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Takeda, Takeshi
JAEA-Data/Code 2023-007, 72 Pages, 2023/07
JAEA-Data-Code-2023-007.pdf:3.24MB
An experiment denoted as IB-HL-01 was conducted on November 19, 2009 using the Large Scale Test Facility (LSTF) in the Rig of Safety Assessment-V (ROSA-V) Program. The ROSA/LSTF experiment IB-HL-01 simulated a 17% hot leg intermediate break loss-of-coolant accident due to a double-ended guillotine break of pressurizer surge line in a pressurized water reactor (PWR). The break was simulated by a long nozzle upwardly mounted flush with a hot leg inner surface. The test assumptions included total failure of both high pressure injection system of emergency core cooling system (ECCS) and auxiliary feedwater system. In the experiment, relatively large size of break led to a fast transient of phenomena. The primary pressure steeply dropped after the break, and became lower than steam generator (SG) secondary-side pressure. Break flow turned from single-phase flow to two-phase flow soon after the break. Core uncovery started simultaneously with liquid level drop in downflow-side of crossover leg before loop seal clearing (LSC). The LSC was induced in both loops by steam condensation on accumulator (ACC) coolant of ECCS injected into cold legs. The whole core was quenched owing to the rapid recovery in the core liquid level after the LSC. Peak cladding temperature of simulated fuel rods was detected almost concurrently with the LSC. During the ACC coolant injection, liquid levels recovered in the hot legs and SG inlet plena because of liquid entrainment from the hot leg into the SG inlet plenum by high-velocity steam flow. After the continuous core cooling was confirmed through the actuation of low pressure injection system of ECCS, the experiment was terminated. This report summarizes the test procedures, conditions, and major observations in the ROSA/LSTF experiment IB-HL-01.
Okuno, Hiroshi; Yamamoto, Kazuya
JAEA-Review 2020-066, 32 Pages, 2021/02
JAEA-Review-2020-066.pdf:3.01MB
The International Atomic Energy Agency (abbreviated as IAEA) has been implementing the Asian Nuclear Safety Network (abbreviated as ANSN) activities since 2002. As part of this effort, Topical Group on Emergency Preparedness and Response (abbreviated as EPRTG) for nuclear or radiation disasters was established in 2006 under the umbrella of the ANSN. Based on the EPRTG proposal, the IAEA conducted 23 Asian regional workshops in the 12 years from 2006 to 2017. Typical topical fields of the regional workshops were nuclear emergency drills, emergency medical care, long-term response after nuclear/radiological emergency, international cooperation, national nuclear disaster prevention system. The Japan Atomic Energy Agency has produced coordinators for EPRTG since its establishment and has led its activities since then. This report summarizes the Asian regional workshops conducted by the IAEA based on the recommendations of the EPRTG.
Tsubaki, Hirohiko; Koizumi, Satoshi*
JAEA-Technology 2020-016, 16 Pages, 2020/11
JAEA-Technology-2020-016.pdf:2.96MB
Maintenance and Operation Section for Remote Control Equipment in Naraha Center for Remote Control Technology Development is the main part of the nuclear emergency response team of JAEA deal with Act on Special Measures Concerning Nuclear Emergency Preparedness. The section needs to train operators from every nuclear facility in JAEA to control crawler-type robots, and so on. A driving training of a crawler-type robot used a reciprocating passage (U-shaped passage look from above) is one of the important training programs. The section always assembled a reciprocating passage with borrowed parts from other sections for every training of being used the passage. The section designed and produced training-way system included a reciprocating passage with stairs in 2019 fiscal year. The system makes the section members labor-saving, possible to set any time for training and diverse training-ways with easy assembling system. This report shows design and produce training-way system for crawler-type robots against nuclear emergency of JAEA facilities by Maintenance and Operation Section for Remote Control Equipment.
Terada, Hiroaki; Nagai, Haruyasu; Tanaka, Atsunori*; Tsuzuki, Katsunori; Kadowaki, Masanao
Journal of Nuclear Science and Technology, 57(6), p.745 - 754, 2020/06
Times Cited Count：10 Percentile：62.96(Nuclear Science & Technology)We have estimated source term and analyzed processes of atmospheric dispersion of radioactive materials released during the Fukushima Daiichi Nuclear Power Station (FDNPS) accident by the Worldwide version of System for Environmental Emergency Dose Information. On the basis of this experience, we developed an dispersion calculation method that can respond to various needs in a nuclear emergency and provide useful information for emergency-response planning. By this method, if a release point is known, it is possible to immediately obtain the prediction results by applying provided source term to the database of dispersion-calculation results prepared in advance. With this function, it is easy to compare results by applying various source term with monitoring data, and to find out the optimum source term, which was applied for the source term estimation of the FDNPS accident. By performing this calculation with past meteorological-analysis data, it is possible to immediately get dispersion-calculation results for various source term and meteorological conditions. This database can be used for pre-accident planning, such as optimization of a monitoring plan and understanding of events to be supposed in considering emergency countermeasures.
Nagai, Haruyasu; Yamazawa, Hiromi*
Environmental Contamination from the Fukushima Nuclear Disaster; Dispersion, Monitoring, Mitigation and Lessons Learned, p.230 - 242, 2019/08
An overview of SPEEDI is provided in the context of it development, functions, and role in the framework of nuclear emergency management. Thereafter, we examine how it was used and how it should be used for the Fukushima Daiichi Nuclear Power Station accident from a system developer perspective. We believe that our review can provide lessons or tasks for improving the prediction system and for considering better utilization of the system; it is also beneficial to consider reconstructing the framework of nuclear emergency management. Furthermore, we hope this review will prove useful in understanding and effectively using the atmospheric dispersion predictions from the system in the case of a similar accident in the future.
Kobayashi, Takuya; Kawamura, Hideyuki; Fujii, Katsuji*; Kamidaira, Yuki
Journal of Nuclear Science and Technology, 54(5), p.609 - 616, 2017/05
Times Cited Count：11 Percentile：64.42(Nuclear Science & Technology)The Japan Atomic Energy Agency has, for many years, been developing a radionuclide dispersion model for the ocean, and has validated the model through application in many sea areas using oceanic flow fields calculated by the ocean model. The Fukushima Dai-ichi Nuclear Power Station accident caused marine pollution by artificial radioactive materials to the North Pacific, especially to coastal waters northeast of mainland Japan. In order to investigate the migration of radionuclides in the ocean caused by this severe accident, studies using marine dispersion simulations have been carried out by JAEA. Based on these as well as the previous studies, JAEA has developed the Short-Term Emergency Assessment system of Marine Environmental Radioactivity (STEAMER) to immediately predict the radionuclide concentration around Japan in case of a nuclear accident.
Kawatsuma, Shinji; Mimura, Ryuji; Asama, Hajime*
ROBOMECH Journal (Internet), 4, p.6_1 - 6_7, 2017/02
It was cleared that portability of emergency response reconnaissance robot had been very important. So, RESQ-A robots, which had been developed by Japan Atomic Energy Research Institute (present Japan Atomic Energy Agency), had been considered from the view point of portability. After Fukushima Daiichi NPPs' accidents occurred, JAEA had modified a RESQ-A robot to JAEA-3 robot in order to meet the anticipated situation of the accidents. However, actual situation was beyond the anticipated situation, and additional modification was required. The actual confused situation was many rubble were scattered and temporary cables and hoses were constructed in the reactor buildings, so that reconnaissance robots should be conveyed by operators through limited route, should be reassembled in short time and should be able to remove cable and tiers for reduce the operators' exposure dose during maintenance. JAEA modified again JAEA-3 robot system, with cooperation of operators from Fukushima Daiichi NPPs. It was lesson learned that emergency response reconnaissance robot needed to be unitized for portability, and "Unitization Policy for emergency response reconnaissance robot" was developed.
Sakaba, Nariaki; Iigaki, Kazuhiko; Kondo, Masaaki; Emori, Koichi
Nuclear Engineering and Design, 233(1-3), p.135 - 145, 2004/10
Times Cited Count：6 Percentile：39.05(Nuclear Science & Technology)The containment structures of the HTTR consist of the reactor containment vessel, the service area, and the emergency air purification system, which minimise the release of fission products in postulated accidents which lead to fission product release from the reactor facilities. The reactor containment vessel is designed to withstand the temperature and pressure transients and to be leak-tight in the case of a rupture of the primary concentric hot gas duct, etc. The pressure inside the service area is maintained at a negative pressure by the emergency air purification system. The emergency air purification system will also remove airborne radio-activity and will maintain a correct pressure in the service area. The leak-tightness characteristics of the containment structures are described in this paper. The measured leakage rates of the reactor containment vessel were enough less than the specified leakage limit of 0.1%/d confirmed during the commissioning tests and annual inspections. The service area was kept the design pressure well below its allowable limitation by the emergency air purification system which filter efficiency of particle removal and iodine removal were well over the limited values. The obtained data demonstrates that the reactor containment structures were fabricated to minimise the release of fission products in the postulated accidents with fission product release from the reactor facilities.
Yoshida, Hiroshi; Glugla, M.*; Hayashi, Takumi; L
sser, R.*; Murdoch, D.*; Nishi, Masataka; Haange, R.*
Fusion Engineering and Design, 61-62, p.513 - 523, 2002/11
Times Cited Count：32 Percentile：85.69(Nuclear Science & Technology)ITER tritium plant is composed of tokamak fuel cycle systems, tritium confinement and detritation systems. The tokamak fuel cycle systems, composed of various tritium sumsystems such as vacuum vessel cleaning gas processing, tokamak exhaust processing, hydrogen isotope separation, fuel storage, mixing and delivery, and external tritium receiving and long-term storage, has been designed to meet not only ITER operation scenarios but safety requirements (minimization of equipment tritium inventory and reduction of environmental tritium release at different off-normal events and accident scenarios). Multiple confinement design was employed because tritium easily permeates through metals (at 
150 
C) and plastics (at ambient temperature) and mixed with moisture in room air. That is, tritium process equipment and piping are designed to be the primary confinement barrier, and the process equipments (tritium inventory 1 g) are surrounded by the secondary confinement barrier such as a glovebox. Tritium process rooms, which contains these facilities, form the tertiary confinement barrier, and equipped with emergency isolation valves in the heating ventillation and air conditioning ducts as well as atmosphere detritiation systems. This confinement approach has been applied to tokamak building, tritium building, and hotcell and radwaste building.
Iigaki, Kazuhiko; Sakaba, Nariaki; Kawaji, Satoshi; Iyoku, Tatsuo
Transactions of 16th International Conference on Structural Mechanics in Reactor Technology (SMiRT-16) (CD-ROM), 7 Pages, 2001/08
no abstracts in English
Seismic Emergency Information System Research Team
JAERI-Tech 2001-036, 294 Pages, 2001/06
JAERI-Tech-2001-036.pdf:23.23MB
no abstracts in English
Seismic Emergency Information System Research Team
JAERI-Tech 2000-063, 143 Pages, 2000/09
JAERI-Tech-2000-063.pdf:7.78MB
no abstracts in English
Chino, Masamichi; Nagai, Haruyasu; Furuno, Akiko; Kitabata, Hideyuki; Yamazawa, Hiromi
Proceedings of 10th International Congress of the International Radiation Protection Association (IRPA-10) (CD-ROM), 8 Pages, 2000/00
no abstracts in English
Nagai, Haruyasu; Chino, Masamichi; Yamazawa, Hiromi
Nihon Genshiryoku Gakkai-Shi, 41(7), p.777 - 785, 1999/07
Times Cited Count：13 Percentile：67.29(Nuclear Science & Technology)no abstracts in English
Ishigami, Tsutomu; Kobayashi, Kensuke
Journal of Nuclear Science and Technology, 35(6), p.443 - 453, 1998/06
Times Cited Count：1 Percentile：14.55(Nuclear Science & Technology)no abstracts in English
Sakaba, Nariaki; Iigaki, Kazuhiro; Kawaji, Satoshi; Iyoku, Tatsuo
JAERI-Tech 98-013, 152 Pages, 1998/03
no abstracts in English
Yamazawa, Hiromi; Chino, Masamichi
Proc. of 6th Topical Meeting on Emergency Preparedness and Response, 0, p.507 - 510, 1997/00
no abstracts in English
Ishigami, Tsutomu
Journal of Nuclear Science and Technology, 32(7), p.691 - 701, 1995/07
Times Cited Count：2 Percentile：27.03(Nuclear Science & Technology)no abstracts in English
Kobayashi, Kensuke; Ishigami, Tsutomu; ; ;
Journal of Nuclear Science and Technology, 32(5), p.476 - 487, 1995/05
Times Cited Count：3 Percentile：36.05(Nuclear Science & Technology)no abstracts in English
Ishikawa, Hirohiko
Journal of Nuclear Science and Technology, 31(9), p.969 - 978, 1994/09
Times Cited Count：7 Percentile：55.74(Nuclear Science & Technology)no abstracts in English
