| Project/Area Number |
16K14535
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Multi-year Fund |
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| Research Field |
Nuclear engineering
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| Research Institution | University of Yamanashi |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000)
Fiscal Year 2018: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2017: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2016: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | 分子拡散 / 自然対流 / 密度成層 / 自然循環流 / 異種気体 / 安定成層 / 超高温ガス炉 / 空気浸入 / 熱流動現象 / 流体制御 / 二成分気体 |
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| Outline of Final Research Achievements |
When a depressurization accident of a Very-High-Temperature Reactor occurs, air is expected to enter into the reactor pressure vessel from the breach. In order to investigate of preventing natural circulation flow by injecting helium gas, the experiment has been done as follows. Firstly, heavy gas is filled with the reverse U-shaped passage and the storage tank. Then, two vertical walls of the high-temperature side passage is heated and cooled. Thus, natural circulation flow will be generated. When the steady state is established, helium gas injects from the top of the passage. Natural circulation will be stopped immediately. After the time elapsed, natural circulation will be regenerated suddenly. Re-onset time of natural circulation increased with increasing the amount of injecting helium gas. From the results obtained from these experiments, if a helium canister is placed in the upper part of the reactor pressure vessel, air ingress from the ruptured pipe can be prevented.
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| Academic Significance and Societal Importance of the Research Achievements |
ヘリウム／空気の密度の異なる気体について，大量の空気が浸入する空気の自然循環流の発生を防止するため，既に自然循環流が発生している状態において，実験装置の上部または下部から微少量のヘリウムガスを注入することにより，空気の自然循環流を停止させことができた．これにより，注入するヘリウムガスの量及び注入位置，注入方法により，空気の自然循環流を制御できる可能性を明らかにした．超高温ガス炉の原子炉設計を行う際に想定事象の一つである一次冷却系主配管破断時の空気浸入事象において，密度の小さい気体により空気の浸入を防止することができれば，今後の安全設計に関して，設計上の安全裕度を各段に向上することができる.
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