Development of neutron transport calculation codes for 3-D hexagonal geometry, 2; Improvement and enhancement of the MINISTRI code

Sugino, Kazuteru; Takino, Kazuo

JAEA-Data/Code 2019-011, 110 Pages, 2020/01

JAEA-Data-Code-2019-011.pdf:3.37MB

A deterministic discrete ordinates method (SN method) transport calculation code for three-dimensional hexagonal geometry has been developed as the MINISTRI code (Ver. 7.0). MINISTRI is based on the triangle-mesh finite difference method, which can perform neutron transport calculations with high accuracy for cores of fast power reactors and assemblies of the Russian BFS critical facility. The present study has derived a proper scheme for remarkably improving the convergence of MINISTRI by investigating the issue of previous MINISTRI (Ver. 1.1), which sometimes plays a poor convergence performance in calculations for large-scale power reactor cores. The verification test of improved MINISTRI has been carried out for various cores by setting the reference result as the multi-group Monte-Carlo calculation with the same cross-sections as used in MINISTRI. As a result, it is found that the agreements are within 0.1% for eigenvalues and within 0.7% for power distributions. Thus, the satisfying accuracy of MINISTRI has been confirmed. In order to reduce the calculation time, the initial diffusion calculation scheme and the parallel processing have been implemented. As a result, the calculation time is reduced to the approximately one tenth compared with previous MINISTRI. Furthermore, adoption of the treatment of the anisotropic cell streaming effect, preparation of the perturbation calculation tool, implementation of the function for specification of the triangle-mesh-wise material and merging of the hexagonal-mesh calculation code MINIHEX have been carried out. Thus, the versatility of MINISTRI has been enhanced.

Observation of nonlinear coupling between small-poloidal wave-number potential fluctuations and turbulent potential fluctuations in Ohmically heated plasmas in the JFT-2M tokamak

Nagashima, Yoshihiko*; Hoshino, Katsumichi; Ejiri, Akira*; Shinohara, Koji; Takase, Yuichi*; Tsuzuki, Kazuhiro; Uehara, Kazuya; Kawashima, Hisato; Ogawa, Hiroaki; Ido, Takeshi*; et al.

Physical Review Letters, 95(9), p.095002_1 - 095002_4, 2005/08

https://doi.org/10.1103/PhysRevLett.95.095002

By a reciprocating electrostatic probe, two types of low frequency coherent electrostatic modes (about1kHz and 10-15kHz) are found,for the first time, in the edge region of ohmically heated plasmas in the JFT-2M tokamak. These modes exists in the last closed surface. The higher frequency mode has features of the geodesic acoustic mode (GAM), though the low frequency mode is not identified yet. A bispectral analysis revealed that significant nonlinear couplings (parametric modulation) between these coherent fluctuations and broadband background turbulent potential fluctuations occur. In the other words, the GAM and the back ground turbulence are modulated by the newly found low frequency electrostatic mode (further, the GAM modulates the background turbulence, also) for the first time. The newly found low frequency mode (frequency about 1kHz) is supposed to contribute to the turbulent diffusion nonlinearly.

Extended calculations of OECD/NEA phase II-C burnup credit criticality benchmark problem for PWR spent fuel transport cask by using MCNP-4B2 code and JENDL-3.2 library

Kuroishi, Takeshi; Hoang, A.; Nomura, Yasushi; Okuno, Hiroshi

JAERI-Tech 2003-021, 60 Pages, 2003/03

JAERI-Tech-2003-021.pdf:4.56MB

The reactivity effect of the asymmetry of axial burnup profile is studied for PWR spent fuel transport cask proposed in OECD/NEA Phase II-C benchmark. The axial burnup profiles are based on in-core flux measurements. Criticality calculations are performed with the continuous energy Monte Carlo code MCNP-4B2 and the nuclear data library JENDL-3.2. Calculations are carried out not only for cases in the benchmark but also for symmetric burnup cases. Both actinide-only approach and actinide plus fission product approach is considered. The end effect is more sensitive to higher burnup asymmetry. The axial fission distribution becomes strongly asymmetric as its peak shifts toward the fuel top end. The peak of fission distribution gets higher with the increase of either the burnup asymmetry or the assembly-averaged burnup. The conservatism of uniform axial burnup assumption for the actinide-only approach is estimated quantitatively in comparison with the keff result calculated with experiment-based strongest asymmetric axial burnup profile for the actinide plus fission product approach.

Measurement of U Doppler Effect using various samples in FCA XVII-1

Ando, Masaki; Okajima, Shigeaki; Oigawa, Hiroyuki

JAERI-Research 2001-017, 20 Pages, 2001/03

JAERI-Research-2001-017.pdf:0.82MB

U Doppler effect measurements were carried out using 6 uranium samples with various composition or diameter varying self-shielding factors of U. Calculation accuracy of the standard analysis method for fast reactor cores at FCA was investigated.The Doppler effect were measured by the sample-heated and reactivity worth measurement method up to 800 degree in the FCA XVII-1 assembly, which simulated Na-cooled MOX fueled FBR. In the analysis, the Doppler effect was calculated using the effective cross sections obtained by the PEACO-X code. The calculated values based on the diffusion theory agreed well with the experiment for the U-metal and UO samples. The calculation underestimated the experiment from 10% to 30% for the UO samples containing BeO. This underestimation was improved by the use of the transport calculation. The calculation, however, underestimated about 20% for the sample whose background cross section is greater than 300 barns.

Benchmark experiment on void effects in a bulk shield assembly and investigation on the predictive ability of these effects by transport calculations

Maekawa, Fujio; Konno, Chikara; Oyama, Yukio; Uno, Yoshitomo; Maekawa, Hiroshi; Ikeda, Yujiro

Fusion Engineering and Design, 42, p.275 - 280, 1998/00

https://doi.org/10.1016/S0920-3796(98)00249-X

no abstracts in English

A Method for Measuring Tritium Production Rate by Lithium-Glass Scientillators

; ; ;

JAERI-M 85-086, 40 Pages, 1985/07

JAERI-M-85-086.pdf:1.12MB

no abstracts in English

Thermal conductivity of electron-irradiated pyrolytic graphite

*;

Journal of the Physical Society of Japan, 49(5), p.1916 - 1919, 1980/00

https://doi.org/10.1143/JPSJ.49.1916

no abstracts in English

Progress of full-f gyrokinetic simulations including a new hybrid kinetic electron model

Idomura, Yasuhiro

no journal, , 

A Gyrokinetic Toroidal 5D full-f Eulerian code GT5D is extended including a new hybrid kinetic electron model, which enables us to address ITER relevant issues related to electron turbulence. In this talk, physics backgrounds and computational properties of the new hybrid kinetic electron model are discussed, and applications of the model to ITER relevant issues such as the isotope effect of turbulent plasma transport and the plasma rotation change induced by electron heating are presented. These simulation studies show that electron turbulence plays a critical role in ITER, and thus, the new hybrid kinetic electron model is essential for analyzing the performance of core plasmas in ITER.