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Yamada, Junya; Hashimoto, Makoto; Seya, Natsumi; Haba, Risa; Muto, Yasunobu; Shimizu, Takehiko; Takasaki, Koji; Yokoyama, Sumi*; Shimo, Michikuni*
Hoken Butsuri, 52(1), p.5 - 12, 2017/03
The purpose of this study is to improve a quick method for estimation of I concentrations in the air using data measured by monitoring posts in case that a nuclear disaster occurs. In this method, I concentrations were estimated by multiplying I count rates of cloud-shine measured with NaI (Tl) detector by concentration conversion factor. A previous study suggested that it was difficult to determine passing-through time of plume from temporal change of I count rates or dose rate. Our study applies the method for estimating passing-through time of plume from temporal change of noble gas counts. The I concentrations in the air at Oarai center, Japan Atomic Energy Agency resulting from the accident at the Fukushima Daiichi Nuclear Power Plant were estimated by proposal technique. The result of comparison of this method with sampling method for I concentrations in the air were within factor 3.
Kato, Hiroshige*; Mine, Tatsuya*; Mihara, Morihiro; Oi, Takao; Honda, Akira
JNC TN8400 2001-029, 63 Pages, 2002/01
Cementitious materials will be used for the TRU waste repository as a component of engineered barrier system. The distribution coefficients which represent the retardation of radionuclides migration for the cementitious materials would be one of the important parameter for the safety assessment. The much information of radionuclide sorption onto the cementitious materials has been accumulated through the study in the world. Therefore it is necessary to compile the information and Kd of the radionuclides reported in previous studies. In this report, the Kd of the important radionuclides, such as C, Ni, Se, Sr, Zr, Nb, Mo, Tc, Sn, I, Cs, Sm, Pb, Ra, Ac, Th, Pa, U, Np, Pu, Am, Cm, for the cementitious materials were compiled as the Sorption Database (SDB). For radionuclides to be sensitive to the redox potential, e.g. Se, Tc, Pa, U, Pu and Np, some Kds measured under the controlled atmosphere had been reported, and few Kds measured under the controlled redox potential had been reported. For Se, Mo, Sm, Cm and Ac, the distribution coefficients had not been reported, therefore distribution coefficients of Se and Mo for OPC (Ordinary Portland Cement) pastes were measured by batch sorption experiments and these data were added into the SDB.
Maruo, Yoshihiro; ; Takeishi, Minoru; ; ; Takeyasu, Masanori;
JNC TN8440 2001-011, 146 Pages, 2001/06
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed since 1975, based on "Safety Regulations for the Tokai Reprocessing Plant, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitants due to the radioactivity discharged from the plant during April 2000 to March 2001. Appendices present comprehensive information, such as monitoring program, monitoring results, meteorological data and annual discharges from the plant.
Shinohara, Kunihiko; ; ; ; ; Kano, Yutaka;
JNC TN8440 2001-004, 62 Pages, 2001/02
Concerming about the action for the criticality accident in JCO Co., Ltd. (JCO) occurred at 10:35 on 30 Sept. 1999, Japan Nuclear Cycle Development Institute(JNC) established "JNC's task force" at 12:35 on the same date in conjuction with Head Office and Tokai Works. And JNC's task force had supported the government of Japan, the local governments and JCO humanly, physically and technically until the jobs of the task force was transferred to "Support Assembly for Countermeasure and Research of JCO Criticality Accident" and routine line on 12 Oct. 1999. This report compiled the results of the environmental monitoring performed by JNC based on the request from the government of Japan and the local governments.
Mizutani, Akihiko; ;
JNC TN9400 2000-013, 66 Pages, 2000/02
Feasibility study on a self-consistent fuel cycle system has been performed in the nuclear fuel recycle system with fast reactors. ln this system, the self-generated MAs (Minor Actinides) and LLFPs (Long-Lived Fission Products) are confined and incinerated in the fast reactor, which is called the "Equilibrium Core" concept. However, as the isotope separations for selected LLFPs have been assumed in this cycle system, it seems that this assumption is far from realistic one from the viewpoint of economy with respect to the fuel cycle system. ln this study, the possibility for realization of the "Equilibrium Core" concept is evaluated for three fuel types such as oxide, nitride and metallic fuels, provided that the isotopic separation of LLFPs is changed to the element one. This study provides, that is to say, how many LLFP elements can be confined in the "Equilibrium Core" with element separation. This report examines the nuclear properties of the "Equilibrium Core" for various combinations of LLFP incineration schemes from the viewpoints of the risk of geological disposal and the limit in confinable quantity of LLFPs. From the viewpoint of the risk of geological disposal estimated by the retardation factor, it is possible to confine with element separation for T, I and Se even in the oxide fueled core. From the standpoint of the limit of confinable amounts of LLFPs, on the other hand, T, I, S, S and Cs can be confined with element separation in case that the nitride fuel is chosen.
J. A. BERRY*; M. BROWNSWORD*; D. J. ILETT*; Linklater, C. M.*; Mason, C.*; TWEED, C. J.*
JNC TJ8400 2000-060, 60 Pages, 2000/02
Batch sorption experiments have been carried out to investigate the sorption behaviour of plutonium onto basalt and sandstone from the appropriate rock-equilibrated waters under different redox eonditions. Redox Potentials in solution were controlled by the addition of two reducing agents and one oxidising agent. Thermodynamic chemical modelling was undertaken to interpret the results. The sorption models were based on iron oxide. They adequately reproduced the data for sorption of plutonium onto sandstone, but tended to underpredict sorption onto basalt.
Mihara, Morihiro; ; Ueta, Shinzo*; *
JNC TN8430 99-011, 27 Pages, 1999/11
In radioactive waste disposal, compacted Na-bentonite has been proposed for a buffer material. However, Na-bentonite would change to Ca-bentonite in the long term period. The change of Na-bentonite to Ca-bentonite might cause the change in the data concerning with nuclides migration properties such as permeability, sorption and diffusion. In this study, effective diffusion coefficients of HTO, Cs, I and C in compacted Ca-bentonite which was changed from Na-bentonite, Kunigel V1, were obtained and were compared to published those of Kunigel V1. In addition, effective diffusion coefficients for compacted Ca-bentonite with syncetic sea system water, SW, were obtained in order to investigate effect of solution composition. The magnitude of effective diffusion coefficients in Ca-bentonite are arranged in smaller order as CsHTOIC. It is estimated that their effective diffusion coefficients are same those of Na-bentonite. About effect of solution composition, effective diffusion coefficients of HTO in 1.8g/cm dry density with SW were almost same values with distilled system water, DW. However, effective diffusion coefficients of HTO in lower density were smaller than values with DW. Regarding as effective diffusion coefficients of Cs in 1.8g/cm dry density, the effect of SW could not be observed as well as HTO. However, effective diffusion coefficients of I and C existing as an anion in pore water of bentonite increased by the reduction in the ion exclusion.
Sagawa, Norihiko*
PNC TJ9613 97-001, 90 Pages, 1997/10
An ionization sensor. which ionizes iodine vapor on a heated filament and collects ionized iodine on a collector at positive potential, was made on an experimental basis. Iodine vapor in rare gas was determined with using the sensor on the line and the characteristic of the sensor was examined. Iodine vapor was generated from iodine crystals in an iodine evaporator and transferred to the sensor with carrier-rare gas. The iodine vapor was continuously monitored by the sensor and trapped in solution of sodium hydroxide. The amount of iodine in the solution was determined by chemical analyses. The integrated value of ion current was compared with the collected amount of the iodine. A proportional relation is observed between the collected amount and the integrated value obtained from the sensor with a platinum collector, but not found between the amount and the value obtained from the sensor with a stainless steel collector.
Sazarashi, Masami*; *; Ikeda, Yasuhisa*; Kumagai, Mikio*; *; *
PNC TJ1564 97-002, 20 Pages, 1997/03
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Sazarashi, Masami*; Ikeda, Yasuhisa*; Kumagai, Mikio*; *; *
PNC TJ1564 96-002, 19 Pages, 1996/03
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