JPH0478960B2 - - Google Patents
Info
- Publication number
- JPH0478960B2 JPH0478960B2 JP62229000A JP22900087A JPH0478960B2 JP H0478960 B2 JPH0478960 B2 JP H0478960B2 JP 62229000 A JP62229000 A JP 62229000A JP 22900087 A JP22900087 A JP 22900087A JP H0478960 B2 JPH0478960 B2 JP H0478960B2
- Authority
- JP
- Japan
- Prior art keywords
- iron
- radioactive
- based structural
- ions
- ferrite layer
- 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.)
- Expired - Lifetime
Links
- 239000000463 material Substances 0.000 claims description 50
- 229910000859 α-Fe Inorganic materials 0.000 claims description 50
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 49
- 150000002500 ions Chemical class 0.000 claims description 41
- 230000002285 radioactive effect Effects 0.000 claims description 36
- 229910052742 iron Inorganic materials 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 22
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 20
- 229910052760 oxygen Inorganic materials 0.000 claims description 20
- 239000001301 oxygen Substances 0.000 claims description 20
- 239000000498 cooling water Substances 0.000 claims description 18
- 239000012857 radioactive material Substances 0.000 claims description 8
- 229910021645 metal ion Inorganic materials 0.000 claims description 5
- 239000000941 radioactive substance Substances 0.000 claims description 5
- 238000001816 cooling Methods 0.000 claims description 3
- 238000002347 injection Methods 0.000 claims description 3
- 239000007924 injection Substances 0.000 claims description 3
- 238000009835 boiling Methods 0.000 claims description 2
- 230000001590 oxidative effect Effects 0.000 claims description 2
- 238000005260 corrosion Methods 0.000 description 27
- 230000007797 corrosion Effects 0.000 description 27
- 238000005253 cladding Methods 0.000 description 11
- 230000008021 deposition Effects 0.000 description 11
- 230000003647 oxidation Effects 0.000 description 8
- 238000007254 oxidation reaction Methods 0.000 description 8
- 238000004140 cleaning Methods 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- 229910000975 Carbon steel Inorganic materials 0.000 description 2
- 230000010062 adhesion mechanism Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000010962 carbon steel Substances 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000001629 suppression Effects 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
Landscapes
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、放射性イオンの付着防止方法、特
に、原子力発電プラントの再循環配管系等のよう
に、放射性物質が溶解している水と接して使用さ
れる鉄系構造材に対する放射性イオンの付着防止
方法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 preventing the adhesion of radioactive ions, particularly to water in which radioactive substances are dissolved, such as in recirculation piping systems of nuclear power plants. The present invention relates to a method for preventing the adhesion of radioactive ions to iron-based structural materials used in construction.
原子力発電プラントの一次冷却水系に使用され
ている構成要素としては、主に鉄系材料を含む配
管、ポンプ、弁等の構造材および機器（以下、構
造材と称する）があるが、長期間使用している
と、これらの構造材から金属不純物が溶出し、原
子炉内に搬入され、ここで中性子照射を受けるこ
とにより放射化され、放射性腐食生成物を生成す
る。この腐食生成物には、冷却水に溶解した成分
（以下、イオンと称する）と、不溶性の固体成分
（以下、クラツドと称する）とがあり、クラツド
は主として原子炉内で、イオンが酸化されて生成
する。
The components used in the primary cooling water system of nuclear power plants include structural materials and equipment (hereinafter referred to as structural materials) such as piping, pumps, and valves that mainly contain iron-based materials. As a result, metal impurities are leached from these structural materials and transported into the reactor, where they are activated by neutron irradiation and generate radioactive corrosion products. These corrosion products include components dissolved in the cooling water (hereinafter referred to as ions) and insoluble solid components (hereinafter referred to as crud).Cruds are mainly produced by oxidation of ions in the reactor. generate.
このようにして、生成した、60Co、58Co、54Mn等
よりなる長半減期の放射性腐食生成物は、一次冷
却水系を循環しているうちに構造材表面に付着す
る。このため、構造材の表面における線量率が高
くなり、保守、点検を実施する際の作業員の放射
線被曝が問題となつている。 The long-half-life radioactive corrosion products produced in this way, such as 60 Co, 58 Co, and 54 Mn, adhere to the surface of the structural material while circulating in the primary cooling water system. For this reason, the dose rate on the surface of the structural material increases, and radiation exposure of workers during maintenance and inspection has become a problem.
このため、構造材の表面線量率の上昇を防止す
る方法として、構造材に付着した放射性腐食物を
機械的に除去する方法が検討され、実施されてい
る。この機械的洗浄方法を用いる場合には、構造
材の表面線量率を一時的に減少させることはでき
るが、放射性付着物の中には、機械的洗浄方法で
は除去が非常に困難なものがあり、この種付着物
の長年月にわたる集積により構造材の表面線量率
は年々増加する傾向にある。 Therefore, as a method for preventing an increase in the surface dose rate of structural materials, methods of mechanically removing radioactive corrosive substances adhering to structural materials have been studied and implemented. When using this mechanical cleaning method, it is possible to temporarily reduce the surface dose rate of structural materials, but some radioactive deposits are extremely difficult to remove using mechanical cleaning methods. Due to the accumulation of this type of deposit over many years, the surface dose rate of structural materials tends to increase year by year.
また、放射性腐食生成物の構造材への付着量を
低減させるため、一次冷却水中の放射性腐食生成
物の濃度を低減させる方法も実施されている。す
なわち、一次冷却水中の金属不純物の大部分は給
水系の構造材が腐食して、原子炉内に搬入され生
成するものであるため、酸素又は過酸化水等を給
水系内に注入して構造材表面に酸化被膜を形成さ
せ構造材の腐食を抑制し、これによつて、腐食生
成物の原子炉内への搬入量を低減させ、原子炉内
での放射化量を低減せしめるものである。 Furthermore, in order to reduce the amount of radioactive corrosion products adhering to structural materials, methods are also being implemented to reduce the concentration of radioactive corrosion products in the primary cooling water. In other words, most of the metal impurities in the primary cooling water are generated when the structural materials of the water supply system corrode and are carried into the reactor. It suppresses corrosion of structural materials by forming an oxide film on the material surface, thereby reducing the amount of corrosion products carried into the reactor and the amount of activation inside the reactor. .
しかし、このような方法を用いても給水系をは
じめとし、一次冷却水系の構造材の腐食を完全に
防止することはできず、一次冷却水中の放射性腐
食生成物を無くすることはできないため、構造材
への放射性腐食生成物の付着による表面線量率の
増加がやはり問題として残つている。
However, even if such methods are used, it is not possible to completely prevent corrosion of the structural materials of the primary cooling water system, including the water supply system, and radioactive corrosion products in the primary cooling water cannot be eliminated. Increased surface dose rates due to adhesion of radioactive corrosion products to structural materials remain a problem.
しかも、給水系の構造材について腐食抑制対策
が実施されているプラントでは、機械的洗浄方法
の実施により除去される放射性付着物の全放射性
付着物に対する割合が小さく、機械的洗浄方法の
実施効果が少ないことが明らかになつた。 Furthermore, in plants where corrosion control measures have been implemented for the structural materials of the water supply system, the ratio of radioactive deposits removed by mechanical cleaning methods to the total radioactive deposits is small, and the effectiveness of mechanical cleaning methods is It became clear that there were few.
本発明は、これらの問題点を除去し、構造材表
面に強固に付着する放射性腐食生成物の付着量の
低減を可能とすることを目的とする。 It is an object of the present invention to eliminate these problems and to make it possible to reduce the amount of radioactive corrosion products that adhere firmly to the surface of structural materials.
本発明は、沸騰水型原子力プラントの運転開始
前に、放射性物質を含む冷却水と接する炉心又は
再循環系統の鉄系構造材の前記冷却水との接触面
の一部ないし全面に対し、（鉄系構造材が実質的
に放射性物質を含む水と接する前に、）前記鉄系
構造材が使用される温度以上の高温で、酸素注入
下にあり実質的に放射性物質を含まなく且つ一次
冷却系に使用される鉄系構造材から発生する金属
イオンを含む水を接触させることにより酸化させ
フエライト層を形成することを特徴とするもので
ある。
The present invention provides that, before the start of operation of a boiling water nuclear power plant, ( Before the iron-based structural material comes into contact with water substantially containing radioactive materials, it is first cooled under oxygen injection, substantially free of radioactive materials, and at a high temperature above the temperature at which said iron-based structural material is used. It is characterized in that it is oxidized by contacting water containing metal ions generated from the iron-based structural material used in the system to form a ferrite layer.
本発明は、炉心又は再循環系統の鉄系構造材を
酸素注入下にあり実質的に放射性物質を含まなく
且つ一次冷却系に使用される鉄系構造材から発生
する金属イオンを含む水と接触させることにより
酸化させ、その表面にフエライト層を形成するも
ので、金属イオンを酸化させることによつてフエ
ライト層を形成する。
The present invention involves contacting iron-based structural materials of a reactor core or recirculation system with water that is under oxygen injection, substantially free of radioactive materials, and containing metal ions generated from the iron-based structural materials used in the primary cooling system. The metal ions are oxidized to form a ferrite layer on the surface, and the ferrite layer is formed by oxidizing metal ions.
本発明は、機械的洗浄方法等によつて除去する
ことが困難な、構造材表面に強固に付着している
放射性腐食生成物が一次冷却水中の放射性イオン
に基づくものであり、この放射性イオンは、非放
射性イオンが構造材表面にフエライト層を形成し
て付着する際に、フエライト層内に固溶した状態
で付着することを実質的に確認し、さらに、フエ
ライト層の付着速度はフエライト層の厚さが厚く
なると小さくなる点に着目してなされたもので、
構造材に放射性物質を含まないフエライト層を予
め、即ち、プラントの運転開始前に形成せしめて
おき、これによつて、一次冷却系の構造材として
使用した場合のフエライト層の生成量を低減さ
せ、併せてフエライト層に固溶する放射性イオン
の付着を防止可能とするものである。 In the present invention, radioactive corrosion products that are firmly attached to the surface of structural materials and which are difficult to remove by mechanical cleaning methods etc. are based on radioactive ions in the primary cooling water. , it was practically confirmed that when non-radioactive ions form a ferrite layer on the surface of a structural material and adhere to it, they adhere in a solid solution state within the ferrite layer, and furthermore, the deposition rate of the ferrite layer is This was done by focusing on the fact that the thickness decreases as the thickness increases.
A ferrite layer that does not contain radioactive substances is formed on the structural material in advance, that is, before the plant starts operating, thereby reducing the amount of ferrite layer produced when used as a structural material for the primary cooling system. In addition, it is possible to prevent the attachment of radioactive ions solidly dissolved in the ferrite layer.
原子力発電プラントの再循環系等の配管、ポン
プ、弁等への放射性腐食生成物の付着機構を解明
するために種々の実験がすでに多数行なわれてい
るが本発明者等も、炭素鋼からの腐食生成物を模
擬し、種々の濃度下で配管への付着量測定実験を
行なつた。この結果、第１図に模式的に示したモ
デルによつて腐食生成物が付着することが明らか
になつた。図において、１は鉄系構造材、２はフ
エライト層、３はクラツド、４は放射性イオンを
示している。すなわち、水中に溶解しているイオ
ンは配管等の表面で酸化され、フエライト層２を
形成し、クラツド３はその表面に比較的ゆるく付
着する。フエライト層２はFeO・Fe2O3又はそれ
を主成分とし、これとNi、Co、Cr等が固溶した
もの、例えばNiO・Fe2O3、CoO・Fe2O3又は
CrO・Fe2O3等が固溶したものとからなつてい
る。放射性イオン４はこのフエライト層２が形成
される際に同時に取り込まれるものと、すでに形
成されたフエライト層２中へ拡散し、同位体交換
反応等により、フエライト層２中のNi、Co、
Mn、Cr等と入れ代わり、強固に固定されるもの
とがある。 Numerous experiments have already been conducted to elucidate the adhesion mechanism of radioactive corrosion products to piping, pumps, valves, etc. in the recirculation system of nuclear power plants. We simulated corrosion products and conducted experiments to measure the amount of corrosion products deposited on piping under various concentrations. As a result, it was revealed that corrosion products adhered according to the model schematically shown in FIG. In the figure, 1 is an iron-based structural material, 2 is a ferrite layer, 3 is a cladding, and 4 is a radioactive ion. That is, ions dissolved in water are oxidized on the surface of piping, etc., forming a ferrite layer 2, and the cladding 3 is relatively loosely attached to the surface. The ferrite layer 2 is made of FeO・Fe 2 O 3 or a material containing FeO・Fe 2 O 3 as a main component and a solid solution of Ni, Co, Cr, etc., such as NiO・Fe 2 O 3 , CoO・Fe 2 O 3 or
It consists of a solid solution of CrO, Fe 2 O 3 , etc. The radioactive ions 4 are taken in at the same time when the ferrite layer 2 is formed, and are also diffused into the ferrite layer 2 that has already been formed, causing Ni, Co,
There are some that replace Mn, Cr, etc. and are firmly fixed.
これに対して、原子炉冷却水中の腐食生成物は
前述のごとく、イオンとクラツドに大別できる。
給水系への酸素注入等による構造材の腐食抑制策
が実施されているプラントにおいては、原子炉冷
却水中の腐食生成物の重量濃度は数ppb又はそれ
以下となつている。このようなプラントにおいて
は、冷却水中の放射性イオンの放射能濃度はクラ
ツドの放射能濃度よりはるかに大きく、その比は
約10以上となつている。 On the other hand, as mentioned above, corrosion products in reactor cooling water can be broadly classified into ions and clades.
In plants where measures are taken to suppress corrosion of structural materials, such as by injecting oxygen into the water supply system, the weight concentration of corrosion products in reactor cooling water is several ppb or less. In such plants, the radioactivity concentration of radioactive ions in the cooling water is much higher than the radioactivity concentration of the cladding, with a ratio of about 10 or more.
したがつて冷却水中の腐食生成物の重量濃度が
数ppbと小さく、イオンの放射能濃度がクラツド
の放射能濃度の約10倍ある場合、配管への付着放
射能を見ると、イオンによるフエライト層中の放
射能がクラツドの付着物中の放射能の約８倍であ
ることがわかつた。この実験から判つたイオンお
よびクラツドの付着速度をもとに、長期間原子炉
を運転した場合の配管表面の線量率を予想した結
果を第２図に示す。図の横軸、縦軸には、それぞ
れ運転年数（年）、配管表面線量率（mR／ｈ）
がとつてあり、Ａ、ＢおよびＣは、それぞれ、イ
オン成分による線量率、クラツド成分による線量
率および線量率合計値を示している。すでに付着
した放射性物質が自然減衰するために、運転開始
後、約10年で線量率は最大値となつている。しか
も、この時のイオン成分からの放射能寄与はクラ
ツド成分の約８倍となつており、配管表面の線量
を低減するためには、イオンの付着防止が重要で
あることが明らかである。 Therefore, if the weight concentration of corrosion products in the cooling water is as small as a few ppb, and the radioactivity concentration of ions is about 10 times that of the cladding, if we look at the radioactivity attached to the pipes, we will find that there is a ferrite layer due to the ions. It was found that the radioactivity inside was about eight times that in the crud deposits. Figure 2 shows the predicted dose rate on the piping surface when the reactor is operated for a long period of time based on the deposition rates of ions and cladding determined from this experiment. The horizontal and vertical axes of the figure are the number of years of operation (years) and the pipe surface dose rate (mR/h), respectively.
A, B, and C indicate the dose rate due to the ion component, the dose rate due to the cladding component, and the total dose rate, respectively. Due to the natural attenuation of radioactive materials that have already adhered to the plant, the dose rate reaches its maximum value approximately 10 years after the start of operation. Furthermore, the contribution of radioactivity from the ion components at this time is about eight times that of the cladding components, and it is clear that prevention of ion adhesion is important in order to reduce the dose on the pipe surface.
フエライト層を形成する際の放射性イオンの付
着速度Ｄ（cm2／ｓ）はLister等（Nuclear
Science and Engineering vol61、p.107（1976））
の解析によれば、フエライト層の厚さをｍ（cm）
とすれば、近似的に以下の式で与えられる時間変
化をする。 The deposition rate D (cm 2 /s) of radioactive ions when forming a ferrite layer is determined by Lister et al. (Nuclear
Science and Engineering vol61, p.107 (1976))
According to the analysis, the thickness of the ferrite layer is m (cm)
Then, the time change is approximately given by the following formula.
Ｄｋdm／dt ……(1)
ここに、ｋ（cm）はフエライトの飽和溶解度お
よび固液分配係数に依存する比例定数であり、ｔ
（ｓ）は時間である。また、フエライト層の厚さ
は、時間と共に第３図に示されるように増加す
る。図の横軸には運転年数（年）、縦軸にはフエ
ライトの厚さ（ｇ／m2）および付着速度（cm／
ｈ）がとつてありＤ、Ｅはそれぞれ、フエライト
の厚さ、付着速度を示している。この結果から、
付着速度を求めると、第３図に示したごとく、運
転年数の経過と共にフエライト層の厚さが増加す
るために、付着速度は急激に低下していくことが
わかつた。 Dkdm/dt...(1) Here, k (cm) is a proportionality constant that depends on the saturated solubility of ferrite and the solid-liquid partition coefficient, and t
(s) is time. Also, the thickness of the ferrite layer increases with time, as shown in FIG. The horizontal axis of the figure is the number of operating years (years), and the vertical axis is the ferrite thickness (g/m 2 ) and deposition rate (cm/m 2 ).
h) is given, and D and E indicate the thickness of the ferrite and the deposition speed, respectively. from this result,
When the deposition rate was determined, it was found that as the years of operation increased, the deposition rate rapidly decreased as the thickness of the ferrite layer increased as shown in FIG.
この結果より、フエライト層の厚さが大きい領
域ではイオンの付着速度が小さいことが明らかで
あり、したがつて、放射性イオンの付着を防止す
るためには、放射性物質を含まないフエライト層
を運転開始前に形成すればよいことが明らかであ
る。 From this result, it is clear that the rate of ion deposition is low in areas where the ferrite layer is thick. Therefore, in order to prevent the deposition of radioactive ions, it is necessary to start operation with a ferrite layer that does not contain radioactive substances. It is clear that it can be formed beforehand.
第４図にあらかじめ形成されるフエライト層の
厚さに対し、30年間の運転中における配管表面線
量率最大値をイオンとクラツドに分けて示す。図
の横軸、縦軸には、それぞれ、あらかじめ形成さ
れるフエライトの厚さ（ｇ／m2）、配管表面線量
率最大値（mR／ｈ）がとつてあり、Ｆ、Ｇは、
それぞれ、イオン、クラツドの場合を示してい
る。これからあらかじめ形成されるフエライト層
の厚さを約５ｇ／m2とした場合、イオン成分から
の線量率寄与がクラツドの寄与と等しくなること
が明らかである。したがつて、あらかじめ形成す
るフエライト層の厚さは５ｇ／m2以上が最適であ
る。 Figure 4 shows the maximum dose rate on the pipe surface during 30 years of operation, divided into ions and cladding, with respect to the thickness of the ferrite layer formed in advance. The horizontal and vertical axes of the figure respectively indicate the thickness of the ferrite formed in advance (g/m 2 ) and the maximum value of the pipe surface dose rate (mR/h), and F and G are
The cases of ions and cladding are shown, respectively. It is clear that if the thickness of the ferrite layer to be preformed is approximately 5 g/m 2 , the dose rate contribution from the ionic component will be equal to the contribution from the cladding. Therefore, the optimal thickness of the ferrite layer formed in advance is 5 g/m 2 or more.
第５図は、本発明の鉄系構造材への放射性イオ
ンの付着防止方法の一実施例を実施するのに使用
される高温水循環供給装置の概略図で、１１は処
理配管、１２は処理配管１１にフエライト層を形
成するためのイオンの供給用のタンク、１３はフ
エライト層形成用のイオン源となる炭素鋼、１４
はフイルタ、１５は処理液循環ポンプ、１６はヒ
ータ、１７，１８は処理配管１１とフエライト層
形成を目的とする部分の含まれる系統とは別の、
新たに設置された処理液配管１９，２０との接続
具である。
FIG. 5 is a schematic diagram of a high-temperature water circulation supply device used to carry out an embodiment of the method for preventing the adhesion of radioactive ions to iron-based structural materials of the present invention, in which 11 is a processing pipe, and 12 is a processing pipe. 11 is a tank for supplying ions for forming a ferrite layer; 13 is a carbon steel serving as an ion source for forming a ferrite layer; 14 is a tank for supplying ions for forming a ferrite layer;
is a filter, 15 is a processing liquid circulation pump, 16 is a heater, 17 and 18 are separate systems from the processing piping 11 and the part intended for forming the ferrite layer,
This is a connection tool for newly installed processing liquid pipes 19 and 20.
この装置において、イオンの供給用のタンク１
１内の炭素鋼１３は供給タンク１１の開放端より
侵入する空気、あるいは、図の処理液循環ポンプ
１５の後段に設けた酸素供給口２１からの酸素に
よつて酸化される。そして循環水中に溶出した腐
食生成物をフイルタ１４を通してクラツドを除去
した後、高濃度のイオン状腐食生成物を含む循環
水を処理液循環ポンプ１５により処理配管１１に
供給する。処理配管１１はイオンの酸化によるフ
エライト層の形成を促進するためにヒータ１６で
加熱される。実験結果によると、水温500℃で運
転した場合、約１週間で５ｇ／m2のフエライト層
が形成できた。このように、処理配管１１はそれ
が使用される温度以上の高温水を流してフエライ
ト層の形成が促進される。 In this device, a tank 1 for supplying ions
The carbon steel 13 in the supply tank 11 is oxidized by air entering from the open end of the supply tank 11 or by oxygen from the oxygen supply port 21 provided downstream of the treatment liquid circulation pump 15 shown in the figure. After the corrosion products eluted into the circulating water are passed through a filter 14 to remove crud, the circulating water containing a high concentration of ionic corrosion products is supplied to the processing piping 11 by the processing liquid circulation pump 15. The processing pipe 11 is heated by a heater 16 to promote the formation of a ferrite layer by oxidation of ions. According to the experimental results, when operating at a water temperature of 500°C, a ferrite layer of 5 g/m 2 could be formed in about one week. In this manner, the formation of the ferrite layer is promoted through the treatment pipe 11 by flowing water at a high temperature above the temperature at which it is used.
この実施例では、構造材の一部に対するフエラ
イト層の形成方法を示し、このように各部品ごと
にフエライト層を形成する方法が最も効率的であ
り、またこのようにしてフエライト層の形成され
た部品を溶接により接合する場合における溶接部
全体の占める割合は小さいので溶接によるフエラ
イト層の消滅の影響は無視し得るが、特に、必要
のある場合は、溶接して組立てられた状態でフエ
ライト層を形成することも可能である。 In this example, a method of forming a ferrite layer on a part of a structural material is shown, and the method of forming a ferrite layer for each part in this way is the most efficient, and the method of forming a ferrite layer in this way is When parts are joined by welding, the proportion of the entire welded area is small, so the effect of the disappearance of the ferrite layer due to welding can be ignored. It is also possible to form
このように、運転開始前に所定の厚さにフエラ
イト層が形成された構造材においては、前述の如
く、イオンの付着量を小さくすることができるた
め、放射性腐食生成物の付着量の低減が可能とな
る。 In this way, in structural materials on which a ferrite layer is formed to a predetermined thickness before the start of operation, the amount of attached ions can be reduced as described above, so the amount of attached radioactive corrosion products can be reduced. It becomes possible.
第６図は、SUS304鋼を285℃の高温水中で溶
存酸素濃度をパラメータに150時間酸化処理後Co
イオンを添加（3ppb）し、溶存酸素濃度200ppb
で300時間浸せき後のCo付着量と前酸化処理時の
溶存酸素濃度との関係を示したもので、横軸、縦
軸には、それぞれ、溶存酸素濃度（ppb）、Co付
着量（ｇ／m2）がとつてある。 Figure 6 shows SUS304 steel coated with Co after being oxidized for 150 hours in high-temperature water at 285℃ using the dissolved oxygen concentration as a parameter.
Added ions (3ppb), dissolved oxygen concentration 200ppb
This graph shows the relationship between the amount of Co deposited after 300 hours of immersion and the dissolved oxygen concentration during pre-oxidation treatment.The horizontal and vertical axes show the dissolved oxygen concentration (ppb) and the amount of Co deposited (g/ m 2 ).
Co付着量は前酸化処理時の溶存酸素濃度の増
加と共に顕著に低下し、約400ppb以上でほぼ一
定の付着量を示す。この結果は、BWR炉水条件
下（溶存酸素濃度約200ppb）におけるCo付着抑
制の為には、200ppb以上の高溶存酸素濃度下に
おける前酸化処理が効果的であることを示してい
る。 The amount of Co deposited decreases significantly as the dissolved oxygen concentration increases during pre-oxidation treatment, and remains almost constant above about 400 ppb. This result indicates that pre-oxidation treatment under high dissolved oxygen concentration of 200 ppb or more is effective for suppressing Co deposition under BWR reactor water conditions (dissolved oxygen concentration of about 200 ppb).
第７図は、第６図と同一実験条件下における酸
化皮膜成長量と、前酸化処理時の溶存酸素濃度と
の関係を示したもので、横軸、縦軸には、それぞ
れ、溶存酸素濃度（ppb）、酸化皮膜がとつてあ
る。溶存酸素濃度の増加と共に形成される皮膜の
耐食性が著しく向上し、Co付着抑制効果の溶存
酸素濃度依存性とよく対応している。 Figure 7 shows the relationship between the amount of oxide film growth and the dissolved oxygen concentration during pre-oxidation treatment under the same experimental conditions as in Figure 6. The horizontal and vertical axes show the dissolved oxygen concentration, respectively. (ppb), oxide film is present. The corrosion resistance of the film formed markedly improves as the dissolved oxygen concentration increases, which corresponds well to the dependence of the Co adhesion suppression effect on dissolved oxygen concentration.
本発明によれば、プラントの運転開始前に、配
管等特に放射性イオンが付着し易い構造材の表面
（冷却水が接する面）に放射性物質を含まないフ
エライト層を形成することにより、運転中に放射
性イオンがフエライト層中へ付着する量を大幅に
低減することができ、配管等の表面線量率を従来
の1/4以下にすることができる。 According to the present invention, before the start of plant operation, a ferrite layer that does not contain radioactive substances is formed on the surface of structural materials such as piping that are particularly susceptible to attachment of radioactive ions (surfaces that come into contact with cooling water). The amount of radioactive ions that adhere to the ferrite layer can be significantly reduced, and the surface dose rate of pipes, etc. can be reduced to one-quarter or less of the conventional level.
以上の如く、本発明の放射性イオンの付着防止
方法は、構造材表面に強固に付着する放射性腐食
生成物の付着量の低減を可能とするもので、産業
上の効果の大なるものである。
As described above, the method for preventing the adhesion of radioactive ions of the present invention makes it possible to reduce the amount of adhering radioactive corrosion products that firmly adhere to the surface of structural materials, and has great industrial effects.
第１図は腐食生成物の付着機構を示す模式図、
第２図は原子力発電プラントの運転年数と配管表
面の総量率との関係を示すグラフ、第３図は同様
に運転年数に対する付着速度およびフエライト層
の厚さとの関係を示すグラフ、第４図はあらかじ
め形成されたフエライト層の厚さと放射性イオン
およびクラツドによる配管表面の線量率の最大値
との関係を示すグラフ、第５図は本発明の鉄系構
造材への放射性イオンの付着防止方法の一実施例
を実施するのに使用される高温水循環供給装置の
概略図、第６図は前酸化処理時における溶存酸素
濃度とCo付着量との関係を示すグラフ、第７図
は前酸化処理時における溶存酸素濃度と酸化皮膜
成長量と関係を示すグラフである。
１……構造材、２……フエライト層、３……ク
ラツド、４……放射性イオン、１１……処理配
管、１２……供給タンク。
Figure 1 is a schematic diagram showing the adhesion mechanism of corrosion products.
Figure 2 is a graph showing the relationship between the number of years of operation of a nuclear power plant and the total amount rate on the pipe surface, Figure 3 is a graph showing the relationship between the number of years of operation and the deposition rate and the thickness of the ferrite layer, and Figure 4 is a graph showing the relationship between the number of years of operation and the thickness of the ferrite layer. Figure 5 is a graph showing the relationship between the thickness of the ferrite layer formed in advance and the maximum dose rate on the pipe surface due to radioactive ions and cladding, which is one of the methods for preventing the adhesion of radioactive ions to iron-based structural materials according to the present invention. A schematic diagram of the high-temperature water circulation supply device used to carry out the examples. Figure 6 is a graph showing the relationship between dissolved oxygen concentration and Co adhesion amount during pre-oxidation treatment. Figure 7 is a graph showing the relationship between dissolved oxygen concentration and Co adhesion amount during pre-oxidation treatment. It is a graph showing the relationship between dissolved oxygen concentration and oxide film growth amount. DESCRIPTION OF SYMBOLS 1... Structural material, 2... Ferrite layer, 3... Clad, 4... Radioactive ion, 11... Processing piping, 12... Supply tank.
Claims (1)
射性物質を含む冷却水と接する炉心又は再循環系
統の鉄系構造材の前記冷却水との接触面の一部な
いし全面に対し、前記鉄系構造材が使用される温
度以上の高温で、酸素注入下にあり実質的に放射
性物質を含まなく且つ一次冷却系に使用される鉄
系構造材から発生する金属イオンを含む水を接触
させることにより酸化させフエライト層を形成す
ることを特徴とする鉄系構造材への放射性イオン
の付着防止方法。 ２ 原子力発電プラントにおける放射性物質を含
む冷却水と接する前記炉心又は再循環系統の鉄系
構造材において、前記冷却水とは別系統のループ
を形成するように配置された水循環供給装置によ
りプラント組み立て後の前記鉄系構造材に前記フ
エライト層を形成させる特許請求の範囲第１項記
載の鉄系構造材への放射性イオンの付着防止方
法。 ３ 原子力発電プラントにおける放射性物質を含
む冷却水と接する前記炉心又は再循環系統の鉄系
構造材において、プラントに組み立てる前に放射
性物質を含まない前記水を前記鉄系構造材に接触
させて前記フエライト層を形成させる特許請求の
範囲第１項記載の鉄系構造材への放射性イオンの
付着防止方法。 ４ 前記フエライト層の厚さを５ｇ／m2以上とし
た特許請求の範囲第２項又は第３項記載の鉄系構
造材への放射性イオンの付着防止方法。[Scope of Claims] 1. Before the start of operation of a boiling water nuclear power plant, a part or entire surface of the iron-based structural material of the core or recirculation system that comes into contact with the cooling water containing radioactive materials is in contact with the cooling water. On the other hand, water containing metal ions generated from the iron-based structural material used in the primary cooling system, which is under oxygen injection and substantially free of radioactive substances, at a high temperature higher than the temperature at which the iron-based structural material is used. A method for preventing the adhesion of radioactive ions to iron-based structural materials, the method comprising oxidizing and forming a ferrite layer by contacting with iron-based structural materials. 2. In the iron-based structural materials of the core or recirculation system that come into contact with cooling water containing radioactive materials in a nuclear power plant, after the plant is assembled by a water circulation supply device arranged to form a loop separate from the cooling water. 2. A method for preventing the adhesion of radioactive ions to an iron-based structural material according to claim 1, wherein the ferrite layer is formed on the iron-based structural material. 3. In the iron-based structural material of the reactor core or recirculation system that comes into contact with cooling water containing radioactive materials in a nuclear power plant, the water not containing radioactive materials is brought into contact with the iron-based structural material before assembly into the plant to form the ferrite. A method for preventing the adhesion of radioactive ions to iron-based structural materials according to claim 1, which comprises forming a layer. 4. The method for preventing adhesion of radioactive ions to iron-based structural materials according to claim 2 or 3, wherein the ferrite layer has a thickness of 5 g/m 2 or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62229000A JPS63271196A (en) | 1987-09-12 | 1987-09-12 | Method for preventing adhesion of radioactive ion to iron structural material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62229000A JPS63271196A (en) | 1987-09-12 | 1987-09-12 | Method for preventing adhesion of radioactive ion to iron structural material |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2897679A Division JPS55121197A (en) | 1979-03-13 | 1979-03-13 | Method for protecting deposition of radioactive ion |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63271196A JPS63271196A (en) | 1988-11-09 |
| JPH0478960B2 true JPH0478960B2 (en) | 1992-12-14 |
Family
ID=16885188
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62229000A Granted JPS63271196A (en) | 1987-09-12 | 1987-09-12 | Method for preventing adhesion of radioactive ion to iron structural material |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63271196A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3945780B2 (en) | 2004-07-22 | 2007-07-18 | 株式会社日立製作所 | Radionuclide adhesion suppression method and film forming apparatus for nuclear plant components |
| JP5208188B2 (en) * | 2010-12-06 | 2013-06-12 | 日立Ｇｅニュークリア・エナジー株式会社 | Method for reducing radiation exposure of nuclear plant, nuclear plant and fuel assembly |
| JP2013029401A (en) * | 2011-07-28 | 2013-02-07 | Hitachi-Ge Nuclear Energy Ltd | Method of suppressing sticking of radioactive nuclide on plant constitution member |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5285696A (en) * | 1976-01-07 | 1977-07-16 | Hitachi Ltd | Corrosion prevention method for pipe arrangement of reactor |
| JPS5439791A (en) * | 1977-09-02 | 1979-03-27 | Hitachi Ltd | Operation method of reactor |
| JPS5439701A (en) * | 1977-09-06 | 1979-03-27 | Toshiba Corp | Method of forming anti-oxidation protective film in condenser/water supply system |
| JPS55121197A (en) * | 1979-03-13 | 1980-09-18 | Hitachi Ltd | Method for protecting deposition of radioactive ion |
-
1987
- 1987-09-12 JP JP62229000A patent/JPS63271196A/en active Granted
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5285696A (en) * | 1976-01-07 | 1977-07-16 | Hitachi Ltd | Corrosion prevention method for pipe arrangement of reactor |
| JPS5439791A (en) * | 1977-09-02 | 1979-03-27 | Hitachi Ltd | Operation method of reactor |
| JPS5439701A (en) * | 1977-09-06 | 1979-03-27 | Toshiba Corp | Method of forming anti-oxidation protective film in condenser/water supply system |
| JPS55121197A (en) * | 1979-03-13 | 1980-09-18 | Hitachi Ltd | Method for protecting deposition of radioactive ion |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63271196A (en) | 1988-11-09 |
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