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三原 武; 浦野 建太; 宇田川 豊
Proceedings of TopFuel 2024 (Internet), 9 Pages, 2024/10
To promote a better understanding of the fission gas behavior during a reactivity-initiated accident (RIA) and its role in the thermo-mechanical loading in the fuel cladding, the Fission Gas Dynamics (FGD) test program has been developed in the framework of the JAEA and Institute for Radiological Protection and Nuclear Safety (IRSN) cooperation. The concept of the FGD test is to understand the effect of fission gas release during a RIA test through transient measurement of the pressure inside a rigid chamber, which contains the test fuel, with its minimum deformation against pressure increase. Since the internal pressure sensor of strain gauge (SG) type used in previous RIA-simulated Nuclear Safety Research Reactor (NSRR) tests is strongly affected by gamma and/or neutron field in the NSRR core, we adopted a new pressure sensor using a linear variable differential transducer (LVDT) for accurate pressure measurement with higher stability against pulse irradiation. JAEA has conducted the first NSRR-FGD test (FGD-1) on high-burnup fuel with doped pellets. In advance, difference in pressure response between LVDT-type and SG-type sensors was carefully examined as performance measure of the LVDT-type sensor. The response delay of the LVDT-type sensor compared with the SG-type one was estimated to be about 1.5 ms when the pressure increasing rate exceeded above 20 MPa/s. In the FGD-1 test, the LVDT-type pressure sensor detected a pressure rise of about 100 MPa/s just after the pulse irradiation, which confirmed the capability of this FGD testing technique to study the kinetics of rapid fission gas release during the simulated RIA conditions.
石橋 良*; 廣坂 和馬*; 山名 貴志*; 柴田 昌利*; 佐々木 政名*; 根本 義之; 檜木 達也*
Proceedings of TopFuel 2024 (Internet), 9 Pages, 2024/10
As a cladding material for accident tolerant fuel, SiC is expected to have an advantage in elevated temperature resistance compared to other candidate materials. End-plug joints are exposed to elevated temperature by heat-upped fuel pellets and loading by difference in internal and external pressure of cladding during a severe accident. For performing sufficient strength against severe accident conditions, we are developing an end-plug joint consisted of mechanical fastening and brazing and evaluation methods for its joint strength. Objectives in this study are to evaluate strength and deformation behavior of the joint using tensile testing and to analyze the deformation mechanism based on estimated loading and temperature conditions during a severe accident. The evaluation results using tensile testing provided information for evaluating the joint by inter pressure testing in the next stage.
Mohamad, A. B.; 相馬 康孝; 根本 義之; 阿部 陽介; 井岡 郁夫; 佐藤 智徳; 石島 暖大; 三輪 周平; 中島 邦久; 山下 真一郎; et al.
Proceedings of TopFuel 2024 (Internet), 8 Pages, 2024/10
In parallel with the Accident Tolerant Fuel development program in Japan, Japan Atomic Energy Agency has established an R&D program on the ATF to provide more scientific support to the ATF fuel vendors in Japan. Based on the phenomenological issues identified, the R&D program covers the issues mainly on the light water reactors conditions such as normal operation, loss of coolant accident, beyond design basis accident, and severe accident. The R&D program such as irradiation test, corrosion test, LOCA test, and etc. are proposed. By acquiring the data from the experiment, the final goal is to implement the experimental data and model into the simulation code in order to predict the fuel performance behaviour at high burn-up.