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Sawazaki, Hiromasa; Kisohara, Naoyuki; Nakamura, Yoshihide; Sato, Takeshi
no journal, ,
Due to the sodium leak accident or troubles such as the furnace relay device falling, the operation of "Monju" has been suspended for approx. 20 years, and the system performance test has not also been executed at the rated power. However, the decay heat removal system (DHRS) has been operated at low flow rates in the primary and secondary sodium circuits, and its operating data are obtained. The performance of system or components can be evaluated using these data. The presentation addresses the overview of the study under the DHRS operation condition, and the following presentations report some of the results.
Sato, Takeshi; Okawachi, Yasushi; Nakamura, Yoshihide; Sawazaki, Hiromasa
no journal, ,
In the Monju, before expanding accident in the unlikely event of a water leak from the steam generator tubes, capturing the hydrogen concentration changes in the secondary sodium, it is important to early detect the corresponding water leak. Its detection sensitivity, the amount of hydrogen diffused from the water side to the secondary sodium in through the heat exchanger tube during normal operation, depends on the performance of the cold trap to remove it. So, this time was carried out to confirm the purification efficiency derived by using the operating data of the actual machine of purification efficiency and about 20 years was expected in the design of the secondary sodium purification system cold trap.
Nakamura, Yoshihide; Sato, Takeshi; Sawazaki, Hiromasa; Kisohara, Naoyuki
no journal, ,
Because the impurity such as NaO in sodium causes material corrosion in SFRs, sodium needs to be controlled under high purity condition. Fuel exchanges and recovering works for troubles have been done in Monju for the past 20 years, therefore, there is the possibility that oxygen in the atmosphere entered the sodium circuits and degraded the sodium purity. The analysis of the 20 year plant data has revealed, however, that the impurity in the primary sodium has been maintained to be low enough by the skillful technique of purity management.
Morioka, Tatsuya; Sawazaki, Hiromasa; Uchida, Takenobu; Sato, Takeshi; Nakamura, Yoshihide; Shiotani, Hiroki; Kunogi, Kosuke
no journal, ,
Thermal natural convection occurred in Ar gas region between the inner and outer casing of the sodium pump in the past, which induces asymmetric circumferential temperature distribution on the casings. This thermal effect causes the contact of the pump shaft with the lower hydrostatic bearing, which places the bearing at risk for damage. This phenomenon strongly appears in long size pumps of sodium fast reactors. To prevent this risk for Monju primary sodium pump, convection prevention plates are installed between the inner and outer casing of the pump. Monju plant data indicates the plates decrease the circumferential temperature difference, and then no contact arose between the pump shaft and the bearing.
Sato, Takeshi; Sawazaki, Hiromasa; Morioka, Tatsuya; Uchida, Takenobu; Nakamura, Yoshihide; Shiotani, Hiroki; Okawachi, Yasushi
no journal, ,
In Monju, it is important to detect and respond to hydrogen concentration changes in secondary sodium at an early stage, before any water leakage from the steam generator heat transfer tube expands. For that purpose, it is necessary to understand the hydrogen concentration during normal operation. In this report, we estimated, using the purification efficiency evaluation of the cold trap reported at the fall programs of 2016, the amount of diffused hydrogen from the characteristic test data of 1995 and evaluated the hydrogen concentration in the secondary sodium during normal operation.
Shiotani, Hiroki; Sawazaki, Hiromasa; Nakamura, Yoshihide; Sato, Takeshi; Uchida, Takenobu; Arai, Masanobu
no journal, ,
We are evaluating operating data of about 20 years (Evaluation of "Monju Research Plan") through the collaboration of both older and younger engineers. In this study, we will propose the use of information technologies and/or statistics tools in future evaluation to make the data treatment in an effective and efficient manner. In addition to that, we will also present a vision for supporting and cooperating technical tradition and knowledge discovery, etc. nuclear engineers by machine learning technologies toward the commercialization of fast reactor cycle systems.
Sawazaki, Hiromasa; Nakamura, Yoshihide; Sato, Takeshi; Morioka, Tatsuya; Uchida, Takenobu; Shiotani, Hiroki; Kisohara, Naoyuki
no journal, ,
We are evaluating operating data of about 20 years (Evaluation of "Monju" Research Plan) Now, In this presentation, We extract the facilities that can be evaluated on the "Monju" research plan and report the result of selecting the evaluation items. In addition, some of the evaluations were found to be possible from another viewpoint. We added them as evaluation items, and we will add evaluation items in order and evaluate them in the future as they become obvious in the future. In addition, we are currently reviewing the results of the research and development on "Monju" including "Monju" Research Plan within the JAEA, and review the evaluation items and the plan itself as necessary.
Uchida, Takenobu; Sawazaki, Hiromasa; Morioka, Tatsuya; Sato, Takeshi; Nakamura, Yoshihide; Shiotani, Hiroki; Okawachi, Yasushi
no journal, ,
The reactor cavity and Primary room Heat Transfer System (PHTS) cells of FBR are designated as water prohibited area to prevent sodium-water reaction phenomena. In Monju, fluorocarbon is used as a refrigerant instead of water refrigerants for Reactor Building (R/B) Heating, Ventilation, and Air Conditioning (HVAC). R/B HVAC chiller system using fluorocarbon is characteristic equipment for FBR, and there is no example in light water reactors. In this study, we evaluated the running performance of R/B HVAC Chiller System by using about 20 years Plant data as an Evaluation of "Monju" Research Plan.
Nakamura, Yoshihide; Sawazaki, Hiromasa; Morioka, Tatsuya; Uchida, Takenobu; Sato, Takeshi; Shiotani, Hiroki; Kisohara, Naoyuki
no journal, ,
With the liquid metal sodium cooled fast reactor, sodium has to be maintained and managed at a high purity to prevent the channel blockage by the precipitation of impurities and the material corrosion with sodium. At Monju, primary heat transport system, secondary heat transport system, and ex-vessel fuel storage tank sodium cooling system are corresponding to this clean-up system. We evaluate the sodium purity control condition of these facilities for more than 20 years by the measurement of the plugging meter and chemical analysis, and confirm that we could maintain the purity with a value lower enough than the management targeted value.
Morioka, Tatsuya; Hashidate, Ryuta; Sawazaki, Hiromasa; Kunogi, Kosuke
no journal, ,
Thermal natural convection occurred in Ar gas region between the inner and outer casing of the sodium pump in the past, which induces asymmetric circumferential temperature distribution on the casings. This thermal effect causes the contact of the pump shaft with the lower hydrostatic bearing, which places the bearing at risk for damage. To prevent this risk for Monju primary sodium pump, convection prevention plates are installed between the inner and outer casing of the pump. The soundness which in 2017 spring meeting, Monju plant data indicates the plates decrease the circumferential temperature difference, and then no contact arose between the pump shaft and the bearing. The circumferential temperature difference of the layer lower part is big compared with the layer upper part and the central part. We confirmed that difference in temperature among the measurement points of the lower gas layer was affected by the sodium vortex prevention plates.
Hashidate, Ryuta; Morioka, Tatsuya; Sawazaki, Hiromasa; Shiotani, Hiroki; Obata, Ikuhito; Uekura, Ryoichi
no journal, ,
We have been evaluating mainly the data acquired by the central computer so far, but we focused on evaluation using preservation data from this time. In this report, we report on the results of examination of the shaft sealing mechanism which constitutes the boundary of the cover gas including sodium vapor from the viewpoint of seal gas effect considered in the design stage for sodium vapor and sealability of the cover gas boundary by using the Monju plant data and conservation data for 20 years.
Naruse, Keiji; Matsui, Kazuaki; Obata, Ikuhito; Sawazaki, Hiromasa; Goto, Takehiro; Jo, Takahisa
no journal, ,
no abstracts in English
Ono, Fumiyasu; Fukushima, Tsubasa; Naruse, Keiji; Matsui, Kazuaki; Obata, Ikuhito; Sawazaki, Hiromasa; Goto, Takehiro; Jo, Takahisa; Uchihashi, Masaya
no journal, ,
By storing fuel assemblies in the fuel pond in Phase 1, MONJU eliminates the residual risk of fuel assemblies remaining in the core, which holds chemically active liquid sodium, and from April 2023, Have moved to Phase 2 of decommissioning. As the decommissioning progresses, plant risks will continue to change. Therefore, we will organize the plant status at each Phase of decommissioning and formulate the concept of performance maintenance facilities for MONJU, which will be necessary in Phase 2, and Performance maintenance facilities were Reconsidered.