報告書番号

T01039

タイトル（和文）

鉛ビスマス冷却高速炉における気泡ポンプ性能 -気泡分布、循環流量に関する実験的研究-

タイトル（英文）

Lift-pump performance with a lead-bismuth cooled fast reactor; Experimental study on bubble distribution and circulation flow rate

概要 （図表や脚注は「報告書全文」に掲載しております）

鉛ビスマス冷却小型炉において気泡ポンプの利用が検討されている。そこで、３種類の直径をもつ上昇管で鉛ビスマス中気泡ポンプ実験を行った。主な結論は以下。１．中・小口径の上昇管においては、従来の性能評価法で求まる以上の鉛ビスマス循環流量が得られ、鉛ビスマス中においても中・小口径の上昇管では、気泡ポンプは機能する。ただし従来の性能評価法での結果と実験結果は異なり、鉛ビスマス中気泡ポンプの精度のよい評価式の構築が必要。２．本実験のガス流量範囲において大口径の上昇管では従来の性能評価法は過大評価となる。これは、口径の大きな上昇管の場合、気泡が上昇管の水平方向にも運動しているが、従来の性能評価法は１次元的なポンプ効果を仮定しているためである。 以上のことから、鉛ビスマス冷却炉に気泡ポンプを適用するためには、精度のよい評価式の構築、大口径上昇管で効率的な循環力を得る構造上の工夫が必要である。

概要 （英文）

The realization of the nuclear fuel cycle is important from the viewpoint of saving resources and global warming prevention. Therefore to approve this cycle, the FBR (Fast Breeder Reactor) plant system which plays a role of the main part of the cycle must have a high economical advantage. If lead-bismuth eutectic is used for coolant of FBR in place of sodium, the intermediate heat transport system required for the sodium-cooled reactor must be eliminated, and rationalization of the plant system design can be expected. In a lead-bismuth cooled reactor, a small reactor which adopts natural circulation cooling to eliminate the mechanical pump is promising. However, the large difference in the vertical position between the core and the steam generator is necessary to obtain circulation head; as a result, the reactor vessel must be tall. To reduce the height of the reactor vessel, it is said that utilizing a gas driven "lift pump" to aid natural circulation and provide sufficient buoyant force for coolant is effective.There is a design method for a "gas lift pump" derived from experimental results in a water / inert gas systems with a riser of comparatively small diameter. However, there is little information about the "gas lift pump" in a lead-bismuth in riser of large diameter. Experiments about void distribution and performance of the gas lift pump in three kinds of risers (inner diameter : 69mm, 106mm, 155mm) were performed by using a lead-bismuth test section. The main results are as follows:(1) The amount of the lead-bismuth circulation more than expecting by the design method derived from water/inert gas systems was obtained in risers of the diameter 69mm and 106mm. However, there is a difference in the result of the examination and the design method. It is necessary to establish the highly accurate evaluation method of lift pump in a lead-bismuth. (2) In the riser with a diameter of 155mm, this design method excessively evaluates the amount of lead-bismuth circulation. The circulation head is not obtained in the experiments such as results of this design method. The reason for this is that the rising void actually moves horizontally in the case of a large riser though this design method assumed the effect of the pump is one dimensional. From the above-mentioned, to apply the lift pump to the lead-bismuth cooled reactor, it is necessary to devise the structure to gain efficient circulation powers in a large diameter riser in addition to constructing the design method with good accuracy.

報告者

キーワード