JPH01320497A - Chemical decontamination method - Google Patents
Chemical decontamination methodInfo
- Publication number
- JPH01320497A JPH01320497A JP15446388A JP15446388A JPH01320497A JP H01320497 A JPH01320497 A JP H01320497A JP 15446388 A JP15446388 A JP 15446388A JP 15446388 A JP15446388 A JP 15446388A JP H01320497 A JPH01320497 A JP H01320497A
- Authority
- JP
- Japan
- Prior art keywords
- clevis
- chemical decontamination
- piping
- heater
- piping system
- 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
- 238000009390 chemical decontamination Methods 0.000 title claims description 26
- 238000000034 method Methods 0.000 title claims description 12
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 25
- 239000007788 liquid Substances 0.000 claims abstract description 17
- 238000005202 decontamination Methods 0.000 claims description 9
- 230000003588 decontaminative effect Effects 0.000 claims description 8
- 239000000941 radioactive substance Substances 0.000 claims description 4
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 abstract description 21
- 238000010438 heat treatment Methods 0.000 abstract description 13
- 238000005260 corrosion Methods 0.000 abstract description 10
- 230000007797 corrosion Effects 0.000 abstract description 10
- 235000006408 oxalic acid Nutrition 0.000 abstract description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 6
- 238000005336 cracking Methods 0.000 abstract description 5
- 238000011010 flushing procedure Methods 0.000 abstract description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052799 carbon Inorganic materials 0.000 abstract description 2
- 238000004140 cleaning Methods 0.000 abstract 1
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 239000007864 aqueous solution Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 150000007524 organic acids Chemical class 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 239000012857 radioactive material Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
- Cleaning Or Drying Semiconductors (AREA)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、液体とくに放射性物質を含む液体を取扱う配
管系統の、化学除染剤を用いて行なう除染方法の改良に
関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a method of decontaminating a piping system that handles liquids, particularly liquids containing radioactive substances, using a chemical decontamination agent.
［従来の技術］
原子力発電所のような施設において、放射性物質を含む
液体が通る配管系統、たとえば−次系や廃液処理設備の
パイプ、そのフランジ接合部、バルブ、ポンプなどに沈
着した放射性腐食生成物を除去する方法として、薬剤を
用いた除染が有効であることが、よく知られている。[Prior art] In facilities such as nuclear power plants, radioactive corrosion deposits are formed on piping systems through which liquids containing radioactive substances pass, such as secondary systems and waste liquid treatment equipment pipes, their flange joints, valves, pumps, etc. It is well known that decontamination using chemicals is an effective method for removing substances.
この除染方法のひとつに、シュウ酸やクエン酸のような
有機酸を主成分とし若干の界面活性剤を添加してなる化
学除染剤を使用し、その水溶液を配管系統にみたして約
９０℃で循環させることによって行なうものがある。One of the decontamination methods is to use a chemical decontamination agent consisting mainly of an organic acid such as oxalic acid or citric acid with some surfactant added, and to apply the aqueous solution to the piping system. Some methods are carried out by circulating at 90°C.
ところで、配管系統には、フランジ接合部、バルブ、ポ
ンプなどの、液が残留する可能性のある、「クレビス」
とよばれる部分が必らず存在する。By the way, there are "clevises" in piping systems where liquid may remain, such as flange joints, valves, and pumps.
There is always a part called.
（クレビスｃｒｅｖｉｃｅの詔は、フレバスｃｒｅｖａ
ｓｓｅと同様に「裂は目」を意味し、本来はフランジ接
合部のような切れ目を指すが、広く液体の残留する可能
性がある部分をまとめてめられすのに用いられる。）
プラントの設計に当っては、クレビス部を極力少なくす
るよう努力するのはもちろんであるが、それでもかなり
のクレビス部がでさることは避けられない。 たとえば
−次系のジェットポンプを用いた場合の配管−ノズル間
のセーフエンドや、温度変化にそなえて設けた熱スリー
ブの部分が、特徴的なりレビス部として挙げられる。(The edict of crevice is phlebas creva.
Like sse, it means "slit" and originally refers to a cut such as a flange joint, but it is widely used to cut together parts where liquid may remain. ) When designing a plant, it goes without saying that efforts are made to minimize the number of clevises, but it is still unavoidable that a considerable number of clevises will appear. For example, the safe end between the piping and nozzle when using a secondary jet pump, and the heat sleeve part provided in preparation for temperature changes are examples of characteristic recesses.
このようなりレビス部に化学除染剤が残留すると、局部
的な腐食が進行し、応力腐食割れ等の好ましくない現象
をひき起す要因となるおそれがある。If the chemical decontamination agent remains in the recesses in this way, local corrosion may progress and cause undesirable phenomena such as stress corrosion cracking.
このような危険をなくすために、除染後、配管系統に純
水を通して洗汗すること（これを「フラッシング」とい
う）が通常実施されている。 フラッシングの効果は、
いうまでもなく多数回くりかえすことにより高まるが、
それはメンテナンスのためにプラントを休止する時間が
長くなり、かつコストが高くなることを意味する。To eliminate such risks, after decontamination, the pipe system is usually flushed with pure water (this is called "flushing"). The effect of flushing is
Needless to say, it increases by repeating it many times,
That means more downtime for the plant for maintenance and higher costs.
［発明が解決しようとする課題］
本発明の目的は、配管系統の化学除染における上記のよ
うな状況を改善し、フラッシングの回数を減らしてもク
レビス部の応力腐食割れの危険がないようにした化学除
染方法を提供することにある。[Problems to be Solved by the Invention] The purpose of the present invention is to improve the above-mentioned situation during chemical decontamination of piping systems, and to eliminate the risk of stress corrosion cracking in the clevis even if the number of flushing operations is reduced. The purpose of this invention is to provide a chemical decontamination method.
［課題を解決するための手段］
本発明の化学除染方法は、液体を取扱う配管系統を化学
除染剤の溶液を使用して除染する方法において、除染後
の配管系統のクレビス部を温度１５０℃以上に加熱して
、残留除染剤を分解除去することを特徴とする。[Means for Solving the Problems] The chemical decontamination method of the present invention is a method for decontaminating a piping system that handles liquid using a solution of a chemical decontamination agent. It is characterized by heating to a temperature of 150°C or higher to decompose and remove residual decontamination agent.
この方法は、配管系統が放射性物質を含む液体を取扱う
ものであるとき、とくに有用である。This method is particularly useful when the piping system handles liquids containing radioactive materials.
クレビス部を加熱する手段は任意でおって、電気ヒータ
ーの使用が多くの場合に好都合であろう。The means for heating the clevis is optional, and the use of an electric heater will often be advantageous.
［作 用］
本発明者らは、前記したように、化学除染剤が有機酸を
主成分とし若干の界面活性剤を添加してなるものであり
、後者もまた有機化合物であって熱に弱いことに着目し
て、市販の化学除染剤１重口％水溶液の加熱分解を試み
た。[Function] As mentioned above, the present inventors discovered that the chemical decontamination agent is composed mainly of an organic acid and contains some surfactant, and the latter is also an organic compound and is resistant to heat. Focusing on its weakness, we attempted to thermally decompose a 1% aqueous solution of a commercially available chemical decontamination agent.
その結果、つぎのように熱分解が進み、０化学除染剤Ａ
を１５０’Ｃに加熱
→Ｃ０２＋Ｈ２Ｏ
０化学除染剤Ｂを２００ ’Ｃに加熱
→ＣＯ２十ト１２Ｑ十Ｎ２十Ｖ
ともにシュウ酸を主成分とする化学除染剤Ａ、 Ｂを実
質上完全に分解除去できることが確認できた。As a result, thermal decomposition progresses as follows, and 0 chemical decontamination agent A
Heating to 150'C → C02 + H2O 0 Heating chemical decontamination agent B to 200'C → CO2 + 12Q + N20V Substantially completely decomposes chemical decontamination agents A and B, both of which have oxalic acid as their main component. It was confirmed that it can be removed.
適用すべき加熱温度および加熱時間は、使用した化学除
染剤の種類、クレビス部への残留量などによって多少異
なるであろうが、必要ならば若干の予備実験を行なうこ
とにより、適切な条件を定めることができる。The heating temperature and heating time to be applied will vary depending on the type of chemical decontamination agent used, the amount remaining in the crevice, etc., but if necessary, it is possible to find the appropriate conditions by conducting some preliminary experiments. can be determined.
［実施例］
化学除染剤による腐食の程度をしらべるため、５ＵＳ３
０４ステンレス鋼で第１図に示ず形状の隙間腐食試験片
を用意した。[Example] In order to examine the degree of corrosion caused by chemical decontamination agents, 5US3
A crevice corrosion test piece made of 04 stainless steel and having a shape not shown in FIG. 1 was prepared.
市販の、シュウ酸を主成分とする化学除染剤の０．２５
％水溶液をつくり、それを９０℃に加熱した中へ上記の
試験片を浸漬し、液を循環させつつ保持した。0.25 of a commercially available chemical decontamination agent whose main component is oxalic acid.
% aqueous solution was prepared and heated to 90° C., the above test piece was immersed in the solution and held while circulating the solution.
３０００時間後に試験片をとり出してしらべたところ、
隙間部分に若干の腐食が認められた。When I took out the test piece after 3000 hours and examined it, I found that
Some corrosion was observed in the gap.
次に、化学除染剤が配管系統のクレビス部に残留する挙
動をしらべるため、第２図に示すような、すなわちタン
ク１内の液をフランジ接合２をもつパイプおよびバルブ
３を通してポンプ４で循環させる構成の実験装置を組み
立てた。Next, in order to investigate the behavior of the chemical decontamination agent remaining in the crevice of the piping system, the liquid in the tank 1 was circulated by a pump 4 through a pipe with a flange connection 2 and a valve 3 as shown in Fig. 2. We assembled an experimental device configured to do this.
１％シュウ酸水溶液を５０時間にわたって流したのち、
配管系統から液を扱いた。 クレビス部に残った液を集
めてシュウ酸濃度を測定したところ、循環していた液の
約２倍市っだ。 クレビス部において化学除染剤が濃縮
されていたわけで、上記した予備実験の結果とあいまっ
て、化学除染剤のクレビス部からの除去の必要性が明ら
かになった。After flowing a 1% oxalic acid aqueous solution for 50 hours,
Handled liquids from the piping system. When the remaining liquid in the clevis was collected and the oxalic acid concentration was measured, it was found to be approximately twice as high as the circulating liquid. The chemical decontamination agent was concentrated in the crevice, and combined with the results of the preliminary experiment described above, it became clear that it was necessary to remove the chemical decontamination agent from the crevice.
そこで、クレビス部を加熱する手段として、フランジ接
合部用、バルブ用およびポンプ用の電気ヒーターを製作
した。 第３図のフランジ接合部用ヒーター６は、柔軟
な面状発熱体６１を耐熱絶縁シート６２でサンドイッチ
してリードをつけ、フランジ接合部をほぼ一周巻くよう
にした構造のものである。 第４図のバルブ用ヒーター
７は、バルブの外形に沿う若干の厚さをもった中空体を
ニラ割りにした形状のヒーター酸７３を金属板で製作し
、殻７３の中にマグネシア粉末の充填材７２で電熱線７
１を埋め込んだ構造のものでおる。Therefore, as a means to heat the clevis, electric heaters for flange joints, valves, and pumps were manufactured. The heater 6 for the flange joint shown in FIG. 3 has a structure in which a flexible planar heating element 61 is sandwiched between heat-resistant insulating sheets 62 and a lead is attached so as to wrap around the flange joint approximately once. The valve heater 7 shown in Fig. 4 is made of a metal plate and has a heater acid 73 in the shape of a hollow body with a slight thickness cut into pieces that follows the outer shape of the valve, and the shell 73 is filled with magnesia powder. Heating wire 7 with material 72
It has a structure in which 1 is embedded.
図示してないが、ポンプ（渦巻型）に対しても、バルブ
用に似た構造の電気ヒーターを製作した。Although not shown, an electric heater with a structure similar to that for the valve was also fabricated for the pump (volute type).
上記の実験装置の各部分をよく洗浄し、再度組み立てた
。 それぞれのヒーターをとりつけ、再び上記の１％シ
ュウ酸水溶液循環を、やはり５０時間行なった。Each part of the experimental apparatus described above was thoroughly cleaned and reassembled. Each heater was attached, and the above 1% aqueous oxalic acid solution was circulated again for 50 hours.
液を仇いた状態でヒーターに通電し、各クレビス部がほ
ぼ２００ ’Ｃに達するまで加熱し、約３０分間保持し
た。While the liquid was being soaked, electricity was applied to the heater to heat each crevice until it reached approximately 200'C, and this was maintained for approximately 30 minutes.
冷却後、装置を分解してクレビス部を少辺の水で洗浄し
た。 洗浄水中のＴＯＣ（仝有□炭素）を測定したとこ
ろ、検出限界以下であった。 このことから、タレビス
部に残留していた化学除染剤は、完全に分解除去された
ことがわかる。After cooling, the device was disassembled and the clevis was washed with a small amount of water. TOC (free carbon) in the wash water was measured and found to be below the detection limit. This indicates that the chemical decontamination agent remaining in the Talebis area was completely decomposed and removed.
［発明の効果１
本発明の化学除染方法によれば、常用の化学除染剤を用
いて配管系統の化学除染を行なったのち、残留する除染
剤を実質上完全に分解除去できる。[Effect of the Invention 1] According to the chemical decontamination method of the present invention, after chemical decontamination of a piping system is performed using a commonly used chemical decontamination agent, the remaining decontamination agent can be substantially completely decomposed and removed.
この効果は、純水による配管系統のフラッシングの回数
を減らしても十分であり、とくに残留除染剤を高度に除
去することを要求される場合でも、１回または少数回の
、従来よりはるかに少ない回数のフラッシングで得られ
る。 このようにして、配管系統の残留除染剤によるク
レビス部の応力腐食割れの危険は、実際上、皆無になっ
たということができ、装置のメンテナンスの時間短縮、
コスト低減、および安全性の向上という利益が得られる
。This effect can be achieved by reducing the number of times the piping system is flushed with pure water, especially when a high degree of removal of residual decontamination agents is required. Achieved with fewer flushes. In this way, it can be said that the risk of stress corrosion cracking in the clevis due to residual decontamination agent in the piping system has virtually been eliminated, reducing equipment maintenance time, and
Benefits include reduced costs and improved safety.
従って本発明は、放射性物質を含有する液を取扱うプラ
ントに適用したときとくに有用であるほか、化学プラン
ト一般に適用できる。Therefore, the present invention is particularly useful when applied to plants that handle liquids containing radioactive substances, and can also be applied to chemical plants in general.
第１図は、本発明の実施例における予備実験に用いた試
験片の形状を示すものであって、Ａは平面図、Ｂは側面
図である。
第２図は、本発明の実施例にお（プる実験装置の構成を
示す、概念的なフローチャートである。
第３図は、本発明の実施例で使用したフランジ接合部用
の電熱ヒーターを示すものであって、Ａは縦断面図、Ｂ
は横断面図である。
第４図は、本発明の実施例で使用したバルブ用の電熱ヒ
ーターを示すものであって、△は縦断面図、Ｂは横断面
図である。
１・・・タンク ２・・・フランジ接合部３
・・・バルブ ４・・・ポンプ６・・・フラ
ンジ接合部用ヒーター
６１・・・面状発熱体 ６２・・・耐熱絶縁シー１〜
７・・・バルブ用ヒーター
７１・・・電熱線 ７２・・・充填材７３・・・
ヒーター酸FIG. 1 shows the shape of a test piece used in a preliminary experiment in an example of the present invention, in which A is a plan view and B is a side view. Fig. 2 is a conceptual flowchart showing the configuration of the experimental apparatus used in the embodiment of the present invention. Fig. 3 shows the electric heater for the flange joint used in the embodiment of the present invention. A is a vertical cross-sectional view, B is a vertical cross-sectional view, and
is a cross-sectional view. FIG. 4 shows an electric heater for a valve used in an embodiment of the present invention, where Δ is a longitudinal cross-sectional view and B is a cross-sectional view. 1...Tank 2...Flange joint 3
...Valve 4...Pump 6...Flange joint heater 61...Sheet heating element 62...Heat-resistant insulation sheet 1~
7...Valve heater 71...Heating wire 72...Filling material 73...
heater acid
Claims (2)
て除染する方法において、除染後の配管系統のクレビス
部を温度１５０℃以上に加熱して残留除染剤を分解除去
することを特徴とする化学除染方法。(1) In a method of decontaminating a piping system that handles liquid using a chemical decontamination agent, the clevis of the piping system after decontamination is heated to a temperature of 150°C or higher to decompose and remove residual decontamination agent. A chemical decontamination method characterized by:
学除染方法。(2) The chemical decontamination method according to claim 1, wherein the liquid contains a radioactive substance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63154463A JPH0758350B2 (en) | 1988-06-22 | 1988-06-22 | Chemical decontamination method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63154463A JPH0758350B2 (en) | 1988-06-22 | 1988-06-22 | Chemical decontamination method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01320497A true JPH01320497A (en) | 1989-12-26 |
| JPH0758350B2 JPH0758350B2 (en) | 1995-06-21 |
Family
ID=15584794
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63154463A Expired - Lifetime JPH0758350B2 (en) | 1988-06-22 | 1988-06-22 | Chemical decontamination method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0758350B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009052955A (en) * | 2007-08-24 | 2009-03-12 | Toden Kogyo Co Ltd | Decontamination liquid, decontamination method, and decontamination system of radioactive contaminant |
| JP2009109253A (en) * | 2007-10-29 | 2009-05-21 | Hitachi-Ge Nuclear Energy Ltd | Method and device for chemical decontamination |
| JP2013117526A (en) * | 2011-11-01 | 2013-06-13 | Mitsubishi Heavy Ind Ltd | Method for treating decontamination liquid |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6355499A (en) * | 1986-08-26 | 1988-03-09 | 株式会社東芝 | Pyrolytic processing method and device for chemically decontaminated waste resin |
-
1988
- 1988-06-22 JP JP63154463A patent/JPH0758350B2/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6355499A (en) * | 1986-08-26 | 1988-03-09 | 株式会社東芝 | Pyrolytic processing method and device for chemically decontaminated waste resin |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009052955A (en) * | 2007-08-24 | 2009-03-12 | Toden Kogyo Co Ltd | Decontamination liquid, decontamination method, and decontamination system of radioactive contaminant |
| JP2009109253A (en) * | 2007-10-29 | 2009-05-21 | Hitachi-Ge Nuclear Energy Ltd | Method and device for chemical decontamination |
| JP2013117526A (en) * | 2011-11-01 | 2013-06-13 | Mitsubishi Heavy Ind Ltd | Method for treating decontamination liquid |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0758350B2 (en) | 1995-06-21 |
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