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Ueno, Fumiyoshi
Zairyo To Kankyo, 68(1), p.2 - 8, 2019/01
It is important to control the cooling water of light water reactors (boiling water reactor and pressurized water reactor) to suitable quality in order to reduce corrosion of structural materials and generation of radioactive corrosion products. For that purpose, monitoring of water quality using electrochemical measurement method is necessary. In this article, the application of ECP measurement to BWR is mainly focused, I describe the water quality of light water reactors and the necessity of electrochemical measurement.
Hanawa, Satoshi; Uchida, Shunsuke; Hata, Kuniki; Chimi, Yasuhiro; Kasahara, Shigeki*; Nishiyama, Yutaka
Proceedings of 20th Nuclear Plant Chemistry International Conference (NPC 2016) (USB Flash Drive), 10 Pages, 2016/10
The authors proposed and ECP evaluation model introducing irradiation-induced diffusion in the oxide layer to simulate neutron irradiation effect, and predicted with this model that ECP is started to depress from the neutron flux of about ten to the fourteenth per square meter. As the JMTR has in-pile loops applicable to water chemistry experiments, degree of irradiation effect on ECP appears in the in-pile loop was estimated by the model. Under oxygen injected condition, ECP in a capsule becomes constant along the vertical direction due to the presence of high amount of oxygen and hydrogen peroxide in a capsule. However, if neutron irradiation depress ECP, ECP in a capsule along vertical direction wouldn't become constant, and the degree to the decrement is detectable by experiments.
Hanawa, Satoshi; Hata, Kuniki; Shibata, Akira; Chimi, Yasuhiro; Kasahara, Shigeki; Tsutsui, Nobuyuki*; Iwase, Akihiro*; Nishiyama, Yutaka
Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 9 Pages, 2014/10
no abstracts in English
Uchida, Shunsuke*; Sato, Tomonori; Morishima, Yusuke*; Hirose, Tatsuya*; Miyazawa, Takahiro*; Kakinuma, Nagao*; Sato, Yoshiyuki*; Usui, Naoshi*; Wada, Yoichi*
Proceedings of 12th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors (CD-ROM), p.19 - 29, 2005/00
Static and dynamic responses of stainless steel specimens exposed to H
O and O in high temperature water were evaluated by analyzing ECP and FDCI (frequency dependent complex impedance). The oxide films on the specimens were characterized by multilateral surface analyses, e.g., LRS, SIMS, XPS and direct electric resistance measurement. As a result of evaluation, it was confirmed that (1) corrosive condition of BWR normal water chemistry (NWC) was simulated by 100 ppb HO without co-existing O, while that of hydrogen water chemistry (HWC) was simulated by 10 ppb HO, (2) ECP under HWC was as high as that under NWC, while dissolution rate of oxide film under HWC was much lower than that under NWC, (3) combination effects of electric resistance and dissolution rate of oxide caused same level ECP for both NWC and HWC, and (4) distinct weight loss of the specimen exposed to 100 ppb HO was observed.
Tsukada, Takashi; Miwa, Yukio; Ugachi, Hirokazu; Matsui, Yoshinori; Itabashi, Yukio; Nagata, Nobuaki*; Dozaki, Koji*
Proceedings of International Conference on Water Chemistry of Nuclear Reactor Systems (CD-ROM), 5 Pages, 2004/10
IASCC initiation and propagation tests will be performed on the per-irradiated specimen in the Japan Materials Testing Reactor (JMTR). Since in core, the radiolysis of water causes a generation of various kind of radical species and some oxidizing species such as hydrogen peroxide, the water chemistry in irradiation capsules must be assessed by measurements of the electrochemical corrosion potential (ECP). For the in-core measurement of ECP in JMTR, we fabricated and tested the Fe/Fe
O
type ECP sensor. After the fabrication, the function of each sensor was examined in high temperature water by out-of-core thermal cycling and high temperature holding tests.
Ishibashi, Masayuki*; Miyoshi, Takako*; Masumoto, Kazuhiko*; Onoe, Hironori; Kawahara, Shuji*; Sekino, Masato*
no journal, ,
no abstracts in English
Uchida, Shunsuke; Hata, Kuniki; Hanawa, Satoshi; Chimi, Yasuhiro
no journal, ,
Stainless steel (Fe base alloy) and Ni base alloy are different in anodic polarization curves in high temperature water, which results in different ECP under the same water chemistry conditions. Based on analysis of the effects of temperature and pH on solubilities of Fe
and Ni, the effects of radiolytic species, HO, O and H, on ECP are analyzed. As a result of the analysis, Ni base alloy showed a little lower ECP than that of stainless steel, and its pH dependence was different from that of stainless steel. The ECPs in the core, its peripherals and SG were analyzed based on radiolytic species concentrations shown in the previous presentation, which were applied to evaluation of the hydrogen injection effects on the major component in the primary cooling system.
Uchida, Shunsuke; Hata, Kuniki; Hanawa, Satoshi; Chimi, Yasuhiro; Sato, Tomonori
no journal, ,
A radiolysis and ECP combined code, WRAC-J, could obtain ECP calculation based on the empirical polarization curve. Newly developed WRAC-JAEA has consisted of (1) calculation of high temperature pH, (2) water radiolysis calculation, and (3) ECP calculation based on the anodic polarization curves of SS and Ni based alloys with involving oxide layer effects and the polarization curves of radilytic species, and then, it can calculate ECP based on plant operational conditions. By applying the WRAC-JAEA, radiolytic species concentrations are calculated based on plant operational conditions, radiation dose rate, pH, ECP is calculated based on the their concentrations direct effects of alkali metal ions, e.g., Li
, and then, the corrosive conditions in BWRs and PWRs are evaluated.
Uchida, Shunsuke; Hata, Kuniki; Hanawa, Satoshi; Chimi, Yasuhiro; Sato, Tomonori
no journal, ,
A radiolysis and ECP combined code, WRAC-JAEA, has been originally developed for analysis of ECP experiments in the JMTR in-pile loop. It was confirmed that the code could be applied for neutral water conditions of BWRs to high pH water conditions of PWRs. The effects of boiling in BWRs on the analytical results were significantly large, while those of subcooled boiling in PWRs should be also considered. Radiolytic species transfer from liquid phase to gas phase in the coolant flow along the fuel was analyzed. As the results, it was confirmed that the combined code could be applied under subcooled boiling conditions as well as boiling conditions, and then, applicable for analysis of corrosive conditions in the nuclear power plants as well as in-pile loops.
