WB-STEM observation of dislocation loop behavior in reactor pressure vessel steel during post-irradiation annealing

Du, Y.*; Yoshida, Kenta*; Shimada, Yusuke*; Toyama, Takeshi*; Inoue, Koji*; Arakawa, Kazuto*; Suzudo, Tomoaki; Milan, K. J.*; Gerard, R.*; Onuki, Somei*; et al.

Materialia, 12, p.100778_1 - 100778_10, 2020/08

https://doi.org/10.1016/j.mtla.2020.100778

In order to ensure the integrity of the reactor pressure vessel in the long term, it is necessary to understand the effects of irradiation on the materials. In this study, irradiation-induced dislocation loops were observed in neutron-irradiated reactor pressure vessel specimens during annealing using our newly developed WB-STEM. It was confirmed that the proportion of loops increased with increasing annealing temperature. We also succeeded in observing the phenomenon that two loops collide into a loop. Moreover, a phenomenon in which dislocation loops decorate dislocations was also observed, and the mechanism was successfully explained by molecular dynamics simulation.

Microstructural assessment of damaged materials in FBR assessment of creep damage in weldment

Momma, Yoshio*; *; ; ; ; Aoto, Kazumi

JNC TN9400 2000-044, 22 Pages, 2000/03

JNC-TN9400-2000-044.pdf:1.37MB

ln the past the microstructural observation was mostly applied to understand the materials behavior qualitatively in R&D of the new materials and the life prediction for the fast breeder reactor components. However, the correlation between the changes in properties and microstrutures must be clarified to ensure the structural integrity. Particularly we are interested in the method to correlate the long-term properties and microstructural changes at high temperatures. The current research is to quantify the changes in microstructure of the weld metal for the welded structure of the reactor vessel. ln this research we have conducted creep testing of the weld metals at 823 and 873K up to 37,000h. Two types of the weld metals (16Cr-8Ni-2Mo and 18Cr-12Ni-Mo) were subjected to the creep testing. Based on the areas of the precipitates, the microstructural characterization with time and creep damage was attempted. The creep strength of the 16Cr-8Ni-2Mo weld metal is lower than that of the 18Cr-12Ni-Mo one at higher stresses, shorter times. But there is a trend toward to become similar strength with lower stresses and increasing times. The creep-rupture ductility of the 16Cr-8Ni-2Mo weld metal is superior to that of the 18Cr-12Ni-Mo one. The creep-rupture takes place at the interface of the sigma () phases precipitated in the delta () ferrites at 823K lower stresses and 873K. The amount of precipitates in the 16Cr-8Ni-2Mo weld metal is smaller than that in the 18Cr-12Ni-Mo one at each temperature and stress. Also it is apparent that the amount of the precipitates is primarily responsible to the decomposition of the phase, because the amount of the residual ferrites measured by the Magne-Gauge reduces with times. Using the Larson-Miller parameter it was possible to correlate the amount of the precipitates linearly with the LMP values.

A Study on Pore Structure of Compacted Bentonite (Kunigel-V1)

Sato, Haruo

JNC TN8400 99-064, 22 Pages, 1999/10

JNC-TN8400-99-064.pdf:1.45MB

Four kinds of diffusion experiments; (1)through-diffusion(T-D) experiments for compaction direction dependency, (2)in-diffusion(I-D) experiments for composition dependency of silica sand in bentonite, (3)I-D experiments for initial bentonite gain size dependency, and (4)I-D experiments for the restoration property of an artificial single fracture in compacted bentonite, were carried out using tritiated water which is a non-sorbing nuclide to evaluate the effect of pore structural factors for eompacted bentonite on diffudion. For(1), effective diffusivities (De) in Na-bentonites, Kunigel-V1 and Kunipia-F were measured for 1.0 and 1.5 Mgm. For(2), apparent diffusivities (Da) in Kunigel-V1 were measured for 0.8, 1.4 and 1.8 Mgm with silica sand of 30 and 50 wt%. For(3), Da values for 0.8, 1.4 and 1.8 Mgm were measured for a granulated Na-bentonite, OT-9607 which grain-size distribution is in a rang between 0.1 and 5 mm. For (4), Da values in Kunigel-V1 which a single fracture was artificially reproduced and was immersed in distilled water for 7 or 28 days for the restoration of the fracture, were measured for 1.8 Mgm. Although De values in Kunigel-V1 were approximately the same for both compacted directions over the density, De values for perpendicular direction to compacted direction were higher than those for the same direction as compacted direction in Kunipia-F. For composition dependency of silica sand in bentonite, no significant effect of the mixure of silica sand in bentonite on Da was found. For initial bentonite grain size dependency, Da values obtained for OT-960 were approximately the same as those for Kunigel-V1 and no effect of initial grain size of bentonite on diffusion was found. For the restoration property of a single fracture in compacted bentonite, no restoration period dependency on Da was found. Based on this, it may be said that diffusion of nuclides in compacted bentonite, ...

None

Tanaka, Hiroshi*

JNC TJ1400 99-041, 93 Pages, 1999/02

JNC-TJ1400-99-041.pdf:3.77MB

no abstracts in English

None

Tanaka, Satoru*; Nagasaki, Shinya*

PNC TJ1602 98-003, 38 Pages, 1998/03

PNC-TJ1602-98-003.pdf:1.02MB

None

Analysis of metallic salt granulation preocess, II

Tokuoka, Naochika*; Kobayashi, Mamoru*; Koyama, Takashi*

PNC TJ1636 96-001, 64 Pages, 1996/03

PNC-TJ1636-96-001.pdf:14.63MB

None

None

PNC TJ1211 94-002, 111 Pages, 1994/03

PNC-TJ1211-94-002.pdf:5.66MB

None

None

Sonobe, Hitoshi; Ishiguro, Katsuhiko

PNC TN8410 92-114, 85 Pages, 1992/03

PNC-TN8410-92-114.pdf:4.03MB

None

Radiation-generated prismatic loops around gas bubbles in alumnium-lithium alloy

Shiraishi, K.; ; Katano, Y.

Radiat.Eff., 21(3), p.161 - 164, 1974/03

no abstracts in English

Trace very light element analysis using soft X-ray emission spectrometry in FE-SEM/EPMA

Takahashi, Hideyuki*; Asahina, Shunsuke*; Murano, Takanori*; Takakura, Yu*; Terauchi, Masami*; Koike, Masato; Imazono, Takashi; Koeda, Masaru*; Nagano, Tetsuya*; Sasai, Hiroyuki*; et al.

no journal, , 

We developed a soft X-ray emission spectrometer (SXES) with a detection range of 50-210 eV to be able to be installed in commercially available EMPAs and FE-SEMs. This SXES has the spectral resolution of 0.2 eV comparably high with X-ray photo emission spectrometers (XPSs) and electron energy-loss spectrometers (EELSs). In addition, it allows us to perform trace light element analysis with high sensitivity because of high peak-to-background ratio (P/B). Therefore, it is shown that the SXES installed in a FE-SEM can detect trace carbon in steel at the level of 100 ppm and below.