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Kasahara, Seiji; Kubo, Shinji; Inagaki, Yoshiyuki; Ogawa, Masuro
Zairyo To Purosesu (CD-ROM), 26(2), p.498 - 501, 2013/09
Outline was discussed for very high temperature reactors (VHTRs), IS process for hydrogen production and hydrogen steelmaking process integrated with them. Hydrogen of 7.07
10
Nm
/d was produced and electricity of 497 MW was generated using 5 VHTRs of 600 MW thermal output to produce steel of 110
t/d, similar scale to a conventional blast furnace (BF) plant. A significant reduction of CO
emission to 13% of that from a BF plant was expected by the hydrogen steelmaking plant. Sensitivity analysis of steelmaking cost on hydrogen production cost showed that the hydrogen production cost of 3.0 US
/kg-H was required for the lower steelmaking cost than conventional steelmaking processes.
Nagae, Yuji
no journal, ,
no abstracts in English
Fujii, Shohei*; Iwata, Mitsunao*; Murata, Yoshinori*; Takaya, Shigeru
no journal, ,
It is necessary to maintain the integrity of structural materials including welded parts for long term for fast breeder reactors. It is known that long-term creep strength of heat affected zone (HAZ) of 9Cr ferritic steels decreases because of change in micro structure. Therefore, it is very important to develop a method to estimate long-term strength from short-term material test results. In this study, we evaluated system free energy of creep test pieces of simulated HAZ material. As result, we have shown that system free energy decreases with time, and the decrease rate depends on load stress. Furthermore, we proposed a new parameter, P, which indicates the rate of decrease of system free energy, and have shown that it is able to evaluate long-term creep strength based on the relationship between load stress and P.
Ebihara, Kenichi; Kaburaki, Hideo; Takai, Kenichi*
no journal, ,
Hydrogen state in steels that is necessary to understand the mechanism of hydrogen embrittlement fracture is influenced by the binding energy between hydrogen atoms and defects. Although the binding energy can be evaluated as the detrapping activation energy from desorption profiles which are obtained by hydrogen thermal desorption analysis, the evaluation accuracy becomes worse when the size of specimens is larger because the Choo-Lee's method for evaluating the detrapping activation energy ignores the hydrogen diffusion effect. In this presentation, using numerical simulations, we estimated the dependence of the detrapping activation energy of tempered martensitic steels (SCN435 steels) which is evaluated by their method. As a result, it was found that the detrapping activation energy can be evaluated comparatively accurately in larger specimens than the pure iron case. The fact that the trap site density of SCM435 steel is larger than that of pure iron causes this result.