Design study on cover soil in the trench disposal facility for very low-level radioactive waste generated from research facilities and other facilities

Ogawa, Rina; Nakata, Hisakazu; Sugaya, Toshikatsu; Sakai, Akihiro

JAEA-Technology 2022-010, 54 Pages, 2022/07

JAEA-Technology-2022-010.pdf:11.07MB

Japan Atomic Energy Agency has considered trench disposal as one of the disposal methods for radioactive wastes generated from research facilities and other facilities. The trench disposal facility is regulated by "Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors". In particular, the design of the trench facility is regulated by a rule under the law. When the rule was amended in 2019, the design of the trench disposal facility required equipment to reduce ingress of rain water and groundwater. In the report, studies on the design of a trench disposal facility to adapt to the amended rule were performed. The trench disposal facility has considered being established in a place lower than groundwater level. Therefore, it was decided to study covering soil at the upper part of the trench facility, because the ingress water in the facility is mainly derived from rain water. In this study, it was decided to evaluate the design of covering soil of the radioactive waste categorized into chemically stable materials. Therefore, as the examination method, a parameter study on varying the permeability coefficient and thickness of the layers composing cover soil. In the parameter study, the velocity of the water infiltrating into the trench facility was evaluated. Based on the results, more efficient design of the layers composing the covering soil was considered. The result showed that the impermeable efficiency of the covering soil was different depending on the thickness and the permeability conductivity of each layer. As a result, it was possible to understand the impermeable performance of covering soil by the permeability coefficient and thickness of each layer. We will plan to decide the specification of the cover soil while examination of future tasks and cost in the basic design.

Estimation of radioactive substance penetration in basement concrete

Tezuka, Masashi; Koda, Yuya; Fujita, Yoshihiko*; Kume, Kyo*

Heisei-26-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 17, P. 78, 2015/10

In order to contribute to the segregated management in accordance with the level of contamination such as dismantling products, as a basis frame concrete specimens of the condenser, which has been laid in the turbine building of the "Fugen", pre-observation of such cracks status of surface on which was carried out to investigate the pollution status of internal specimen.

Annual data compilation of water balance observation in the Regional Hydrogeological Study Project (RHS Project); For the fiscal year 2013

Ueno, Tetsuro; Takeuchi, Ryuji

JAEA-Data/Code 2015-006, 22 Pages, 2015/06

JAEA-Data-Code-2015-006.pdf:5.05MB
JAEA-Data-Code-2015-006-appendix(CD-ROM).zip:14.52MB

Tono Geoscience Center of Japan Atomic Energy Agency (JAEA) has carried out the subsurface water balance observation in order to estimate groundwater recharge rate for setting the upper boundary conditions on groundwater flow simulation and to obtain data for calibration of hydrogeological model. In the subsurface water balance observations, precipitation data and river flow rate have been observed in the Garaishi River and the Hiyoshi River watersheds. The missing or abnormal data in the monitoring data during the fiscal year 2013 were complemented or corrected, and these data were compiled in data set.

Water permeability test of rock specimen with natural fractures using high viscosity liquid

*;

JNC TN8430 2001-006, 65 Pages, 2001/10

JNC-TN8430-2001-006.pdf:15.23MB

We had been conducted to study hydraulic permeability along fracture intersection by NETBLOCK system using natural rock specimen. Since the permeability of this rock specimen fracture is high, it was suggest that turbulent flow might be occurred in available range of measurement system. In case of turbulent flow, estimated permeability and fracture aperture from test data tend to be low. Therefore we should achieve laminar flow. This study was used the high viscosity liquid instead of water, and test conditions which could attain laminar flow with the rock specimen was examined. The rock specimen is granite rock, has natural Y-type fractures intersection. A solution of Methyl-cellulose is used as high viscosity liquid. Due to the high viscosity liquid, hydraulic head could be measured in the wide range, and high viscosity liquid improved the accuracy of measurement. Laminar flow could be achieved in the rock specimen by the high viscosity liquid over 0.1wt%.

Examination of hydraulic property of natural rock specimen

*; *;

JNC TN8430 2001-003, 64 Pages, 2001/03

JNC-TN8430-2001-003.pdf:10.04MB

Handling methods and test conditions of hydraulic tests for NETBLOCK system had been examined by using acrylic and/or artificial rock specimen. A natural rock specimen (granite : excavated from Kamaishi mine) with fracture intersection was formed into practicable size for NETBLOCK system. Recently, we conducted a series of hydraulic test, in order to study the influence of fracture intersection by using the natural rock specimen. Hydraulic tests were conducted under several centimeters of head, which could be controlled by improved system because hydraulic permeability of target fractures were high. As a result, 1010(m/s) orders of hydraulic transmissivity of target fractures could be measured. A low permeability in the NW direction at the lower fracture was estimated from the heterogeneous head distribution. However, it is also expected that turbulence flow might be occurred under this study condition because fracture permeability is high and flow rate through the fracture is relatively high. In case of turbulence-flow, an estimated hydraulic transmissivity is low. High-viscosity fluid hydraulic test to achieve laminar flow will be needed for correcting an evaluated transmissivity.

None

*

JNC TJ7400 2000-015, 203 Pages, 2000/08

JNC-TJ7400-2000-015.pdf:6.07MB

no abstracts in English

Reliability evaluation of simulation models for nearfield groundwater flow and radionuclide transport computation

*; *; *; *

JNC TJ8400 2000-005, 71 Pages, 2000/05

JNC-TJ8400-2000-005.pdf:4.0MB

In this research, simulations with some parameters which characterize ground water flow and the reliability evaluation for the expansion of the calculation method of groundwater flow were carried out by using the radionuclide transport computations in nearfield heterogeneous porous media. Concretely contents are follows: (1)With the series of calculation method for three-dimensional saturated/unsaturated groundwater flow and one-dimensional radionuclide transport, the computational analyses with the parameters used in JNC report in 2000 was carried out and the influence of the different input flux was evaluated. (2)The examination of the application for the different ways of inverse laplace transformation which is used in one-dimensional radionuclide transport analysis code "MATRICS" was carried out. (3)The examination of the application of multi-element "MATRICS" (m-MATRICS) for radionuclide transport computations in nearfield heterogeneous porous media was carried out. (4)The series of calculation methods from three-dimensional saturated/unsaturated ground water flow simulation code to one-dimensional radionuclide transport simulation code was integrated.

None

JNC TN1400 99-016, 171 Pages, 1999/08

JNC-TN1400-99-016.pdf:8.97MB

no abstracts in English

None

*

JNC TJ1400 99-016, 24 Pages, 1999/02

JNC-TJ1400-99-016.pdf:0.86MB

no abstracts in English

None

; ; Ishibashi, Yuzo; Takeda, Seiichiro; *; Fujisaku, Kazuhiko*; *

PNC TN8410 98-116, 147 Pages, 1998/08

PNC-TN8410-98-116.pdf:8.42MB

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