JP4420838B2 - Hydrogen injection method for nuclear power plant - Google Patents
Hydrogen injection method for nuclear power plant Download PDFInfo
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Description
本発明は、原子力発電プラントの水素の注入方法に関し、特に、沸騰水型原子炉（ＢＷＲ）の給水系を介して炉水に水素を注入する原子力発電プラントの水素の注入方法に関するものである。 The present invention relates to a method for injecting hydrogen into a nuclear power plant, and more particularly to a method for injecting hydrogen into a nuclear power plant that injects hydrogen into reactor water via a water supply system of a boiling water reactor (BWR).
近年、原子力発電プラントの運転年数の増大に伴い、沸騰水型原子炉の一次系構造材料の劣化、損傷の事象が顕在化している。このため、これらの事象を抑制する対策を施し、原子力発電プラントの安全運転を長期に渡って確保する必要性が生じている。 In recent years, with the increase in the operating years of nuclear power plants, events of deterioration and damage of the primary structural material of boiling water reactors have become apparent. For this reason, it is necessary to take measures to suppress these events and ensure the safe operation of the nuclear power plant for a long time.
沸騰水型原子炉の一次系構造材料の劣化、損傷の一事例として、ステンレス鋼、ニッケル基合金等の材料の応力腐食割れ（ｓｔｒｅｓｓ ｃｏｒｒｏｓｉｏｎ ｃｒａｃｋｉｎｇ）が挙げられる。 One example of deterioration and damage of the primary structural material of a boiling water reactor is stress corrosion cracking of materials such as stainless steel and nickel-base alloys.
応力腐食割れは、材料（応力腐食割れに対する感受性を有する材料）、応力（溶接残留応力等の高い引張応力）、水質環境（塩素、酸素、過酸化水素等の酸化性化学種を含む水質環境）の３因子が重なったときに発生することは周知である（例えば、非特許文献１参照。）。 Stress corrosion cracking includes materials (materials that are sensitive to stress corrosion cracking), stress (high tensile stress such as welding residual stress), and water quality environment (water quality environment that includes oxidizing species such as chlorine, oxygen, and hydrogen peroxide). It is well known that it occurs when these three factors overlap (for example, see Non-Patent Document 1).
従来、上記のような応力腐食割れに対処するため、沸騰水型原子炉の給水系を介して炉水に水素を注入し、炉水中の溶存酸素濃度、過酸化水素濃度等を低減させて水質環境を改善し、一次系構造材料の腐食電位（腐食環境の度合いを示す指標）を低下させて、応力腐食割れに対する感受性を低減させることが行なわれている。 Conventionally, in order to cope with the stress corrosion cracking as described above, hydrogen is injected into the reactor water through the water supply system of the boiling water reactor to reduce the dissolved oxygen concentration, hydrogen peroxide concentration, etc. in the reactor water, thereby improving the water quality. The environment is improved, and the corrosion potential (an index indicating the degree of the corrosive environment) of the primary structural material is lowered to reduce the sensitivity to stress corrosion cracking.
例えば、炉水の腐食電位、溶存酸素濃度及び溶存水素濃度を測定し、この測定値に応じて沸騰水型原子炉の給水系を介して炉水に水素を注入し、炉水の溶存酸素濃度、過酸化水素濃度等を低減させ、ステンレス鋼等からなる一次系構造材料の腐食電位を低下させて、応力腐食割れに対する感受性を低減させるように構成したものが知られている（例えば、特許文献１参照。）。 For example, the corrosion potential, dissolved oxygen concentration and dissolved hydrogen concentration of the reactor water are measured, and hydrogen is injected into the reactor water through the water supply system of the boiling water reactor according to the measured values, and the dissolved oxygen concentration of the reactor water is In addition, it is known that the hydrogen peroxide concentration is reduced, the corrosion potential of the primary structural material made of stainless steel or the like is lowered, and the susceptibility to stress corrosion cracking is reduced (for example, patent document) 1).
また、他の例として、沸騰水型原子炉底部の腐食電位、又は主蒸気系の線量率を測定し、これらの測定値に応じて沸騰水型原子炉の給水系を介して炉水に水素を注入し、炉水の溶存酸素濃度、過酸化水素濃度等を低減させ、ステンレス鋼等からなる一次系構造材料の腐食電位を低下させ、応力腐食割れに対する感受性を低減させるように構成したものが知られている（例えば、特許文献２参照。）。 As another example, the corrosion potential at the bottom of the boiling water reactor or the dose rate of the main steam system is measured, and hydrogen is added to the reactor water via the feed water system of the boiling water reactor according to these measured values. Is used to reduce the dissolved oxygen concentration, hydrogen peroxide concentration, etc. of the reactor water, reduce the corrosion potential of primary structural materials made of stainless steel, etc., and reduce the susceptibility to stress corrosion cracking. It is known (for example, refer to Patent Document 2).
ところで、上記のような構成の水素の注入方法にあっては、水素の炉水への注入によって沸騰水型原子炉の一次系構造材料の応力腐食割れに対する感受性を低減させることはできる。 By the way, in the hydrogen injection method having the above-described configuration, the sensitivity to stress corrosion cracking of the primary structural material of the boiling water reactor can be reduced by injection of hydrogen into the reactor water.
しかしながら、一定の期間（約３００日）連続して水素を注入しながら原子力発電プラントの連続運転を行なっているため、配管系へのクロム酸化物の蓄積量が増加してしまう。 However, since the nuclear power plant is continuously operated while injecting hydrogen continuously for a certain period (about 300 days), the amount of chromium oxide accumulated in the piping system increases.
また、原子力発電プラントの連続運転の後に水素の注入を停止した場合においては、炉水の水質環境が還元性雰囲気から酸化性雰囲気に急激に変化することによって配管の内面に蓄積されているクロム酸化物がクロム酸イオンとして炉水中に溶出すること、及び原子炉再循環系（ＰＬＲ）ポンプの出口側に渦流が発生することによって配管の内面に蓄積されているクロム酸化物が炉水中に大量に吐き出されること等から、配管内面のクロム酸化物層に凹凸が形成されてしまう。 In addition, when hydrogen injection is stopped after continuous operation of the nuclear power plant, the chromium oxidation accumulated on the inner surface of the pipe is caused by a sudden change in the water quality environment of the reactor water from the reducing atmosphere to the oxidizing atmosphere. A large amount of chromium oxide accumulated on the inner surface of the piping is generated in the reactor water due to the leaching of substances in the reactor water as chromate ions and the generation of vortex on the outlet side of the reactor recirculation system (PLR) pump. Since it is discharged, irregularities are formed in the chromium oxide layer on the inner surface of the pipe.
その後、水素の注入を再開した場合においては、炉水の水質環境が酸化性雰囲気から還元性雰囲気に変化するために放射性物質濃度が急激に上昇してしまう。特に、原子炉再循環系（ＰＬＲ）ポンプの出口側の配管に放射性クラッドが大量に付着してしまい、その部分の線量当量率が上昇してしまう。
本発明は、上記のような従来の問題に鑑みなされたものであって、沸騰水型原子炉の一次系構造材料の応力腐食割れに対する感受性を低減させることができて、安全運転を長期に渡って確保することができるとともに、沸騰水型原子炉の給水系を介して炉水に一定の期間水素を注入した後に、定期点検等のために水素注入を停止させた場合に、配管の内面に蓄積されているクロム酸化物が原子炉再循環系（ＰＬＲ）ポンプの出口側の渦流等によって大量に吐き出されて配管内面のクロム酸化物層に凹凸が形成されるようなことがなく、さらに、水素の注入を再開した場合に、炉水の水質環境が酸化性雰囲気から還元性雰囲気に変化しても放射性物質濃度が急激に増加することなく、かつ線量当量率も上昇しない、原子力発電プラントの水素の注入方法を提供することを目的とするものである。 The present invention has been made in view of the above-described conventional problems, and can reduce the susceptibility to stress corrosion cracking of the primary structural material of a boiling water nuclear reactor, thereby enabling safe operation over a long period of time. If the hydrogen injection is stopped for periodic inspection after injecting hydrogen into the reactor water for a certain period via the boiling water reactor water supply system, The accumulated chromium oxide is not expelled in a large amount by the vortex on the outlet side of the reactor recirculation system (PLR) pump and unevenness is formed on the chromium oxide layer on the inner surface of the pipe. When restarting hydrogen injection, even if the water quality of the reactor water changes from an oxidizing atmosphere to a reducing atmosphere, the concentration of radioactive materials does not increase rapidly and the dose equivalent rate does not increase. Of hydrogen It is an object to provide the incoming process.
本発明は、上記のような課題を解決するために、以下のような手段を採用している。 The present invention employs the following means in order to solve the above problems.
すなわち、本発明の一つでは、原子力発電プラントの原子炉の給水系を介して炉水に水素を注入する原子力発電プラントの水素の注入方法であって、原子力発電プラントの運転中に、水素の注入を２〜３ヶ月継続する第１期間、水素の注入を２日間かけて段階的に減らす第２期間、水素の注入を２〜３日間停止する第３期間、及び水素の注入を２日間かけて段階的に増やす第４期間からなるサイクルを繰り返し行うことにより、一定期間の水素の連続注入、停止を繰り返し行なう。 In other words, in one of the invention, a method of implanting hydrogen nuclear power plants to inject hydrogen into the reactor water through the water supply system of the nuclear reactor of a nuclear power plant, during operation of the nuclear power plant, the hydrogen The first period in which the injection is continued for 2 to 3 months, the second period in which the hydrogen injection is gradually reduced over 2 days, the third period in which the hydrogen injection is stopped for 2 to 3 days, and the hydrogen injection over 2 days By repeating the cycle consisting of the fourth period that increases stepwise, hydrogen is continuously injected and stopped for a certain period.
本発明による原子力発電プラントの水素の注入方法によれば、一定期間の水素の連続注入により、沸騰水型原子炉の一次系構造材料の応力腐食割れに対する感受性を低減させることができる。 According to the method of injecting hydrogen in a nuclear power plant according to the present invention, the sensitivity to stress corrosion cracking of the primary structural material of a boiling water reactor can be reduced by continuous hydrogen injection for a certain period.
また、一定期間の水素の連続注入の後、水素の注入を停止することにより、配管系に蓄積されているクロム酸化物を適宜に炉水中に溶出させることができ、配管系へのクロム酸化物の蓄積量を減少させることができる。 In addition, by stopping hydrogen injection after continuous injection of hydrogen for a certain period, chromium oxide accumulated in the piping system can be appropriately eluted in the reactor water, and chromium oxide into the piping system Can be reduced.
また他の発明の一つでは、前記第２期間において、例えば、水素の注入を停止する前日に給水水素濃度を０．４５〜０．２ｐｐｍとし、水素の注入を停止する日に０．２〜０ｐｐｍとする。In another aspect of the invention, in the second period, for example, the hydrogen concentration of the feed water is set to 0.45 to 0.2 ppm on the day before stopping the hydrogen injection, and 0.2 to 0.2 on the day when the hydrogen injection is stopped. 0 ppm.
また前記第４期間において、１日目に給水水素濃度を０〜０．２ｐｐｍとし、２日目に０．２〜０．４５ｐｐｍとする。In the fourth period, the hydrogen concentration in the feed water is set to 0 to 0.2 ppm on the first day and is set to 0.2 to 0.45 ppm on the second day.
本発明による原子力発電プラントの水素の注入方法によれば、２〜３ヶ月の水素の連続注入により、沸騰水型原子炉の一次系構造材料の応力腐食割れに対する感受性を低減させることができる。また配管系に蓄積されているクロム酸化物を適宜に炉水に溶出させることができ、配管系へのクロム酸化物の蓄積量を減少させることができる。また一定期間（例えば、２〜３ヶ月）の水素の連続注入の後、水素の注入を停止する場合に、給水水素濃度を段階的に変化させながら停止させ、例えば２〜３日間の停止の後に注入を再開させる場合に、水素の濃度を段階的に変化させながら連続注入に移行することになる。したがって、炉水の水質環境が酸化雰囲気から還元雰囲気に、又は還元雰囲気から酸化雰囲気に緩やかに変化し、放射性物質濃度が急激に増加することが防止される。 According to the method of injecting hydrogen in a nuclear power plant according to the present invention, the sensitivity to stress corrosion cracking of the primary structural material of a boiling water reactor can be reduced by continuous hydrogen injection for 2 to 3 months. Further, the chromium oxide accumulated in the piping system can be appropriately eluted in the reactor water, and the amount of chromium oxide accumulated in the piping system can be reduced. In addition , when hydrogen injection is stopped after continuous injection of hydrogen for a certain period (for example, 2 to 3 months), it is stopped while gradually changing the feedwater hydrogen concentration, for example, after stopping for 2 to 3 days. When the injection is resumed, the process shifts to continuous injection while changing the hydrogen concentration stepwise. Accordingly, it is possible to prevent the water quality environment of the reactor water from gradually changing from the oxidizing atmosphere to the reducing atmosphere or from the reducing atmosphere to the oxidizing atmosphere, and the radioactive substance concentration from being rapidly increased.
本発明による原子力発電プラントの水素の注入方法によれば、一定期間（例えば、２〜３ヶ月）の水素の連続注入により、沸騰水型原子炉の一次系構造材料の応力腐食割れに対する感受性を低減させることができる。したがって、安全な運転を長期的に確保することができる。 According to the hydrogen injection method of the nuclear power plant according to the present invention, the susceptibility to stress corrosion cracking of the primary structural material of the boiling water reactor is reduced by continuous hydrogen injection for a certain period (for example, 2 to 3 months). Can be made. Therefore, safe driving can be ensured in the long term.
また、一定期間（例えば、２〜３ヶ月）の水素の連続注入の後、水素の注入を停止することにより、配管系に蓄積されているクロム酸化物を炉水に適宜に溶出させることができる。したがって、原子力発電プラントを停止させて定期点検を行なうような場合に、配管系に蓄積されているクロム酸化物が大量に吐き出されて、配管内面のクロム酸化物層に凹凸が形成されることがなくなる。 In addition, after continuous injection of hydrogen for a certain period (for example, 2 to 3 months), chromium oxide accumulated in the piping system can be appropriately eluted in the reactor water by stopping the hydrogen injection. . Therefore, when a nuclear power plant is stopped and a periodic inspection is performed, a large amount of chromium oxide accumulated in the piping system is discharged, and irregularities are formed in the chromium oxide layer on the inner surface of the piping. Disappear.
さらに、水素の連続注入の後、水素の注入を停止する場合に、水素の濃度を段階的に変化させながら停止させ、２〜３日間の停止の後に注入を再開させる場合に、水素の濃度を段階的に変化させながら連続注入に移行するように構成したので、炉水の水質環境を酸化雰囲気から還元雰囲気に、又は還元雰囲気から酸化雰囲気に緩やかに変化させることができる。したがって、水質環境の変化によって放射性物質濃度が急激に増加することなく、配管系の線量当量率も増加しないので点検作業に影響をおよぼすことはなく、定期点検を安全にかつ容易に行なうことができる。 Furthermore, when the hydrogen injection is stopped after the continuous injection of hydrogen, the hydrogen concentration is stopped while changing the hydrogen concentration stepwise, and when the injection is restarted after the stop for two to three days, the hydrogen concentration is changed. Since it is configured to shift to continuous injection while changing in stages, the water quality environment of the reactor water can be gradually changed from the oxidizing atmosphere to the reducing atmosphere or from the reducing atmosphere to the oxidizing atmosphere. Therefore, the concentration of radioactive materials does not increase sharply due to changes in the water quality environment, and the dose equivalent rate of the piping system does not increase, so there is no impact on inspection work, and periodic inspections can be performed safely and easily. .
以下、本発明の実施の形態について説明する。 Embodiments of the present invention will be described below.
本発明による原子力発電プラントの水素の注入方法は、沸騰水型原子炉（ＢＷＲ）を備えた原子力発電プラントに適用したものであって、沸騰水型原子炉の給水系を介して炉水に水素を注入するように構成したものである。 The method for injecting hydrogen in a nuclear power plant according to the present invention is applied to a nuclear power plant equipped with a boiling water reactor (BWR), and hydrogen is supplied to the reactor water through a feed water system of the boiling water reactor. Is configured to be injected.
沸騰水型原子力発電プラントの配管系は、図１に示すように、沸騰水型原子炉１の炉心で発生した蒸気をタービン２ａに送る主蒸気系の配管３と、タービン２ａで仕事をした蒸気は復水器２ｂにて復水され、この復水を復水脱塩器４に送る復水系の配管５と、復水脱塩器４から復水昇圧ポンプ１２、加熱器１３、給水ポンプ６を介して復水を沸騰水型原子炉１に送る給水系の配管７と、沸騰水型原子炉１内の冷却水を再循環ポンプ８により再循環させる再循環系の配管９とから構成されている。
As shown in FIG. 1, the piping system of the boiling water nuclear power plant is composed of a main steam system piping 3 for sending steam generated in the core of the
一次系構造材料としては、耐食性、靭性、強度、溶接性等に優れるものが好ましく、例えば、各種のステンレス鋼、各種の炭素鋼等が使用される。また、給水ポンプ６、再循環ポンプ８のケーシング、羽根車、弁等の構成部品も、耐食性、靭性、強度、溶接性等に優れるものが好ましく、各種のステンレス鋼、各種の炭素鋼等が使用される。
As the primary structural material, those having excellent corrosion resistance, toughness, strength, weldability and the like are preferable. For example, various stainless steels, various carbon steels and the like are used. In addition, components such as the casing, impeller, and valve of the
水素注入装置１０は、沸騰水型原子炉１の配管系のうち、例えば、復水脱塩器４と給水ポンプ６との間の給水系の配管７に配管１１を介して接続される。ただし、この箇所に限らず、給水系の配管７内を流通する給水内に水素を注入できる箇所であれば良い。
The
水素注入装置１０としては、例えば、高圧のガスボンベから所定の圧力に減圧してガス状の水素を給水系の配管７内を流通する給水内に注入する装置、水の電気分解により水素を製造し、ガス状の水素を給水系の配管７内を流通する給水内に注入する装置等が挙げられる。ただし、これらの装置に限らず、水素を給水系を介して給水内に注入できる装置であれば良い。
Examples of the
そして、上記のような構成の沸騰水型原子炉１を備えた原子力発電プラントの運転中に、水素注入装置１０により給水系の配管７内を流通する給水に所定の濃度の水素を注入することにより、水の放射線分解により生じた酸素、過酸化水素等の酸化性物質と水素の再結合反応が促進され、炉水内における酸化性物質の濃度が低下する。
Then, during operation of the nuclear power plant equipped with the boiling
そして、水素の注入を一定期間（例えば、２〜３ヶ月）継続した後、水素の注入を停止し、停止期間を２〜３日とした後、水素の注入を再開させる。この場合、水素の停止を２日間かけて行ない、段階的に水素の濃度を減らすとともに、水素の注入開始を２日間かけて行ない、段階的に水素の濃度を増やすことを行なう。そして、このような一定期間の水素の連続注入、水素の注入の停止を繰り返し行ない、定期点検の時期が来たときに、原子力発電プラントの運転及び水素の注入を完全に停止して、原子力発電プラントの点検を行なう。 Then, after the hydrogen injection is continued for a certain period (for example, 2-3 months), the hydrogen injection is stopped, and after the stop period is 2-3 days, the hydrogen injection is restarted. In this case, hydrogen is stopped for 2 days, the hydrogen concentration is decreased stepwise, and hydrogen injection is started for 2 days, and the hydrogen concentration is increased stepwise. Such continuous injection of hydrogen for a certain period of time and stop of hydrogen injection are repeated, and when the time for periodic inspection comes, the operation of the nuclear power plant and hydrogen injection are completely stopped to Check the plant.
上記のように構成したこの実施の形態による原子力発電プラントの水素の注入方法にあっては、水素の注入を一定期間（例えば、２〜３ヶ月）継続して行っているので、沸騰水型原子炉１の炉水の酸化性物質の濃度を低下させることができる。
In the method of injecting hydrogen in the nuclear power plant according to this embodiment configured as described above, hydrogen injection is continuously performed for a certain period (for example, 2 to 3 months). The density | concentration of the oxidizing substance of the furnace water of the
したがって、一次系構造材料の腐食電位を低下させて、応力腐食割れに対する感受性を低減させることができるので、原子力発電プラントの安全運転を長期に渡って確保することができる。 Therefore, since the corrosion potential of the primary structural material can be lowered and the sensitivity to stress corrosion cracking can be reduced, safe operation of the nuclear power plant can be ensured for a long period of time.
また、水素の注入を一定期間（２〜３ヶ月）継続して行なった後に、水素の注入を停止しているので、配管系に蓄積されているクロム酸化物を炉水に適宜に溶出させることができる。したがって、定期点検の時期に水素の注入を完全に停止させる場合においては、配管系に蓄積されているクロム酸化物が大量に吐き出されて、配管内面のクロム酸化物層に凹凸が形成されることがなくなる。 In addition, hydrogen injection is stopped after hydrogen injection is continuously performed for a certain period (2 to 3 months), so that chromium oxide accumulated in the piping system is appropriately eluted in the reactor water. Can do. Therefore, when hydrogen injection is completely stopped at the time of periodic inspection, a large amount of chromium oxide accumulated in the piping system is discharged, and irregularities are formed in the chromium oxide layer on the inner surface of the piping. Disappears.
さらに、水素の連続注入の後、水素の注入を停止する場合に、水素の濃度を段階的に変化させながら停止させ、例えば２〜３日間の停止の後に注入を再開させる場合に、水素の濃度を段階的に変化させながら連続注入に移行しているので、炉水の水質環境を酸化雰囲気から還元雰囲気に、又は還元雰囲気から酸化雰囲気に緩やかに変化させることができる。したがって、水質環境の変化によって放射性物質濃度が急激に増加することなく、配管系の線量当量率も増加しないので点検作業に影響をおよぼすことなく、定期点検を安全にかつ容易に行なうことができる。 Further, when the hydrogen injection is stopped after the continuous injection of hydrogen, the hydrogen concentration is stopped while gradually changing the hydrogen concentration, for example, when the injection is restarted after the stop for 2 to 3 days. Therefore, the water quality environment of the reactor water can be gradually changed from the oxidizing atmosphere to the reducing atmosphere or from the reducing atmosphere to the oxidizing atmosphere. Therefore, the radioactive substance concentration does not increase rapidly due to changes in the water quality environment, and the dose equivalent rate of the piping system does not increase, so that the periodic inspection can be performed safely and easily without affecting the inspection work.
以下に本発明の実施例について図面を用いて詳細に説明する。 Embodiments of the present invention will be described below in detail with reference to the drawings.
本発明による原子力発電プラントの水素の注入方法（実施後）と、従来の原子力発電プラントの水素の注入方法（実施前）とを用い、線量当量率、導電率、クロム酸濃度、Ｃo−６０イオン濃度、Ｃo−６０クラッド濃度について測定し、比較した結果を下記に示す。 Using the hydrogen injection method (after implementation) of the nuclear power plant according to the present invention and the conventional hydrogen injection method (before implementation) of the nuclear power plant, the dose equivalent rate, conductivity, chromic acid concentration, Co-60 ion Concentration and Co-60 cladding concentration were measured and compared, the results are shown below.
まず、初めに、従来の水素の注入方法を用いた場合と本発明による水素の注入方法を用いた場合との測定条件をそれぞれについて示す。 First, measurement conditions for the case of using the conventional hydrogen injection method and the case of using the hydrogen injection method according to the present invention will be described.
従来の水素の注入方法（実施前）を用いた場合の測定条件は、水素の連続注入日数を３００日とし、これを１サイクルとした。また、水素の注入開始及び停止の際は、給水水素濃度をそれぞれ０から０．５ｐｐｍ、０．５から０ｐｐｍに短時間で変化させた。 Measurement conditions in the case of using the conventional hydrogen injection method (before implementation) were set to 300 days for continuous hydrogen injection, and this was defined as one cycle. In addition, when hydrogen injection was started and stopped, the feed water hydrogen concentration was changed from 0 to 0.5 ppm and from 0.5 to 0 ppm in a short time.
本発明の水素の注入方法（実施後）を用いた場合の測定条件は、１サイクルを６分割して水素の連続注入日数を１０２日、６７日、８０日、１０６日、３２日、１６日とし、１サイクルの間に５回の水素の注入停止を行った。ただし、従来の水素の注入方法（実施前）と本発明の水素の注入方法（実施後）との１サイクルの日数は業務の都合により同一ではない。また、水素の注入方法は、水素注入開始の際は、給水水素濃度を１日目に０〜０．２ｐｐｍ、２日目に０．２〜０．４５ｐｐｍとし、その後、上記に示す所定日数だけ水素を連続注入し、水素注入停止の際は、注入停止の前日に０．４５〜０．２ｐｐｍ、停止日に０．２〜０ｐｐｍとした。そして、次の注入まで、炉水の導電率を安定させるために２日間水素の注入を停止した。 The measurement conditions in the case of using the hydrogen injection method of the present invention (after implementation) are as follows. One cycle is divided into six, and the hydrogen continuous injection days are 102 days, 67 days, 80 days, 106 days, 32 days, and 16 days. The hydrogen injection was stopped five times during one cycle. However, the number of days in one cycle of the conventional hydrogen injection method (before implementation) and the hydrogen injection method of the present invention (after implementation) are not the same for business reasons. In addition, when hydrogen injection is started, the hydrogen supply hydrogen concentration is set to 0 to 0.2 ppm on the first day and 0.2 to 0.45 ppm on the second day, and thereafter, for the predetermined number of days shown above. Hydrogen was continuously injected, and when hydrogen injection was stopped, it was set to 0.45 to 0.2 ppm on the day before the injection stop and 0.2 to 0 ppm on the stop day. Then, until the next injection, hydrogen injection was stopped for 2 days in order to stabilize the conductivity of the reactor water.
図２は従来の原子力発電プラントの水素の注入方法（実施前）と本発明による原子力発電プラントの水素の注入方法（実施後）とを用い、１サイクル運転後のそれぞれの原子炉再循環系（ＰＬＲ）ポンプ出口配管のＡ、Ｂの２箇所の線量当量率の測定結果を示す図である。 FIG. 2 shows a conventional nuclear power plant hydrogen injection method (before implementation) and a nuclear power plant hydrogen injection method (after implementation) according to the present invention. (PLR) It is a figure which shows the measurement result of the dose equivalent rate of two places of A and B of pump outlet piping.
図２に示すとおり、原子炉再循環系（ＰＬＲ）ポンプ出口配管の線量当量率（ｍＳｖ／ｈ）は、従来の水素の注入方法（実施前）がＡ：２．１、Ｂ：３．９で、本発明による水素の注入方法（実施後）がＡ：０．６、Ｂ：０．６である。本発明による水素の注入の方法（実施後）が従来の水素の注入の方法（実施前）に比べて、原子炉再循環系（ＰＬＲ）ポンプ出口配管での線量当量率が大幅に低下している。 As shown in FIG. 2, the dose equivalent rate (mSv / h) of the reactor recirculation system (PLR) pump outlet pipe is A: 2.1, B: 3.9 for the conventional hydrogen injection method (before implementation). Thus, the hydrogen injection method (after execution) according to the present invention is A: 0.6 and B: 0.6. The dose injection rate at the reactor recirculation system (PLR) pump outlet pipe is greatly reduced in the hydrogen injection method (after implementation) according to the present invention compared to the conventional hydrogen injection method (before implementation). Yes.
したがって、連続する注入期間を従来の約３００日から約１００日以下とすることにより、点検作業に影響をおよぼさない線量当量率にすることが可能である。 Therefore, by setting the continuous injection period to about 100 days or less from the conventional about 300 days, it is possible to achieve a dose equivalent rate that does not affect the inspection work.
次に、給水水素濃度を段階的に増加させた場合において、放射性物質であるＣo−６０イオン濃度及びＣo−６０クラッド濃度の測定結果を示す。 Next, measurement results of Co-60 ion concentration and Co-60 clad concentration, which are radioactive materials, are shown when the feedwater hydrogen concentration is increased stepwise.
図３は従来の原子力発電プラントの水素の注入方法（実施前）と本発明による原子力発電プラントの水素の注入方法（実施後）とを用い、水素注入時に給水水素濃度を段階的に増加させたときの炉水中のＣo−６０イオン濃度の変化を示す図である。 FIG. 3 shows a conventional method for injecting hydrogen in a nuclear power plant (before implementation) and a method for injecting hydrogen in a nuclear power plant according to the present invention (after implementation). It is a figure which shows the change of Co-60 ion concentration in the reactor water at the time.
図３に示すとおり、従来の水素の注入方法で給水水素濃度を短時間で０〜０．５ｐｐｍに増加させた場合においては、Ｃo−６０イオン濃度（Ｂｑ／ｍｌ）は約５．１で、本発明による水素の注入方法で給水水素濃度を段階的に増加させた場合においては、すべての連続注入期間でＣo−６０イオン濃度は約４．０より小さい値を示している。また、水素注入開始から給水水素濃度が段階的に増加し、給水水素濃度が０．４５ｐｐｍとなるまでのＣo−６０イオン濃度はほぼ同じ濃度である。したがって、給水水素濃度を段階的に増加させる場合においては、炉水中のＣo−６０イオン濃度はほぼ一定となり、Ｃo−６０イオン濃度の急激な溶出が阻止され、炉水中の水質環境の急激な変化を緩和することが可能である。 As shown in FIG. 3, when the feedwater hydrogen concentration was increased to 0 to 0.5 ppm in a short time by the conventional hydrogen injection method, the Co-60 ion concentration (Bq / ml) was about 5.1. In the case where the feed water hydrogen concentration is increased stepwise by the hydrogen injection method according to the present invention, the Co-60 ion concentration is less than about 4.0 in all the continuous injection periods. Further, the Co-60 ion concentration from the start of hydrogen injection until the feedwater hydrogen concentration gradually increases until the feedwater hydrogen concentration reaches 0.45 ppm is substantially the same. Therefore, when the feedwater hydrogen concentration is increased stepwise, the Co-60 ion concentration in the reactor water becomes substantially constant, and the rapid elution of the Co-60 ion concentration is prevented, and the water environment in the reactor water changes rapidly. Can be mitigated.
図４は従来の原子力発電プラントの水素の注入方法（実施前）と本発明による原子力発電プラントの水素の注入方法（実施後）とを用い、水素注入時に給水水素濃度を段階的に増加させたときの炉水中のＣo−６０クラッド濃度の変化を示す図である。 FIG. 4 shows a conventional method for injecting hydrogen in a nuclear power plant (before implementation) and a method for injecting hydrogen in a nuclear power plant according to the present invention (after implementation). It is a figure which shows the change of Co-60 clad density | concentration in the reactor water at the time.
図４に示すとおり、従来の水素の注入方法で給水水素濃度を短時間で０〜０．５ｐｐｍに増加させた場合においては、Ｃo−６０クラッド濃度（Ｂｑ／ｍｌ）は約０．９で、本発明による水素の注入方法で給水水素濃度を段階的に増加させた場合においては、すべての連続注入期間でＣo−６０クラッド濃度は約０．３より小さい値を示している。また、水素注入開始から給水水素濃度が段階的に増加し、給水水素濃度が０．４５ｐｐｍとなるまでのＣo−６０クラッド濃度はほぼ同じ濃度である。したがって、給水水素濃度を段階的に増加させる場合においては、炉水中のＣo−６０クラッド濃度はほぼ一定となり、Ｃo−６０クラッド濃度の急激な溶出が阻止され、炉水中の水質環境の急激な変化を緩和することが可能である。 As shown in FIG. 4, when the feedwater hydrogen concentration was increased to 0 to 0.5 ppm in a short time by the conventional hydrogen injection method, the Co-60 cladding concentration (Bq / ml) was about 0.9. In the case where the feedwater hydrogen concentration is increased stepwise by the hydrogen injection method according to the present invention, the Co-60 clad concentration is less than about 0.3 in all the continuous injection periods. Further, the Co-60 cladding concentration from the start of hydrogen injection until the feedwater hydrogen concentration gradually increases until the feedwater hydrogen concentration reaches 0.45 ppm is substantially the same. Therefore, when the feedwater hydrogen concentration is increased step by step, the Co-60 cladding concentration in the reactor water becomes substantially constant, and the rapid elution of the Co-60 cladding concentration is prevented, and the water environment in the reactor water changes rapidly. Can be mitigated.
これらの結果から、段階的に給水水素濃度を増加させた場合においては、炉水中の放射性物質濃度は低く、かつ安定していることから安全な線量当量率を維持することが可能となる。 From these results, when the feedwater hydrogen concentration is increased stepwise, the radioactive substance concentration in the reactor water is low and stable, so that a safe dose equivalent rate can be maintained.
図５は従来の原子力発電プラントの水素の注入方法（実施前）と本発明による原子力発電プラントの水素の注入方法（実施後）とを用い、水素注入停止時における炉水中の導電率のピーク値及びクロム酸濃度のピーク値の測定結果を示す図である。 FIG. 5 shows the peak value of the conductivity in the reactor water when hydrogen injection is stopped, using the conventional hydrogen injection method for nuclear power plants (before implementation) and the hydrogen injection method for nuclear power plants according to the present invention (after implementation). It is a figure which shows the measurement result of the peak value of chromic acid concentration.
図５に示すとおり、炉水中の導電率のピーク値（ｕＳ／ｍ）は、従来の水素の注入方法（実施前）が２０で、本発明による水素の注入方法（実施後）の１６日が８、３２日が８、６７日が９、８０日が１１、１０２日が１１、１０６日が１０、である。 As shown in FIG. 5, the peak value (uS / m) of conductivity in the reactor water is 20 for the conventional hydrogen injection method (before implementation), and 16 days after the hydrogen injection method (after implementation) according to the present invention. 8, 32 days are 8, 67 days are 9, 9, 80 days are 11, 11, 102 days are 11, and 106 days are 10.
また、炉水中のクロム酸濃度のピーク値（ｐｐｂ）は、従来の水素の注入方法（実施前）が２０で、本発明による水素の注入方法（実施後）の１６日が９、３２日が１５、６７日が１９、８０日が２３、１０２日が２１、１０６日が１９である。 The peak value (ppb) of the chromic acid concentration in the reactor water is 20 for the conventional hydrogen injection method (before implementation), and 9 and 32 days for the 16th day of the hydrogen injection method (after implementation) according to the present invention. The 15th and 67th days are 19, the 80th day is 23, the 102nd day is 21, and the 106th day is 19.
水素の連続注入の期間が短いほど炉水中の導電率及びクロム酸濃度のピーク値は小さくなる傾向を示している。したがって、連続注入期間を短くすることにより炉水中の導電率及びクロム酸濃度のピーク値を小さくすることが可能である。 As the period of continuous hydrogen injection is shorter, the peak values of conductivity and chromic acid concentration in the reactor water tend to be smaller. Therefore, it is possible to reduce the peak values of conductivity and chromic acid concentration in the reactor water by shortening the continuous injection period.
これらの結果より、水素注入を約３ヶ月に１回程度停止する断続運転とすることにより、クロム酸化物の吐き出し量が少なくなるために配管内面のクロム酸化物層に凹凸が形成されることがなくなる。 From these results, the intermittent operation in which hydrogen injection is stopped about once every about three months can reduce the amount of chrome oxide discharged, so that irregularities are formed in the chrome oxide layer on the inner surface of the pipe. Disappear.
１ 沸騰水型原子炉
２ａ タービン
２ｂ 復水器
３ 主蒸気系の配管
４ 復水脱塩器
５ 復水系の配管
６ 給水ポンプ
７ 給水系の配管
８ 再循環ポンプ
９ 再循環系の配管
１０ 水素注入装置
１１ 配管
１２ 復水昇圧ポンプ
１３ 加熱器
DESCRIPTION OF
Claims (3)
原子力発電プラントの運転中に、
水素の注入を２〜３ヶ月継続する第１期間、
水素の注入を２日間かけて段階的に減らす第２期間、
水素の注入を２〜３日間停止する第３期間、及び
水素の注入を２日間かけて段階的に増やす第４期間
からなるサイクルを繰り返し行うことにより、
一定期間の水素の連続注入、停止を繰り返し行なう
ことを特徴とする原子力発電プラントの水素の注入方法。 A method for injecting hydrogen into a nuclear power plant that injects hydrogen into reactor water via a nuclear reactor water supply system,
During the operation of the nuclear power plant,
A first period of 2 to 3 months of hydrogen injection,
A second period in which hydrogen injection is gradually reduced over 2 days,
A third period of stopping hydrogen injection for 2-3 days, and
Fourth period to increase hydrogen injection step by step over 2 days
By repeating the cycle consisting of
A method for injecting hydrogen into a nuclear power plant, characterized in that continuous injection and stop of hydrogen for a certain period are repeated.
前記第２期間において、水素の注入を停止する前日に給水水素濃度を０．４５〜０．２ｐｐｍとし、水素の注入を停止する日に０．２〜０ｐｐｍとするIn the second period, the hydrogen concentration in the feed water is set to 0.45 to 0.2 ppm on the day before the hydrogen injection is stopped, and is set to 0.2 to 0 ppm on the day when the hydrogen injection is stopped.
ことを特徴とする原子力発電プラントの水素の注入方法。A method of injecting hydrogen into a nuclear power plant.
前記第４期間において、１日目に給水水素濃度を０〜０．２ｐｐｍとし、２日目に０．２〜０．４５ｐｐｍとするIn the fourth period, the hydrogen concentration of feed water is 0 to 0.2 ppm on the first day, and 0.2 to 0.45 ppm on the second day.
ことを特徴とする原子力発電プラントの水素の注入方法。A method of injecting hydrogen into a nuclear power plant.
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