Modelling of marine radionuclide dispersion in IAEA MODARIA program; Lessons learnt from the Baltic Sea and Fukushima scenarios

Periez, R.*; Bezhenar, R.*; Brovchenko, I.*; Duffa, C.*; Iosjpe, M.*; Jung, K. T.*; Kobayashi, Takuya; Lamego, F.*; Maderich, V.*; Min, B. I.*; et al.

Science of the Total Environment, 569-570, p.594 - 602, 2016/11

https://doi.org/10.1016/j.scitotenv.2016.06.131

State-of-the art dispersion models were applied to simulate Cs dispersion from Chernobyl Nuclear Power Plant disaster fallout in the Baltic Sea and from Fukushima Daiichi Nuclear Plant releases in the Pacific Ocean after the 2011 tsunami. Models were of different nature, from box to full three-dimensional models, and included water/sediment interactions. Agreement between models was very good in the Baltic. In the case of Fukushima, results from models could be considered to be in acceptable agreement only after a model harmonization process consisting of using exactly the same forcing (water circulation and parameters) in all models. It was found that the dynamics of the considered system (magnitude and variability of currents) was essential in obtaining a good agreement between models. The difficulties in developing operative models for decision-making support in these dynamic environments were highlighted.

Study on the measurements and evaluation of environmental external exposure after the nuclear accident

Sakamoto, Ryuichi; Saito, Kimiaki; Tsutsumi, Masahiro; Nagaoka, Toshi

Hoken Butsuri, 36(4), p.297 - 307, 2001/12

https://doi.org/10.5453/jhps.36.297

There are many factors which affect external exposure in contaminated area: distributions of fallout, compositions of radioactive nuclides, soil conditions, depth profile of radioactivity in soil, rain fall, snow cover, radioactive decay, shielding effects of houses and other structures, de-contamination measures, and the 'occupancy factor' which accounts for the fraction of time that inhabitants spend in different locations. In this study, several important issues concerning these factors have been investigated using field measurements and computational simulations since 1992 in the Chernobyl area. The objectives of the study were: (1) The development of a mobile survey method to collect radiation data of the contaminated area over a wide area in a short time; (2) The verification of a method to infer external doses to the population; (3) The provision of basic data used for the evaluation of external dose due to gamma ray using a Monte Carlo simulation method. (4) Characteristics of the radiation fields in contaminated area. In this report, the results were summerized.

WSPEEDI (worldwide version of SPEEDI): A Computer code system for the prediction of radiological impacts on Japanese due to a nuclear accident in foreign countries

Chino, Masamichi; Ishikawa, Hirohiko; Yamazawa, Hiromi; ; Moriuchi, Shigeru

JAERI 1334, 54 Pages, 1995/09

JAERI-1334.pdf:3.54MB

no abstracts in English

Evaluation of the effect of horizontal diffusion on the long-range atmospheric transport simulation with Chernobyl data

Ishikawa, Hirohiko

Journal of Applied Meteorology, 34(7), p.1653 - 1665, 1995/07

no abstracts in English

Development of regionally extended/worldwide version of system for prediction of environmental emergency dose information: WSPEEDI, II; Long-range transport model and its application to dispersion of cesium-137 from Chernobyl

Ishikawa, Hirohiko; Chino, Masamichi

Journal of Nuclear Science and Technology, 28(7), p.642 - 655, 1991/07

https://doi.org/10.3327/jnst.28.642

no abstracts in English

Contamination and radiation dose in European countries due to the Chernobyl accident

KURRI-TR-298, p.13 - 21, 1987/00

no abstracts in English

SPEEDI: System for prediction of enviromental emergency dose information

Hoken Butsuri, 21, p.285 - 294, 1986/00

https://doi.org/10.5453/jhps.21.285

no abstracts in English

Experimental study on the microbial degradation of the fuel debris

Liu, J.; Dotsuta, Yuma; Kitagaki, Toru; Kozai, Naofumi; Onuki, Toshihiko

no journal, , 

In Fukushima Daiichi accident, molten core flowed down the structural materials and formed the fuel debris, which consists of uranium dioxide fuel, iron, zirconium, and concrete. Now the decommission of damaged nuclear plant and countermeasure of fuel debris are under discussion. It is essential to understand the current status of fuel debris and possible change during the defueling activities. Considering the appearance of microorganisms in TMI-2 and Chernobyl plant, the existence of microorganisms in Fukushima Daiichi Nuclear Power Plant was expected. Here, the microbial effect on fuel debris, specially the microbial degradation, was experimentally studied. It was found that oxidization and dissolution of iron and zirconium into the medium would mainly cause the degradation of fuel debris.