JPH01176081A - Surface treatment for nuclear reactor pipe and the like - Google Patents
Surface treatment for nuclear reactor pipe and the likeInfo
- Publication number
- JPH01176081A JPH01176081A JP62332435A JP33243587A JPH01176081A JP H01176081 A JPH01176081 A JP H01176081A JP 62332435 A JP62332435 A JP 62332435A JP 33243587 A JP33243587 A JP 33243587A JP H01176081 A JPH01176081 A JP H01176081A
- Authority
- JP
- Japan
- Prior art keywords
- base material
- hydrazine
- base
- atmosphere
- reactor
- 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
- 238000004381 surface treatment Methods 0.000 title claims description 20
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 claims abstract description 68
- 239000000463 material Substances 0.000 claims abstract description 58
- 229910001220 stainless steel Inorganic materials 0.000 claims abstract description 20
- 239000010935 stainless steel Substances 0.000 claims abstract description 20
- 239000000498 cooling water Substances 0.000 claims abstract description 15
- 229910000975 Carbon steel Inorganic materials 0.000 claims abstract description 14
- 239000010962 carbon steel Substances 0.000 claims abstract description 14
- 238000004140 cleaning Methods 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims description 24
- 239000007788 liquid Substances 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 abstract description 12
- 239000000126 substance Substances 0.000 abstract description 10
- 150000007524 organic acids Chemical class 0.000 abstract description 9
- 239000003795 chemical substances by application Substances 0.000 abstract description 7
- 238000009825 accumulation Methods 0.000 abstract description 3
- VEPSWGHMGZQCIN-UHFFFAOYSA-H ferric oxalate Chemical compound [Fe+3].[Fe+3].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O VEPSWGHMGZQCIN-UHFFFAOYSA-H 0.000 abstract description 3
- 239000012857 radioactive material Substances 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 33
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 16
- 238000005253 cladding Methods 0.000 description 14
- 238000009390 chemical decontamination Methods 0.000 description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 239000000243 solution Substances 0.000 description 9
- 238000010828 elution Methods 0.000 description 8
- 229910052759 nickel Inorganic materials 0.000 description 8
- 238000007254 oxidation reaction Methods 0.000 description 7
- 230000005855 radiation Effects 0.000 description 7
- 235000005985 organic acids Nutrition 0.000 description 6
- 230000001681 protective effect Effects 0.000 description 6
- 238000005260 corrosion Methods 0.000 description 5
- 230000007797 corrosion Effects 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 238000006386 neutralization reaction Methods 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 238000005498 polishing Methods 0.000 description 4
- 239000011253 protective coating Substances 0.000 description 4
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000010953 base metal Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 210000003754 fetus Anatomy 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 239000002253 acid Substances 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 238000005422 blasting Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000005202 decontamination Methods 0.000 description 2
- 230000003588 decontaminative effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 241000244206 Nematoda Species 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 125000000717 hydrazino group Chemical group [H]N([*])N([H])[H] 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 239000000941 radioactive substance Substances 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 238000005406 washing Methods 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
-
- 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
Abstract
Description
【発明の詳細な説明】
「産業上の利用分野」
本発明は原子炉配管等の表面処理方法に係り、特に、沸
騰水型原子炉や加圧水型原子炉における原子炉冷却水系
の配管内面に、原子炉運転に伴う放射性物質の蓄積を防
止する技術に関するものである。Detailed Description of the Invention "Industrial Application Field" The present invention relates to a method for surface treatment of nuclear reactor piping, etc., and in particular, to the inner surface of piping of a reactor cooling water system in a boiling water reactor or a pressurized water reactor. This relates to technology to prevent the accumulation of radioactive materials associated with nuclear reactor operation.
「従来の技術」
一般に、原子力発電プラントには、炭素鋼やオーステナ
イト系ステンレス鋼材等が使用されているが、沸騰水型
原子炉や加圧水型原子炉の場合であると、原子炉冷却材
として水を使用しているために、核加熱によって放射化
された” Ｃｏ ＋ ” Ｍ ｎ ＋１３４Ｃ８及びそ
の酸化物等（以下、クラッドという）が、原子炉の一次
冷却系の配管等に次第に付着し、管路の放射線量を上昇
させてしまう可能性がある。"Conventional technology" Carbon steel and austenitic stainless steel materials are generally used in nuclear power plants, but in the case of boiling water reactors and pressurized water reactors, water is used as a reactor coolant. As a result, "Co + " M n +134C8 and its oxides (hereinafter referred to as cladding) activated by nuclear heating gradually adhere to the piping of the reactor's primary cooling system, causing This may increase the radiation dose in the road.
したがって、原子炉冷却水用の配管やその部品等におい
ては、材料の吟味を十分に行なうことが必要とされると
ともに、原子炉建設時等において、例えばステンレス鋼
管の場合であると、その内部に３００℃の高温加湿空気
を１５０時間程度以上挿通させる方法で、クラッド（放
射化粒子）に対して化学的な親和性を持たせないような
表面処理を予め施しておくことが有効である。Therefore, it is necessary to carefully examine the materials used in reactor cooling water piping and its parts. It is effective to previously perform a surface treatment that does not have chemical affinity for cladding (activated particles) by passing high-temperature humidified air at 300° C. for about 150 hours or more.
一方、このような表面処理を施した場合であっても、原
子炉を一度運転すると、クラッドが配管等の構成母材の
表面に徐々に付着する現象が生じるとともに、８０ Ｃ
Ｏ等が、母材表面に付着したクラッド及び母材表面の酸
化層（Ｆｅｔｕｓ酸化層、Ｆｅ３Ｏ４耐食性層、不働態
化被膜層等）の中に、内向拡散現象によって僅かずっ入
り込む現象が加わることや、ステンレス鋼等からニッケ
ルが溶出して、５８Ｃｏが生成される現象等によって、
第２図においてＳ−Ａ曲線で示すように、配管系の放射
線量が次第に増加するものと考えられる。On the other hand, even if such surface treatment is applied, once the reactor is operated, a phenomenon occurs in which the clad gradually adheres to the surface of the base material such as piping, and 80 C
There is also a phenomenon in which O, etc. enters into the cladding attached to the surface of the base material and the oxidized layer on the surface of the base material (Fetus oxide layer, Fe3O4 corrosion-resistant layer, passivation film layer, etc.) due to an inward diffusion phenomenon. , due to the phenomenon that nickel is eluted from stainless steel etc. and 58Co is generated.
As shown by the SA curve in FIG. 2, it is thought that the radiation dose in the piping system gradually increases.
従来、原子炉運転開始後において、クラッドが付着した
配管等の放射線量を低減する方法としては、定期点検時
や補修時に、ブラスト処理によって前記クラッド層を研
磨除去する方法や、有機酸（例えばしゅう酸）を主とす
る化学除染剤を使用して、クラッド層とその下の酸化層
とを化学研磨によって除去する方法が提案されている。Conventionally, methods for reducing the radiation dose from piping with attached cladding after the start of reactor operation include polishing and removing the cladding layer by blasting during periodic inspections and repairs, and removing the cladding layer with organic acids (e.g. A method has been proposed in which the cladding layer and the oxide layer thereunder are removed by chemical polishing using a chemical decontamination agent mainly containing acids.
「発明が解決しようとする問題点」
しかしながら、前者のブラスト処理法であると、母材表
面に付着した状態のクラッド層を機械的に除去すること
は可能であるが、その下の酸化層を研削するまでに至ら
ないために、残された酸化要分の８０ｃｏ等に相当する
放射線源のために、線量の低減には限度がある。``Problems to be Solved by the Invention'' However, with the former blasting method, it is possible to mechanically remove the clad layer that is attached to the surface of the base material, but it is difficult to remove the oxide layer underneath. Since grinding is not performed, there is a limit to the reduction in dose due to the radiation source equivalent to 80 co of remaining oxidation content.
また、後者の化学除染法であると、クラッド層とともに
酸化層を除去して、第２図においてＡ−８曲線で示すよ
うに、除染後の線量を著しく低減することができるが、
研磨によって母材表面が活性化されてしまう。このため
、母材表面に着した化学除染剤を水洗によって除去する
とともに、大気にさらすような条件が伴うと、活性化状
態の母材表面が、水や酸素の存在によって、容易に酸化
されてしまう現象を生じる。In addition, with the latter chemical decontamination method, the oxidized layer is removed together with the cladding layer, and the dose after decontamination can be significantly reduced, as shown by the A-8 curve in Figure 2.
Polishing activates the surface of the base material. Therefore, if the chemical decontamination agent adhering to the surface of the base material is removed by washing with water and exposed to the atmosphere, the surface of the base material in an activated state will be easily oxidized by the presence of water and oxygen. This will cause a phenomenon where the
このような酸化条件下では、炭素鋼の場合であると、母
材表面にＦｅｔｕ３の錆層が形成されて、クラッドが付
着し易い状態となり、ステンレス鋼の場合には、前述し
た高温加湿空気を挿通させる適当な表面処理を施した場
合と異なり、クラッドが付着し易くなるとともに、ニッ
ケルの溶出現象が生じて”Ｎｉが生成され易くなり、ま
た、除染処理に使用した前記しゅう酸が炭素原子を含む
ために、化学除染剤が配管の中に残っていると、伝熱阻
害を起こす原因の一つとなる。Under such oxidation conditions, in the case of carbon steel, a rust layer of Fetu3 is formed on the surface of the base material, making it easy for crud to adhere, while in the case of stainless steel, the above-mentioned high-temperature humidified air is Unlike the case where a suitable surface treatment is applied to allow penetration, the cladding becomes more likely to adhere, nickel elution occurs, and nickel is more likely to be generated. If the chemical decontamination agent remains in the pipes, it becomes one of the causes of heat transfer inhibition.
したがって、原子炉を再び運転状態に戻すと、クラッド
層の形成速度が高まることや、８０Ｃｏの内向拡散現象
等によって、第２図においてＢ−Ｃ曲線で示すように、
除染作業後の運転開始とともに線量が急速に増加する現
象か現れ、以後の原子炉の補修時までの運転期間を短縮
せざるを得なくなる等の問題点を生じる。Therefore, when the reactor is brought back into operation, the rate of formation of the cladding layer increases, the inward diffusion of 80Co, etc. causes the
When the operation starts after decontamination work, a phenomenon appears in which the radiation dose increases rapidly, causing problems such as having to shorten the operation period until the reactor is repaired.
本発明は、このような問題点を有効に解決するとともに
、原子炉配管等がステンレス鋼または炭素鋼によって構
成されている場合が多いことを考慮して、母材表面を不
活性状態にして放射性物質の蓄積を妨げることにより放
射線量の増加速度を遅らせ、また、容易の実施可能な処
理方法を提案するものである。The present invention effectively solves these problems, and takes into account that nuclear reactor piping is often made of stainless steel or carbon steel, and makes the surface of the base material inert and radioactive. The aim is to slow down the rate of increase in radiation dose by preventing the accumulation of substances, and also to propose a treatment method that is easy to implement.
「問題点を解決するための手段」
本発明に係る原子炉配管等の表面処理方法は、化学除染
処理された母材表面が、ステンレス鋼である場合には、
その母材表面をヒドラジン雰囲気で還元処理し、該ヒド
ラジン液の除去後に運転雰囲気の原子炉冷却水を接触さ
せるもので、化学除染処理によって活性化された母材表
面を速やかに還元雰囲気として、この還元雰囲気のまま
原子炉運転雰囲気に導いて、高温状態の原子炉冷却水と
母材表面とを接触させることにより、母材表面に良質の
不働態化被膜層による保護被膜層を速やかに形成する。"Means for Solving the Problems" The method for surface treatment of nuclear reactor piping, etc. according to the present invention, when the surface of the base material subjected to chemical decontamination treatment is stainless steel,
The surface of the base material is subjected to a reduction treatment in a hydrazine atmosphere, and after the hydrazine solution is removed, the reactor cooling water in the operating atmosphere is brought into contact with the base material surface, which is activated by chemical decontamination treatment, and is immediately brought into a reducing atmosphere. By introducing this reducing atmosphere into the reactor operating atmosphere and bringing the high-temperature reactor cooling water into contact with the base metal surface, a high-quality passivated protective film layer is quickly formed on the base metal surface. do.
そして、以下において、該保護被膜層に基づいて、クラ
ッドの付着防止とニッケルの溶出防止とがなされる。In the following, the protective film layer is used to prevent the adhesion of cladding and the elution of nickel.
また、化学除染された母材表面が、ステンレス鋼または
炭素鋼の単独表面、または両方を含む場合においては、
前記還元処理の前に、ヒドラジンの希薄還元雰囲気での
洗浄を行なうことによって、母材表面の金属組織の粒界
中等に、化学除染剤における有機酸や難溶解質であるし
ゅう酸鉄等が残されている場合であっても、アルカリ雰
囲気と希薄還元雰囲気とによって、有機酸成分や難溶解
質を剥離分解除去するとともに、特に、Ｆｅｔｕｓの発
生等の母材表面の酸化を抑制する。次いで、前述したよ
うに、ヒドラジン雰囲気で還元処理することにより、炭
素鋼部分の母材表面に対しては、Ｆｅ＋０＊からなる耐
食性層を発生させ、さらに、原子炉運転雰囲気とするこ
とにより、該耐食性層を安定化状態の保護被膜層として
、以下、クラッドの付着防止等を行なうものである。In addition, if the chemically decontaminated base material surface includes a single stainless steel or carbon steel surface, or both,
By cleaning in a dilute reducing atmosphere of hydrazine before the reduction treatment, organic acids in chemical decontamination agents and iron oxalate, which is a hardly soluble substance, are removed from the grain boundaries of the metal structure on the surface of the base material. Even if they remain, the organic acid components and poorly soluble substances are peeled off and decomposed by the alkaline atmosphere and dilute reducing atmosphere, and in particular, oxidation of the base material surface, such as the generation of Fetus, is suppressed. Next, as mentioned above, a corrosion-resistant layer consisting of Fe+0* is generated on the base metal surface of the carbon steel part by reduction treatment in a hydrazine atmosphere, and further, by creating a nuclear reactor operating atmosphere, The corrosion-resistant layer is used as a protective film layer in a stabilized state to prevent the adhesion of cladding, etc.
「実施例」
以下、本発明に係る原子炉配管等の表面処理方法の一実
施例を第１図に基づいて説明する。なお、該−実施例で
は、母材が炭素鋼である場合を例にする。"Example" Hereinafter, an example of the method for surface treatment of nuclear reactor piping, etc. according to the present invention will be described based on FIG. 1. In addition, in this Example, the case where the base material is carbon steel is taken as an example.
［化学除染工程後の母材表面状態］
原子炉運転開始によって、原子炉配管の内面等、母材表
面に、クラッドが付着する等によって線量が増加した場
合に、有機酸（例えばしゅう酸）を主とする化学除染剤
によって、化学研磨を行なうことにより、母材表面から
クラッド層とその下の酸化層とが除去されて、母材表面
が活性化された状態となる。また、化学除後の母材表面
は、第２図においてＡ−Ｂ−Ｃ曲線で示すように、線虫
が著しく低減した状態となる。[Surface condition of base material after chemical decontamination process] When the radiation dose increases due to the adhesion of crud to the surface of the base material, such as the inner surface of reactor piping, due to the start of reactor operation, organic acids (e.g. oxalic acid) By performing chemical polishing using a chemical decontamination agent mainly consisting of , the cladding layer and the oxidized layer thereunder are removed from the surface of the base material, and the surface of the base material is brought into an activated state. Further, the surface of the base material after chemical removal is in a state where nematodes are significantly reduced, as shown by the ABC curve in FIG.
［′ｆｃ浄中和工程］
化学除染処理された母材表面が濡れている状態のまま、
該母材表面に対して、３０〜１０１００ｐｐ！１度及び
常温〜８０℃のヒドラジン希釈水溶液を、配管系に循環
挿通する等の方法で接触させる。['FC purification and neutralization process] While the surface of the base material that has been chemically decontaminated is still wet,
30 to 10100pp to the surface of the base material! A diluted aqueous solution of hydrazine at a temperature of 1° C. and room temperature to 80° C. is brought into contact with the solution by circulating it through the piping system or the like.
該ヒドラジン希薄水溶液を母材表面に接触させることに
より、母材表面は、希薄還元雰囲気に保持される。By bringing the dilute aqueous hydrazine solution into contact with the surface of the base material, the surface of the base material is maintained in a dilute reducing atmosphere.
そして、希薄還元雰囲気での洗浄によって、母材表面に
付着残留している有機酸（シ１〉う酸）等を除去すると
ともに、母材の金属組織の粒界中等に、化学除染剤にお
ける有機酸や難溶解質であるしゅう酸鉄等が残されてた
場合には、ヒドラジンに基づく弱アルカリ液を接触させ
ることによって、これらを分解して剥離させ、また、ヒ
ドラジン希薄水溶液に流動性を付与することによって、
除去洗浄する。Then, by cleaning in a dilute reducing atmosphere, organic acids (oxylic acid) etc. that remain attached to the surface of the base material are removed, and chemical decontamination agents are applied to the grain boundaries of the metal structure of the base material. If organic acids or poorly soluble substances such as iron oxalate remain, contact with a weak alkaline solution based on hydrazine will decompose and peel them off, and also add fluidity to the dilute aqueous hydrazine solution. By giving
Remove and wash.
この場合にあって、母材表面は、化学除染後に速やかに
希薄還元雰囲気とすることによって、酸化反応の発生を
抑制し、特に、Ｆｅｔｕ３の発生等を抑制した状態を維
持する。希薄還元雰囲気とする時間は、化学除染処理の
有機酸の使用条件、あるいは、ヒドラジン希薄水溶液の
濃度及び温度によって、適宜に設定する必要があるが、
例えば３時間程度とする。In this case, the base material surface is kept in a dilute reducing atmosphere immediately after chemical decontamination to suppress the occurrence of oxidation reactions, and in particular to maintain a state in which the generation of Fetu3 and the like is suppressed. The time to create a dilute reducing atmosphere needs to be set appropriately depending on the usage conditions of the organic acid in chemical decontamination treatment or the concentration and temperature of the dilute aqueous hydrazine solution.
For example, it is about 3 hours.
［ヒドラジン希薄水溶液の排出］
これら洗浄中和工程の終了後、ヒドラジン希薄水溶液を
母材表面から除去する。[Discharge of dilute aqueous hydrazine solution] After completing these cleaning and neutralization steps, the dilute aqueous hydrazine solution is removed from the surface of the base material.
［還元工程］
次いで、ヒドラジン希釈水溶液によって濡れか残ってい
る母材表面に対して、５００ｐｐｍないし１１０００ｐ
ｐ濃度及び８０°Ｃ以上（例えば８０〜１００°Ｃ）の
ヒドラジン還元用水溶液を、前工程と同様に循環挿通さ
せる等の方法で、例えば３時間程度接触させる。[Reduction process] Next, 500 ppm to 11,000 ppm is added to the surface of the base material that remains wet with the diluted hydrazine aqueous solution.
An aqueous solution for reducing hydrazine with a p concentration of 80° C. or higher (for example, 80 to 100° C.) is brought into contact with the solution for about 3 hours, for example, by circulating it in the same way as in the previous step.
該ヒドラジン還元用水溶液の接触によって、母材表面は
、より強い還元雰囲気となる。この還元雰囲気では、反
応温度を比較的高温に維持することによって、水溶液中
の酸素を鉄に反応させて、Ｆｅ！０３の発生がほとんど
ともなうことがなく、ごく薄いＦｅ５Ｏ４層、即ち、耐
食性層が形成される。The contact with the aqueous hydrazine reducing solution creates a stronger reducing atmosphere on the surface of the base material. In this reducing atmosphere, by maintaining the reaction temperature at a relatively high temperature, oxygen in the aqueous solution reacts with iron, resulting in Fe! A very thin Fe5O4 layer, ie, a corrosion-resistant layer, is formed with almost no occurrence of 03.
［ヒドラジン還元用水溶液の排出］
これら還元工程の終了後、ヒドラジン還元用水溶液を母
材表面から除去する。[Discharge of hydrazine reducing aqueous solution] After these reduction steps are completed, the hydrazine reducing aqueous solution is removed from the surface of the base material.
［保護被膜層形成工程コ
ヒドラジン還元用水溶液の排出後、ヒドラジン還元用水
溶液によって濡れている母材表面に対して、母材表面を
原子炉運転雰囲気の原子炉冷却水に接触させる。例えば
、原子炉を運転状態とする等により、脱塩水、つまり、
原子炉冷却水を接触させ、母材表面のＦｅ３Ｏ４層を安
定させる。高温状態での原子炉冷却水による酸化反応に
よっても、Ｆｅ５０＊層が形成されて安定状態となるた
め、前述した錆、Ｆｅｔｕｓの形成が抑制され、母材表
面に耐食性層を形成することができる。[Protective film layer formation process After discharging the aqueous solution for reducing cohydrazine, the surface of the base material wetted by the aqueous solution for reducing hydrazine is brought into contact with reactor cooling water in the reactor operating atmosphere. For example, by putting a nuclear reactor into operation, desalinated water, i.e.
Contact with reactor cooling water to stabilize the Fe3O4 layer on the surface of the base material. An Fe50* layer is also formed by the oxidation reaction caused by the reactor cooling water in a high-temperature state, resulting in a stable state, which suppresses the formation of the aforementioned rust and Fetus, making it possible to form a corrosion-resistant layer on the surface of the base material. .
この工程は、原子炉を通常状態で運転再開することによ
って、高温雰囲気（例えば２７３℃）と原子炉冷却水と
が容易に得られるため、原子炉の運転再開を考慮して、
ヒドラジン還元用水溶液を排除する時期を設定すればよ
く、原子炉運転と別に保護被膜層形成工程をわざわざ設
定しなくてもよい。This process is carried out in consideration of restarting the reactor operation, since a high temperature atmosphere (e.g. 273°C) and reactor cooling water can be easily obtained by restarting the reactor operation under normal conditions.
It is only necessary to set the timing for removing the aqueous solution for hydrazine reduction, and there is no need to take the trouble to set a process for forming a protective film layer separately from the reactor operation.
［残留物の影響］
ここまでの処理によって、少量のヒドラジンが配管系の
中に残される可能性がある。しかし、ヒドラジンは、Ｎ
、Ｈいつまり、窒素原子と水素原子とを含むが、これら
は、Ｎ、ガスと水とに変換され、原子炉配管等に対して
直接的な影響を及ぼすことがない。[Effect of residue] The processing up to this point may leave a small amount of hydrazine in the piping system. However, hydrazine is
, H, in other words, contains nitrogen atoms and hydrogen atoms, but these are converted into N, gas, and water, and do not have a direct effect on reactor piping and the like.
［保護被膜層による放射性物質の付着］そして、以下に
おいて、該保護被膜層に基づいて、クラッドの付着防止
とニッケルの溶出防止とがなされるが、このような処理
を施した場合でも、原子炉運転時間の経過とともに、第
２図において、Ｂ−Ｄ曲線で示すように、線量が増加す
る。[Adhesion of radioactive substances by the protective coating layer] In the following, the adhesion of crud and the elution of nickel are prevented based on the protective coating layer, but even when such treatment is performed, the nuclear reactor As the operating time elapses, the dose increases as shown by the BD curve in FIG.
しかし、ヒドラジン処理後における線量増加は、後述す
るように、原子炉の建設当初において、前述した良好な
条件で母材表面を不活性処理した場合と同様に、緩やか
な線量増加となる。However, as will be described later, the dose increase after the hydrazine treatment is a gradual increase, similar to the case where the base material surface is inertly treated under the above-mentioned favorable conditions at the beginning of the construction of the nuclear reactor.
なお、一実施例では、［洗浄中和工程］において、ヒド
ラジンを使用したが、希薄ヒドラジンにアンモニアを加
えて、より顕著なアルカリ雰囲気として、有機酸及びそ
の生成物の洗浄を行なうことができる。アンモニアが配
管系に残された場合にあっても、ヒドラジンと同様に分
子の分解及び化学反応によって、Ｎ、ガスまたはＨ，Ｏ
となるので、原子炉の運転に支障を来すことがない。In one example, hydrazine was used in the [cleaning and neutralization step], but it is also possible to add ammonia to dilute hydrazine to create a more pronounced alkaline atmosphere for cleaning organic acids and their products. Even if ammonia is left in the piping system, like hydrazine, it can be released as N, gas or H, O through molecular decomposition and chemical reactions.
Therefore, there is no problem with the operation of the reactor.
［ステンレス鋼の表面処理について］
化学除染処理された母材表面が、ステンレス鋼である場
合にあっても、前述した各工程によって、活性化された
母材表面を速やかに還元雰囲気とするとともに、この還
元雰囲気のまま原子炉運転雰囲気に導くことにより、前
述した高温加湿空気を挿通させて処理した場合と同様に
、安定性の高い良質の保護被膜層を形成して、クラッド
の付着防止とニッケルの溶出防止とを行なうことができ
る。[About stainless steel surface treatment] Even if the surface of the base material that has been chemically decontaminated is stainless steel, the activated base material surface can be quickly brought into a reducing atmosphere through the steps described above, and By introducing this reducing atmosphere into the reactor operating atmosphere, a highly stable and high-quality protective film layer is formed, which prevents the adhesion of crud, similar to the treatment described above by passing high-temperature humidified air through the reactor. Elution of nickel can be prevented.
また、特に、ステンレス鋼の表面処理にあっては、空気
や水との接触によって、腐食酸化状態とはならないので
、前述した［洗浄中和工程コを省略することが可能であ
るが、この場合でも、母材の表面電位が活性状態となら
ないように還元処理工程は必要である。In addition, especially when treating the surface of stainless steel, contact with air or water will not result in a corrosive oxidation state, so it is possible to omit the cleaning and neutralization step described above, However, a reduction treatment step is necessary to prevent the surface potential of the base material from becoming active.
［ステンレス鋼における表面処理実験例］ステンレス鋼
（ＪＩＳ３１６ＮＧ材）について、沸騰水型原子炉の冷
却水環境、例えば２８４℃、圧カフ ０ ｋｇ／ ｃｍ
２、溶存酸素２００ｐｐｂに対して、処理条件の相異に
よる金属成分の冷却水への溶出特性を実験し、第１表の
結果を得た。[Surface treatment experiment example for stainless steel] Stainless steel (JIS316NG material) was tested in a boiling water reactor cooling water environment, for example, 284°C, pressure cuff 0 kg/cm
2. For 200 ppb of dissolved oxygen, experiments were conducted on the elution characteristics of metal components into cooling water due to differences in treatment conditions, and the results shown in Table 1 were obtained.
第１表（単位ｕｇ／ｄｍ″１５０Ｈｒｓ）この結果から
明らかなように、■ヒドラジン処理、つまり、本発明の
方法による表面処理を施したステンレス鋼は、保護被膜
層が形成される結果、他の表面処理に比較して、各金属
の溶出量を少なくでき、特に、ニッケルの溶出による５
８ＣＯの生成を抑制することができる。Table 1 (unit: ug/dm" 150Hrs) As is clear from the results, stainless steel subjected to hydrazine treatment, that is, the surface treatment by the method of the present invention, has a protective coating layer formed on it. Compared to surface treatment, the amount of elution of each metal can be reduced, and in particular, the amount of nickel elution can be reduced.
Generation of 8CO can be suppressed.
［炭素鋼及びステンレス鋼混用配管系等の表面処理につ
いて］
化学除染された母材表面が、ステンレス鋼及び炭素鋼の
両方を含む場合においては、炭素鋼の表面処理によって
、ステンレス鋼を表面処理することが可能であり、一実
施例において炭素鋼で説明した工程に準じて表面処理を
行なうのか良い。つまり、一実施例で説明した工程によ
って、−度に炭素鋼及びステンレス鋼の両方を表面処理
することができる。[Surface treatment of carbon steel and stainless steel mixed piping systems, etc.] If the surface of the chemically decontaminated base material contains both stainless steel and carbon steel, surface treatment of stainless steel by surface treatment of carbon steel is required. In one embodiment, surface treatment may be performed in accordance with the process described for carbon steel. That is, by the process described in one embodiment, it is possible to surface-treat both carbon steel and stainless steel at the same time.
なお、母材表面の処理を行なうための各工程において、
母材表面が濡れている状態で次の工程を行なうように、
液を順次入れ替えるようにすることができるが、各工程
でアルカリあるいは還元雰囲気となる液を使用している
ため、乾燥状態となることを許容している。また、本発
明は、配管形状のものに限定するものではなく、管体、
ブロック状等の任意形状のものに対しても適用すること
ができる。In addition, in each process for treating the surface of the base material,
Make sure to carry out the next process while the base material surface is wet.
Although it is possible to replace the liquid sequentially, each process uses a liquid that creates an alkaline or reducing atmosphere, allowing it to become dry. Furthermore, the present invention is not limited to pipe-shaped objects, but includes pipe bodies,
It can also be applied to objects of arbitrary shapes such as block shapes.
「発明の効果」
以上説明したように、本発明に係る原子炉配管等の表面
処理方法によれば、次のような優れた効果を奏すること
ができる。"Effects of the Invention" As explained above, according to the method for surface treatment of nuclear reactor piping, etc. according to the present invention, the following excellent effects can be achieved.
（ａ）化学除染によって活性化状態となった母材表面を
還元性雰囲気に置換し、運転雰囲気の原子炉冷却水と接
触させるものであるから、腐食性酸化を生じさせること
なく、保護被膜層を形成して、クラッドの付着防止を図
り、また、組織中のニッケルの溶出現象の発生を抑制し
て、配管系等の線量を低くすることができる。(a) The surface of the base material, which has been activated by chemical decontamination, is replaced with a reducing atmosphere and brought into contact with the reactor cooling water in the operating atmosphere, so the protective coating can be formed without causing corrosive oxidation. By forming a layer, it is possible to prevent the adhesion of the cladding, and also to suppress the occurrence of nickel elution phenomenon in the tissue, thereby lowering the dose to the piping system, etc.
（ｂ）ステンレス鋼及び炭素鋼の両方に適用することが
できるとともに、混用されている配管路等に対しても有
効であり、取り扱い性及び実用性を向上させることがで
きる。(b) It can be applied to both stainless steel and carbon steel, and is also effective for piping lines etc. that are mixedly used, and can improve handleability and practicality.
（Ｃ）表面処理に使用したヒドラジノが、原子炉冷却水
系に残された場合においても有害物質とならず、実用性
や取り扱い性が高く、容易に実施することができる。(C) Hydrazino used for surface treatment does not become a harmful substance even if left in the reactor cooling water system, is highly practical and easy to handle, and can be easily carried out.
第１図は本発明に係る原子炉配管等の表面処理方法の一
実施例における工程説明図、第２図は原子炉配管系にお
ける汚染線量の変化曲線図である。
出願人 石川島播磨重工業株式会社
第１図
第２図FIG. 1 is a process explanatory diagram of an embodiment of the method for surface treatment of nuclear reactor piping, etc. according to the present invention, and FIG. 2 is a diagram showing a change curve of contamination dose in the reactor piping system. Applicant Ishikawajima Harima Heavy Industries Co., Ltd. Figure 1 Figure 2
Claims (1)
ジン雰囲気で還元処理し、該ヒドラジン液の除去後に運
転雰囲気の原子炉冷却水を接触させることを特徴とする
原子炉配管等の表面処理方法。 ｉｉ、化学除染処理されたステンレス鋼または炭素鋼表
面をヒドラジンの希薄還元雰囲気で洗浄してから、ヒド
ラジン雰囲気で還元処理し、該ヒドラジン液の除去後に
運転雰囲気の原子炉冷却水を接触させることを特徴とす
る原子炉配管等の表面処理方法。[Claims] i. A nuclear reactor characterized in that the surface of a stainless steel base material that has been chemically decontaminated is subjected to a reduction treatment in a hydrazine atmosphere, and after the hydrazine solution is removed, it is brought into contact with reactor cooling water in an operating atmosphere. Surface treatment method for piping, etc. ii. Cleaning the chemically decontaminated stainless steel or carbon steel surface in a dilute reducing atmosphere of hydrazine, then subjecting it to reduction treatment in the hydrazine atmosphere, and after removing the hydrazine liquid, contacting it with reactor cooling water in the operating atmosphere. A method for surface treatment of nuclear reactor piping, etc., characterized by:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62332435A JP2508170B2 (en) | 1987-12-28 | 1987-12-28 | Surface treatment method for reactor piping |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62332435A JP2508170B2 (en) | 1987-12-28 | 1987-12-28 | Surface treatment method for reactor piping |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01176081A true JPH01176081A (en) | 1989-07-12 |
| JP2508170B2 JP2508170B2 (en) | 1996-06-19 |
Family
ID=18254940
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62332435A Expired - Lifetime JP2508170B2 (en) | 1987-12-28 | 1987-12-28 | Surface treatment method for reactor piping |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2508170B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998005940A1 (en) * | 1996-08-02 | 1998-02-12 | Siemens Aktiengesellschaft | Corrosion monitoring process |
| JP2007232432A (en) * | 2006-02-28 | 2007-09-13 | Hitachi Ltd | Chimney of natural circulation type boiling water reactor |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52111834A (en) * | 1976-03-15 | 1977-09-19 | Halliburton Co | Method of treating surface of ironncontaining metal |
-
1987
- 1987-12-28 JP JP62332435A patent/JP2508170B2/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52111834A (en) * | 1976-03-15 | 1977-09-19 | Halliburton Co | Method of treating surface of ironncontaining metal |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998005940A1 (en) * | 1996-08-02 | 1998-02-12 | Siemens Aktiengesellschaft | Corrosion monitoring process |
| JP2007232432A (en) * | 2006-02-28 | 2007-09-13 | Hitachi Ltd | Chimney of natural circulation type boiling water reactor |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2508170B2 (en) | 1996-06-19 |
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