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Herranz, L. E.*; Pellegrini, M.*; Lind, T.*; Sonnenkalb, M.*; Godin-Jacqmin, L.*; L
pez, C.*; Dolganov, K.*; Cousin, F.*; 玉置 等史; Kim, T. W.*; et al.
Nuclear Engineering and Design, 369, p.110849_1 - 110849_7, 2020/12
被引用回数：20 パーセンタイル：93.95(Nuclear Science & Technology)OECD/NEAプロジェクト"福島第一原子力発電所事故に関するベンチマーク研究"のフェーズ2は2015年中期に開始された。このプロジェクトの目的は、解析期間を地震発生から3週間に拡張、核分裂生成物(FP)の挙動や環境への放出、そして放射線に関するデータや逆解析によるソースターム推定等の様々なデータとの比較を行うことである。6か国9組織が異なるシビアアクシデント解析コードを用いて1号機の事故解析を行った。本報告では、参加機関の1号機の解析結果やプラントデータとの比較から得られた知見、事故進展の評価及び最終的な原子炉内の状態について述べる。特に原子炉圧力容器の状態、溶融炉心の放出及びFP挙動及び放出について焦点を当てる。また、1号機特有の事柄に焦点を当て、不確かさや必要となるデータも含めコンセンサスを得た点についてまとめる。
Sonnenkalb, M.*; Pellegrini, M.*; Herranz, L. E.*; Lind, T.*; Morreale, A. C.*; 神田 憲一*; 玉置 等史; Kim, S. I.*; Cousin, F.*; Fernandez Moguel, L.*; et al.
Nuclear Engineering and Design, 369, p.110840_1 - 110840_10, 2020/12
被引用回数：22 パーセンタイル：94.98(Nuclear Science & Technology)OECD/NEAプロジェクト"福島第一原子力発電所事故に関するベンチマーク研究"のフェーズ2において、6か国9組織が異なるシビアアクシデント解析コードを用いて2号機の事故解析を行った。本報告では、参加機関の2号機の解析結果やプラントデータとの比較から得られた知見、事故進展の評価及び最終的な原子炉内の状態について述べる。特に原子炉圧力容器の状態、溶融炉心の放出及びFP挙動及び放出について焦点を当てる。また、2号機特有の事柄に焦点を当て、不確かさや必要となるデータも含めコンセンサスを得た点についてまとめる。
Pellegrini, M.*; Herranz, L.*; Sonnenkalb, M.*; Lind, T.*; 丸山 結; Gauntt, R.*; Bixler, N.*; Morreale, A.*; Dolganov, K.*; Sevon, T.*; et al.
Nuclear Technology, 206(9), p.1449 - 1463, 2020/09
被引用回数：35 パーセンタイル：98.38(Nuclear Science & Technology)The OECD/NEA Benchmark Study at the Accident of Fukushima Daiichi Nuclear Power Station (BSAF) project, which started in 2012 and continued until 2018, was one of the earliest responses to the accident at Fukushima Daiichi. The project, divided into two phases addressed the investigation of the accident at Unit 1, 2 and 3 by Severe Accident (SA) codes until 500 h focusing on thermal-hydraulics, core relocation, Molten Corium Concrete Interaction (MCCI) and fission products release and transport. The objectives of BSAF were to make up plausible scenarios based primarily on SA forensic analysis, support the decommissioning and inform SA codes modeling. The analysis and comparison among the institutes have brought up vital insights regarding the accident progression identifying periods of core meltdown and relocation, Reactor Pressure Vessel (RPV) and Primary Containment Vessel (PCV) leakage/failure through the comparison of pressure, water level and CAMS signatures. The combination of code results and inspections (muon radiography, PCV inspection) has provided a picture of the current status of the debris distribution and plant status. All units present a large relocation of core materials and all of them present ex-vessel debris with Unit 1 and Unit 3 showing evidences of undergoing MCCI. Uncertainties have been identified in particular on the time and magnitude of events such as corium relocation in RPV and into cavity floor, RPV and PCV rupture events. Main uncertainties resulting from the project are the large and continuous MCCI progression predicted by basically all the SA codes and the leak pathways from RPV to PCV and PCV to reactor building and environment. The BSAF project represents a pioneering exercise which has set the basis and provided lessons learned not only for code improvement but also for the development of new related projects to investigate in detail further aspects of the Fukushima Daiichi accident.
玉置 等史; 石川 淳; 杉山 智之; 丸山 結
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.72 - 82, 2019/08
原子力機構では、BSAF2計画に参加し、THALES2/KICHEコードを用いた福島第一原子力発電所の事故解析結果を提供した。THALES2/KICHEコードの重要な特徴の一つとして、液相における速度論に基づくヨウ素化学をモデル化している。本報告では、BSAF2計画における共通の境界条件や仮定に加え、格納容器の破損として、ベント弁が完全に閉まらなかったために引き起こされるベントラインからの継続的な漏洩をモデル化した1号機の3週間にわたる解析結果について紹介する。本仮定に基づく解析では、原子炉冷却系や格納容器の圧力履歴を再現できており、解析期間の3週間で環境に放出されたヨウ素及びセシウムの初期インベントリに対する割合は、各々約6%及び約1%であった。
玉置 等史; 石川 淳; 杉山 智之; 丸山 結
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.100 - 111, 2019/08
JAEAでは、BSAF2計画に参加し、THALES2/KICHEコードを用いた福島第一原子力発電所の事故解析結果を提供した。THALES2/KICHEコードの重要な特徴の一つとして、液相における速度論に基づくヨウ素化学をモデル化している。本報告では、BSAF2計画における共通の境界条件や仮定に基づいた3週間にわたる2号機の解析結果、特にBSAF2計画では、2号機の事故進展に関し、3月14日の20時から15日2時の間に観測された3つの圧力容器内圧力ピークの生じた理由に着目しており、この時期の事故進展挙動を含め紹介する。また、本解析では、圧力抑制室の下部に破損を仮定し、水の漏洩を含め、格納容器圧力挙動を再現した。解析期間の3週間で環境に放出されたヨウ素及びセシウムの初期インベントリに対する割合は、各々約3%及び約0.1%であった。
石川 淳; 玉置 等史; 杉山 智之; 丸山 結
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.536 - 547, 2019/08
Japan Atomic Energy Agency is pursuing the development and application of the integrated severe accident analysis code, THALES2/KICHE for analysis of severe accident progression and source term. The accident at the Fukushima Daiichi Nuclear Power Station (NPS) from units 1 to 3 were analyzed using THALES2/KICHE code for better understanding of the accident in the OECD/NEA BSAF2 project. This paper describes three week analysis for the accident at unit 3. The leakage through the drywell head flange and an equipment hutch was assumed in order to reproduce the tendency of drywell pressure history in addition to the intermittent activation of the containment vessel venting system via the suppression chamber. As for the source term analysis, the dominant chemical forms for cesium and iodine were assumed to be cesium iodine (CsI) and cesium molibdate (Cs
MoO
) based on the insights of the PHEBUS/FP experiments. The iodine chemical reaction kinetics in the containment aqueous phase, which were associated with the production of molecular iodine and organic iodide, were taken into consideration in the present analysis. The released iodine and cesium within three weeks after the earthquake were predicted to be approximately 3% and 6% of the initial inventory, respectively.
Pellegrini, M.*; Herranz, L.*; Sonnenkalb, M.*; Lind, T.*; 丸山 結; Gauntt, R.*; Bixler, N.*; Morreale, A.*; Dolganov, K.*; Sevon, T.*; et al.
Proceedings of 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-18) (USB Flash Drive), p.1147 - 1162, 2019/08
The OECD/NEA Benchmark Study at the Accident of the Fukushima Daiichi NPS project (BSAF) has started in 2012 until 2018 as one of the earliest responses to the accident at Fukushima Daiichi NPS. The project addressed the investigation of the accident at Units 1, 2 and 3 by severe accident (SA) codes focusing on thermal-hydraulics, core relocation, molten core/concrete interaction (MCCI) and fission products release and transport. The objectives of BSAF were to make up plausible scenarios based primarily on SA forensic analysis, support the decommissioning and inform SA codes modeling. The analysis and comparison among the institutes have brought up vital insights regarding the accident progression identifying periods of core meltdown and relocation, reactor vessel (RV) and primary containment vessel (PCV) leakage/failure through the comparison of pressure, water level and CAMS measurement. The combination of code results and inspections has provided a picture of the current state of the debris distribution and plant state. All units present a large relocation of core materials and all of them present ex-vessel debris with units 1 and 3 showing evidences of undergoing MCCI. Uncertainties have been identified in particular on the time and magnitude of events such as corium relocation in RV and into cavity floor, RV and PCV rupture events. Main uncertainties resulting from the project are the large and continuous MCCI progression predicted by basically all the SA codes and the leak pathways from RV to PCV and PCV to reactor building and environment. The BSAF project represents a pioneering exercise which has set the basis and provided lessons learned not only for code improvement but also for the development of new related projects to investigate in details further aspects of the Fukushima Daiichi NPS accident.
