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Structural and compositional characteristics of Fukushima release particulate material from Units 1 and 3 elucidates release mechanisms, accident chronology and future decommissioning strategy

Martin, P. G.*; Jones, C. P.*; Bartlett, S.*; Ignatyev, K.*; Megson-Smith, D.*; 佐藤 志彦; Cipiccia, S.*; Batey, D. J.*; Rau, C.*; 末木 啓介*; et al.

Scientific Reports (Internet), 10, p.22056_1 - 22056_17, 2020/12

 被引用回数:0 パーセンタイル:0.01(Multidisciplinary Sciences)

The structural form and elemental distribution of material originating from different Fukushima Daiichi Nuclear Power Plant reactors (Units 1 and 3) is hereby examined to elucidate their contrasting release dynamics and the current in-reactor conditions to influence future decommissioning challenges. Complimentary computed X-ray absorption tomography and X-ray fluorescence data show that the two suites of Si-based material sourced from the different reactor Units have contrasting internal structure and compositional distribution. The known event and condition chronology correlate with the observed internal and external structures of the particulates examined, which suggest that Unit 1 ejecta material sustained a greater degree of melting than that likely derived from reactor Unit 3. In particular, we attribute the near-spherical shape of Unit 1 ejecta and their internal voids to there being sufficient time for surface tension to round these objects before the hot (and so relatively low viscosity) silicate melt cooled to form glass. In contrast, a more complex internal form associated with the sub-mm particulates invoked to originate from Unit 3 suggest a lower peak temperature, over a longer duration. Using volcanic analogues, we consider the structural form of this material and how it relates to its environmental particulate stability and the bulk removal of residual materials from the damaged reactors. We conclude that the brittle and angular Unit 3 particulate are more susceptible to further fragmentation and particulate generation hazard than the round, higher-strength, more homogenous Unit 1 material.


Simulation-based Level 2 multi-unit PRA using RAVEN and a simplified thermal-hydraulic code

Zheng, X.; Mandelli, D.*; Alfonsi, A.*; Smith, C.*; 杉山 智之

Proceedings of 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference (ESREL 2020 and PSAM-15) (Internet), p.2176 - 2183, 2020/11

The paper introduces a simulation-based Level 2 probabilistic risk assessment (PRA) of a multi-unit nuclear power plant. We propose the methodology by quantifying risk for a station-blackout accident scenario, initialized by a loss-of-offsite-power event. Contrary to classical PRA that applies static models such as event-tree/fault-tree, the analysis is seamlessly integrated with mechanistic simulation and PRA models, including: (1) a simplified thermal-hydraulic code for simulating system behaviors; (2) a Markovian model for the failure mechanism of decay-heat-removal systems, to investigate the interaction between mechanistic simulation and reliability analysis; and (3) classical containment event trees for evaluating containment performances and hydrogen-explosion risk under severe accident conditions. All dynamic and static models, including plant dependencies, are unified within the RAVEN computational framework, applying RAVEN components, External Model, Ensemble Model, and PRA Plugins. The study demonstrates an integrated assessment of risks by considering accident progression and inter-unit system interactions, both time dependent. Statistical data analysis is used to quantifying risk metrics, including core damage frequencies, large early release frequencies and plant damage status. The methodology pertains to modern risk-analysis methodologies such as risk-informed safety margin characterization (RISMC) and dynamic PRA.


International network of nuclear structure and decay data evaluators

Dimitriou, P.*; Basunia, S*; Bernstein, L.*; Chen, J.*; Elekes, Z.*; Huang, X.*; Hurst, A.*; 飯村 秀紀; Jain, A. K.*; Kelley, J.*; et al.

EPJ Web of Conferences, 239, p.15004_1 - 15004_4, 2020/09

 被引用回数:0 パーセンタイル:0.19

評価済み核構造データファイル(Evaluated Nuclear Structure Data File: ENSDF)は、原子核構造と崩壊に関する様々な実験データを全ての核種について集めて、それらの実験データの評価値を与えてある世界唯一のデータファイルである。ENSDFは定期的に更新されており、そのための評価作業は各国の評価者で分担している。評価作業を速やかに行うために、IAEAの援助の下に評価者の国際的なネットワークが組織されている。この発表では、ネットワークの最近の活動のうち、ENSDFの処理コードの開発、測定が必要とされているデータのリストの作成、インターネット版核図表の利用の拡充などについて報告する。また、核構造・崩壊データの需要が増大しているにもかかわらず、評価者が減っている問題についても述べる。


$$alpha$$-decay branching ratio of $$^{180}$$Pt

Cubiss, J. G.*; Harding, R. D.*; Andreyev, A. N.; Althubiti, N.*; Andel, B.*; Antalic, S.*; Barzakh, A. E.*; Cocolios, T. E.*; Day Goodacre, T.*; Farooq-Smith, G. J.*; et al.

Physical Review C, 101(1), p.014314_1 - 014314_4, 2020/01

 被引用回数:5 パーセンタイル:84.86(Physics, Nuclear)



Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes; Coulomb excitation of $$^{182}$$Hg, $$^{184}$$Hg, $$^{186}$$Hg and $$^{188}$$Hg

Wrzosek-Lipska, K.*; Rezynkina, K.*; Bree, N.*; Zieli$'n$ska, M.*; Gaffney, L. P.*; Petts, A.*; Andreyev, A. N.; Bastin, B.*; Bender, M.*; Blazhev, A.*; et al.

European Physical Journal A, 55(8), p.130_1 - 130_23, 2019/08

 被引用回数:7 パーセンタイル:80.58(Physics, Nuclear)

The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass $$^{182-188}$$Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of 0$$^{+}_{1,2}$$, 2$$^{+}_{1,2}$$, and 4$$^{+}_{1}$$ states was observed in all nuclei under study. Reduced $$E2$$ matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions.


Neutron-hole states in $$^{131}$$Sn and spin-orbit splitting in neutron-rich nuclei

Orlandi, R.; Pain, S. D.*; Ahn, S.*; Jungclaus, A.*; Schmitt, K. T.*; Bardayan, D. W.*; Catford, W. N.*; Chapman, R.*; Chipps, K. A.*; Cizewski, J. A.*; et al.

Physics Letters B, 785, p.615 - 620, 2018/10

 被引用回数:5 パーセンタイル:56.63(Astronomy & Astrophysics)

Low-lying neutron-hole states in $$^{131}$$Sn were populated via the $$^{132}$$Sn(d,t) reaction at Oak Ridge National Laboratory. The triton angular distributions were compared to DWBA calculations and revealed spectroscopic factors compatible with a single-hole nature of the states populated. The data permit to determine the spin-orbit splitting of the strongly bound $$d_{3/2}$$ and $$d_{5/2}$$ neutron orbits below the shell gap, which was compared to the splitting of the weakly bound 3$$p$$ and 2$$f$$ orbits above the gap. The comparison revealed a smaller energy splitting of the 3$$p$$ orbits. All splittings were reproduced using Woods-Saxon calculations, and the lower splitting of the 3$$p$$ orbits was explained to arise from the large radial extent of the wavefunction and small value of the amplitude at the surface. This result is important to understand at a fundamental level the spin-orbit interaction, and its effects on neutron-rich nuclei.


EXILL; A High-efficiency, high-resolution setup for $$gamma$$-spectroscopy at an intense cold neutron beam facility

Jentschel, M.*; Blanc, A.*; de France, G.*; K$"o$ster, U.*; Leoni, S.*; Mutti, P.*; Simpson, G.*; Soldner, T.*; Ur, C.*; Urban, W.*; et al.

Journal of Instrumentation (Internet), 12(11), p.P11003_1 - P11003_33, 2017/11

 被引用回数:27 パーセンタイル:86.8(Instruments & Instrumentation)

A highly efficient array of high-purity germanium (HPGe) detectors was developed and operated at the cold neutron beam facility PF1B of the Institut Laue-Langevin (ILL) to carry out nuclear structure studies, via measurements of $$gamma$$-rays following neutron-induced capture and fission reactions. The setup consisted of a collimation system producing a pencil beam with a thermal capture equivalent flux of about 10$$^8$$ns$$^{-1}$$cm$$^{-2}$$ at the target position and negligible neutron halo. The target was surrounded by an array of eight to ten anti-Compton shielded EXOGAM Clover detectors, four to six anti-Compton shielded large coaxial GASP detectors and two standard Clover detectors. For a part of the campaign the array was combined with 16 LaBr$$_{3}$$:(Ce) detectors from the FATIMA collaboration.


$$B(E2;2^+_1rightarrow 0^+_1)$$ value in $$^{90}$$Kr

R$'e$gis, J.-M.*; Jolie, J.*; Saed-Samii, N.*; Warr, N.*; Pfeiffer, M.*; Blanc, A.*; Jentschel, M.*; K$"o$ster, U.*; Mutti, P.*; Soldner, T.*; et al.

Physical Review C, 90(6), p.067301_1 - 067301_4, 2014/12

 被引用回数:21 パーセンタイル:82.71(Physics, Nuclear)

A smooth onset of collectivity in $$^{88,92,94,96}$$Kr has been determined from reported $$B(E2;2^+_1rightarrow 0^+_1)$$ and E(2$$^+_1$$) values. This is in contrast to the sudden onset in even-even Zr, Mo, and Sr isotopes. Our objective was to complete the systematics by determining the $$B(E2;2^+_1rightarrow 0^+_1)$$ value in $$^{90}$$Kr, which was produced by cold-neutron-induced fission of $$^{235}$$U. The lifetime of the 2$$^+_1$$ state in $$^{90}$$Kr was measured via the electronic $$gamma - gamma$$ timing technique using the EXILL and FATIMA spectrometers. Based on the measured mean lifetime of $$tau$$ = 15(10) ps, the $$B(E2;2^+_1rightarrow 0^+_1)$$ value of 13$$^{+26}_{-5}$$ W.u. in $$^{90}$$Kr is determined for the first time and the smooth onset of deformation in the even-even Kr isotopes beyond neutron number N=50 is confirmed.


ENDF/B-VII.1 nuclear data for science and technology; Cross sections, covariances, fission product yields and decay data

Chadwick, M. B.*; Herman, M.*; Oblo$v{z}$insk$'y$, P.*; Dunn, M. E.*; Danon, Y.*; Kahler, A. C.*; Smith, D. L.*; Pritychenko, B.*; Arbanas, G.*; Arcilla, R.*; et al.

Nuclear Data Sheets, 112(12), p.2887 - 2996, 2011/12

 被引用回数:1623 パーセンタイル:100(Physics, Nuclear)



Cross-shell excitations near the "island of inversion"; Structure of $$^{30}$$Mg

Daecon, A. N.*; Smith, J. F.*; Freeman, S. J.*; Janssens, R. V. F.*; Carpenter, M. P.*; Hadinia, B.*; Hoffman, C. R.*; Kay, B. P.*; Lauritsen, T.*; Lister, C. J.*; et al.

Physical Review C, 82(3), p.034305_1 - 034305_7, 2010/09

 被引用回数:19 パーセンタイル:75.27(Physics, Nuclear)



$$^{235}$$U nuclear relaxation rates in an itinerant antiferromagnet USb$$_2$$

Baek, S.-H.*; Curro, N. J.*; 酒井 宏典; Bauer, E. D.*; Cooley, J. C.*; Smith, J. L.*

Physical Review B, 81(5), p.054435_1 - 054435_5, 2010/02

 被引用回数:5 パーセンタイル:28.15(Materials Science, Multidisciplinary)

$$^{235}$$U nuclear spin-lattice ($$T_1^{-1}$$) and spin-spin ($$T_2^{-1}$$) relaxation rates in the itinerant antiferromagnet USb$$_2$$ are reported as a function of temperature in zero field. The heating effect from the intense rf pulses that are necessary for the $$^{235}$$U NMR results in unusual complex thermal recovery of the nuclear magnetization which does not allow measuring $$T_1^{-1}$$ directly. By implementing an indirect method, however, we successfully extracted $$T_1^{-1}$$ of the $$^{235}$$U. We find that the temperature dependence of $$T_1^{-1}$$ for both $$^{235}$$U and $$^{121}$$Sb follows the power law ($$propto T^{n}$$) with the small exponent $$n$$ = 0.3 suggesting that the same relaxation mechanism dominates the on-site and the ligand nuclei, but an anomaly at 5 K was observed, possibly due to the change in the transferred hyperfine coupling on the Sb site.


Computational infrastructure for nuclear astrophysics

Smith, M. S.*; Lingerfelt, E. J.*; Scott, J. P.*; Nesaraja, C. D.*; Hix, W. R.*; Chae, K.*; 小浦 寛之; Meyer, R. A.*; Bardayan, D. W.*; Blackmon, J. C.*; et al.

AIP Conference Proceedings 847, p.470 - 472, 2006/07

インターネット上で利用可能な天体核物理に関するコンピュータシステムのサイトを再構築した。これは、天体物理のシミュレーションを最新の原子核物理の結果を用いて行うように作成されたシステムで、URL: nucastrodata.orgから無料で利用可能である。Java言語を用いて作成されたシステムであり、Windows, Macintosh, Unixといったプラットホームに依存せず、数回のマウス操作で中性子捕獲反応率、原子核質量等といった核データの可視化や、p過程やr過程といった元素合成計算の結果をアニメーション動画として表示することを平易に行うことが可能である。今回の再構築で特に原子核質量の可視化及びr過程元素合成の動画化のシステムを新たに開発した。


Multipass beam breakup in energy recovery linacs

Pozdeyev, E.*; Tennant, C.*; Bisognano, J. J.*; 沢村 勝; 羽島 良一; Smith, T. I.*

Nuclear Instruments and Methods in Physics Research A, 557(1), p.176 - 188, 2006/02

 被引用回数:12 パーセンタイル:65.95(Instruments & Instrumentation)



New features in the computational infrastructure for nuclear astrophysics

Smith, M. S.*; Lingerfelt, E. J.*; Scott, J. P.*; Nesaraja, C. D.*; Chae, K.*; 小浦 寛之; Roberts, L. F.*; Hix, W. R.*; Bardayan, D. W.*; Blackmon, J. C.*

Proceedings of Science (Internet), 5 Pages, 2006/00



The ITER-QUELL, a quench propagation experiment on a long length CICC with central channel

Anghel, A.*; 高橋 良和; Smith, S.*; Pourrahimi, S.*; Zhelamskij, M.*; Blau, B.*; Fuchs, A.*; Heer, B.*; 濱田 一弥; Fujisaki, H.*; et al.

Fusion Technology 1996, p.185 - 190, 1996/00



Nuclear masses; Theoretical models, experimental evaluations, & web disseminations

Smith, M. S.*; Kondev, F.*; 小浦 寛之; Lingerfelt, E. J.*; Buckner, K.*; Nesaraja, C. D.*

no journal, , 



Visualization, analyis, and management of nuclear mass information at nucearmasses.org

Smith, M. S.*; Lingerfelt, E. J.*; Buckner, K.*; Nesaraja, C. D.*; 小浦 寛之; Kondev, F.*

no journal, , 

原子核質量データを効率的に利用するためのインターネットツール"nuclearmasses.org"を開発した。このWebツールはPC, Macといったプラットホームに依存しないクライアント/サーバアプリケーションで、原子核質量の多量の測定値,原子核質量の理論モデル、及び原子核の評価済み質量データを自由に利用することが可能である。このツールの用途としては以下のものが挙げられる。(1)基礎・応用科学における原子核質量の広範囲の利用、(2)大規模測定能力、施設、及び新しい結果における物凄い成長、及び、(3)原子核の質量情報を広める既存のシステムの不適当のために。本システムを用いることで、研究者自身による大規模データセットのアップロード、格納、共有、カスタマイズし、これらを平易に可視化することが可能である。


Masses of unstable nuclei; Visualization and analysis at nuclearmassess.org

Smith, M. S.*; Lingerfelt, E. J.*; Buckner, K.*; Nesaraja, C. D.*; 小浦 寛之; Kondev, F.*

no journal, , 



Nuclear masses; Sharing, visualization, and analysis at nuclearmasses.org

Smith, M. S.*; Lingerfelt, E. J.*; Nesaraja, C. D.*; 小浦 寛之; Kondev, F. G.*

no journal, , 



Nuclear mass visualization and analysis at nuclearmasses.org

Smith, M. S.*; Lingerfelt, E. J.*; Nesaraja, C. D.*; 小浦 寛之; Kondev, F. G.*

no journal, , 

超新星爆発におけるr過程元素合成に代表されるような、さまざまな天体物理学の環境や事象をシミュレー ションする際に、原子核の質量の情報は極めて不可欠な要素である。近年の質量実験の進歩により、新たな原子核質量の測定数及び精度は年々向上しているが、こういった情報の研究者間の共有・普及といった面ではまだ不十分であるといえる状況である。われわれは研究者が原子核の質量データセットを共有,管理,可視化,アクセス操作,比較,分析といったさまざまな作業を行うのをすばやく効率的に可能にするオンラインサイトを構築した。このシステムはプラットホームから独立したクライアントサーバアプリケーションであり、最新の質量測定,理論的質量モデル、及び原子核の質量の評価済み値の大部な数値表などを自由に利用可能である。このシステムを用いることで、大量のデータセットのアップロード,格納,他の研究者との共有が可能となり、比較的短時間で次元及び次元表示の計算及び可視化が容易である。また、このウェブサイトは、原子核の質量に関する理論モデル,測定値、及びレビュー記事を参照として関連付けることも可能である。

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