Migration behavior of stable and radioactive strontium in natural aquifer

Tanaka, Tadao; Mukai, Masayuki; Maeda, Toshikatsu; Munakata, Masahiro; Matsumoto, Junko; Ogawa, Hiromichi; Bamba, Tsunetaka*; Wang, Z.*; Yang, Y.*; Zhao, Y.*

Proceedings of International Symposium on Radioecology and Environmental Dosimetry, p.179 - 184, 2003/00

Migration behaviors of stable strontium element and radioactive nuclide strontium 90 in natural aquifer were studied by a field test, which was performed in the aquifer loess zone at 30 m under the ground surface of the field test site of China Institute for Radiation Protection. The migration behavior of stable strontium was a little different from that of Sr. The difference was evaluated by applying the distribution coefficient considering Sr and coexistent ion concentrations. Migration behavior of radionuclide in natural environment has been generally demonstrated on field tests without radioactive tracers and/or large-scale column tests with radioactive tracers. Such tests seem to be valuable to improve reliability of the migratory evaluation.

Behavior of carbon-14 in the Tokai reprocessing plant

; ; ;

JNC-TN8410 2001-021, 33 Pages, 2001/09

JNC-TN8410-2001-021.pdf:4.37MB

Carbon-14 released from the nuclear facilities is an important radionuclide for the safety assessment, because it tends to accumulate in environment through food chain and has as a significant impact to personal dose. Carbon-14 has been monitored routinely as one of the main gaseous radionuclides exhausted from the Tokai Reprocessing Plant (TRP) since OCtober of 1991. Furthermore, behavior of carbon-14 in TRP has been investigated through the reprocessing operation and the literature survey. This report describes the result of investigation about the behavior of carbon-14 in TRP as followings. (1)Only a very small amount of carbon-14 in the fuel was liberated into the shear off-gas and most of it was liberated into the dissolver of-gass. Part of the carbon-14 was trapped at the caustic scrubber installed in the of-gas treatment process, and untrapped carbon-14 was released into the environment from the main stack. Amount of carbon-14 released from the main stack was about 4.16.5GBq every ton of uranium reprocessed. (2)Carbon-14 trapped at the caustic scrubbers installed in the dissolver off-gas and in the vessel off-gas treatment process is transferred to the low active waste vessel. Amount of carbon-14 transferred to the low active waste vessel was about 5.4 9.6GBq every ton of uranium reprocessed. (3)The total amount of carbon-14 input to TRP was summed up to about 11.915.5 GBq every ton of uranium reprocessed considering the released amount from the main stack and the trapped amount in the off-gas treatment devices. The amount of nitrogen impurity in the initial fuel was calculated about 1522ppm of uranium metal based on the measured carbon-14. (4)The solution in the low active waste vesselis concentrated at the evaporator.Most of the carbon-14 in the solution was transferred into concentrated solution. (5)Tokai vitrification Demonstration Facility (TVF) started to operate in 1994. Since then, carbon-14 has been measured in the ...

Annual report on the environmental radiation monitoring around Tokai reprocessing plant FY 2000

Maruo, Yoshihiro; ; Takeishi, Minoru; ; ; Takeyasu, Masanori;

JNC-TN8440 2001-011, 146 Pages, 2001/06

JNC-TN8440-2001-011.pdf:2.98MB

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.

The Results of the envilonmental monitoring related to the criticality accident in JCO

Shinohara, Kunihiko; ; ; ; ; Kano, Yutaka;

JNC-TN8440 2001-004, 62 Pages, 2001/02

JNC-TN8440-2001-004.pdf:4.17MB

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.

Macroscopically and microscopically research about structure of faults at a repository scale

*; *; Morooka, Koichi*

JNC-TJ8400 2000-043, 171 Pages, 2000/03

JNC-TJ8400-2000-043.pdf:5.27MB

This study is an object to collect and arrange data about the mass transfer path during a natural barrier system by grasping actual rock feature, in order to be useful for a performance assessment of a natural barrier system at geological disposal of HLW. An existence of permeability high large-scale faults extends a large influence over a performance assessment of geological disposal. With "The Second Progress Report on Research and Development for the Geological Disposal of HLW in Japan" which Nuclear Cycle Development Institute (JNC) issued, it is as" A repository would be located at least 100 meters away from major faults and major fracture zones which could adversely affect the stability and performance of the repository" as a Reference Case concept model of a natural barrier system, Then, they are as "in the Reference Case, the transport path consists of the host rock and the downstream fault". It will not be easy to know the distribution of faults in the subsurface deep division without data acquired from many boreholes and underground laboratory. With this study, specific data on the large-scale faults and fracture zones has been collected and arranged by investigating in underground galleries and on the literatures of a post-operated mine site. Based on this result, a consideration on the principal transfer pass at a natural barrier system has been conducted. The contents conducted in this report is the follows. (1)investigation of literature about data of fracture, shear zone, and geology, (2)field investigation of fracture and shear zone in the rock, (3)arrangement of these results, (4)modeling of the major water conductive feature, and (5)evaluation of an assumption which has been introduced in the Second Progress Report issued by JNC.

Study on the nuclide behavior in nuclear fuel recycling system

Fujii, Toshiyuki*; *

JNC-TJ9400 2000-003, 36 Pages, 2000/02

JNC-TJ9400-2000-003.pdf:1.36MB

For establishing a recycling system based on low-decontamination, the distribution behaviors of radionuclides in the process are essential information for the design of the system. Molybdenum and palladium are less radioactive fission products, but attention should be paid to them because they are likely to extremely affect the performance of the recycled fuels. In this context, in this study, the extraction behaviors of molybdenum and palladium under conditions of PUREX and TRUEX extraction process were experimentally studied, and their chemical mechanisms were discussed. In cojunction with the extraction experiments, absorption spectrometry was applied to identify the related species and the extraction mechanism. As a result, knowledge for the distribution characteristics of molybdenum and palladium in PUREX and TRUEX process was reinforced.

None

Ikeda, Takao*; Yoshida, Hideji*; *

JNC-TJ8400 2000-045, 134 Pages, 2000/02

JNC-TJ8400-2000-045.pdf:4.12MB

None

Study on microbial transport and adsorption behavior on engineering barrier for geological disposal of radioactive wastes

Fukunaga, Sakae*; Yokoyama, Hidekazu*; Arai, Kazuhiro*; Asano, Hidekazu*; Senjyu, Takafumi*; Kudo, Akira*

JNC-TJ8400 2000-029, 36 Pages, 2000/02

JNC-TJ8400-2000-029.pdf:1.28MB

It is easy to assume from the past data that microbial transport do not find at 100%-sodium bentonite. Microbial transport do not find at 100%-calcium bentonite too. There are no effects to distribution ration (Kd) of Neptunium (Np) and Plutonium (Pu) with bentonite by sterilizing on low Eh condition (Eh = -500mv). Kd values of Np and Pu show behavior, which are increasing on the hard acidic and alkali conditions. Especially, Kd values of Pu shows one of Kd value is about 100 ml/g on pH = 36, but the other of Kd value is about 400,000 ml/g on pH = 13. Precipitating plutonium hydrates occurred the large Kd value on alkali condition.

Distribution of actinide elements among various environmental factors (II)

Kudo, Akira*; *

JNC-TJ8400 2000-010, 67 Pages, 2000/02

JNC-TJ8400-2000-010.pdf:2.17MB

The first and second environmental releases of man-made Pu came from nuclear explosions at Alamagordo and Nagasaki in 1945. The release at Nagasaki was more serious than at Alamagordo, because it happened in an area with a high population density. Unfissioned Pu and various fission products have been interacting here with various environmental materials (soils, sediments, and plants) under wet and temperature conditions for more than 45 years. To assess the environmental mobility of Pu, the distributions of radionuclides from this release were investigated at Nishiyama where heavy black rain containing unfissioned plutonium and fission products fell 30 minutes after the nuclear explosion. The vertical distributions of Cs and Pu were determined in unsaturated soil cores up to 450cm deep. Most radionuclides were found in the soil column 30cm from the ground surface. However, Pu were detected in the groundwater as well below a depth of 200cm. No Cs was found below 40cm from the ground surface or in groundwater. These observations reveal that about 3% of the total Pu have been migrating in the soil at a faster rate than the remaining Pu. Sharp peak of Cs and Pu, indicating heavy deposition from the Nagasaki local fallout of 1945, were found in sediment cores collected from the Nishiyama reservoir. Pu peaks were unexpectedly discovered in pre-1945 sediment core sections. NO Cs was found. By contrast to the distribution in sediment cores, Cs in tree rings had spread by diffusion from the bark to the center of the tree without holding a fallout deposition record. Most of the Pu was distributed in the tree rings following a similar deposition record to that found in sediment cores. Furthermore, a very small amount of Pu (about 1%) was found unexpectedly in pre-1945 tree rings. The only reasonable ...

Tests on decisive proof for the incinerating and melting facility using the in-can type high frequency induction heating

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JNC-TN9410 2000-002, 149 Pages, 1999/12

JNC-TN9410-2000-002.pdf:23.51MB

LEDF (Large Equipment Dismantling Facility) is the solid waste processing technology development facility that carries out high-volume reduction and low dosage processing. The high-volume reduction processing of the high dose -waste configured with combustible waste, pvc & rubber, spent ion exchange resin, and noncombustible waste have been planned the incinerating and melting facility using the in-can type high frequency induction heating in LEDF. This test is intended to clarify the design data. It was confirmed that the incinerating and melting performance, molten solid properties and exhaust gas processing performance with pilot testing equipment and bench scale equipment. The result of this test are as follows. (1)Processing speed is 6.7kg/h for the combustible waste, 13.0kg/h for the ion exchange resin, and 30.0kg/h for the noncombustible waste. For above optimum processing conditions are as follows. (a)Operating temperature is 1000C for the combustible waste, 1300C for the ion exchange resin, 1500C for the noncombustible waste. (b)Air flow is 90Nm/h. Air temperature is 300C. Air velocity is 20m/s. (2)Incineration time per day is 5h. Warm-up time and incineration time from the stop of waste charging is 0.5h. Melting time per day is 5h inconsideration of heating hold time of incinerated ash and melting of quartz. Warm-up time is 0.5h. (3)The system decontamination factor in Co, Cs and Ce with pilot testing equipment is 10 or more. (4)Design data of the iron doped silica gel judged to be have a applicability as RuO gas absorber is as follows. (a)Its diameter distribute in the range of 0.8-1.7mm. (b)To have a decontamination factor of 10 can achieve for retention time of 3 seconds and its life time is about 1 year. (5)In terms of the distribution of the nuclear species in molten solid is evenly distributed. It was also confirmed that the distribution of main elements in ceramic layer is ...