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加藤 慎也; 松場 賢一; 神山 健司; Mukhamedov, N.*; Akayev, A.*; Pakhnits, A.*; Vurim, A.*; Baklanov, V.*
no journal, ,
To achieve the In-Vessel Retention (IVR) in case of Core Disruptive Accidents (CDAs) is of prime importance in enhancing safety of sodium-cooled fast reactors (SFRs). In order to ensure IVR, we are investigating the feasibility of the controlled material relocation (CMR) which enables to decrease the reactivity of degraded core and encourage cooling of relocated material. EAGLE-1 and -2, which have already conducted as the collaboration studies of Japan Atomic Energy Agency (JAEA) and the National Nuclear Center of the Republic of Kazakhstan (NNR-RK), focused on the molten-fuel discharge on the early phase of CDAs and demonstrated the molten-material discharge through the intra-subassembly sodium-filled duct without an inner structure1). In EAGLE-3, the discharge of molten-core material, which gradually expands in the core region by decay heat during the later phase of CDAs, toward the lower sodium plenum through the control rod guide tubes (CRGTs) has been focused. CRGTs have internal structures, such as a sodium-flow regulator, which could affect fuel discharge. Thus, in order to clarify the effect of the internal structures in the CRGT on the discharge behavior of the molten-core material, a series of experiments has been conducted. The knowledge obtained through the EAGLE-3 experiments are presented here.
Sr/Y under gamma-ray field using the liquid light guide Cerenkov counter寺阪 祐太
no journal, ,
In this presentation, we will introduce a method for selectively detecting the Sr/Y distribution in a gamma-ray environment using a liquid light guide, which is an optical fiber with a liquid core material. This method applies the aforementioned time-of-flight analysis to the liquid light guide to determine the location of radioactive materials. Here, the Cerenkov radiation from Sr/Y is selectively detected by using the reflection at the light guide's end face, caused by the radiation energy dependence of the Cerenkov radiation angle. The Cerenkov radiation from Sr/Y is characterized by a larger emission angle and a smaller emission angle for the Cerenkov radiation from gamma-ray emitting nuclides. Therefore, the latter has a greater proportion of reflected components at the light guide's end face compared to the former. Utilizing this feature, the in-situ radioactivity distribution of Sr/Y can be detected.
深堀 智生
no journal, ,
日本原子力研究開発機構(JAEA)は、「災害対策基本法」の指定公的機関として、東京電力福島第一原子力発電所(1F)の放射線測定、専門家の派遣など様々な形で対応するとともに、事故の対処に係る研究開発を行ってきた。本講演では、廃止措置の現状、事故直後の初動から組織及び拠点を整備、研究開発活動の概要を紹介し、JAEAの研究成果の最近のトピックスを報告する。
今泉 悠也; 青柳 光裕; 神山 健司; 松場 賢一; Akaev, A.*; Mikisha, A.*; Baklanov, V.*; Vurim, A.*
no journal, ,
The cooling of the residual degraded core materials, which is called "in-place cooling", is one of the important factors for the in-vessel retention (IVR). For the evaluation of the in-place cooling, behavior in a SFR core which is cooled down by the sodium inflow through CRGT was simulated by a safety analysis code, SIMMER-III. As a result of the analysis, the core materials which were initially 2500 
C were cooled down in several minutes. In order to analyze the in-place cooling, the method of phenomena identification and ranking table (PIRT) was applied, and several factors of thermal-hydraulic dynamics were extracted. Out-of-pile experiments which focus on the extracted factors were conducted, and continuous oscillations of sodium level were observed in the experiments. Analyses by SIMMER-III for the experiments were conducted, but the sodium level oscillation was not fully simulated in the analysis of IPCO-1. By investigation of the analysis result, it was revealed that the difference was due to partial occupation of non-condensable gas. In order to pre-vent the unrealistic occupation, the analysis model of inter-cell gas mixing was newly developed, and the agreement between experiment and analysis was significantly improved by that.
神山 健司; 松場 賢一; 加藤 慎也; 今泉 悠也; Mukhamedov, N.*; Akayev, A.*; Pakhnits, A.*; Vurim, A.*; Baklanov, V.*
no journal, ,
日本原子力研究開発機構は、カザフスタン共和国国立原子力センター(NNC-RK)とナトリウム冷却高速炉の炉心安全に関する研究協力を25年に渡って行ってきた。この研究協力はEAGLE計画と呼ばれ、NNC-RKの研究施設を用いた先進的かつ挑戦的な研究計画である。EAGLE計画の背景と概要、並びに実施状況と主要成果を紹介する。