JOPSS - Search Results

Journal Articles

Neutron spectrum change with thermal moderator temperature in a compact electron accelerator-driven neutron source and its effects on spectroscopic neutron transmission imaging

Ishikawa, Hirotaku*; Kai, Tetsuya; Sato, Hirotaka*; Kamiyama, Takashi*

Journal of Nuclear Science and Technology, 56(2), p.221 - 227, 2019/02

https://doi.org/10.1080/00223131.2018.1561339

Times Cited Count：3 Percentile：31.36(Nuclear Science & Technology)

Journal Articles

Radionuclide release from mixed-oxide fuel under high temperature at elevated pressure and influence on source terms

Hidaka, Akihide; Kudo, Tamotsu; Ishikawa, Jun; Fuketa, Toyoshi

Journal of Nuclear Science and Technology, 42(5), p.451 - 461, 2005/05

https://doi.org/10.3327/jnst.42.451

Times Cited Count：6 Percentile：40.41(Nuclear Science & Technology)

The radionuclide release from MOX under severe accident conditions was investigated in VEGA program to contribute to the technical bases for safety evaluation including PSA for LWR using MOX. The MOX specimens irradiated at ATR Fugen were heated up to 3123K in helium at 0.1 and 1.0MPa. The release of volatile FP was slightly enhanced below 2200K compared with that of UO $_{2}$ . The volatile FP release at elevated pressure was decreased as in the case with UO $_{2}$ . The total fractional release of Cs reached almost 100% while almost no release of low-volatile FP even after the fuel melting. The release rate of plutonium above 2800K increased rapidly although the amount was small. Since the existing models cannot predict this increase, an empirical model was prepared based on the data. There is no large difference in FP inventories between UO $_{2}$ and MOX, and the fractional releases from MOX can be mostly predicted by the model for UO $_{2}$ . This suggests that the consequences of LWR using MOX are mostly equal to those using UO $_{2}$ from a view point of risks.

Journal Articles

Impact of perturbed fission source on the effective multiplication factor in Monte Carlo perturbation calculations

Nagaya, Yasunobu; Mori, Takamasa

Journal of Nuclear Science and Technology, 42(5), p.428 - 441, 2005/05

https://doi.org/10.3327/jnst.42.428

Times Cited Count：61 Percentile：95.82(Nuclear Science & Technology)

A new method to estimate a change in the effective multiplication factor due to the perturbed fission source distribution has been proposed for Monte Carlo perturbation calculations with the correlated sampling and differential operator sampling techniques. The method has been implemented into the MVP code for verification. Simple benchmark problems have been set up for fast and thermal systems and the applicability of the method has been verified with the problems. In consequence, it has been confirmed that the method is very effective to estimate the change. It has been also shown that there are some cases where the perturbed source effect is significant and the change in reactivity cannot be estimated accurately without taking the effect into account. Even in such cases, the new method can estimate the perturbed source effect and the estimation of the change in reactivity has been remarkably improved.

JAEA Reports