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Abe, Yuta; Yamashita, Takuya; Sato, Ikken; Nakagiri, Toshio; Ishimi, Akihiro
Journal of Nuclear Engineering and Radiation Science, 6(2), p.021113_1 - 021113_9, 2020/04
Abe, Yuta; Yamashita, Takuya; Sato, Ikken; Nakagiri, Toshio; Ishimi, Akihiro; Nagae, Yuji
Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 9 Pages, 2018/07
Abe, Yuta; Nakagiri, Toshio; Watatani, Satoshi*; Maruyama, Shinichiro*
JAEA-Technology 2017-023, 46 Pages, 2017/10
JAEA-Technology-2017-023.pdf:8.01MB
This is a report on Abrasive Water Jet (AWJ) cutting work carried out on specimen, which was used for Simulated Fuel Assembly Heating Examination by Collaborative Laboratories for Advanced Decommissioning Science (CLADS) molten core behavior analysis group in February 2016. The simulated fuel assembly is composed of Zirconia for the outer crucible/simulated fuel, stainless steel for the control blade and Zircaloy (Zr) for the cladding tube/channel box. Therefore, it is necessary to cut at once substances having a wide range of fracture toughness and hardness. Moreover, it is a large specimen with an approximate size of 300 mm. In addition, epoxy resin has high stickiness, making it more difficult to cut. Considering these effects, AWJ cutting was selected. The following two points were devised, and this specimen could be cut with AWJ. If it was not possible to cut at one time like a molten portion of boride, it was repeatedly cut. By using Abrasive Suspension Jet (ASJ) system with higher cutting ability than Abrasive Injection Jet (AIJ, conventional method) system, cutting time was shortened. As a result of this work, the cutting method in Simulated Fuel Assembly Heating Examination was established. Incidentally, in the cutting operation, when the cutting ability was lost at the tip of the AWJ, a curved cut surface, which occurs when the jet flowed away from the feeding direction, could be confirmed at the center of the test body. From the next work, to improve the cutting efficiency, we propose adding a mechanism such as turning the cutting member itself for re-cutting from the exit side of the jet and appropriate traverse speed to protect cut surface.
Maruyama, Shinichiro*; Watatani, Satoshi*
Mitsui Sumitomo Kensetsu Gijutsu Kenkyu Kaihatsu Hokoku, (15), p.107 - 112, 2017/10
It is essential to estimate characteristics and forms of fuel debris for safe and reliable removing at the decommissioning of the Fukushima Daiichi Nuclear Power Plant (1F). For the estimation, melting behavior of fuel assembly in the accident is being researched. To proceed the research, the fuel debris were need to cut, and the abrasive water jet (AWJ) which had enough results for cutting ceramic material or mixed material of zirconium alloy and stainless. The test results demonstrated that AWJ could cut the fuel assembly and accumulated the cutting data which will be subservient when removing the fuel debris in future.
Abe, Yuta; Sato, Ikken; Nakagiri, Toshio; Ishimi, Akihiro; Nagae, Yuji
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 7 Pages, 2017/04
Abe, Yuta; Sato, Ikken; Ishimi, Akihiro; Nakagiri, Toshio; Nagae, Yuji
Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 7 Pages, 2016/06
A new experimental program using non-transfer type plasma heating is under consideration in JAEA to clarify the uncertainty on core-material relocation (CMR) behavior of BWR. In order to confirm the applicability of this new technology, authors performed preparatory plasma heating tests using small-scale test pieces (107 mm 
107 mm 222 mmh). Based on these preliminary results, an excellent perspective in terms of applicability of the non-transfer plasma heating technology to the SA (Severe Accident) experimental study was obtained. Furthermore, JAEA is preparing for the next step intermediate-scale preparatory tests in 2016 using ca. 50 rods and a control blade that would not only confirm its technical applicability, but also some insights relevant to the issue on CMR itself.
Hanus, G.*; Sato, Ikken; Iwama, Tatsuya*
Proceedings of International Waste Management Symposia 2016 (WM2016) (Internet), 12 Pages, 2016/03
JAEA plans a large-scale test to evaluate damage and relocation behavior of BWR core materials consisting of fuel rods, channel boxes, control blade and lower support structures. Its purpose is to contribute to understanding of core material relocation behavior in the event of severe accidents with the BWR design conditions for which existing experimental database is quite limited. Prior to large-scale testing, JAEA desires preliminary investigations to examine melting test pieces. The purpose of such tests is to verify the materials and test piece will be heated by plasma to the target temperature (ca.2900K) and to collect data about the material relocation behavior. Results from preliminary computational simulations are presented illustrating the effectiveness of a 150 kW non-transferred plasma jet. An experimental test program using the computational analyses as a basis and a plasma torch is described.
JNC TN9400 2000-038, 98 Pages, 2000/04
JNC-TN9400-2000-038.pdf:7.49MB
As an effort in the feasibility study on commercialized Fast Breeder Reactor cycle systems, an evaluation of the measures to prevent the energetic re-criticality in sodium-cooled large MOX core, which is one of the candidates for the commercialized reactor, has been performed. The core disruptive accident analysis of Demonstration FBR showed that the fuel compaction of the molten fuel by radial motion in a large molten core pool had a potential to drive the severe super-prompt re-criticality phenomena in ULOF sequence. ln order to prevent occurrence of the energetic re-criticality, a subassembly with an inner duct and the removal of a part of LAB are suggested based on CMR (Controlled Material Relocation) concept. The objective of this study is the comparison of the effectiveness of CMR among these measures by the analysis using SIMMER-III. The molten fuel in the subassembly with inner duct flows out faster than that from other measures. The subassembly with inner duct will work effectively in preventing energetic re-criticality. Though the molten fuel in the subassembly without a part of LAB flows out a little slower, it is still one of the promising measures. However, the UAB should be also removed from the same pin to prevent the fuel re-entries into the core region due to the pressurization by FCl below the core, unless it disturbs the core performance. The effect of the axial fuel length of the center pin to CMR behavior is small, compared to the effect of the existence of UAB.
Abe, Yuta; Sato, Ikken; Nakagiri, Toshio; Nagae, Yuji; Ishimi, Akihiro
no journal, ,
no abstracts in English
Sato, Ikken; Abe, Yuta; Nakagiri, Toshio; Nagae, Yuji; Ishimi, Akihiro
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Abe, Yuta; Nakagiri, Toshio; Sato, Ikken; Nakano, Natsuko*; Tanaka, Hiroshi*; Yamaguchi, Hidenobu*
no journal, ,
no abstracts in English
Abe, Yuta; Nakagiri, Toshio; Sato, Ikken; Nakano, Natsuko*; Yamaguchi, Hidenobu*
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no abstracts in English
Kawakami, Tomohiko*; Abe, Yuta; Spaziani, F.*; Nakano, Natsuko*; Nakagiri, Toshio
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no abstracts in English
Abe, Yuta; Nakagiri, Toshio; Sato, Ikken; Nakano, Natsuko*; Yamaguchi, Hidenobu*; Maruyama, Shinichiro*
no journal, ,
no abstracts in English
Kawakami, Tomohiko*; Abe, Yuta; Spaziani, F.*; Nakano, Natsuko*; Nakagiri, Toshio
no journal, ,
no abstracts in English
Maruyama, Shinichiro*; Abe, Yuta; Nakagiri, Toshio; Watatani, Satoshi*; Takashima, Yuji*
no journal, ,
no abstracts in English
Okazaki, Kodai*; Abe, Yuta; Spaziani, F.*; Nakano, Natsuko*; Kawakami, Tomohiko*
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no abstracts in English
Noro, Junji*; Abe, Yuta; Yamashita, Takuya; Matsushima, Tomohiro*
no journal, ,
no abstracts in English
Tada, Kenichi
no journal, ,
Many accelerated methods are introduced and implemented to increase the speed of the neutronics calculation. However, there is no good Japanese text book, which explains these methods for beginner. This paper explains the detail of these methods and example of the application of the diffusion calculation code. The coarse mesh diffusion calculation method is widely used for the current neutronics analysis codes and this method is used spatial homogenization method. To improve the understanding of this method, this paper also explains the spatial homogenization methods. This paper explains the discontinuity factor and the Superhomogenization (SPH) method for the spatial homogenization method and the Successive Over Relaxation (SOR) method, the Chebyshev extrapolation method, the Wielandt method, the Coarse Mesh Rebalance (CMR) method, the Coarse Mesh Finite Difference (CMFD) method, and the Generalized Coarse Mesh Rebalance (GCMR) method for the acceleration method.
阿部 雄太
not registered
JP, 2018-200792 Patent licensing information
【課題】測定対象元素の特性X線に対応するピークと干渉元素の特性X線に対応するピークとが干渉する場合に、測定対象元素の組成を高精度で算出する。 【解決手段】解析部は、ZR(干渉元素)の発する特性X線のうち、Bに起因する測定対象ピークと干渉しないものに対応する波長(参照用波長)を設定し、上記の測定点におけるこの参照用波長での強度(補正用強度)も測定する。測定対象ピーク(BのKα1線)に対応する波長λ1周囲においては、測定対象ピークP11がある。この測定対象ピークP11に近接して、ZRのMZ線のピーク(干渉ピーク)P21が存在する。補正用強度測定工程においては、参照用波長λ2として、ZRのLα線のピーク(参照用ピークP41)に対応する波長が設定される。測定点におけるB組成のみを反映するI11(補正後強度)は、実測強度I31から補正用強度I41に補正係数Cを乗じた値を減じた式で表すことができる。
