The OECD/NEA Working Group on the Analysis and Management of Accidents (WGAMA); Advances in codes and analyses to support safety demonstration of nuclear technology innovations

Nakamura, Hideo; Bentaib, A.*; Herranz, L. E.*; Ruyer, P.*; Mascari, F.*; Jacquemain, D.*; Adorni, M.*

Proceedings of International Conference on Topical Issues in Nuclear Installation Safety; Strengthening Safety of Evolutionary and Innovative Reactor Designs (TIC 2022) (Internet), 10 Pages, 2022/10

A Scaling approach for retention properties of crystalline rock; Case study of the in-situ long-term sorption and diffusion experiment (LTDE-SD) at the sp Hard Rock Laboratory in Sweden

Tachi, Yukio; Ito, Tsuyoshi*; Gylling, B.*

Water Resources Research, 57(11), p.e2020WR029335_1 - e2020WR029335_20, 2021/11

https://doi.org/10.1029/2020WR029335

This paper focuses on the scaling approach for sorption and diffusion parameters from laboratory to in-situ conditions using the dataset of LTDE-SD experiment performed at the sp HRL. The near-surface heterogeneities at both fracture surface and rock matrix could be evaluated by conceptual model with high porosity and diffusivity, and sorption capacity, and their gradual change at the near-surface zones. The modelling results for non-sorbing Cl-36 and weak-sorbing Na-22 could validate the model concept and the parameter estimation of porosity and diffusivity, by considering the disturbed zone of 5 mm thickness with gradual parameter changes. The De values of these cationic and anionic tracers showed typical cation excess and anion exclusion effects. The modelling results for high sorbing tracers (Cs-137, Ra-226, Ni-63 and Np-237) with different sorption mechanism could confirm the validity of the scaling approaches of Kd values as a function of particle size and their relation to the near-surface disturbances.

Cross-section-induced uncertainty evaluation of MA sample irradiation test calculations with consideration of dosimeter data

Sugino, Kazuteru; Numata, Kazuyuki*; Ishikawa, Makoto; Takeda, Toshikazu*

Annals of Nuclear Energy, 130, p.118 - 123, 2019/08

https://doi.org/10.1016/j.anucene.2019.02.035

In MA sample irradiation test data calculations, the neutron fluence during irradiation period is generally scaled by using dosimetry data in order to improve calculation accuracy. In such a case, appropriate correction is required to burnup sensitivity coefficients obtained by the conventional generalized perturbation theory because some cancellations occur in the burnup sensitivity coefficients. Therefore, a new formula for the burnup sensitivity coefficient has been derived with the consideration of the neutron fluence scaling effect (NFS). In addition, the cross-section-induced uncertainty is evaluated by using the obtained burnup sensitivity coefficients and the covariance data based on the JENDL-4.0.

Contributions of OECD ROSA & ROSA-2 Projects for thermal-hydraulic code validation

Nakamura, Hideo

Proceedings of Seminar on the Transfer of Competence, Knowledge and Experience gained through CSNI Activities in the Field of Thermal-Hydraulics (THICKET 2016) (CD-ROM), 29 Pages, 2016/06

no abstracts in English

Origin of the various beta dependences of ELMy H-mode confinement properties

Takizuka, Tomonori; Urano, Hajime; Takenaga, Hidenobu; Oyama, Naoyuki

Plasma Physics and Controlled Fusion, 48(6), p.799 - 806, 2006/06

https://doi.org/10.1088/0741-3335/48/6/007

Dependence of the ELMy H-mode confinement on the beta has been investigated for a long time, but a common conclusion has not yet been obtained.The IPB98(y,2) scaling shows a strong degradation with beta, while DIII-D and JET experiments exhibited the absence of the beta degradation. Recent JT-60U experiment demonstrated that the strong beta degradation really exists for the ELMy H-mode. In the present paper, we analyze the JT-60U ELMy H-mode confinement database and confirm the strong power degradation of the confinement time, which corresponds to the strong beta degradation consistent with the above result. We analyze also the ITPA H-mode confinement database in detail. How the beta dependence of the confinement time is changed by the externally given parameters, such as the shape parameters, are investigated.

Scaling of the energy confinement time with and collisionality approaching ITER conditions

Cordey, J. G.*; Thomsen, K.*; Chudnovskiy, A.*; Kardaun, O. J. W. F.*; Takizuka, Tomonori; Snipes, J. A.*; Greenwald, M.*; Sugiyama, L.*; Ryter, F.*; Kus, A.*; et al.

Nuclear Fusion, 45(9), p.1078 - 1084, 2005/09

https://doi.org/10.1088/0029-5515/45/9/007

The condition of the latest version of the ELMy H-mode database has been re-examined. It is shown that there is bias in the ordinary least squares regression for some of the variables. To address these shortcomings three different techniques are employed: (a)principal component regression, (b)an error in variables technique and (c)the selection of a better conditioned dataset with fewer variables. Scalings in terms of the dimensionless physics valiables, as well as the standard set of engineering variables, are derived. The new scalings give a very similar performance for existing scalings for ITER at the standard beta, but a much improvement performance at higher beta.

An Observation of a nascent fractal pattern in MD simulation for a fragmentation of an fcc lattice

Chikazumi, Shimpei*; Iwamoto, Akira

Chaos, Solitons and Fractals, 23(1), p.73 - 78, 2005/01

https://doi.org/10.1016/j.chaos.2004.03.002

To seek for a possible origin of fractal pattern in nature, we perform a molecular dynamics simulation for a fragmentation of an infinite fcc lattice. The fragmentation is induced by the initial condition of the model that the lattice particles have the Hubble-type radial expansion velocities. As time proceeds, the average density decreases and density fluctuation develops. By using the box counting method, it is found that the frequency-size plot of the density follows instantaneously a universal power-law for each Hubble constant up to the size of a cross-over. This cross-over size corresponds to the maximum size of fluctuation and is found to obey a dynamical scaling law as a function of time. This instantaneous generation of a nascent fractal is purely of dynamical origin and it shows us a new formation mechanism of a fractal patters different from the traditional criticality concept.

Calibration of epithermal neutron beam intensity for dosimetry at JRR-4

Yamamoto, Kazuyoshi; Kumada, Hiroaki; Kishi, Toshiaki; Torii, Yoshiya; Sakurai, Yoshinori*; Kobayashi, Toru*

Proceedings of 11th World Congress on Neutron Capture Therapy (ISNCT-11) (CD-ROM), 15 Pages, 2004/10

To carry out the boron neutron capture therapy (BNCT) using the epithermal neutron, the epithermal neutron beam intensity was measured by using Au reaction rate activated on the resonance absorption peak (4.9eV). Two scaling factors, which are the reactor power calibration factor and the calculation/experiment (C/E) scaling factor, are necessary in order to correct with the simulation and actual irradiation experiment. First, an optimum detector position was investigated using MCNP code. The result of MCNP calculation showed that the influence of subject placed at the collimator was below 1% when the detector was placed in the distance of over 20cm from the collimator. Therefore we installed the monitor holders near the bismuth block in order to set three gold wire monitors. The factors were determined in the calibration experiments that measure the thermal neutron flux in the phantom and reaction rate of the gold wire monitors. The monitoring technique to measure epithermal neutron beam intensity was applied to clinical irradiation with the epithermal neutron beam.

Total cross sections for charge transfer by multiply charged neon and argon ions colliding with various hydrocarbons at keV energies

Kusakabe, Toshio*; Miyamoto, Yoshiharu*; Ishida, Rikiya*; Ito, Kojiro*; Kuroyanagi, Nobuhiro*; Nakai, Yota*; Shirai, Toshizo

Nuclear Instruments and Methods in Physics Research B, 205, p.600 - 604, 2003/05

https://doi.org/10.1016/S0168-583X(03)00591-3

no abstracts in English

ITER L mode confinement database

Kaye, S. M.*; Greenwald, M. J.*; U.Stroth*; O.Kardaun*; A.Kus*; Schissel, D. R.*; J.DeBoo*; Bracco, G.*; K.Thomsen*; Cordey, J. G.*; et al.

Nuclear Fusion, 37(9), p.1303 - 1328, 1997/00

https://doi.org/10.1088/0029-5515/37/9/I10

no abstracts in English