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Nagase, Fumihisa; Chuto, Toshinori; Fuketa, Toyoshi
Journal of Nuclear Science and Technology, 48(11), p.1369 - 1376, 2011/11
Times Cited Count：11 Percentile：64.09(Nuclear Science & Technology)Ring compression tests were conducted with specimens sampled from high-burnup fuel cladding segments which had been ruptured, oxidized at 1405 - 1484 K and quenched in the LOCA-simulated experiments. The plastic strain to failure and the maximum load decrease with increasing oxidation and hydrogen. Embrittlement of the cladding is seen when the hydrogen concentration is above 300 - 400 ppm. Although all the examined fuel cladding segments did not facture in the LOCA-simulated experiments, most the specimens failed without plastic deformation in the ring compression tests. The obvious discrepancy between the fracture/no-fracture criterion and the embrittlement criterion is likely caused by difference in the loading conditions in the two tests.
Sasajima, Hideo; Sugiyama, Tomoyuki; Chuto, Toshinori; Nagase, Fumihisa; Nakamura, Takehiko; Fuketa, Toyoshi
Journal of Nuclear Science and Technology, 47(2), p.202 - 210, 2010/02
Times Cited Count：5 Percentile：35.74(Nuclear Science & Technology)Fission gas release positions in high burnup fuel pellets were examined after the pulse-irradiations which simulated reactivity initiated accident (RIA) conditions in the Nuclear Safety Research Reactor (NSRR). The ratio of xenon to krypton ((Xe/Kr) ratio) in the released gas showed that fission gas was released from the entire region of the pellets of the examined PWR fuels during the pulse-irradiations. On the other hand, most fission gas was released from the center and/or intermediate regions of the examined BWR fuel pellets. Consequently, it is likely that fission gas is not released selectively from the rim structure at the pellet periphery under RIA conditions.
Nagase, Fumihisa; Chuto, Toshinori; Fuketa, Toyoshi
Proceedings of Top Fuel 2009 (DVD-ROM), p.527 - 537, 2009/09
Experiments simulating the whole LOCA sequences are performed in Japan, while ring-compression tests of oxidized cladding are performed for evaluating cladding embrittlement in a LOCA. In order to compare the two test methodologies and discuss about the safety limits appropriate to the high burn-up fuel, the ring compression test at 135
C was performed with specimens sampled from the high burn-up fuel cladding which was tested in the LOCA-simulated experiments. Oxidation temperature in the LOCA-simulated experiments ranges about 1130 to 1210C, the oxidation ranges about 11 to 22% ECR and hydrogen concentrations ranges about 200 to 1400 ppm. Although the examined high burn-up cladding did not fracture on the quenching in the LOCA-simulated experiments, the specimens fractured without showing plastic deformation in the ring compression tests. Considering the severity to the fuel, up to the quench phase, the ring compression test could provide conservative results.
Nagase, Fumihisa; Chuto, Toshinori; Fuketa, Toyoshi
Journal of Nuclear Science and Technology, 46(7), p.763 - 769, 2009/07
Times Cited Count：40 Percentile：92.23(Nuclear Science & Technology)LOCA-simulated experiments were performed with the MDA, ZIRLO, M5, NDA and Zircaloy-2 cladding specimens sampled from high burnup fuel rods which were irradiated to 66-76 MWd/kg (local). Short test rods fabricated with the cladding specimens and dummy pellets were heated, isothermally oxidized at 1459 to 1480 K in steam flow, and finally quenched in flooding water. Neither split-fracture nor fragmentation occurred during the quench for the cladding specimens, oxidized to about 18-27% of the metallic thickness. Accordingly, the fracture boundary, a most important safety issue, is not reduced significantly by the high burn-up and use of the new alloys in the examined scope, though it may be somewhat reduced with pre-hydriding during the reactor operation as observed in unirradiated specimens.
Chuto, Toshinori; Nagase, Fumihisa; Fuketa, Toyoshi
Nuclear Engineering and Technology, 41(2), p.163 - 170, 2009/03
In order to evaluate high-temperature oxidation behavior of the advanced alloy cladding under LOCA conditions, isothermal oxidation tests in steam were performed with cladding specimens prepared from high burnup PWR fuel rods (79 MWd/kg). Cladding materials were M5 and ZIRLO which are Nb-containing alloys. Ring-shaped specimens were isothermally oxidized in flowing steam at temperatures from 1173 to 1473 K for the duration between 120 and 4000 s. Protective effect of the pre-formed corrosion layer is seen for the shorter time range at the lower temperatures. Influence of pre-hydriding is not significant for the examined range. Alloy composition change generally has small influence on the oxidation in the examined temperature range, though M5 shows obviously smaller oxidation constant at 1273 K. Consequently, the oxidation rates of the high burnup M5 and ZIRLO cladding are comparable or lower than that of unirradiated Zircaloy-4 cladding.
Fuketa, Toyoshi; Nakamura, Takehiko; Nagase, Fumihisa; Nakamura, Jinichi; Suzuki, Motoe; Sasajima, Hideo; Sugiyama, Tomoyuki; Amaya, Masaki; Kudo, Tamotsu; Chuto, Toshinori; et al.
JAEA-Review 2006-004, 226 Pages, 2006/03
JAEA-Review-2006-004.pdf:34.43MB
Fuel Safety Research Meeting 2005, which was organized by the Japan Atomic Energy Agency was held on March 2-3, 2005 at Toshi Center Hotel, Tokyo. The purposes of the meeting are to present and discuss the results of experiments and analyses on reactor fuel safety and to exchange views and experiences among the participants. The technical topics of the meeting covered the status of fuel safety research activities, fuel behavior under Reactivity Initiated Accident (RIA) and Loss of coolant accident (LOCA) conditions, high fuel behavior, and radionuclide release under severe accident conditions. This summary contains all the abstracts and sheets of viewgraph presented in the meeting.
Shimada, Sachio; Chuto, Toshinori; Nagase, Fumihisa; Fuketa, Toyoshi
no journal, ,
no abstracts in English
Sasajima, Hideo; Nakamura, Takehiko; Chuto, Toshinori; Sugiyama, Tomoyuki; Hosoyamada, Ryuji; Fuketa, Toyoshi
no journal, ,
no abstracts in English
Nagase, Fumihisa; Chuto, Toshinori; Fuketa, Toyoshi
no journal, ,
LOCA-simulated experiments were conducted with high burnup PWR fuel cladding (
79 GWd/t) composed of advanced alloys in order to examine high burnup effect on fuel behavior under LOCA conditions. Obvious effect of high burnup and use of advanced alloys were not seen in terms of ballooning, rupture fracture behavior and oxidation conditions for fracture.
Nagase, Fumihisa; Chuto, Toshinori; Fuketa, Toyoshi
no journal, ,
LOCA-simulated experiments were conducted with high burnup PWR fuel cladding composed of advanced alloys in order to examine high burnup effect on fuel behavior under LOCA conditions. Obvious effect of high burnup and use of advanced alloys were not seen in terms of ballooning, rupture fracture behavior and oxidation conditions for fracture.
Chuto, Toshinori; Nagase, Fumihisa; Fuketa, Toyoshi
no journal, ,
no abstracts in English
Nagase, Fumihisa; Chuto, Toshinori; Hatakeyama, Yuichi; Fuketa, Toyoshi
no journal, ,
LOCA-simulated experiments were conducted with irradiated PWR and BWR fuel cladding (77 GWd/t) to investigate high burnup effect on LWR fuel behavior under LOCA conditions. In the experiments, MDA, NDA, ZIRLO, M5 and Zircaloy-2 cladding specimens were sampled from the high burnup fuels irradiated at European power plants, and they were oxidized at 1563 to 1480 K and quenched. The cladding specimens oxidized to 18.3 to 27.3% ECR did not fracture during the quench. Consequently, the fracture boundary is not significantly reduced in the examined burnup range. Obvious high burnup effect was not seen also in the ballooning, rupture, fracture behavior.
Chuto, Toshinori; Nagase, Fumihisa; Ono, Katsuto; Fuketa, Toyoshi
no journal, ,
In order to investigate effect of burnup on high temperature oxidation of the advanced cladding alloys, isothermal oxidation tests were performed with specimens prepared from high burnup fuel cladding which were irradiated up to 79 MWd/kg as well as non-irradiated cladding. Oxidation kinetics was evaluated from weight gain and oxide layer growth. Oxide layer thickness on the cladding outside diameter (OD) is smaller in the irradiated cladding. It is considered that the oxidation at the cladding OD was suppressed by the pre-formed corrosion layer. Results of the weight gain measurement also suggest lower oxidation rates in the irradiated cladding. Difference in the alloy composition hardly affected the oxidation rates.
Ikatsu, Nobuhiko; Chuto, Toshinori; Nagase, Fumihisa; Fuketa, Toyoshi
no journal, ,
no abstracts in English
Nagase, Fumihisa; Chuto, Toshinori; Suzuki, Kazuhiro; Fuketa, Toyoshi
no journal, ,
Ductility of high burnup fuel cladding which experienced rupture, high-temperature oxidation and quenching in the LOCA-simulated integral test was evaluated by the ring compression test. Although ductility was remarkably reduced in the cladding which absorbed hydrogen of above about 500 ppm and was oxidized above 1270 K, effects of the high burnup are small except for hydrogen absorption. It is considered that the ring compression test provides more conservative criteria than the integral test regarding the integrity of the cladding in LOCAs.
Chuto, Toshinori
no journal, ,
In order to investigate effect of burnup on high temperature oxidation of the advanced cladding alloy, isothermal oxidation test was performed with specimens prepared from high burnup fuel cladding which were irradiated up to 79 MWd/kg as well as non-irradiated cladding. Oxidation kinetics was evaluated from weight gain and oxide layer growth. Growth of the inner surface oxide layer formed in the irradiated cladding is almost equivalent to that in the non-irradiated cladding, while growth of the outer surface oxide layer is slightly smaller in the irradiated cladding. It is considered that the oxidation at the outer surface is suppressed by the pre-formed corrosion layer. Results of the weight gain measurement also suggest lower oxidation rates in the irradiated cladding. Consequently, it is concluded that high-burnup effect on high temperature oxidation is small for the examined range, though pre-formed corrosion layer may have the protective effect.
