Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Chiba, Go
JAEA-Conf 2009-004, p.107 - 110, 2009/10
The fission spectrum is given as a matrix in the ENDF-formatted nuclear data files. On the other hand, most deterministic neutron transport codes treat the fission spectrum as a vector. The objectives of the present study are (1) to realize criticality calculations with the fission spectrum matrix and (2) to assess the accuracy of the criticality calculation methods with the fission spectrum vector. Discrete ordinates neutron transport calculations were carried out for bare sphere cores, reflected sphere cores and thermal solution systems. Errors of about 0.2%dk/kk' were observed when there is an inconsistency between the neutron flux of the target system and the neutron flux used to generate the fission spectrum vector. It was found that the errors of the neutron transport calculations with the fission spectrum vector are negligible if the fission spectrum vector is prepared in prior from the fission spectrum matrix and a proper weight function.
Chiba, Go
JAEA-Conf 2009-004, p.101 - 106, 2009/10
It has been suggested that an eigenvalue separation is considered as an index of reactor core stability, and that core design study can be carried out more effectively with it. The objective of the present study is to grasp a degree of nuclear data-induced uncertainty for the eigenvalue separation. The nuclear-data induced uncertainty for the eigenvalue separations were calculated at less than 1.0% for both the medium-sized and large-sized fast reactors. It can be concluded that nuclear data-induced uncertainty of eigenvalue separations is negligible.
Chiba, Go; Okumura, Keisuke
JAEA-Conf 2009-004, p.21 - 26, 2009/10
We performed an integral test of the preliminary version of JENDL-4 for thermal and fast neutron systems. The preliminary version of JENDL-4 shows very good performance on neutronics calculations for both thermal and fast neutron systems. In addition, we estimated an impact of Am-241 (n,g) cross section in thermal energy range on characteristic of thermal neutron systems, and concluded that large value of Am-241 (n,g) cross section is desirable from a view point of integral data.
Nakashima, Hiroshi
JAEA-Conf 2009-004, p.39 - 44, 2009/10
J-PARC (Japan Proton Accelerator Research Complex) is a high-energy proton accelerator complex of the world's highest beam power. The characteristics of high beam intensity and energy cause many difficulties on radiological safety. In order to overcome the problems, some radiation shielding methods were developed by benchmarking based on experimental data. This paper reviews the development of the radiation shielding design methods for radiological safety of J-PARC.
Koura, Hiroyuki; Tachibana, Takahiro*; Chiba, Satoshi
JAEA-Conf 2009-004, p.135 - 140, 2009/10
We have developed an original model based on the macroscopic and mean-field models to describe the global features of nuclear masses, called the KTUY (Koura-Tachibana-Uno-Yamada) nuclear mass model. The standard deviation of this prediction from known masses is 0.67 MeV, and below 0.4 MeV from some separation energies. The calculated separation energies shows a change of magicities from 
=20 (or 14) to 16, =28 to 32 (or 34), =50 to 58 etc.
-decay, 
-decay, proton emission and spontaneous fission ranging from light nuclei to superheavy nuclei including unknown ones, and estimated the dominant nuclear decay modes. A file of these nuclear data is presented. The total number of nuclei having more than 1 ns is estimated to be approximately ten thousands.
-delayed fission and neutron emission probabilities with the use of gross theory and KTUY mass formulaTachibana, Takahiro*; Koura, Hiroyuki; Chiba, Satoshi
JAEA-Conf 2009-004, p.129 - 134, 2009/10
Probabilities of the -delayed neutron emission are important information for decay heat calculation and, recently, the effect of the -delayed fission to the r-process nucleosynthesis is a quite interesting topic. We make an improvement of the calculation of the probabilities of -delayed fission and neutron emission for nuclei in the region far from the experimentally known nuclides. The probabilities of -delayed fission and neutron emission are estimated by using the gross theory of nuclear -decay. This theory includes the allowed (Fermi and Gamow-Teller) and first-forbidden transitions. In order to estimate the decay width 
and 
, we improve the calculation of nuclear level density formula by Kawano et. al. to take into account the effects of collective motion. We adopted the KTUY mass model for obtaining 
-values, neutron separation energies and fission barrier heights. The shell and the paring energies are also obtained by KTUY mass model for the calculation of the nuclear level density. We will apply these data to an r-process network calculation and briefly discuss the effect of nuclear fission to the r-process abundance in the presentation.
