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Morita, Yasuji; Tsubata, Yasuhiro
JAEA-Data/Code 2019-015, 45 Pages, 2020/01
JAEA-Data-Code-2019-015.pdf:2.09MB
Decay heat from radioactive elements in high-level liquid waste (HLLW) and separated solutions in partitioning process was evaluated as a basic data for safety assessment of partitioning process. In the evaluation of HLLW from spent UO
fuel burned-up to 45 GWd/t in light water reactor, decay heat value from fission products decreased as the cooling period become longer but heat from actinides, Am and Cm, was almost constant until 50-year cooling. Decay heat density in solutions of Am, Cm and rare earth elements and of Am and Cm without concentration for volume reduction does not exceed the heat density of HLLW, but the concentration should be required to minimize the scale of the partitioning process. Separated solution of Am and Cm must be concentrated to convert the two elements to a solid state to make fuel for transmutation, and the decay heat density of the concentrated solution of Am and Cm is 10 times higher compared with the Pu solution of same element concentration. Higher burn-up UO fuel and MOX fuel in light water reactor and minor-actinide-recycled MOX fuel in fast reactor were also considered and the evaluated decay heat was compared among the spent fuels.
Abe, Hitoshi; Tashiro, Shinsuke; Miyoshi, Yoshinori
Nihon Genshiryoku Gakkai Wabun Rombunshi, 6(1), p.10 - 21, 2007/03
In MOX fuel fabrication facility, zinc stearate will be added into the MOX powder as addition material. If the material is added in large excess by miss operation, criticality characteristics of the MOX fuel would be influenced because it has neutron moderation effect. If criticality condition should be induced by the excess addition, physical variations, such as melting and pyrolysis of the material, must be caused by the fission energy and dynamic characteristics of the MOX fuel must be affected. To contribute quantitative evaluation of the dynamic characteristics, thermal properties data such as exo/endothermic calorific values, reaction rates, etc. with the respective physical variations and release behavior of pyrolysis gas were measured. It was found the exo/endothermic behavior with rinsing temperature of the material could be divided into six regions and rapid pressure rise caused by the pyrolysis reaction over about 400 
C. Furthermore, on the basis of the results, evaluation model for the thermal properties under the criticality condition was also investigated.
Ida, Mizuho*; Nakamura, Hiroo; Shimizu, Katsusuke*; Yamamura, Toshio*
Fusion Engineering and Design, 75-79, p.847 - 851, 2005/11
Times Cited Count：3 Percentile：24.22(Nuclear Science & Technology)no abstracts in English
Nishitani, Takeo; Yamauchi, Michinori*; Izumi, Mikio*; Kusama, Yoshinori
JAERI-Tech 2005-047, 34 Pages, 2005/09
JAERI-Tech-2005-047.pdf:6.75MB
no abstracts in English
Morita, Yasuji
Genshikaku Kenkyu, 47(6), p.21 - 30, 2003/06
This paper describes the present state and future prospect of research and development on the separation of long-lived radionuclides from high-level waste (partitioning), which is indispensable for the transmutation of those nuclides. The main items described are composition of high-level waste, selection of elements to be separated, the purpose of partitioining, and development of partitioning process in JAERI.
Morioka, Atsuhiko; Sakasai, Akira; Masaki, Kei; Ishida, Shinichi; Miya, Naoyuki; Matsukawa, Makoto; Kaminaga, Atsushi; Oikawa, Akira
Fusion Engineering and Design, 63-64, p.115 - 120, 2002/12
Times Cited Count：11 Percentile：58.11(Nuclear Science & Technology)no abstracts in English
Aoyagi, Takayoshi*; *; Mihara, Morihiro; Okutsu, Kazuo*; Maeda, Munehiro*
JNC TN8400 2001-024, 103 Pages, 2001/06
JNC-TN8400-2001-024.pdf:8.84MB
In the disposal concept of TRU waste, concentrated disposal of wastes forms in large cross-section underground cavities is envisaged, because most of TRU waste is no-heat producing in spite of large generated volume as compared with HLW. In the design of engineered barrier system based on large cross-section cavities, it is necessary to consider the long-term mechanical process such as creep displacement of the host rock from the viewpoint of the stability of engineered barrier system. In this study, the long-term creep displacement of the host rock was calculated using the non-linear viscoelasticity model and the effects on the stability of engineered barrier system was evaluated. As a result, in the disposal concept of crystalline rock, no creep displacement occurred at the time after 1 milion year. On the other hand, in the disposal concept of sedimentary rock, creep displacement of 80
90mm occurred at the time after 1 milion year. Also, in this calculation, a maximum reduction of 45mm concerned with the thickness of buffer material was estimated. But these values resulted within allowance of design values. Therefore, these results show that the effects of the creep displacement on the stability of engieered barrier system would not be significant.
Kai, Tetsuya; Teshigawara, Makoto; Watanabe, Noboru; Harada, Masahide; Sakata, Hideaki*; Ikeda, Yujiro
JAERI-Conf 2001-002, p.786 - 792, 2001/03
no abstracts in English
; Ohno, Shuji;
JNC TN2400 2000-006, 56 Pages, 2000/12
JNC-TN2400-2000-006.pdf:1.22MB
Sodium combustion analyses were performed using ASSCOPS version 2.1 in order to obtain background data for evaluating the validity of the mitigation system against secondary sodium leak of MONJU. The calculated results are summarized as follows. (1)Peak atmospheric pressure 4.3 kPa[gage] (2)Peak floor liner temperature 870C, Maximum thinning of liner 2.6mm (3)Peak hydrogen concentration <2% (4)Peak floor liner temperature in the spilt sodium storage eell 400C , Peak floor concrete temperature in the spilt sodium storage cell 140C.
JNC TN9400 2000-008, 323 Pages, 2000/02
JNC-TN9400-2000-008.pdf:25.2MB
This rport presents numerical results on theemal striping characteristics at a tee junction of LMFBR coolant pipe, carried out using a direct numerical simulation code DINUS-3. In the numerical investigations, it was considered a tee junction system consisted of a main pipe (1.33 cm
) with a 90 elbow and a branch pipe, and four parameters, j.e., (1)diameter ratio 
between both the pipes, (2)flow velocity ratio 
between both the pipes, (3)angle 
between both the pipes, and (4)Reynolds number Re. From the numerical investigations, the following characteristics were obtained: (1)According to the decreasing of the diameter ratio, significant area of second-order moments was expanded in the fixed condition of =1.0. (2)Significant second-order moments area was expanded for the increasing of the flow velocity ratio specified by varying of the main pipe velocity in the case of a = 1.0 constant condition. 0n the other hand, the area was expanded for the decreasing of the velocity ratio defined by varying of the branch pipe velocity in the case of a = 3.0 constant condition. (3)Maximum second-order moments values were generated in the case of = 180 due to the influence of interactions between main pipe flows and jet flows from the branch pipe. (4)According to the increase of Reynolds number, significant area of second-order moments was expanded due to the activation of turbulence mixing in the main pipe.
Ishiyama, Shintaro; Fukaya, Kiyoshi; Eto, Motokuni; Kikuchi, Mitsuru; Sato, Ikuo*; Kusuhashi, Mikio*; Hatakeyama, Tsuyoshi*; Takahashi, Heishichiro*
Nihon Genshiryoku Gakkai-Shi, 42(2), p.116 - 123, 2000/02
Times Cited Count：2 Percentile：19.44(Nuclear Science & Technology)no abstracts in English
Koyama, Tomozo; ; Omori, Eiichi; ; ; Shibata, Atsuhiro; Shigetome, Yoshiaki
JNC TN8410 99-027, 423 Pages, 1999/12
The bituminization demonstration facility of Tokai Reprocessig Plant had a fire and explosion incident. The cause of the incident was investigated. Also, the facility condition and release of radioactive materials were evaluated. The cause of the fire and subsequent explosion was determined in a two year investigation. The main cause of the fire was that the temperature of the bituminized product rose to an unusually high temperature by a physical heating phenomena inside the extruder, which was caused by the lowering the feed rate of liquid waste. A moderate chemical reaction in the bituminized product continued and consequently the bituminized product overheated and ignited. The cause of the explosion was the accumulation of flammable gases generated from insufficiently extinguished bituminized product in the filling room in which the ventilation system had been shut down. The flammable gas was ignited by another bituminized product that overheated to the flash point temperature. This report details the condition of the facility before and after the incident, cause of the incident, and an evaluated amount of released radioactive materials.
Miura, Akihiko;
JNC TN8410 99-046, 35 Pages, 1999/10
Judging from several evidences which are operators' testimony, observation result, and so on, the "Committee for an Investigation into the Fire and Explosion Incident at the BDF of the Reprocessing plant of Tokai Works" concluded another fire incident occurred in the filling room (R152) after the explosion (hereafter called second fire incident). This report explains the simulation result of second fire incident. Calculated air temperature and radiation intensity are used another calculations that indicate the thermal influence from the fire name to the extruder or neighboring drums. About second fire incident, calculated result indicates first fire occurred from the No.30104 drum that was produced in 30B or several drums including No.30104 drum. It is estimated that temperature and thermal runaway reaction was not due to fire of neighboring drum because the drum doesn't receive large influence thermally by radiation from the neighboring fire name. Each result suggests the all burnt 29B and 30B drums were filled at higher temperature than usual.
Miura, Akihiko;
JNC TN8410 99-044, 189 Pages, 1999/10
This report includes several results that were made by calculation with several methods to clarify the cause of the fire and explosion incident. In the early times, we didn't have exact information of chemicaI property, reaction rate and any physical constants that we needed. But because the only data that indicate the cooling process of bituminized product was reported, we made heat-transporting calculation with taking this data. Based on the theory of the thermal hazard evaluation that was called Semenov theory or Frank-Kamenetskii theory, the amount of heat generation was estimated using the heat transporting calculation. Common theories were introduced in first section. In the second section, several results of heat transporting calculation were indicated. Calculations were made as follows. First, the model of bituminized product that was filled in the drum was created with the data of cooling process. Second, when the heat was generated in the drum, time-dependent temperature distribution was calculated. And last, judging from the balance of heat generation and heat radiation the critical heat rate was estimated.
; Miura, Akihiko; ;
JNC TN8410 99-043, 135 Pages, 1999/10
All result of chemical analysis and operators observation suggest non-chemical mechanism raised the filling temperature of the bituminized product at the incident. We, Tokai reprocessing plant safety evaluation and analysis team, performed the experiment using laboratory scale extruder and viscosity measurement to explain the high temperature of mixture. The result of the experiment using laboratory scale extruder showed that the phenomena of salt enrichment and salt accumulation oceured and they raised mixture temperature at the decreased feeed rate. These phenomena depend on the feed rate and they have large contribution of heat transportation and rise of operational torque due to the friction between screw and mixture. Based on the experiment result and all information, we investigated the operation procedure, operational records and machine arrangement to try to explain the behavior of the mixture in the extruder. Judging from each torque and temperature behavior, we succeeded in explaining a sequential behavior in the incident. It is estimated that mixture temperature was raised by physical heat generation in the extruder and this report explains each operation, investigated result and estimated event sequences.
Chijimatsu, Masakazu*; Sugita, Yutaka; Fujita, Tomoo; Amemiya, Kiyoshi*
JNC TN8400 99-034, 177 Pages, 1999/07
It is an important part of the near field perfformance assessment of nuclear waste disposal to evaluate coupled thermo-hydro-mechanical (T-H-M) phenomena, e.g., thermal effects on groundwater flow through rock matrix and water seepage into the buffer material, the generation of swelling pressure of the buffer material, and thermal stresses potentially affecting porosity and fracture apertures of the rock. An in-situ T-H-M experiment named 'Engineered Barrier Experiment' has been conducted at the Kamaishi Mine, of which host rock is granodiorite, in order to establish conceptual models of the coupled T-H-M processes and to build confidence in mathematical models and computer codes. In 1995, fourteen boreholes were excavated in order to install the various sensors. After the hydraulic tests, mechanical tests were carried out to obtain the rock properties. After that, a test pit, 1.7m in diameter and 5.0m in depth, was excavated. During the excavation, the change of pore pressure, displacement and temperature of rock mass were measured. In 1996, the buffer material and heater were set up in the test pit, and then coupled thermo-hydro-mechanical test was started. The duration of heating phase was 250 days and that of cooling phase was 180 days. The heater surface was controlled to be 100C during heating phase. Measurment, was carried out by a number pf sensors installed in both buffer and rock mass during the test. The field experiment leads to a better understanding of the behavior of the coupled thermo-hydro-mechanical phenomena in the near field.
Shigetome, Yoshiaki; ; ; Miura, Akihiko; Sato, Yoshihiko; Koyama, Tomozo
JNC TN8200 99-001, 128 Pages, 1999/07
None
Ikeda, Yujiro; Maekawa, Fujio; Kasugai, Yoshimi; Uno, Yoshitomo; A.Kumar*; M.Z.Youssef*; M.A.Abdou*; Konno, Chikara; Wada, Masayuki*
Fusion Engineering and Design, 42, p.289 - 297, 1998/00
Times Cited Count：6 Percentile：49.22(Nuclear Science & Technology)no abstracts in English
Ikeda, Yujiro; A.Kumar*; Maekawa, Fujio; Wada, Masayuki*; Kasugai, Yoshimi; M.A.Abdou*
Fusion Technology 1998, 2, p.1469 - 1472, 1998/00
no abstracts in English
