報告書番号

T98062

タイトル（和文）

２次系削除タンク型FBR「ARES」のプラント熱流動特性(2) --事故時過渡特性--

タイトル（英文）

Thermal Hydraulic Characteristics of the Pool-Type FBR "ARES"Eliminating Intermediate HeatTransfer System (2)- Transient Characteristics in Typical accidents-

概要 （図表や脚注は「報告書全文」に掲載しております）

２次系削除タンク型ＦＢＲ「ＡＲＥＳ」の特徴的な過渡事象を選定し、プラント動特性解析により安全性評価に必要な熱流動上の特徴を明らかにした。1.誤サイフォンブレーク機構事象の解析の結果、冷却材が沸騰に至ることなく、炉心が十分に冷却された。2.ＳＧ給水流量増大事象の解析を行ったところ、ＳＧでの外乱は原型炉の約半分程度の時間で伝わるが、温度の推移などは原型炉の場合と類似していた。２次系削除型プラントでは、ＳＧ外乱の炉心への到達時間について注意を払う必要があるものの、プラントの運転上、２次系削除の問題点はないと判断できる。3.全交流電源喪失の解析の結果、トリップ直後にDRACSでの自然循環のみで冷却すると、冷却材が沸騰する恐れがあるが、ＳＧ流路側での冷却にも期待できる場合には、沸騰を回避できた。これらにより、選定された事象において、炉心冷却が十分に行える見通しが得られた。

概要 （英文）

An innovative plant concept (ARES) , which eliminates intermediate heat-transfer system, was proposed in order to reduce the construction cost of the liquid metal cooled fast breeder reactor (LMFBR) . In the present study, representative events of the ARES were picked up and plant transient analysis was conducted in order to reveal the thermal hydraulic characteristics of the ARES. The main results of the analysis are as follows:(1) The core was sufficiently cooled without sodium boiling in an event of mis-operation of the siphon break system.(2) The disturbances of the SG transfer to the core within about 30 seconds in a event of the feed water increasing. This transition period is less than half that of the conventional LMFBR. However, the transient characteristics of the ARES are very similar to those of the conventional LMFBR. Based on these results, it is concluded that no problem during plant operation will be caused by eliminating the intermediate system. It is only necessary to consider the short transition period in order to design the control system.(3) Based on the results of the calculation of a total blackout accident, it is concluded that the use of the SG-side cooling together is profitable in order to satisfy the design safety criteria.Based on these results, the ARES in expected to satisfy the design safety criteria in design basis events. In the case of full natural-circulation cooling, the use of the SG-side cooling together is profitable in order to satisfy the design safety criteria.

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