Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 25

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Retraction; Estimation of corrosion rate of Zr-2.5wt%Nb alloy (Fugen pressure tube) under low-temperature, low-oxygen, and high-pH conditions

Sakatani, Keiichi*; Nakatani, Takayoshi; Funabashi, Hideyuki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 18(1), P. 43, 2019/03

The article authored by Keiichi Sakatani et al. and titled "Estimation of corrosion rate of Zr-2.5wt%Nb alloy (Fugen pressure tube) under low-temperature, low-oxygen, and high-pH conditions", Journal of the Atomic Energy Society of Japan, Vol.14, No.4, p.261-267 (2015), has been found to have a problem about reliability of the corrosion data acquisition, and thus retracted by the authors.

Journal Articles

Retraction; Estimation of corrosion rate of Zr-2.5wt%Nb alloy (Fugen pressure tube) under low-temperature, low-oxygen, and high-pH conditions

Sakatani, Keiichi; Nakatani, Takayoshi; Funabashi, Hideyuki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 14(4), p.261 - 267, 2015/12

The safety assessment of the sub-surface disposal system should ensure that calculated dose rate will be lower than the dose rate assigned to the scenario in question over the whole evaluation period. For activated metal wastes which are the reactor structural materials classified as one of the subject wastes, the rate of nuclide elution under the disposal environment is an important parameter in safety assessment. Some reports have shown that nuclides in a metal matrix are released with corrosion congruently. However, the corrosion rate under low temperature, low oxygen and high pH conditions assuming the disposal environment is not reported about Zr-2.5wt%Nb alloy, which is used in the pressure tube of Fugen (ATR). The gas-accumulating type corrosion test on Zr-2.5wt%Nb alloy was conducted in order to obtain corrosion rate. The corrosion rate after 1 month, 3 months, 6 months, 12 months and 24 months was obtained during the test period.

JAEA Reports

Development of the assessment tools for land use scenarios concerning sub-surface disposal

Sakatani, Keiichi; Sugaya, Toshikatsu; Nakatani, Takayoshi; Funabashi, Hideyuki

JAEA-Data/Code 2014-008, 53 Pages, 2014/06

JAEA-Data-Code-2014-008.pdf:39.9MB

The safety assessment of the sub-surface disposal system should ensure that calculated dose will be lower than the dose assigned to the scenario in question during the period from now to future. In order to realize the safety disposal, we have developed several assessment tools on the GoldSim platform and calculated doses since 2008, and these assessment tools have been improved reflecting the last view of assessment. This report describes idea of assessment models and structure of assessment tools for land use scenarios.

JAEA Reports

Development of the assessment tool for groundwater scenario concerning sub-surface disposal

Sakatani, Keiichi; Sugaya, Toshikatsu; Nakatani, Takayoshi; Funabashi, Hideyuki

JAEA-Data/Code 2013-015, 63 Pages, 2013/11

JAEA-Data-Code-2013-015.pdf:8.75MB

The safety assessment of the sub-surface disposal system should ensure that calculated dose will be lower than the dose assigned to the scenario in question during the period from now to future. In order to realize the safety disposal, we have developed several assessment tools on the GoldSim platform and calculated doses since 2008, and these assessment tools have been improved reflecting the last view of assessment. This report describes safety functions of the disposal system, idea of nuclide migration, formulas for nuclides migration, formulas of exposure dose and structure of assessment tool for groundwater scenario.

JAEA Reports

Corrosion test of Fugen pressure tube (Zr-2.5wt%Nb alloy) under the sub-surface disposal environment; Examination of processable method for specimen and confirmation of optimal test conditions

Sakatani, Keiichi; Nakatani, Takayoshi; Funabashi, Hideyuki

JAEA-Technology 2012-034, 20 Pages, 2012/12

JAEA-Technology-2012-034.pdf:10.22MB

We planned the gas-accumulating type corrosion test on Zr-2.5wt%Nb alloy which is used in the pressure tube of Fugen (ATR) in order to obtain long-term corrosion rate data under the low oxygen and alkaline conditions assuming the disposal environment. Before starting the test, we examined the specimen machining method and confirmed the corrosion test conditions.

JAEA Reports

Study of parameters for safety assessment of sub-surface disposal; Tunnel-excavating speed and thickness of additional soil in residential land development by filling

Ishitoya, Kimihide; Sugaya, Toshikatsu; Funabashi, Hideyuki

JAEA-Research 2011-046, 32 Pages, 2012/02

JAEA-Research-2011-046.pdf:3.52MB

Nuclear Safety Commission of Japan (NSC) issued "Policy of the Safety Assessment of Sub-surface Disposal after the Period for Active Control" (April 1, 2010). Then, we investigated the parameters for dose assessment in tunnel excavation scenario and large-scale land use scenario which were described in the "Policy of the Safety Assessment", in order to perform the assessment based on actual conditions. To be concrete, we investigated the tunnel excavating speeds in Japan for the former scenario, and investigated technical standards of the filling for the latter scenario. We studied the realistic parameters for the dose assessment with the results of those investigations.

JAEA Reports

A Study for the safety evaluation of geological disposal of TRU waste and influence on disposal site design by change of amount of TRU waste (Joint research)

Hasegawa, Makoto; Kondo, Hitoshi; Kamei, Gento; Hirano, Fumio; Mihara, Morihiro; Takahashi, Kuniaki; Funabashi, Hideyuki; Kawatsuma, Shinji; Ueda, Hiroyoshi*; Oi, Takao*; et al.

JAEA-Research 2011-003, 47 Pages, 2011/02

JAEA-Research-2011-003.pdf:3.99MB

In 2009, NUMO and JAEA set up a technical commission to investigate the reasonable TRU waste disposal following a cooperation agreement between these two organizations. In this report, the calculation result of radionuclide transport for a TRU waste geological disposal system was described, by using the TIGER code and the GoldSim code at identical terms. Comparing the calculation result, a big difference was not seen. Therefore, the reliability of both codes was able to be confirmed. Moreover, the influence on the disposal site design (Disposal capacity: 19,000 m$$^{3}$$) was examined when 10% of the amount of TRU waste increased. As a result, it was confirmed that the influence of the site design was very little based on the concept of the Second Progress Report on Research and Development for TRU Waste Disposal in Japan.

JAEA Reports

Study of sub-surface disposal concepts for uranium waste, 6

Nakatani, Takayoshi; Ishitoya, Kimihide; Funabashi, Hideyuki; Sasaki, Ryoichi*; Kurosawa, Mitsuru*

JAEA-Research 2010-050, 104 Pages, 2011/02

JAEA-Research-2010-050.pdf:2.03MB

In July 2007, the Nuclear Safety Commission of Japan (NSC) formulated "Basic Policy for Safety Regulation Concerning Land Disposal of Low-Level Radioactive Waste (Interim Report)". "Classification of Scenarios into Three Types" and their "Standard Dose Values" were indicated in this report. In this study, some scenarios for safety assessment were developed as "Inadvertent Human Intrusion or Rare Natural Event Scenarios" based on the previous technical documents. The parameters were set up for dose calculation and the exposure doses were calculated. As the result, exposure doses in all cases were less than 10 mSv/y$$sim$$100 mSv/y (standard exposure dose of "Inadvertent Human Intrusion or Rare Natural Event Scenarios").

JAEA Reports

Study of "Inadvertent Human Intrusion or Rare Natural Event Scenarios" for sub-surface disposal of radioactive waste

Nakatani, Takayoshi; Ishitoya, Kimihide; Funabashi, Hideyuki; Sugaya, Toshikatsu; Sone, Tomoyuki; Shimada, Hidemitsu*; Nakai, Kunihiro*

JAEA-Research 2009-064, 104 Pages, 2010/03

JAEA-Research-2009-064.pdf:14.45MB

The purpose of this study was to assess exposure dose of "Inadvertent Human Intrusion or Rare Natural Event Scenarios" on sub-surface disposal. It was one of "Classification of three types scenarios" in "Basic Policy for Safety Regulation Concerning Land Disposal of Low-Level Radioactive Waste (Interim Report)" formulated by the Nuclear Safety Commission of Japan. Selection of the assessed scenarios, development of the assessment tool and preliminary exposure dose assessment were conducted. Exposure dose of "Well water drinking scenario" was the highest in the assessed scenarios. This scenario assumed that the groundwater in Excavation Disturbed Zone (EDZ) was directly used as drinking water without any dilution. Although this was very conservative condition and the result exceeded 10 mSv/y, it was under the upper limit of standard dose value (10$$sim$$100 mSv/y) in the Interim Report for "Inadvertent Human Intrusion or Rare Natural Event Scenarios".

JAEA Reports

Study of "Likely Scenarios" and "Less-likely Scenarios" for sub-surface disposal of radioactive waste

Sugaya, Toshikatsu; Sone, Tomoyuki; Nakatani, Takayoshi; Ishitoya, Kimihide; Funabashi, Hideyuki; Sasaki, Ryoichi*; Shimoda, Satoko*; Kurosawa, Mitsuru*

JAEA-Research 2009-063, 80 Pages, 2010/03

JAEA-Research-2009-063.pdf:8.35MB

The purpose of this study was to assess exposure dose of "Likely Scenarios" and "Less-likely Scenarios" on sub-surface disposal. They were two of "Classification of three types scenarios" in "Basic Policy for Safety Regulation Concerning Land Disposal of Low-Level Radioactive Waste (Interim Report)" formulated by the Nuclear Safety Commission of Japan. Selection of the assessed scenarios, development of the assessment tool and preliminary exposure dose assessment were conducted. Maximum exposure doses for "Likely Scenarios" and "Less-likely Scenarios" were less than each standard dose value in the Interim Report (Likely Scenarios: 10$$mu$$Sv/y, Less-likely Scenarios: 300$$mu$$Sv/y).

JAEA Reports

Study of subsurface disposal concepts for uranium waste, 5

Nakatani, Takayoshi; Ishitoya, Kimihide; Funabashi, Hideyuki; Sasaki, Ryoichi*; Kurosawa, Mitsuru*

JAEA-Research 2009-028, 47 Pages, 2009/10

JAEA-Research-2009-028.pdf:13.29MB

This study was carried out the evaluation of exposure dose on "Less-likely Scenarios" according to "Basic Policy for Safety Regulation Concerning Land Disposal of Low-Level Radioactive Waste (Interim Report)" (In July 2007, the Nuclear Safety Commission of Japan). When the evaluation modeling was constructed, "Evaluation scenario" and "Fluctuating parameter" were simplified "Physical, chemical change of the disposal system according to the climatic variation and the tectonic movement" that was the event foreseen happening in the future to "Release coefficient from the disposal facilities of the nuclide", "Distribution coefficient of the natural barrier", "Velocity of the underground water", and "Distance of the transfer path". As the result, exposure doses in all cases for "Less-likely scenarios" were less than 300 $$mu$$Sv/y (standard exposure dose of "Less-likely Scenarios").

JAEA Reports

Study of subsurface disposal concepts for uranium waste, 4

Ishitoya, Kimihide; Nakatani, Takayoshi; Funabashi, Hideyuki; Sasaki, Ryoichi*; Takase, Toshio*; Kurosawa, Mitsuru*

JAEA-Research 2008-092, 64 Pages, 2008/12

JAEA-Research-2008-092.pdf:6.33MB
JAEA-Research-2008-092(errata).pdf:0.23MB

In this study, some scenarios for safety assessments were developed. According to each developed scenario, the parameters were set up for dose calculation. Calculated results were analyzed and summarized from the viewpoints of effects of radionuclide migration parameters such as release coefficient, distribution coefficient, ground water velocity and migration distance. Dose more than 10 $$mu$$ Sv/y was calculated in some cases. Increase of ground water velocity or decrease of distribution coefficient caused by sea water inflow into migration path influenced slightly on the dose excess. In case of rapid change of the parameters, severe influences on the dose excess were observed. But, it wasn't thought that this rapid change would happen actually. On the other hand, in case of linear assumption of parameter change from 10,000 y to 100,000 y, dose less than 10 $$mu$$ Sv/y was calculated.

JAEA Reports

Study of sub-surface disposal concepts for uranium waste, 3

Tsujimura, Seiichi; Funabashi, Hideyuki; Ishibashi, Makoto*; Takase, Toshio*; Kurosawa, Mitsuru*

JAEA-Research 2007-030, 105 Pages, 2007/03

JAEA-Research-2007-030.pdf:7.72MB

Uranium waste has characteristics that it is rarely expected to decay its radioactivity and it is not almost recessary to consider external exposure to radiation from waste package. We studied resonable sub-surface disposal concepts for uranium waste considering the characteristics. It showed feasibility of this system. In 2006, the study was done to evaluate the correlation between dose to the public and the parameter in consideration of the uncertainty of the parameter by comprehensive sensitivity analysis calculating repeatedly dose with the data sets by random sampling in parameter ranges given adequately, because last year's study was an evaluation intended for a limited site. The result was that two parameters, "flow velocity of underground water of repository neighborhood" and "distribution coefficient of uranium in natural barrier", had correlation with dose to the public.

Journal Articles

Clearance concerning the Uranium Handling Facilities

Funabashi, Hideyuki; Katayose, Naoto*; Iwasawa, Nobuo*

Dekomisshoningu Giho, (34), p.40 - 44, 2006/09

The characteristics of Uranium contaminated waste and the expected material for clearance from the Uranium handling facilities of Japan Nuclear Fuel Limited, Uranium fuel fabricators and Japan Atomic Energy Agency are described. This paper also explains the method to establish the value of activity concentration applicable to clearance level of Uranium stated in the IAEA safety guide RS-G-1.7 "Application of the Concepts of Exclusion, Exemption and Clearance" and the applicability of the method in Japan.

JAEA Reports

Study of sub-surface disposal concepts for uranium waste, 2

Tsujimura, Seiichi; Funabashi, Hideyuki; Ishibashi, Makoto*; Takase, Toshio*; Kurosawa, Mitsuru*

JAEA-Research 2006-029, 96 Pages, 2006/07

JAEA-Research-2006-029.pdf:3.97MB

Uranium waste has characteristics that it is rarely expected to decay its radioactivities and it is not almost necessary to consider external exposure to radiation from waste package. We studied reasonable sub-surface disposal concepts for uranium waste in 2004 and 2005 considering the characteristics. In 2005, we studied necessity of engineered barrier for the disposal of uranium waste, considering change of chemical condition around disposal facilities over long periods of time. Safety assessment was made to analyze effect of difference in sorption parameters at reduction and oxidation conditions. The assessment showed that change from reduction to oxidation around disposal facilities did not lead to increase dose to the public. The assessment with realistic sorption parameters showed that dose to the public was not more than 10 $$mu$$Sv/y. The results proved that it was not necessary to keep reduction conditions around disposal facilities. This two-year- study showed that there was possibility of sub-surface disposal system without engineered barrier for uranium waste.

Oral presentation

Characteristics of waste from nuclear fuel facilities

Hirai, Teruyuki*; Funabashi, Hideyuki; Iwasawa, Nobuo*

no journal, , 

no abstracts in English

Oral presentation

None

Kawatsuma, Shinji; Funabashi, Hideyuki; Yagi, Naoto; Kudo, Kenji; Tsujimura, Seiichi; Fukushima, Tadashi

no journal, , 

no abstracts in English

Oral presentation

Study of subsurface disposal concepts for uranium waste

Nakatani, Takayoshi; Funabashi, Hideyuki; Ishitoya, Kimihide; Sasaki, Ryoichi*; Takase, Toshio*; Kurosawa, Mitsuru*

no journal, , 

no abstracts in English

Oral presentation

Safety assessment of sub-surface disposal for uranium waste

Nakatani, Takayoshi; Funabashi, Hideyuki; Ishitoya, Kimihide; Sasaki, Ryoichi*; Kurosawa, Mitsuru*

no journal, , 

no abstracts in English

Oral presentation

Dose assessment for sub-surface disposal of radioactive waste, 1; Study of "Likely Scenarios" and "Less-likely Scenarios"

Nakatani, Takayoshi; Sugaya, Toshikatsu; Sone, Tomoyuki; Ishitoya, Kimihide; Funabashi, Hideyuki; Sasaki, Ryoichi*; Shimoda, Satoko*; Kurosawa, Mitsuru*

no journal, , 

The propose of study was safety assessment of "Likely scenarios" and "Less-likely scenarios" on sub-surface disposal. They were two of "Classification of three types scenarios" in "Basic Policy for Safety Regulation Concerning Land Disposal of Low-Level Radioactive Waste (Interim Report)" formulated by the NSC. Selection of the assessed scenarios, development of the assessment tool and preliminary exposure dose assessment were conducted according to the standard of the AESJ. As the results, Maximum exposure doses for "Likely Scenarios" and "Less-Likely Scenarios" were less than each standard dose value in the Interim Report (Likely Scenarios: 10$$mu$$Sv/y, Less-Likely Scenarios: 300$$mu$$Sv/y).

25 (Records 1-20 displayed on this page)