Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Kojima, Atsushi; Kamiya, Kensaku; Iguchi, Harukazu*; Fujita, Takaaki; Kakiuchi, Hideto*; Kamada, Yutaka
Review of Scientific Instruments, 79(9), p.093502_1 - 093502_5, 2008/00
Times Cited Count：10 Percentile：44.77(Instruments & Instrumentation)A high-brightness and low-divergence neutral lithium beam is obtained for a Zeeman polarimetry of edge plasmas on JT-60U. In order to achieve high-brightness and low divergence angle simultaneously, the beam optics is designed after detailed numerical simulation taking the space charge effects into account. The newly-developed ion gun is operated on a test stand which simulates the diagnostic arrangement on JT-60U. The ion beam current of 10 mA is successfully extracted from the electron beam heated ion source. A sodium vapor neutralizer neutralizes the collimated ion beam fully at the temperature of 300
C. The neutral lithium beam is transported for 6.5 m long from the neutralizer. The HWHM radius of 26 mm and the equivalent beam current of 3 mA with the beam divergence angle of 0.2 degree are obtained. Those parameters satisfy the requirements of the Zeeman polarimetry. Furthermore, a long pulse extraction with a current of 10 mA and duration of 50 seconds is attained.
superconductivity"Arai, Masatoshi; Yokoo, Tetsuya*; Kajimoto, Ryoichi; Nakajima, Kenji; Shamoto, Shinichi; Yamada, Kazuyoshi*; Fujita, Masaki*; Ino, Takashi*; Soyama, Kazuhiko; Nakamura, Mitsutaka; et al.
JAEA-Review 2006-033, 58 Pages, 2006/11
JAEA-Review-2006-033.pdf:17.22MB
A research project entitled "Development of the 4D Space Access Neutron Spectrometer (4SEASONS) and Elucidation of the Mechanism of Oxide High- Superconductivity" has started in 2005 (repr. by M. Arai). It is supported by MEXT, Grant-in-Aid for Specially Promoted Research and is going to last until fiscal 2009. The goal of the project is to elucidate the mechanism of oxide high- superconductivity by neutron scattering technique. For this purpose, we will develop an inelastic neutron scattering instrument 4SEASONS (4d SpacE AccesS neutrON Spectrometer) for the spallation neutron source in Japan Proton Accelerator Research Complex (J-PARC). The instrument will have 100 times higher performance than existing world-class instruments, and will enable detailed observation of anomalous magnetic excitations and phonons in a four-dimensional momentum-energy space. This report summarizes the progress in the research project in fiscal 2007.
; ; ; Omori, Eiichi
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 4.1
6.5GBq 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 ...
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 99-043, 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.
Shibata, Atsuhiro; ; ; Kitajima, Takafumi;
JNC TN8410 99-029, 192 Pages, 1999/09
This report describes the results of investigation of the bituminized products in drums, liquid waste in the receiving tank V21 and the bituminized mixture in the extruder. The investigation of the products in drums showed most of the unburned products filled after 28 B had abnormality, such as hardened surfaces, caves and porous brittle products. The particle sizes of the salt fixed in bituminized products depended neither on batch number nor on feed rate. It indicates the filling of the salt particle caused by the decreased feed rate did not occur. The measured concentrations of metals and anions in the bituminized products showed no abnormality. The catalytic content was not recognized in the products. The infrared absorption spectra obtained with the bituminized products show the oxidation at the incident occrred without oxygen. There was no organic phase on the surface of liquid waste in V21. Chemical analysis and thermal analysis on the precipitate in V21 showed no abnormality. Concentration of sodium nitrate/nitrite in the mixture collected from the extruder was lower than normal products. These results show no chemical activation of the bituminized products. It can be concluded that the chemical characteristics of the products had little abnormality even around the incident.
Maki, Akira; Nojiri, Ichiro; ; ; Yamanouchi, Takamichi
JNC TN8440 99-002, 366 Pages, 1998/11
The fire and explosion incident of the bituminization facility happened in March 1997 although JNC had taken enough care of the safety of TRP. JNC reflected on it and decided to evaluate the safety of TRP voluntarily. This evaluation has included five activities, that is, (1)confirmation of the structure and organization of TRP, (2)research of the data for operation, radiation and maintenance of TRP, (3)research of reflection of the accidents and troubles which have happened at the past, (4)evaluation on the prevention system, (5)evaluation on the mitigation system. We publish this report to contribute to inheritance of accumulated knowledge and techniques from generation to generation, and remind us of lesson from the fire and explosion incident of the bituminization.
; Maki, Akira; ; ; ; ;
JNC TN8410 99-004, 1679 Pages, 1998/11
JNC-TN8410-99-004(1).pdf:46.84MBJNC-TN8410-99-004(2).pdf:38.58MBJNC-TN8410-99-004(3).pdf:33.27MB
JNC reflected on the fire and explosion incident of the bituminization facility and decided to evaluate on the safety of TRP voluntarily. This evaluation has included three activities, that is, (1)evaluation on the prevention system, (2)evaluation on the mitigation system, (3)confirmation on the method of the criticality safety analysis and the radiation shielding analysis. This report describes the results of the evaluation on the prevention system of the TRP's processes. We used HAZOP and FMEA to pick about 4000 abnormal conditions of each process up and selected about 700 abnormal transients. We estimated on a progress of all abnormal tansients and confirmed proprieties of prevention systems. We will reflect these results to improvement of system and operation manual and to education, training for stuffs and operators.
; ; Kurosawa, A.; Hayashi, Naomi; Kobayashi, Kentaro; Kitajima, Takafumi; Sato, Yoshihiko
PNC TN8410 98-047, 278 Pages, 1998/02
The fire and explosion incident occurred at the Bituminization Demonstration Facility of the Tokai Reprocessing Plant on march 11th, 1997. For investigation of Bituminization Demonstration Facility Incident and prevention relapse, Investigation Group for Bituminization Demonstration Facility incident was set up. It has been investigated the situation at the time of incident was occurred. The result of investigated was presented for Science and Technology Agency. This report is arranged the result of investigated the situation for investigation and prevention relapse.
Kosaka, Ichiro; Yamanouchi, Takamichi;
PNC TN8410 98-027, 114 Pages, 1998/02
At 11th, March, 97, the fire incident happened, and after the fire incident, the explosion happened in the Bitiminization Demonstration Facility. It has been suspected that the reverse air flow to filling room(R152) from the vessel ventilation system made the explosive atmosphere after the fire incident. The calculation of the reverse flow rate to the cell was therfore carried out, using FIRAC computer code. The FIRAC is designed for the calculation of a fluid temperature, pressure and flow rate, using lumped-parameter method. In the FIRAC, the network system is modeled as nodes and branches. As the results of calculation, the reverse air flow rate to R152 from vessel ventilation system is about 94 m
/h and the reverse air flow rate to the other cells are slight, assuming that the leak rate from R152 is 650 m/h and others are 1 vol%/h when the pressure difference is 40 mmAq. On the other hand, the reverse air flow rate to R152 is about 34m/h, the reverse air flow rate to the cells in the underground stairs is about 39 m/h and to the others are from 5 to 10 m/h, assuming that the leak rate from all cells are 1 vol%/h when the pressure difference is 40 mmAq.
; Funasaka, Hideyuki; ; Koyama, Tomozo
PNC TN8600 97-007, 109 Pages, 1997/11
no abstracts in English
Ochiai, Kenichi; Murayama, Yasumi; Fujita, Hideto; *; *
PNC TN8410 97-118, 68 Pages, 1997/05
None
Ochiai, Kenichi; Murayama, Yasumi; Fujita, Hideto; *; *
PNC TN8410 97-117, 93 Pages, 1997/05
None
Ochiai, Kenichi; Murayama, Yasumi; Fujita, Hideto; Takeda, Keiji; *; *
PNC TN8410 97-116, 105 Pages, 1997/05
None
Ochiai, Kenichi; Murayama, Yasumi; Fujita, Hideto; Takeda, Keiji; *; *
PNC TN8410 97-115, 106 Pages, 1997/05
None
; ; ;
PNC TN8410 92-234, 26 Pages, 1992/09
Low-level radioactive liquid wastes generated in the PNC Tokai Reprocessing Plant are solidified in bitumen, and solvent wastes generated in the Plant are solidified in plastics. They have been stored in the storage facility. To make sure that the stored wastes and their packages are in good condition, we evaluated the fundamental characteristics, eg, hardness, compressive strength, penetration, water content for solidified wastes, and observation thickess for packages. As a result, the characteristics of the stored wastes have not changed since they were solidified.
*; ; *; *; *; *
PNC TN8420 89-011, 137 Pages, 1989/03
In Bituminization Demonstration Facility, low-level radioactive liquid waste has been solidfying with asphalt to institution, whereas in Solvent Waste Treatment Demonstration Facility, solvent waste has been solidfying with epoxy resin or PVC (henceforth designated as plastic solidfied product). The radiochemically analytical techniques were investigated and examined in order to carry out the evaluation of those products, and decide to the plan for development of the experiment on the application of these techniques were performed. A summary of contents of practice is indicated as follows: (1)Investigation of radiochemically analytical techniqueson solidified product of radioactive wastes. (a)Methods of preliminary treatment of samples. THe methods of ashing or liquedying in solvents are effective to Inorganically and solvolysis for the samples, however as operating conditions, it is important that the operation temperature control, and prevented the scattering of ofject nuclides. (b)Method of separating and isolating of ofject nuclides. The ofject nuclides were previously classified into the groupes being similar in chemical behavior, after it was indicated that the methods for isolating and measuring each group is effective. For these techniques, it is desirable to adopt the ion exchange and extracting methods. (2)Plan for development of experiment. It was indicated that simulated Cold and Hot tests were necessary to operate in order to investigate the functions of the recovery, distribution and handling with preliminaly treatment, methods of separating and isolating in the radio chemically analytical technique.
Kajimoto, Ryoichi; Yokoo, Tetsuya*; Nakajima, Kenji; Nakamura, Mitsutaka; Inamura, Yasuhiro; Soyama, Kazuhiko; Ino, Takashi*; Oyama, Kenji*; Sakai, Makiko; Aizawa, Kazuya; et al.
no journal, ,
4SEASONS is one of the day-one chopper spectrometers for the spallation neutron facility in Japan Proton Accelerator Research Complex (J-PARC). The spectrometer targets high- superconductors and related strongly correlated materials utilizing incident energies of 5-300 meV. 4SEASONS supplies high flux at a sample by moderating the resolution (
-6% at 
) and incorporating efficient neutron optic devices. A new Fermi chopper is designed to multiply the measurement efficiency by repetition rate multiplication (RRM). Recently, we have decided to enlarge the detector coverage by 
in horizontal direction (with the maximum scattering angle being 
) to let the spectrometer have more flexibility. The designing of the vacuum scattering chamber has been almost completed. Examination of the 2.5m-
He PSD on neutron beam and manufacturing of a prototype of a slit package of the new chopper are going on.
Kajimoto, Ryoichi; Yokoo, Tetsuya*; Nakajima, Kenji; Nakamura, Mitsutaka; Inamura, Yasuhiro; Maruyama, Ryuji; Soyama, Kazuhiko; Suzuya, Kentaro; Ino, Takashi*; Oyama, Kenji*; et al.
no journal, ,
no abstracts in English
