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Suzuki, Motoe; Sugiyama, Tomoyuki; Udagawa, Yutaka; Nagase, Fumihisa; Fuketa, Toyoshi
Proceedings of Top Fuel 2009 (DVD-ROM), p.473 - 479, 2009/09
Two cases of the Reactivity-Initiated-Accident-simulating pulse irradiation experiments conducted in the NSRR using a high burnup PWR fuel are analyzed by using the RANNS code. One case was performed in a stagnant coolant water of room temperature and at atmospheric pressure, and the other in the stagnant coolant of high temperature at 7 MPa pressure. The two cases resulted in failure. Behavior in a fast transient of the fuels is investigated by comparing the two experiments. Specifically, the temperature of rod, pellet-clad mechanical interaction, and stress/strain of cladding etc. are calculated and the results are discussed in comparison with the experimental observations. The metallography of cladding shows that the cladding failed by macroscopic shear gliding from a tip of a crack. The calculated plastic strains of claddings at failure reasonably coincide with the observed local strains if the latter strains are averaged over the total circumference.
Sugiyama, Tomoyuki; Umeda, Miki; Sasajima, Hideo; Suzuki, Motoe; Fuketa, Toyoshi
Proceedings of Top Fuel 2009 (DVD-ROM), p.489 - 496, 2009/09
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.
Fuketa, Toyoshi; Sugiyama, Tomoyuki; Umeda, Miki; Sasajima, Hideo; Nagase, Fumihisa
Proceedings of Top Fuel 2009 (DVD-ROM), p.465 - 472, 2009/09
Hanawa, Satoshi; Ogiyanagi, Jin; Inaba, Yoshitomo; Sasajima, Hideo; Nakamura, Jinichi; Nakamura, Takehiko
Proceedings of Top Fuel 2009 (DVD-ROM), p.350 - 356, 2009/09
In order to perform power transient tests of new design LWR's fuels, new power transient test capsules, the natural convection capsule and the forced convection capsule, are being developed. The natural convection capsule has relatively simple structure, and the test fuel rod is cooled by the natural convection of the coolant. The basic technologies for the natural convection capsule have already been established and the power transient tests will be started by using this capsule. The forced convection capsule has relatively complicated structure for circulating the cooling water and controlling the cooling water temperature. By performing several mock-up test, we confirmed that the target linear heat rate is achievable by the capsules, and elemental technologies to realize the forced convection capsule is feasible.
Yanagisawa, Kazuaki
Proceedings of Top Fuel 2009 (DVD-ROM), p.1226 - 1235, 2009/09
Power transient test was conducted on unirradiated silicide miniplate fuels. A failure threshold of tested fuel is revealed between 82 and 94 cal per gram fuel plate. Failure mechanism of a through-plate cracking is a thermal stress caused by a large temperature drop (larger than 94 C), combined with a rapid quench (smaller than 0.13s). Additionally, a water channel closure (plate bowing) was studied by triplet and single plate configuration as a function of peak cladding surface temperature (PCST). Adaptability of licensing criteria (228 C) applied to the water channel closure of JRR-3 and JMTR silicide fuels are experimentally confirmed.
Horiguchi, Hironori; Shibata, Taiju; Yagi, Masahiro; Yokoo, Kenji; Oyama, Koji; Kusunoki, Tsuyoshi
no journal, ,
The Japan Research Reactor No.4 (JRR-4) are used for medical irradiation (Boron Neutron Capture Therapy), education and training for engineers, activation analysis and researches in various fields. A crack was found on the weld of aluminum cladding of a reflector element, in which graphite reflector was set. A survey on the reflector element confirmed that the crack was caused by growth of graphite. The growth of graphite was observed in the other reflector elements by the radiographic testing (RT). In order to understand the relations between irradiation fluence and irradiation growth, the dimensions of irradiated graphite reflectors were precisely measured after dismantling the reflector elements. We revealed that the growth of graphite increased with fast neutron fluence at low temperature which was estimated below 200C under JRR-4 operation condition.