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Ogawa, Yusuke*; Suzuki, Satoru*; Taniguchi, Naoki; Kawasaki, Manabu*; Suzuki, Hiroyuki*; Takahashi, Rieko*
Materials and Corrosion, 72(1-2), p.52 - 66, 2021/01
Times Cited Count：2 Percentile：12.36(Materials Science, Multidisciplinary)Cast steel is one of the promising alternative to forged steel that is the current reference material for carbon steel overpack. In this study, the full-scale cast steel overpack was produced experimentally and the distribution of casting defects were investigated. The corrosion test regarding corrosion rate and stress corrosion cracking (SCC) susceptibility were also conducted using samples taken from the full-scale cast steel overpack and the corrosion resistance of cast steel was compared with that of forged steel. From above two corrosion tests, it can be said that the corrosion resistance of cast steel is mostly the same as that of forged steel.
*; *; Tanai, Kenji
JNC TN8400 99-047, 54 Pages, 1999/11
This paper reports on the design process for a carbon-steel overpack as a key component in the engineered barrier system of a deep geological repository described in the 2nd progress report. The results of the research and development regarding design requirements, configuration, manufacturing and inspection of overpack are also described. The concept of a composite overpack composed of two different materials is also considered. First, the design requirements for an overpack and presume environmental and design conditions for a repository are provided. For a candidate material of carbon steel overpack, forging material is selected considering enough experience of using this material in nuclear power boilers and other components. Second, loading conditions after emplacement in a repository are set and the pressure-resistant thickness of overpack is calculated. The corrosion thickness to achieve an assigned 1000 year life time and the required thickness to prevent radiolysis of ground water which might enhance corrosion rate are also determined. As aresult, the total required thickness of a carbon-steel overpack is conservatively estimated to 190 mm. This is a reduction of about 30% from the previous estimate provided in the 1st Progress Report. Additional items that must be considered in manufacturring and operating overpacks (i.e. sealing of vitrified waste, examination of main body and sealing welding, mechanism of handling) are evaluated on the basis of current technology, specific future data needs are identified. With respect to the concept of composite overpack (i.e., an outer vessel to provide corrosion-allowance or corrosion-resistant performance and an inner vessel to provide pressure-resistance), the differences in design concepts between the carbon-steel overpack and such composite overpacks are analyzed. Future data needs and analytical capabilities with respect to overpacks are also summarized.
; Hirakawa, Yasushi; Furukawa, Tomohiro; *; *; *; *
PNC TN9450 91-004, 71 Pages, 1991/07
In order to advancement in materials strength standard on elevated temperature design guide of the FBRs and evaluation method of materials strength behavior, this report are presented about the low-cycle fatigue properties of Mod.9Cr-1Mo steel, based on the R&D results obtained through the sctivities of material tests. Contents of the data sheet are as follows; [Material ; Mod.9Cr-1Mo steel(SR)] F2 Heat 1,000
1,00012mm
(Plate) F4 Heat 1,0001,000250mm(Forging) F6 Heat 1,0001,00025mm(Plate) [Environment; In Air and in Sodium] [Test temperature ; 450, 500, 550, 600 and 650
C] [Strain rate ; 0.1%/sec (10
mm/mm/sec)] [Strain range ; 0.38% 
1.86%] [Number of deta ; 83 points]
280mm t); ; Yoshida, Eiichi;
PNC TN9410 91-099, 106 Pages, 1991/02
This stady was performed in order to confirm the influence of sampling method on Creep properties of 9Cr-Mo steel forgings which are promising as candidate materials for steam generator of large scale fast breeder reactor. This results are to be reflected on fundation of materials strength standard. Test materials are four kinds of 9Cr-Mo steel forgings (thickness:250280mmt) such as Mod.9Cr-1Mo (F4, F8 heats), 9Cr-1Mo-Nb-V(G3 heat), 9Cr-2Mo (H6 heat) steels. Results obtained are summarized as follows. (1)In order to evaluation of fundamental material properties, creep-rupture data on three kinds of 9Cr-Mo steel forgings such as Mod.9Cr-1Mo, 9Cr-2Mo and 9Cr-1Mo-Nb-V steels was obtained up to 10,000 hours. (2)The Mod.9Cr-1Mo steel exhibited most excellent creep-rupture strength and the 9Cr-2Mo steel was the worst among the three. (3)The effect of the sampling location of specimens on creep strength was not significant for Mod.9Cr-1Mo steel. But for 9Cr-1Mo-Nb-V steel and 9Cr-2Mo steel, longer creep rupture time was observed with spcimens taken from just below the center of the surface with direction of L, and shorter creep rupture time was observed for those taken from t/2 thickness at the center with direction of Z. (4)Creep strength of 9Cr-2Mo steel was lower than that of Mod.9Cr-1Mo (F4, F8)and 9Cr-1Mo-Nb-V steel. But rupture elongation and reduction of area of 9Cr-2Mo steel was greater than hat of other three materials, irrespective of the sampling location of specimens.
280mmt).*
PNC TN9410 90-122, 58 Pages, 1990/06
This study was performed to examine the tensile properties of 9Cr-Mo steel forgings, which are promising as the candidate materials for steam generator of large scale fast breeder reactor the influence of thermal aging and sampling location/direction. These results are to be reflected on fundation of materials strength standard. Test materials are three kinds of 9Cr-Mo steel forgings (thichiness:250280mmt) such as Mod.9Cr-1Mo (F4,F8 heats), 9Cr-1Mo-Nb-V(G3 hrats), 9Cr-2Mo (H6 heats) steels. The heat treatment on the thermal aging were carried out at 500, 550C for 3000hours. Results obtained are summarized as follows. (1)Tensile properties were much about the same between Mod.9Cr-1Mo and 9Cr-1Mo-Nb-V Steel forgings. (2)Tensile strength of four materials at direction Z was slightly lower than that of direction L or C and there are no significant diffrence on the sampling location/direction. (3)Tensile strength of Mod.9Cr-1Mo steel and 9Cr-1Mo-Nb-V steel forgings after thermal aging for 3000hours was same as that of as-received ones. However, the strength of 9Cr-2Mo steel forging at high temperature dicreased because of aging effect. (4)The 0.2 percent yield stress and tensile strength of forged steels satisfied the PNC preliminary design standard values of Sy and Su, but inferior to plating and tubing steels. However, tensile strengh of Mod.9Cr-1Mo steel forging (F8 heat) at the lower temperature than 400C and 9Cr-2Mo steel forging after thermal aging were lower than that of preliminary values. These results were reflected to advance the specification of Mod.9Cr-1Mo steel thick forgings.
