Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Togawa, Orihiko; Okura, Takehisa; Kimura, Masanori
JAEA-Review 2022-049, 76 Pages, 2023/01
Before construction and after operation of nuclear facilities, environmental consequence assessments are conducted for normal operation and an emergency. These assessments mainly aim at confirming safety for the public around the facilities and producing relief for them. Environmental consequence assessments are carried out using observations/ measurements by environmental monitoring and/or model predictions by calculation models, sometimes using either of which and at other times using both them, according to the situations and necessities. First, this report investigates methods, roles, merits/demerits and relationship between observations/measurements and model predictions which are used for environmental consequence assessments of nuclear facilities, especially holding up a spent nuclear fuel reprocessing plant at Rokkasho, Aomori as an example. Next, it explains representative examples of utilization of data on observations/measurements and results on model predictions, and considers points of attention at using them. Finally, the report describes future direction, for example, improvements of observations/measurements and model predictions, and fusion of both them.
Miwa, Kazuji; Obata, Hajime*; Suzuki, Takashi
Journal of Nuclear Science and Technology, 57(5), p.537 - 545, 2020/05
Times Cited Count:2 Percentile:21.22(Nuclear Science & Technology)This study investigated the vertical distribution of Iodine-129 (I) which is mainly produced by European nuclear reprocessing plants in the Chukchi Sea and Bering Sea. I was found to be distributed almost uniformly in fallout level, and an increasing in I concentration levels caused by high I water inflow from the Atlantic Ocean was not observed. Additionally, we revealed the vertical distribution of iodide, one chemical form of iodine, from the Bering Shelf area to the Chukchi Sea for the first time. The increasing tendency of iodide near sea bottom was observed.
Nakajima, Ken*; Itahara, Kuniyuki*; Okuno, Hiroshi
Proceedings of International Conference on Nuclear Criticality Safety (ICNC 2015) (DVD-ROM), p.496 - 502, 2015/09
An outline of the standard "Procedures for Applying Burnup Credit to Criticality Safety Control of a Reprocessing Facility: 2014" (AESJ-SC-F025: 2014) published in April 2015 by the Atomic Energy Society of Japan (AESJ) is presented. The AESJ published more than 60 Standards. However, many of them were in the field of nuclear power reactors or radioactive wastes. Ten years ago the AESJ published "Basic Items of Criticality Safety Control: 2004" (AESJ-SC-F004:2004), which prescribed basic ideas, requirements and methods on nuclear criticality safety controls of facilities handling with nuclear fuel materials in general for preventing a nuclear criticality accident. However, it did not include any specific procedures for adopting burnup credit. Therefore, a new standard was envisaged as the first Standard for fuel reprocessing plants, which clarified the specific procedures to apply burnup credit to designers, operators, maintenance persons and administrators.
Watanabe, Koji; Tashiro, Shinsuke; Abe, Hitoshi; Takada, Junichi; Morita, Yasuji
JAERI-Tech 2004-029, 48 Pages, 2004/03
In a part of building ventilating installation of a nuclear fuel facility, a reprocessing plant for example, the pre-filters are adopted as one of the ventilation filters. In a fire accident, it is supposed that, because of the pre-filter clogging by large smoke, its differential pressure (p) is evolved up to the value at its breakage. Therefore, in regard to maintaining the confinement of radioactive materials, it is important to predict the time course of p of the pre-filter accurately. In the current study, it was assumed that the empirical equation for the DF of the pre-filter as function of smoke particle diameter (SPD), between 0.7-2 m, could be applied to estimating its DF for SPD above 2 m. Under this assumption, the time corresponding to its p at its breakage, calculated by CELVA-1D, was agreed well with the experimental result.
Kobayashi, Takuya; Lee, S.; Chino, Masamichi
Journal of Nuclear Science and Technology, 39(2), p.171 - 179, 2002/02
Times Cited Count:3 Percentile:23.39(Nuclear Science & Technology)A three-dimensional model system was developed to predict oceanic dispersions of radionuclides released into the eastern area of Shimokita Peninsula. This system is a combination of the Princeton Ocean Model (POM) for predicting ocean currents and a particle random walk model for oceanic dispersion of radionuclides. The model was verified by using measured currents, temperature and salinity at the coastal area of Shimokita, Aomori-ken, Japan, where a nuclear fuel reprocessing plant is under construction. The results obtained from simulations area as follows; (1) Wind and the Tsugaru Warm Current entering into the objective region through the Tsugaru Strait significantly affect the structure of current over the region. (2) POM can represent seasonal variations of the Tsugaru Warm Current well with hypothetical oceanographic data. The calculation succeeded to reproduce the coastal mode from winter to spring and the gyre mode from summer to autumn.
Department of Decommissioning and Waste Management
JAERI-Review 2000-013, 49 Pages, 2000/09
no abstracts in English
Noguchi, Hiroshi
Nihon Genshiryoku Gakkai-Shi, 39(11), p.915 - 916, 1997/00
no abstracts in English
Togawa, Orihiko
Journal of Nuclear Science and Technology, 33(10), p.792 - 803, 1996/10
Times Cited Count:3 Percentile:32.75(Nuclear Science & Technology)no abstracts in English