Monte Carlo criticality analysis of random media under bounded fluctuation driven by normal noise

Ueki, Taro

Journal of Nuclear Science and Technology, 55(10), p.1180 - 1192, 2018/10

AA2018-0157.pdf:1.15MB

https://doi.org/10.1080/00223131.2018.1483846

In Monte Carlo criticality analysis under material distribution uncertainty, it is necessary to evaluate the response of neutron effective multiplication factor () to the space-dependent random fluctuation of volume fractions within a prescribed bounded range. Normal random variables, however, cannot be used in a straightforward manner since the normal distribution has infinite tails. To overcome this issue, a methodology has been developed via forward-backward-superposed reflection Brownian motion (FBSRBM). Here, the forward-backward superposition makes the variance of fluctuation spatially constant and the reflection Brownian motion confines the fluctuation driven by normal noise in a bounded range. FBSRBM was implemented using Karhunen-Loeve expansion and applied to the fluctuation of volume fractions in a model of UO-concrete media with stainless steel.

Cross-section adjustment methods based on minimum variance unbiased estimation

Yokoyama, Kenji; Yamamoto, Akio*

Journal of Nuclear Science and Technology, 53(10), p.1622 - 1638, 2016/10

AA2015-0624.pdf:0.29MB

https://doi.org/10.1080/00223131.2016.1146637

On the basis of the minimum variance approach, the unified formulation for three types of the cross-section adjustment methods has been derived in a straightforward way without assuming the normal distribution. These methods are intended to minimize the variances of the predicted target core parameters, the adjusted cross-section set, and the calculated integral experimental values. The first and the second methods are found to be slightly different from the extended and the conventional cross-section adjustment methods based on the Bayesian approach with the normal distribution assumption, respectively. However, they become equivalent in some cases and results. The third method is a new method, which is necessary from the viewpoint of the symmetry of the formulation. The derivation procedure proposed in the present paper is potentially applicable to developing more sophisticated cross-section adjustment methods because of the less assumptions on the probability density function.

Creep damage of Hastelloy XR at very high temperatures in simulated HTGR helium gas

*; Tsuji, Hirokazu; *; *; *; Nakajima, Hajime

Creep: Characterization,Damage and Life Assessments, p.551 - 555, 1992/00

no abstracts in English

Statistical fracture characteristics of an isotropic graphite for HTGR core components

; Nishiyama, Yutaka; Konishi, Takashi*

SMiRT 11 Transactions,Vol. G, p.313 - 318, 1991/08

no abstracts in English

Biaxial tensile strengths of isotropic and near-isotropic graphites

Nishiyama, Yutaka;

Int. Symp. on Carbon New Processing and New Applications; Extended Abstracts,Vol. l, p.202 - 205, 1990/11

no abstracts in English

Retardation factor of radioactive strontium in a Japanese sanday soil layer

Onuki, Toshihiko

Waste Management 87, Vol.3, p.213 - 217, 1987/00

no abstracts in English

Goodness-of-fit tests of annual doses in JAERI to theoretical distributions

Kumazawa, Shigeru; Ito, Masashi; ; Numakunai, Takao

Hoken Butsuri, 16(2), p.141 - 144, 1981/00

https://doi.org/10.5453/jhps.16.141

no abstracts in English

PLUTO-A Program to compute cloud gamma dose by point-kernel integration

*; Kishimoto, Yoichiro; Narita, Osamu; Shinohara, Kunihiko*; *

PNC TN843 77-05, 25 Pages, 1977/06

PNC-TN843-77-05.pdf:0.51MB

A computer program has been written to calculate the exposure dose at an arbitrary point in the atmosphere caused by the emission of radioactive materials from a stack. The dispersion of materials in air is expressed by the Gaussian plume model with ground surface and inversion lid reflections. The exposure or absorbed dose in air is calculated by the spatial integration of point-kernels. Several approximate methods, such as homogeneous-infinite-slab approximation, submersion approximation, etc, have been incorporated as well.

Cross section adjustment methods based on minimum variance unbiased estimate

Yokoyama, Kenji; Yamamoto, Akio*

no journal, , 

no abstracts in English

Monte Carlo criticality calculation of random media with bounded fluctuation due to normal noise

Ueki, Taro

no journal, , 

Monte Carlo particle transport calculation of random media is an effective means for evaluating the uncertainty of criticality. In this presentation, the author reports Monte Carlo criticality calculation methodology for the random media with bouded fluctuation modeled by superposed Brownian motion and implemented by Karhunen-Loeve expansion.