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Yano, Yasuhide; Yoshitake, Tsunemitsu; Abe, Yasuhiro
JNC TN9400 2003-028, 44 Pages, 2002/12
JNC-TN9400-2003-028.pdf:1.75MB
The effect of fast neutron irradiation on impact properties of the PNC-FMS (2WFK) and ODS martensitic steel (H35), which were irradiated in the JOYO/CMIR-5 and MARICO-1, were investigated, because it was well known that irradiation-embrittlement was one of the most important issue to apply these ferritic steels to FBR core materials. The post irradiation half-sized and miniaturized Charpy impact tests were carried out to understand the impact properties of these ferritic steels. The results obtained in this study are as follows: (1) In all irradiated 2WFK specimens, the impact properties depended on irradiation temperature rather than neutron fluence under these irradiation conditions. The impact properties of 2WFK specimens irradiated at the temperature range of 400 to 500
C almost scarcely change, however, those of 2WFK specimens irradiated at 659C obviously decreased. (2) The impact properties of 2WFK specimens irradiated at 495C were similar to those of as-received 2WFK specimen. This indicates that the effects of thermal aging improvement and irradiation degradation canceled each other. Moreover, the impact properties of 2WFK specimens irradiated at 659C decreased more remarkably than those of thermal aged specimens at 650C. It is suggested that these 2WFK impact properties seemed to be understood by microstructure behaviors, especially precipitation behaviors, by means of irradiation and thermal aging. (3) It is suggested that the anisotropy of H35 ODS steel was considerably improved by the 
/
phase transformation, and H35 specimens had superior impact properties even after irradiation because no radiation hardening and no change of impact properties under these irradiation conditions were observed.
Yoshitake, Tsunemitsu; Akasaka, Naoaki; Abe, Yasuhiro
JNC TN9400 2002-073, 42 Pages, 2002/12
The cladding samples of the 12Cr-ferritic oxide Dispersion Strengthened (ODS) steel claddings with recrystallized microstructure (F94 and F95) and the 9Cr-martensitic ODS steel cladding (M93), in which their high temperature strengths were improved by the recrystallization and the - phase transformation, respectively, were irradiated in the JOYO/SVIR-1. Post-irradiation ring-tensile tests and microstructural examination were carried out on these cladding samples in order to understand the effects of fast neutron irradiation on their ring-tensile properties. The results obtained in this study are as follows; (1)The strength of F94, F95 and M93 claddings was higher than that of 11Cr-ferritic/martensitic steel without oxide dispersion, and lower than that of the first trial ODS ferritic steel cladding manufactured by warm working that had the strong strength anisotropy (1DS). The uniform and total elongations of these claddings were considerably increased by the improvement of their microstructures using recrystallization and (- phase transformation, compared with 1DS. (2)The strength of these claddings was increased about 10% by the irradiation hardening under the irradiation conditions examined where the fast neutron fluence was between 0.5 
10
and 3.0 10 n/m
(E
0.1 Mev) and the irradiation temperature ranged from 397 to 534 C. No significant dependence of fast neutron fluence on the ring-tensile properties was observed and these claddings retained respectable elongation after the irradiation. (3)From these results and consideration, it is suggested that the ring-tensile properties of these ODS steel claddings (F94, F95 and M93) after irradiation would be excellent within the fluence level achieved in this irradiation test. However, it is necessary to conduct the irradiation tests on them because the irradiation data are still insufficient to evaluate their irradiation behavior ...
; ;
JNC TN9400 2001-116, 71 Pages, 2001/07
JNC-TN9400-2001-116.pdf:6.52MB
The effects of high fluence irradiation and swelling on the tensile properties of austenitic steel fuel claddings; PNC316 and 15Cr-20Ni steel, which were irradiated in the FFTF as the MONJU type fuel assemblies (MFA-1 and MFA-2), were investigated. Tension tests were carried out to understand the irradiation effect on the tensile properties of these highly irradiated claddings with significant swelling, The results obtained in this study are as follows; (1)The yield stresses and ultimate tensile strengths at each test temperatures of PNC316 cladding samples were almost same as that of the lower-fluence samples (previous data). It is considered that there was no obvious decrease in strengths with increasing fluence up to 2.1 10
n/m. (2)The yield stresses and ultimate tensile strengths at each test temperatures of 15Cr-20Ni steel cladding samples showed similar behavior to that of PNC316 samples. There was no obvious difference in tensile properties between PNC316 and 15Cr-20Ni steel. (3)The uniform and total elongations of both materials samples decreased significantly at 400 and 450 C and total elongation tended to be close to uniform elongation. This suggested that there was considerable irradiation embrittlement under irradiation conditions of this study, although samples retained a certain ductility after irradiation. (4)There was no significant deterioration in tensile properties of PNC316 and 15Cr-20Ni steel craddings with considerable swelling about 10%.
; ; Miyakawa, Shunichi
JNC TN9400 2001-105, 41 Pages, 2001/07
JNC-TN9400-2001-105.pdf:1.33MB
The effect of fast neutron irradiation on the mechanical properties of the oxide dispersion strengthened (ODS) ferritic steel claddings (1DS & 1DK) which were manufuctured by warm working as the first trial cladding tube manufucturing in JNC, were investigated. The samples were irradiated in JOYO/CMIR-4&5. Uni-axial tensile test, ring-tensile test, burst test and miniaturized Charpy impact test were carried out to study the mechanical properties such as strength and elongation, of irradiated ODS ferritic claddings. The results of this study showed that there was no considerable deterioration on the mechanical properties of these ODS ferritic steel cladding samples under the irradiation conditions examined. The results obtained in this study are as follows; (1)The increase in strength due to irradiation hardening appeared in higher temperatures (
600,650C) than that of austenitic steels such as PNC316. (2)There was an anisotropy in the short time range strengths after irradiation due to its particular crystalline structure so called "bamboo structure". (3)The elongation of hoop direction after irradiation was significantly tended to be much lower than that of longitudinal direction because of its particular "bamboo structure". (4)There was no obvious decrease in elongation and miniaturized Charpy impact properties under irradiation conditions examined. (5)TEM observation showed that there was no significant change in microstructure before and after irradiation except the precipitation of Laves phase on grain boundary after irradiation and that Y
O
particles and their fine distribution might be stable during irradiation.
Donomae, Takako; Akasaka, Naoaki; Yamagata, Ichiro
JNC TN9400 2001-092, 44 Pages, 2001/03
JNC-TN9400-2001-092.pdf:1.36MB
None
; ; Sakamoto, Naoki; *; Akasaka, Naoaki;
JNC TN9400 2000-095, 110 Pages, 2000/07
JNC-TN9400-2000-095.pdf:13.57MB
The effects of high fluence irradiation and swelling on the transient burst properties of austenitic steel fuel claddings; PNC316 and 15Cr-20Ni stcel, which were irradiated as the MONJU type fuel assemblies (MFA-1&MFA-2) in the FFTF reactor, were investigated. The temperature-transient-to-burst tests were conducted on a total of eight irradiation conditions. Fractographic examination and TEM observation were performed in order to evaluate the effect of high dose irradiation on the transient burst property and the relation between failure mechanism and microstructural change during rapid (ramp) heating. The results of the PIE showed that there was no significant effect of irradiation on the transient burst properties of these fuel claddings under the irradiation conditions examined. the results obtained in this study are as follows; (1)The rupture temperature of the irradiated PNC316 fuel cladding of MFA-1 was as same as that of our previous works for the fluence range up to 2.1310 n/m. There was no noticeable decrease in rupture temperature with increasing fluence in lower hoop stress region(100MPa). (2)The rupture temperature of the irradiated 15Cr-20Ni fuel cladding of MFA-2 was almost as same as that of as-received cladding for the hoop stress range up to about 200MPa. The rupture temperature did not decrease significantly with fluence. (3)The rupture temperature of the irradiated PNC316 cladding tested at hoop stress 69MPa, which was the design hoop stress for MONJU fuel, was 1055.6C. This suggested that the design cladding maximum temperature limit for MONJU (830C) was conservative. (4)There was no obvious relation between rupture temperature, swelling and microstructural change during transient heating under the irradiation conditions examined.
; Yamagata, Ichiro; Donomae, Takako; Akasaka, Naoaki
JNC TN9400 2000-046, 24 Pages, 2000/02
lt is well known that solute atoms are segregated on surface, grain boundary, etc. and composition changed partially in irradiated austenitic stainless steel. For understanding radiation induced segregation (RIS), we adopt a Fe-15Cr-20Ni-x (x: Si, Mo) which is basically alloy system in PNC1520, and size of Si, Mo are different from matrix atoms to investigate RIS behaviors. The specimens were irradiated by "Joyo" fast reactor that irradiation condition is 3.5 10 n/m (E>0.1Mev) at 476C. After irradiation, the specimen were observed and analyzed with EDS (Energy Dispersive X-ray Spectroscope) of 400kV TEM (Transmission Electron Microscope). The behavior of RIS depends on size of solute atoms of alloy. For example, oversized atoms are decreased and undersized atoms are increased in sink. RIS of voids are as same as or more than grain boundaries and smaller than precipitates. The void denuded zone was existed nearby G.B. in case of combinations between the grains from G.B.0ne of the reasons in this, the voids swepted by moving G.B. in radiation induced G.B. migration.
Donomae, Takako; ; ; Akasaka, Naoaki; Yamagata, Ichiro; ;
JNC TN9400 2000-075, 374 Pages, 1999/08
JNC-TN9400-2000-075.pdf:18.85MB
The irradiation test of the Monju-type fuel subassembly, MEA-1, was conducted at FFTF as a Joint Research Program of Fuels and Materials between DOE and PNC. MFA-1 subassembly is consisted of cladding tube, wrapper tube, wrapping wire which are all made of PNC316, as well as 85% low density pellet. The pellet peak burnup and maximum fast neutron fluence reached 147.1GWd/t and 21.410n/m, respectively. Based on the results of Post-irradiation examination, Subassembly and fuel elements behaviors have been evaluated, and the following results were obtained. (1)The wrapper tube elongation and dilation are relatively small, and the fuel pin diameter changes were measured to be about 4% in maximum. The Bundle-Duct lnteraction (BDI) was confirmed not to be severe condition in Monju-type fuel assembly up to the fast neutron fluence of 21.410n/m. (2)In the claddings with the sand-brusted treatment to shave the flaw on the inner surface, the enhanced sweIling was measured, compared with PNC316 claddings manufactured by the usual process. lt is considered that this swelling enhancement in sand-brusted claddings attributed to relatively higher level of residual stress and lower cold-worked. (3)The deferent temperature dependency in swelling was evaluated for cladding and wrapping wire: the peak swelling temperature to be 495C for cladding and 475C for wrapping wire. 0n the contrary, the swelling-temperature dependency for wrapper tube was not able to be determined.