Assessment of nuclear simulation credibility

Tanaka, Masaaki; Nakada, Kotaro*; Kudo, Yoshiro*

Nihon Kikai Gakkai-Shi, 123(1222), p.26 - 29, 2020/09

In the nuclear engineering, simulations are used in radiation, thermal hydraulic, chemical reaction, and structural fields, and the integrated fields thereof, to be applied to the design, construction and operation of nuclear facilities. This article describes brief history of discussion in the AESJ to the publication and introductory explanation of the procedures in the five major elements described in the "Guideline for Credibility Assessment of Nuclear Simulations (AESJ-SC-A008: 2015)". And also, a practical experience of the V&V activity according to the fundamental concept indicated in the Guideline is introduced.

Study on improvement of reactor physics analysis method for FBRs with various core concept

*; Kitada, Takanori*; Tagawa, Akihiro; *; Takeda, Toshikazu*

JNC TJ9400 2000-006, 272 Pages, 2000/02

JNC-TJ9400-2000-006.pdf:9.69MB

Investigation was made on the follwing three themes as a part of the improvement of reactor physics analysis method for FBR with various core concept. Part 1: Investigation of Error Estimation of Neutron Spectra in FBR and Suggestions to Improve the Accuracy. In order to improve the spectrum unfolding method used in fast experimental reactor JOYO, a trial was made to evaluate the error in the estimated neutron spectrum, cause by cause. And the evaluated errors were summed up to obtain the most probable and reasonable error as possible. The summed up error was found relatively small compared to the error caused by the uncertainty of cross section data: most of the error in the spectrum unfolding method can be attributed to the error in cross sections. It was also found that the error due to the fission spectrum causes a considerable error in the high energy neutron spectrum which is over several MeV. Part 2: Study on Reactor Physics Analysis Method for Gas-Cooled FBR. In gas-cooled FBR, the portion of coolant channels in core volume is larger than sodium-cooled FBR. This leads to strong neutron streaming effects. For sodium-cooled FBR, several methods were proposed to evaluate the neutron streaming effect, however, these methods can not be used directly to gas-cooled reactor because the direction dependent diffusion coefficient becomes infinitive along the direction pararel to the coolant chammel. In this study, a new method is proposed to evaluate the neutron streaming effect, based on the method taking the axial buckling into consideration, which method was originally proposed by Khler. Part 3: Study on Reactor Physics Analysis Method for Water-Cooled FBR An investigation was made on low-moderated water-cooled FBR, on the point that the ordinary used analysis method for FBR may give considerable difference in results in such core. In light water reactors, it is well known that the space dependence of self-shielding effect of heavy nuclides are considerably ...

Fundamental concept of VVUQ (verification and validation plus uncertainty quantification); Challenging activities for implementation of VVUQ methodology

Tanaka, Masaaki

no journal, , 

In the nuclear engineering, simulations are used in radiation, thermal hydraulic, chemical reaction, and structural fields, and the integrated fields thereof, to be applied to the design, construction and operation of nuclear facilities. This document describes outline of the V&V guideline "Guideline for Credibility Assessment of Nuclear Simulations (AESJ-SC-A008: 2015)" published from AESJ. An application study of the methodologies, e.g., GCI method, area validation metrics, for verification and validation plus uncertainty quantification (VVUQ) is introduced using numerical simulation results of the fluid-structure thermal interaction analysis in a water experiment of a T-junction piping system.

Fundamental concept of VVUQ (verification and validation plus uncertainty quantification); Challenging activities for implementation of VVUQ methodology

Tanaka, Masaaki

no journal, , 

In the nuclear engineering, simulations are used in radiation, thermal hydraulic, chemical reaction, and structural fields, and the integrated fields thereof, to be applied to the design, construction and operation of nuclear facilities. This document describes outline of the V&V guideline "Guideline for Credibility Assessment of Nuclear Simulations (AESJ-SC-A008: 2015)" published from AESJ. An application study of the methodologies, e.g., GCI method, area validation metrics, for verification and validation plus uncertainty quantification (VVUQ) is introduced using numerical simulation results of the fluid-structure thermal interaction analysis in a water experiment of a T-junction piping system.