2次系削除高速増殖炉概念の検討

Design study on FBR concept eliminating secondary cooling systems

飯田 正明*; 小杉 敏夫*; 神戸 満*; 永井 寛*; 田中 信夫*; 土屋 毎雄*; 奈良 義彦*

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従来からの懸案事項である2次系削除FBRプラント概念を明確にし,その成立のための条件とコスト低減の効果を把握することを目的に設計研究を実施した。本概念の主要な検討課題は「蒸気発生器内で発生するNa―水反応の炉心への影響」について明らかにすることであり,この問題に直接関係する炉心,蒸気発生器,格納容器,Na-水反応生成物処理装置等に焦点を絞り設計検討を実施した。その結果以下を把握することができた。(1)2次系削除プラント概念とその問題点、(2)Na-水反応生成物のうち特に水素ガスの炉心へ及ぼす影響,限界水リーク率、(3)その影響の抑制方式、(4)2次系削除プラントのためのNa-水反応セーフティマップの概念と水リーク検出系への要求事項、(5)財産保護の観点からの2重管SGの必要性、(6)2次系削除した時の物量及び建設費の削減効果。なお、本作業を通じて設計研究の実際を経験することかできたことを付記しておく。

A design study was conducted in order to establish the concept of the FBR plant eliminating the secondary sodium loop. Conditions for realization and effectivenesses for cost reduction were also studied for this plant. The main topic for understanding this plant concept was recognized as to clearify "the influence of sodium-water reaction to the reactor core", broken out in the steam generator. Discussions were mainly focussed on the reactor core, the steam generator, the containment vessel, sodium-water reaction product relief system and so on, which were supposed to be especially important for this plant concept. Following items were recognized. (1) Total image and concept of the FBR plant eliminating the secondary sodium loop. (2) Influence of the sodium-water reaction product, especially hydrogen gas, to reactor core and limit of the water-leak rate for core damage. (3) Countermeasures for reduction and elimination of these influences. (4) Concepts of the safety map for sodium-water reaction of this plant and requirements for water leak detection systems. (5) Necessity of the duplex tube type steam generator from the view point of property protection. (6) Reduction effect for the amount of materials and construction cost by adopting this concept of plant. A overall process for design study was experienced throuqh the activities of this work.