Thermal fatigue test on dissimilar welded joint between Gr.91 and 304SS

Wakai, Takashi; Kobayashi, Sumio; Kato, Shoichi; Ando, Masanori; Takasho, Hideki*

Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 7 Pages, 2017/07

https://doi.org/10.1115/ICONE25-66099

This paper describes a thermal fatigue test on a structural model with a dissimilar welded joint. In the present design of JSFR, there may be dissimilar welded joints between ferritic and austenitic steels especially in IHX and SG. Creep-fatigue is one of the most important failure modes in JSFR components. However, the creep-fatigue damage evaluation method has not been established for dissimilar welded joint. To investigate the evaluation method, structural test will be needed for verification. Therefore, a thermal fatigue test on a thick-wall cylinder with a circumferential dissimilar welded joint between Mod.9Cr-1Mo steel and 304SS was performed. Since the coefficients of thermal expansion of these steels were significantly different, buttering layer of Ni base alloy was installed between them. After the completion of the test, deep cracks were observed at the HAZ in 304SS, as well as at HAZ in Mod.9Cr-1Mo steel. There were many tiny surface cracks in BM of 304SS. According to the fatigue damage evaluation based on the finite element analysis results, the largest fatigue damage was calculated at HAZ in 304SS. Large fatigue damage was also estimated at BM of 304SS. Fatigue cracks were observed at HAZ and BM of 304SS in the test, so that analytical results are in a good agreement with the observations. However, though relatively small fatigue damage was estimated at HAZ in Mod.9Cr-1Mo steel, deep fatigue cracks were observed in the test. To identify the cause of such a discrepancy between the test and calculations, we performed a series of finite element analyses. Some metallurgical investigations were also performed.

Multiaxial creep behavior of nickel-base heat-resistant alloys Hastelloy XR and Ni-Cr-W superalloy at elevated temperatures

Tsuji, Hirokazu; Nishi, Hiroshi; Kaji, Yoshiyuki; Muto, Yasushi; Penkalla, H. J.*; Schubert, F.*

Proceedings of the 7th International Conference on Creep and Fatigue at Elevated Temperatures (CREEP7), p.101 - 106, 2001/06

A series of uniaxial and multiaxial creep tests was carried out on Hastelloy XR and Ni-Cr-W superalloy, which were developed as the high temperature structural materials for nuclear application at the JAERI, in order to investigate multiaxial creep behaviors of these materials. Norton's creep law and von Mises' flow rule were applied to the prediction of multiaxial creep behavior of a tube under some significant loading condition. In most cases the multiaxial creep behavior of these materials were successfully described with the constitutive equations based on the material parameter fitting uniaxial creep test results, though a few exceptional cases were observed. The present study has revealed that the method based on Norton's creep law and von Mises' flow rule are basically applicable for the description of the multiaxial creep behavior for Hastelloy XR and Ni-Cr-W superalloy as the conventional design method.

Study on the reliability of silicide fuels at elevated temperatures

Yanagisawa, Kazuaki;

Proc. of 4th Asian Symp. on Research Reactors; ASRR-IV, p.58 - 69, 1993/00

no abstracts in English

Rapid ion-exchange separations of actinides

Journal of Radioanalytical and Nuclear Chemistry, 123(2), p.619 - 631, 1988/02

https://doi.org/10.1007/BF02034922

no abstracts in English

Anion exchange behaviour of the transplutonium elements in hydrochloric acid-alcohol media at elevated temperature

Journal of Radioanalytical and Nuclear Chemistry, 111(2), p.477 - 485, 1987/02

https://doi.org/10.1007/BF02072879

no abstracts in English

Development of a sensor for in-situ measurement of hydrogen peroxide in irradiation field by using frequency dependent complex impedance analysis

Hanawa, Satoshi; Hata, Kuniki; Uchida, Shunsuke; Nishiyama, Yutaka

no journal, , 

Water in the primary circuit of Nuclear Power Plants (NPPs) decomposes by radiolysis, then oxidants such as hydrogen peroxide and oxygen are generated as a result. Hydrogen peroxide is one of the major factor for initiation and propagation of stress corrosion cracking (SCC) in structural materials, hence in-situ monitoring of hydrogen peroxide at the point of interest in irradiation field is quite important to assure the integrity of NPPs. Concentration of hydrogen peroxide in irradiation field is governed by energy deposition by neutron and -ray in which the degree of energy is different in locations, while concentration in un-irradiation area decreases due to thermal decomposition. Quantitative evaluation of hydrogen peroxide is, however, available only by analyzing sampled water at present, and therefore in-situ monitoring of hydrogen peroxide at the point of interest becomes quite important. Frequency dependent complex impedance (FDCI) analysis gives characteristics of oxide film on the materials, and it becames clear by recent activities that the low frequency semicircles in Cole-Cole plots shows linear correlation to the concentration of hydrogen peroxide. JAEA is now developing a sensor for in-situ monitoring of hydrogen peroxide applicable to irradiation environment by applying FDCI. The outline and overall schedule of the sensor development will be reported in the presentation.