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Tashiro, Shinsuke; Uchiyama, Gunzo; Ono, Takuya; Amano, Yuki; Yoshida, Ryoichiro; Abe, Hitoshi
Nuclear Technology, 208(7), p.1205 - 1213, 2022/07
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)A clogging behavior of a high-efficiency particulate air (HEPA) filter at solvent fire accidents for reprocessing facilities has been studied. In this study, the burning rates of 30% tri-butyl phosphate (TBP)/dodecane (DD) mixed solvent and DD solvent and the differential pressure (
P) of a high airflow typed HEPA filter applied in the actual facilities in Japan were measured. It was confirmed that the mainly burned was DD at the early stage of the mixed solvent burning and the TBP at the late stage. Furthermore, it was found that the P rapidly rose at the late stage of the mixed solvent burning. The increase of the release ratio of the unburned particulate composition (TBP, its degraded solvent and inorganic phosphorus (P
O
)) was considered to contribute to the rapid rise. The correlating formulas with the P and the mass of the loading particulates, except for the region of the rapid rise of P, could be induced.
Umeda, Ryota; Kondo, Toshiki; Kikuchi, Shin; Kurihara, Akikazu
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 9 Pages, 2021/08
In this study, in order to obtain the fundamental information on aerosol transport behavior between cells, the Multiple cells with Expandable connecting pipe Test facility (MET) was manufactured and preliminary experiments were performed. In the preliminary experiments, simulated particles were used in a test system with two cells connected horizontally or vertically, and their transport behavior was measured. As a result, it was possible to confirm the behavior of the simulated particles transporting to the horizontal or vertical cells from the results such as images and sedimentation data.
Kawasaki, Kohei; Shinada, Kenta; Okamoto, Naritoshi; Kageyama, Tomio; Eda, Takashi; Okazaki, Hiro; Suzuki, Hiromichi; Yamamoto, Kazuya; Otabe, Jun
JAEA-Technology 2020-025, 80 Pages, 2021/03
JAEA-Technology-2020-025.pdf:3.72MB
Plutonium Fuel Production Facility was built in 1988 for the purpose of mainly producing MOX fuel of the prototype fast breeder reactor MONJU, and large glove boxes were installed for handling unsealed nuclear fuel material remotely. The panels of these glove boxes are made of acrylic, except for those installed after December 2013. For fires inside the glove box, automatic fire extinguishing systems using halides have been introduced since the beginning of construction, but for fires outside the glove box, there have been issues with direct measures for acrylic. Therefore, we have developed a fireproof sheet that mitigates the effect of fire outside the glove box on the panels as much as possible. As a result, fire-retardant sheets have been selected and attached to the glove box panels. We conducted a flammability test of the acrylic plate attached with these fireproof sheets and a usage environment influence test of fireproof sheets, and obtained good results. In addition, we set up a working group in the Plutonium Fuel Development Center in view of reducing external exposure during the work of attaching fireproof sheets, in which we discussed and examined the work procedure, and summarized it in the basic procedure manual.
Iketani, Shotaro; Yokobori, Tomohiko; Ishikawa, Joji; Yasuhara, Toshiyuki*; Kozawa, Toshiyuki*; Takaizumi, Hirohide*; Momma, Takeshi*; Kurosawa, Shingo*; Iseda, Hirokatsu; Kishimoto, Katsumi; et al.
JAEA-Review 2018-016, 46 Pages, 2018/12
JAEA-Review-2018-016.pdf:12.79MB
Japan Atomic Energy Agency (JAEA) adopts melting process for the waste processing and packaging method of radioactive miscellaneous solid waste in NSRI because melting process is effective in radioactivity evaluation, volume reduction, and stabilization treatment. Metal melting processing facilities, Incinerator, and Nonmetal melting processing facilities (hereinafter referred to as melting process facilities) have taken lots of safety measures, including measures for preventing the recurrence of the fire accidents. To exchange opinions and discuss the validity of these measures and so on with internal personnel and external experts, "Discussions on Melting Process Facilities" was held. As a document collection, this paper summarizes presentation materials of discussion meetings. Presentation materials describe "Outline of AVRF", "Safety measures in the melting facilities in WVRF", "Operation management of the melting facilities in WVRF", "Comparison of the past accident cases between facilities in and outside Japan and WVRF", and "Introduction of past accident cases and safety measures in other facilities from each committee".
Abe, Yuta; Nagai, Keiichi; Maie, Mitsuyoshi*; Nakano, Natsuko*; Kawashima, Yuichi*; Takesue, Naohisa*; Saito, Junichi
Dai-23-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (USB Flash Drive), 5 Pages, 2018/06
no abstracts in English
Okano, Yasushi; Yamano, Hidemasa
Proceedings of Asian Symposium on Risk Assessment and Management 2017 (ASRAM 2017) (USB Flash Drive), 3 Pages, 2017/11
Forest fire hazard assessment methodologies using a logic tree have been applied for the evaluation of combination hazard curves of a forest fire with lightning as an initiator of a forest fire and with a strong wind being independent from a forest fire. The complex shape of the combinational hazard curve of forest fire and lighting is due to that both lightning and high velocity wind tend to appear under unstable weather conditions, and there is correlation between two hazards. The evaluated combinational hazard curve of forest fire and strong wind for the instantaneous wind velocity over 80 m/s has extremely small frequency in the range below 10
/year.
Shimomura, Yusuke; Hanari, Akira*; Sato, Isamu*; Kitamura, Ryoichi
JAEA-Technology 2015-062, 47 Pages, 2016/03
JAEA-Technology-2015-062.pdf:1.85MB
In response to new standards for regulating waste management facilities, it was carried out impact assessment of forest fires on the waste management facilities existed in Oarai Research and Development Center of Japan Atomic Energy Agency. At first, a fire spread scenario of forest fires was assumed. The intensity of forest fires was evaluated from field surveys, forest fire evaluation models and so on. As models of forest fire intensity evaluation, Rothermel Model and Canadian Forest Fire Behavior Prediction (FBP) System were used. Impact assessment of radiant heat to the facilities was carried out, and temperature change of outer walls for the assumed forest fires was estimated. The outer wall temperature of facilities was estimated around 160
C at the maximum, it was revealed that it doesn't reach allowable temperature limit. Consequently, it doesn't influence the strength of concrete. In addition, a probability of fire breach was estimated to be about 20%. This report illustrates an example of evaluation of forest fires for the new regulatory standards through impact assessment of the forest fires on the waste management facilities.
Okano, Yasushi; Yamano, Hidemasa
Proceedings of International Topical Meeting on Probabilistic Safety Assessment and Analysis (PSA 2015) (USB Flash Drive), p.22 - 31, 2015/04
An external hazard curve of a forest fire is evaluated based on a logic tree. The logic tree consists domains of "forest fire breakout and spread conditions", "weather condition" and "vegetation and topographical conditions". A location nearby a typical nuclear power plant site in Japan was selected, and the frequency of a large forest fire of the location is approximately 1/5 of the average in Japan. Forest fire breakout points were selected considering typical forest fire causes in Japan. The weather conditions are represented by two parameter sets of "temperature-humidity" and "wind direction-wind speed". A number of forest fire simulations were performed to obtain a response surface for a frontal fireline intensity. The hazard curve is therefore evaluated by a Monte Carlo simulation such that the annual exceedance probability is about 1.0
10
per year for the frontal fireline intensity of 200 kW/m and about 1.310
per year for 300 kW/m.
Hori, Toshihiko*; Chishiro, Etsuji; Yamazaki, Masayoshi*; Suzuki, Hiroyuki*; Hasegawa, Kazuo
Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.212 - 214, 2004/08
no abstracts in English
Takada, Junichi; Hayashi, Shiro*; Watanabe, Koji; Takita, Koji*; Tsukamoto, Michio; Tashiro, Shinsuke; Abe, Hitoshi*; Uchiyama, Gunzo*
JAERI-Tech 2002-102, 87 Pages, 2003/01
JAERI-Tech-2002-102.pdf:3.27MB
no abstracts in English
Abe, Hitoshi; Watanabe, Koji*; Tashiro, Shinsuke; Takada, Junichi; Uchiyama, Gunzo
JAERI-Research 2001-052, 18 Pages, 2001/11
JAERI-Research-2001-052.pdf:1.83MB
no abstracts in English
Noda, Kimio; Shinohara, Kunihiko; Kanamori, Masashi
JNC TN8410 2001-010, 35 Pages, 2000/10
JNC-TN8410-2001-010.pdf:3.85MB
We, the radiation control section of JNC have had two important experiences on the JCO critical accident and the JNC fire-explosion accident. Especially, at the critical accident in JCO, it was essential to take an action on the radiation protection activities for the evacuated neighboring inhabitants to the safety area. During the accident, we carried out the radiation protection activities, at the beginning of the accident, environmental monitoring of the surrounding area. Especially for the JCO accident, we took an action to terminate criticality, radiation shielding and monitoring, environmental monitoring, radiation survey of the residents, radiation monitoring of exhaust air.
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.
Nishihara, Tetsuo; *
JAERI-Tech 99-061, 70 Pages, 1999/09
no abstracts in English
Fujine, Sachio; Murata, Mikio; Abe, Hitoshi; Takada, Junichi; Tsukamoto, Michio; Miyata, Teijiro*; Ida, Masaaki*; Watanabe, Makio; Uchiyama, Gunzo; Asakura, Toshihide; et al.
JAERI-Research 99-056, p.278 - 0, 1999/09
JAERI-Research-99-056.pdf:22.73MB
no abstracts in English
Shigetome, Yoshiaki; ; ; Miura, Akihiko; Sato, Yoshihiko; Koyama, Tomozo
JNC TN8200 99-001, 128 Pages, 1999/07
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