Takanobu Kamei

Prediction uncertainty evaluation methods of core performance parameters in large liquid-metal fast breeder reactors

AbstractFormulas for predicting the uncertainty of neutronic performance parameters are derived for three methods: the bias factor method, the adjustment method, and the combined method. The prediction uncertainties are obtained by including both experimental and method errors. The adjustment method, in principle, yields the same uncertainty as the combined method. The derived formulas are applied to a large homogeneous l000-MW(electric) liquid-metal fast breeder reactor core.

Burnup Sensitivity Analysis in a Fast Breeder Reactor—Part II: Prediction Accuracy of Burnup Characteristics

Evaluation quantitative de la precision des caracteristiques de combustion en utilisant des coefficients de sensibilite dans un grand surregenerateur refroidi au sodium et la matrice des covariances des donnees nucleaires

Status of Axial Heterogeneous Liquid-Metal Fast Breeder Reactor Core Design Studies and Research and Development

The current status of axial heterogeneous core (AHC) design development in Japan, which consists of an AHC core design in a pool-type demonstration fast breeder reactor (DFBR) and research and development activities supporting AHC core design, is presented. The DFBR core design objectives developed by The Japan Atomic Power Company include (a) favorable core seismic response, (b) core compactness, (c) high availability, and (d) lower fuel cycle cost. The AHC concept was selected as a reference pool-type DFBR core because it met these objectives more suitably than the homogeneous core (HOC). The AHC core layouts were optimized emphasizing the reduction of the burnup reactivity swing, peak fast fluence, and power peaking. The key performance parameters resulting from the AHC, such as flat axial power/flux distribution, lower peak fast fluence, lower burnup reactivity swing, etc., were evaluated in comparison with the HOC. The critical experiments at the Japan Atomic Energy Research Institutes Fast Critical Assembly facility demonstrate the key AHC performance characteristics. The large AHC engineering benchmark experiments using the zero-power plutonium reactor and the AHC fuel pin irradiation test program using the JOYO reactor are also presented.

STUDY OF RESONANCE ABSORPTION NEAR SODIUM RESONANCE AT 2.85 keV.

A method of calculating the neutron flux in a heterogeneous system, utilizing a combination of two different energy meshes — coarse and fine — is presented. The method has been programmed into a computer code EXRE-2. This method is particularly suitable for computations of fast reactor spectra that carry both broad and fine undulations. Pointwise cross section curves are prepared by superposition of the Breit-Wigner single level formura. In the energy region where the resonance is not resolved, a random sampling procedure is used for the derivation of resonance parameters. Group averaged resonance capture and fission cross sections and the temperature dependence of these quantities are computed for a typical fast reactor. An examination is made of the applicability of the conventional narrow resonance (NR) approximation applied over a rather wide energy group, and the heterogeneity effect on the resonance cross sections, near the sodium resonance at 2.85 keV. The error due to the NR approximation was foun...

EFFECTS OF MUTUAL SHIELDING ON RESONANCE INTEGRALS OF

The results of some quantitative studies on resonance interference are presented. The calculations were performed on a FORTRAN IV program RICM2, which solves numerically the slowing down of neutrons over many resonance levels in a two region lattice, and gives reaction rates, average cross sections and effective resonance integrals of the nuclides concerned. Three combinations of resonant nuclides, 235U-238U, 230Pu-238U and 239Pu-210Pu, were considered, in conjunction with three oxide fuel rod radii, 0.2, 0.5 and 2.0 cm, the moderator (light water) to fuel volume ratio being maintained constant at 2.0. An energy range below 150eV has been covered by the present calculations. The effects of resonance interference have been found to be appreciable in this energy range.