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.*; Satou, Yukihiko; Cipiccia, S.*; Batey, D. J.*; Rau, C.*; Sueki, Keisuke*; et al.

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

https://doi.org/10.1038/s41598-020-79169-2

Provenance of uranium particulate contained within Fukushima Daiichi Nuclear Power Plant Unit 1 ejecta material

Martin, P. G.*; Louvel, M.*; Cipiccia, S.*; Jones, C. P.*; Batey, D. J.*; Hallam, K. R.*; Yang, I. A. X.*; Satou, Yukihiko; Rau, C.*; Mosselmans, J. F. W.*; et al.

Nature Communications (Internet), 10, p.2801_1 - 2801_7, 2019/06

https://doi.org/10.1038/s41467-019-10937-z

Synchrotron radiation (SR) analysis techniques alongside secondary ion mass spectrometry (SIMS) measurements have been made on sub-mm particulate material derived from reactor Unit 1 of the Fukushima Daiichi Nuclear Power Plant (FDNPP). Using these methods, it has been possible to investigate the distribution, state and isotopic composition of micron-scale U particulate contained within the larger Si-based ejecta material. Through combined SR micro-focused X-ray fluorescence (SR-micro-XRF) and absorption contrast SR micro-focused X-ray tomography (SR-micro-XRT), the U particulate was found to be located around the exterior circumference of the highly-porous particle. Synchrotron radiation micro-focused X-ray absorption near edge structure (SR-micro-XANES) analysis of a number of these entrapped particles revealed them to exist within the U(IV) oxidation state, as UO, and identical in structure to reactor fuel. Confirmation that this U was of nuclear origin (U-enriched) was provided through secondary ion mass spectrometry (SIMS) analysis with an isotopic enrichment ratio characteristic of a provenance from reactor Unit 1 at the FDNPP. These results provide clear evidence of the event scenario (that a degree of core fragmentation and release occurred from reactor Unit 1), with such spent fuel ejecta existing; (i) within the stable U(IV) oxidation state; and (ii) contained within a bulk Si-based particle. While this U is unlikely to represent an environmental or health hazard, such assertions would likely change, however, should break-up of the Si-containing bulk particle occur. However, more important to the long-term decommissioning of the reactors (and clean-up) on the FDNPP, is the knowledge that core integrity of reactor Unit 1 was compromised with nuclear material existing outside of the reactors primary containment.

Instrumentation for diagnostics and control of laser-accelerated proton (ion) beams

Bolton, P.; Borghesi, M.*; Brenner, C.*; Carroll, D. C.*; De Martinis, C.*; Fiorini, F.*; Flacco, A.*; Floquet, V.*; Fuchs, J.*; Gallegos, P.*; et al.

Physica Medica; European Journal of Medical Physics, 30(3), p.255 - 270, 2014/05

https://doi.org/10.1016/j.ejmp.2013.09.002

Fluid moments in the reduced model for plasmas with large flow velocity

Miyato, Naoaki; Scott, B. D.*

Plasma and Fusion Research (Internet), 6, p.1403147_1 - 1403147_11, 2011/12

https://doi.org/10.1585/pfr.6.1403147

Gyrokinetic studies of turbulence, equilibrium, and flows in the tokamak edge

Scott, B. D.*; Da Silva, F.*; Kendl, A.*; Miyato, Naoaki; Ribeiro, T.*

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

http://www-naweb.iaea.org/napc/physics/FEC/FEC2010/html/node342.htm#70341

We report on developments in the theory and computation of gyrokinetic turbulence in the tokamak edge. A new formulation of the gyrokinetic Lagrangian for the strong EB-flow regime is been found, with clear correspondence to previous forms and to reduced MHD. Conservation of energy, mo-mentum, entropy, and particles is demonstrated at both theoretical and computational level. Neoclassical phenomena and MHD equilibration are shown in our electromagnetic total-f phase-space computational model FEFI. Delta-f gyrokinetic edge turbulence is computed on the full flux surface with the local fluxtube model delta-FEFI and results on the edge/core transition are given. We also present ongoing gyrofluid studies of ELM crash scenarios, including the influence of the bootstrap current in an edge pedestal model on both the initial instability and the resulting turbulence.

Global nonlinear electromagnetic simulations of tokamak turbulence

Bottino, A.*; Scott, B. D.*; Brunner, S.*; McMillan, B. F.*; Tran, T. M.*; Vernay, T.*; Villard, L.*; Jolliet, S.; Hatzky, R.*; Peeters, A. G.*

IEEE Transactions on Plasma Science, 38(9), p.2129 - 2135, 2010/09

https://doi.org/10.1109/TPS.2010.2055583

Modification on the gyrokinetic quasi-neutrality condition due to large flow

Miyato, Naoaki; Scott, B. D.*

Proceedings of 37th European Physical Society Conference on Plasma Physics (EPS 2010) (CD-ROM), 4 Pages, 2010/06

http://ocs.ciemat.es/EPS2010PAP/pdf/P1.1070.pdf

Reduced kinetic models such as gyrokinetic models are constructed by phase space transformation from particle phase space to guiding-centre phase space. In the reduced quasi-neutrality condition or the Poisson equation for electrostatic potential, particle density should be represented in terms of guiding-centre things. It is called push-forward representation of particle density. Recently a reduced kinetic model with large flow was derived by modifying the standard guiding-centre transformation. The model can be regarded as a natural extension of the standard model to the large flow regime because the symplectic part in the guiding-centre phase space Lagrangian is the same as the standard one formally. The push-forward representation of particle density or the reduced quasi-neutrality condition in the transonic case is derived by the variational method. It is found that corrections due to the flow appear in the polarisation density.

Spectroscopy of Rf

Qian, J.*; Heinz, A.*; Khoo, T. L.*; Janssens, R. V. F.*; Peterson, D.*; Seweryniak, D.*; Ahmad, I.*; Asai, Masato; Back, B. B.*; Carpenter, M. P.*; et al.

Physical Review C, 79(6), p.064319_1 - 064319_13, 2009/06

https://doi.org/10.1103/PhysRevC.79.064319

-, -, and conversion electron spectroscopy experiments for Rf have been performed using Fragment Mass Analyzer at Argonne National Laboratory. A new isomer with a half-life of 160 s has been discovered in Rf, and it is interpreted as a three-quasiparticle high- isomer. Neutron configurations of one-quasiparticle states in No, the -decay daughter of Rf, have been assigned on the basis of -decay hindrance factors. Excitation energies of the 1/2[620] states in =151 isotones indicate that the deformed shell gap at =152 increases with the atomic number.

Gyroviscous force in plasmas with strong EB flow

Miyato, Naoaki; Scott, B. D.*; Yagi, Masatoshi

no journal, , 

Reduced fluid models are widely used for nonlinear simulations of magnetised fusion plasmas. Traditionally they are derived from more rigorous fluid model such as the Braginskii model by imposing assumptions like low frequency perturbations. In the traditional derivation, calculation of the gyroviscosity is needed and it is very complicated. Alternatively reduced fluid models can be derived from fluid moment equations of reduced kinetic models. We can bypass the calculation of the gyroviscosity in the alternative method. Recently we derived a reduced kinetic model for plasmas with large EB velocity. Based on the reduced kinetic model, reduced fluid equations are derived and the gyroviscous force is obtained by comparing the reduced equations and fluid equations without reduction.

Comparison of push-forward representations of particle flux in the standard electrostatic gyrokinetic model

Miyato, Naoaki; Yagi, Masatoshi; Scott, B. D.*

no journal, , 

Since the standard gyrokinetic model is constructed by the two-step phase space transformation, fluid moments can be represented in terms of a gyro-center distribution function and gyro-center coordinates in two ways. The representations of fluid moments are called push-forward representations. In the representation used in the standard gyrokinetic formulation, the gyro-center transformation part emerges as the pull-back transformation of the gyro-center distribution function and is separated from the guiding-center transformation part. In the alternative representation, the gyro-center part moves to the parts except the gyro-center distribution function and is combined with the guiding-center part. We compare the two representation by deriving explicit representations of particle flux.