Faculty Profiles - ENDO Tomohiro

MISC - ENDO Tomohiro

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Uncertainty Quantification of Activation Due to Cross Section Data in Neutron Shielding Calculation Reviewed International journal

K. Yokoi, T. Endo, A. Yamamoto, R. Mizuno, Y. Kimura

Trans. Am. Nucl. Soc. Vol. 115 page： 1085 - 1087 2016.11

Language：English Publishing type：Research paper, summary (international conference) Publisher：American Nuclear Society

The random sampling method is applied to neutron shielding calculation using ANISN/TRANSX in order to estimate uncertainties of neutron flux and activation in a structure material (iron). The calculation results indicate that the magnitude of uncertainty of activation of Co59 due to cross section is approximately 10% inside structural material, which is not very large when attenuation of neutron flux is taken into account.

Prediction on Underestimation of Statistical Uncertainty in Monte Carlo Eigenvalue Calculation for Two-dimensional Heterogeneous Color Set Geometry Reviewed International journal

K. Hayashi, T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc. Vol. 115 page： 1213 - 1216 2016.11

Language：English Publishing type：Research paper, summary (international conference) Publisher：American Nuclear Society

Theoretical formula for behavior of noise term is derived, which is necessary for prediction of underestimation ratio of statistical uncertainty in Monte Carlo eigenvalue calculation. By using the proposal theoretical formula, underestimation ratio of flux of each fuel cell in 2×2 UO2-MOX assembly geometry is predicted and compared with the reference results obtained by 1000 GMVP runs. The prediction results show reasonable agreement with the reference regarding to relative spatial shape, which suggest the validity of the theoretical formula of the underestimation ratio and the noise term. However, there is considerable difference on the absolute values of the underestimation ratio and investigation of the causes of the difference would be a future task.

Analysis and Interpretation of the KUCA ADS Benchmarks with Deterministic Analysis Codes Reviewed International journal

W.F.G. van Rooijen, G. Chiba, T. Endo, C.H. Pyeon

Proc. PHYSOR2016 page： 4200 - 4216 2016.5

Language：English Publishing type：Research paper, summary (international conference) Publisher：American Nuclear Society

This manuscript discusses the analysis of the KUCA-A ADS with deterministic codes (specifically diffusion theory). The KUCA-A ADS is a small, thermal-spectrum ADS driven by 100MeV protons. Several sets of experiments are available as an international benchmark. In our analysis, we calculated the multiplication factor, prompt neutron decay constant (α-eigenvalue), performed the analysis of an irradiation experiment, and used time-dependent diffusion theory to analyze pulsed neutron operation of the KUCA-A ADS in 3D. The results are that the multiplication factor is generally well predicted as long as the void regions in the core remain of a limited extent. The time-eigenvalue (α-eigenvalue) is also well predicted, and knowledge of the α-mode can be effectively used in the selection of measurement data for curve fitting methods.

Variance Reduction Factor Calculations for Neutronics Parameters of Accelerator-Driven System Reviewed International journal

G. Chiba, W.F.G. van Rooijen, T. Endo, C.H. Pyeon

Proc. PHYSOR2016 page： 1661 - 1668 2016.5

Language：English Publishing type：Research paper, summary (international conference) Publisher：American Nuclear Society

In order to identify nuclear data on which further improvement is effective to reduce nuclear data-induced uncertainties of accelerator-driven system (ADS) neutronics parameters, variance reduction factors (VRFs) for keff, beff and coolant void reactivity are calculated. Obtained VRFs suggest that improvement of plutonium-238 nuclear data is quite effective to reduce the uncertainties of keff and beff during the operation of ADS, and that improvement of lead-206 elastic and inelastic scattering cross sections is also important to reduce the uncertainties of coolant void reactivity. Important energy ranges of these nuclear data are also specified by VRFs.

GENESIS - A Transport Solver in Three-Dimensional Heterogeneous Geometry Based on the LEAF Method Reviewed International journal

A. Yamamoto, A. Giho, T. Endo

Proc. PHYSOR2016 page： 4080 - 4106 2016.5

Language：English Publishing type：Research paper, summary (international conference) Publisher：American Nuclear Society

A heterogeneous transport solver in three dimensional geometry, GENESIS, is being developed incorporating recent developments of the method of characteristics (MOC) in three dimensional geometry. The Legendre Expansion of Angular Flux (LEAF) method is implemented in the GENESIS code, in which neutron transport is calculated in two-dimensional "characteristics planes" rather than in one-dimensional characteristics lines adopted in the conventional approach of 3D MOC. Unlike the planner MOC method that combines 2D MOC calculations through axial leakages, the GENESIS code explicitly considers angular and spatial dependence of outgoing and incoming angular fluxes between axial planes. Thus the GENESIS code eliminates a crucial approximation used in the planner MOC method. The GENESIS code can handle flexible shape of objects in rectangular or hexagonal geometry. Two-level, multi-group generalized coarse mesh rebalance (GCMR) acceleration method is adopted for efficient convergence of neutron transport calculation. Performance of the GENESIS code is verified through various benchmark calculations. The calculation results indicate the fidelity of the GENESIS code.

Theoretical Expression of Area Ratio Method using Detected-Neutron Multiplication Factor Reviewed International journal

T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc. Vol. 113 page： 1208 - 1211 2015.11

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper, summary (international conference) Publisher：American Nuclear Society

In the present paper, the area ratio method is expressed by the detected-neutron multiplication factor kdet. In addition, an appropriate detector position is discussed by investigating the difference between kdet and the effective neutron multiplication factor keff.

Application of Data Assimilation based on Bayesian Theory to Subcriticality Measurements using Area Ratio Method Reviewed International journal

K. Maeno, T. Endo, A. Yamamoto

Trans. Am. Nucl. Soc. Vol. 113 page： 1282 - 1286 2015.11