. Moreover, since the remaining metal waste does not contain radioactive substances, it can be disposed of as general waste after the radiation dose is measured.
【００１１】なお、溶解をスタートさせるためには塗布
面の一部を加温する方法の他に、金属廃棄物の表面を削
って酸化被膜を除去する方法を取ってもよい。酸化被膜
を除去された面で溶解が開始されると、それによって生
じた溶解熱がその周囲を加熱し、前記したように酸化被
膜のある金属廃棄物の表面を順次溶解することとなる。In order to start the dissolution, a method of removing the oxide film by scraping the surface of the metal waste may be used in addition to the method of heating a part of the coated surface. When the dissolution is started on the surface from which the oxide film has been removed, the heat of dissolution generated thereby heats the surroundings and sequentially melts the surface of the metal waste having the oxide film as described above.
【００１２】[0012]
【発明の効果】以上に説明したように、本発明の金属廃
棄物の除染方法によれば金属廃棄物の表面に除染ペース
トを塗布し、塗布面の一部を削るか加温することにより
除染ペーストによる金属廃棄物表面の溶解を開始させ、
これにより発生する溶解熱を利用して塗布面の残部を溶
解させるので、従来のように除染槽の全体を加熱するこ
となく、金属廃棄物の除染を行うことができる。このた
め、除染槽自体が侵食されるおそれがなく、余分のエネ
ルギーを必要としない利点がある。As described above, according to the method for decontaminating metal waste of the present invention, the decontamination paste is applied to the surface of the metal waste, and a part of the applied surface is scraped or heated. To start the dissolution of the metal waste surface with the decontamination paste,
Since the rest of the coated surface is melted by utilizing the heat of dissolution generated by this, it is possible to decontaminate the metal waste without heating the entire decontamination tank as in the conventional case. Therefore, there is an advantage that the decontamination tank itself is not eroded and extra energy is not required.
【図１】除染ペーストの塗布量と溶解厚さとの関係を示
すグラフである。FIG. 1 is a graph showing a relationship between a coating amount of a decontamination paste and a dissolution thickness.
【図２】金属廃棄物の溶解温度と、酸化皮膜溶解時間と
の関係を示すグラフである。FIG. 2 is a graph showing a relationship between a melting temperature of a metal waste and a dissolution time of an oxide film.
【図３】金属廃棄物の溶解温度と溶解厚さとの関係を示
すグラフである。FIG. 3 is a graph showing the relationship between the melting temperature and the melting thickness of metal waste.
Claims (1)
混酸をペースト助剤と混合した除染ペーストを塗布し、
塗布面の一部を削るか加温することにより金属廃棄物表
面の溶解を開始させ、これにより発生する溶解熱を利用
して塗布面の残部まで溶解を進行させることを特徴とす
る金属廃棄物の除染方法。1. A surface of a metal waste on which an oxide film is formed,
Apply decontamination paste with mixed acid mixed with paste aid,
Metal waste characterized by starting melting of the surface of the metal waste by shaving or heating a part of the coating surface, and using the heat of fusion generated thereby to proceed to the rest of the coating surface Decontamination method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05165542A JP3105703B2 (en) | 1993-07-05 | 1993-07-05 | Decontamination method of metal waste |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05165542A JP3105703B2 (en) | 1993-07-05 | 1993-07-05 | Decontamination method of metal waste |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0720291A true JPH0720291A (en) | 1995-01-24 |
| JP3105703B2 JP3105703B2 (en) | 2000-11-06 |
Family
ID=15814366
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP05165542A Expired - Fee Related JP3105703B2 (en) | 1993-07-05 | 1993-07-05 | Decontamination method of metal waste |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3105703B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7146737B2 (en) | 2000-11-02 | 2006-12-12 | Boerner Kunststoff- Und Metallwarenfabrik Gmbh | Kitchen appliance for slicing various products |
| JP2012185097A (en) * | 2011-03-07 | 2012-09-27 | Mitsubishi Heavy Ind Ltd | Radioactive waste decontamination method |
| JP2016065818A (en) * | 2014-09-25 | 2016-04-28 | 三菱重工業株式会社 | Radioactive waste decontamination method |
-
1993
- 1993-07-05 JP JP05165542A patent/JP3105703B2/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7146737B2 (en) | 2000-11-02 | 2006-12-12 | Boerner Kunststoff- Und Metallwarenfabrik Gmbh | Kitchen appliance for slicing various products |
| US7966737B2 (en) | 2000-11-02 | 2011-06-28 | Boerner Kunststoff- Und Metallwarenfabrik Gmbh | Food cutting appliance |
| JP2012185097A (en) * | 2011-03-07 | 2012-09-27 | Mitsubishi Heavy Ind Ltd | Radioactive waste decontamination method |
| JP2016065818A (en) * | 2014-09-25 | 2016-04-28 | 三菱重工業株式会社 | Radioactive waste decontamination method |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3105703B2 (en) | 2000-11-06 |
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|---|---|---|---|
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Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20000818 |
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| LAPS | Cancellation because of no payment of annual fees |