平成7年度 実用リサイクル炉概念検討報告書; 炉心設計検討

JFY 1995 Progress report of conceptual design study on the recycle reactor; Study of core design

永沼 正行  ; 笠井 重夫; 林 秀行; 向坊 隆一

Naganuma, Masayuki; Kasai, Shigeo; Hayashi, Hideyuki; Mukaibou, Ryuichi

最終目標としてのFBRには,経済性,安全性向上はもとより超長半減期核種の低減による環境負荷低減,Pu需給に柔軟に対応し余剰Puの発生を抑制することによる核拡散抵抗性の強化などが求められる。このため,1)自ら発生する固体廃棄物を削減するダクトレス炉心,2)炉心の組替えで各種富化度のPuを燃焼する炉心,3)受動的安全性炉心,窒化物燃料炉心について検討した。主な結果は以下の通りである。1)MOXダクトレス燃料炉心は,増殖比,燃焼反応度の向上が図れるが,安全性に係わる反応度係数は厳しくなる。ATWSに関してはロッドストップの設置が必要,2)Pu燃焼炉心では,増殖比1.2,燃焼度15万MWd/tが達成可能,3)窒化物炉心は,MOX燃料炉心に比べ炉心特性に優れ,ATWSにおいても有利,であることを確認した。

As the goal requested to FBR in the future practical time, there is the improvement of economy and safety, moreover, the decrease of risk to environment by burning the long-lived nuclides and the rise of nuclear non proliferation by preventing accumulation of Pu by dealing flexibly with supply and demand of Pu will be requested. To attain these goals, it is requested that the core has the capability to receive flexibly Actinide (Minor Actinide and Pu). In other words, the concept of the core (Recycle Core) that corresponds to recycle technology (Advanced Recycle Technology), receives various fuels (including MA, low decontaminated, high Pu enriched and so on) and can permit change of nuclear property and safety characteristic by receiving such fuels is demanded. In 1995' work, to examine the concept ofthis new core, authors conducted design studies about the following contents, and evaluated characteristics of these cores. (1)Design study about MOX ductless fueled core. In adopting the ductless fuel concept, the nuclear property is improved by the increase of volume ratio of fuel, and amount of the solid waste is decreased by the deletion of wrapper tube. Thus, the economic feature is improved and the risk to environment is decreased. In such reason, we designed MOX ductless fueled core (power : 600MWe, the cycle length : 18 months, Average burnup : 150000MWd/t) as the reference core of Recycle Reactor, and estimated some performances of this core. (1)In the ductless fueled core, the volume ratio of fuel became 13% larger than the duct fueled core, and that effect made breeding ratio increase 0.08 and burnup reactivity improve about 40%. (2)By adding 3% of MA (with 20% RE of MA), Pu enrichment and breeding ratio hardly change and burnup reactivity was improved about 30%. But Doppler coefficient and Na void reactivity became about 20% worse, and this reactor got severer in respect of safety. (3)ATWS analysis was conducted to the reference core, and ...