Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Hayakawa, Masato; Shimoyama, Kazuhito; Miyakoshi, Hiroyuki; Suzuki, Shigeaki*
JAEA-Technology 2021-027, 33 Pages, 2022/01
At the Oarai Research and Development Institute of the Japan Atomic Energy Agency, experimental studies in various sodium environments are being conducted in connection with the research and development of sodium-cooled fast reactors such as the experimental fast reactor Joyo and the prototype fast reactor Monju. The dismantling of sodium test facilities and equipment that have achieved their purpose has been carried out sequentially, and a wealth of experience and technology has been accumulated. On the other hand, a large amount of metallic sodium used for research and testing is being reused for new testing facilities, and the large sodium tanks that contained the metallic sodium are being dismantled. In order to dismantle these tanks safely and efficiently, it is important to reduce the residual sodium inside the tanks (especially at the bottom) as much as possible before dismantling. Therefore, we have been working on the reduction of residual sodium at the bottom of several large sodium tanks of 100 m class. This report describes the technologies and experiences related to the reduction of residual sodium that have been carried out so far.
Matsumoto, Toshiyuki; Yoshida, Eiichi; Suzuki, Shigeaki*; Yasu, Tomohisa*
JAEA-Technology 2007-035, 35 Pages, 2007/03
In the future, a large amount of sodium (Na) containing radioactive wastes must be processed at the time of final shutdown/ decommissioning of FBR plant or radioactive sodium facilities in Japan. Therefore, its disposal technology should be established in consideration of economical efficiency, safety, etc. In the existing technology, since the method of processing sodium directly into radioactive waste is not established, conversion of sodium into chemically stable material can be considered. Then, basic experiments in which sodium was injected at 10 kg/h into solution of sodium hydroxide (NaOH) were conducted, with the improved Sodium Conversion Test Apparatus (SCOT). The conditions of NaOH solution were temperature of 100C, and NaOH concentration of 45-50 wt%. Consequently, the injected sodium reacted completely in the NaOH solution, and NaOH temperature, NaOH concentration, etc. were controlled properly. It validated that the system of this apparatus was appropriate. Moreover, in case sodium is injected into NaOH solution, a nozzle blockades sometimes. Therefore, the methods to eliminate the cause of nozzle blockage were examined.
Matsumoto, Toshiyuki; Yoshida, Eiichi; Suzuki, Shigeaki*; Yasu, Tomohisa*
JAEA-Research 2007-038, 32 Pages, 2007/03
Decommissioning of a sodium cooled fast reactor or an experimental facility which used radioactive sodium will bring a lot of radioactive sodium. However, technology to deal with such the radioactive sodium and decommission is not well established in Japan. Then, basic experimental study has been carried out in order to find and estimate an economic and safety process of the radioactive sodium decommission. There were some examples in overseas to convert the sodium into sodium hydroxide via sodium-water reaction. This method was examined by a basic sodium conversion test apparatus. In the experiment, liquid metal sodium was injected into the sodium hydroxide. Influences of temperature and concentration of the sodium hydroxide were investigated. Nitrogen gas was injected into the sodium hydroxide as atomizing gas in order to protect the sodium injection nozzle and also to mix the sodium. Then the gas flow rate was also varied to see the desired effects. Injected sodium temperature and mass flow rate were fixed at 200C and 10kg/h, respectively. The atomizing gas flow rate, the temperature and concentration of the sodium hydroxide were varied in ranges of 60-100 l/min, 70-100C and 40-60wt%, respectively. The influences of these parameters on the sodium conversion reaction were evaluated. The experiments showed that increase of the atomizing gas resulted in stable injection of the sodium and also larger reaction area. The temperature of the sodium hydroxide had small influences on the reaction, however, the sodium injection nozzle tended to choke up when the temperature was less than 70C. The lower concentration resulted in larger temperature fluctuation and also enlarged the reaction area. Unstable reaction, for example, sudden increase of reaction rate due to excess sodium, was not found under the conditions above listed ranges and stable sodium conversion was confirmed.
Nomura, Yasushi; *; *; *; *; Nishio, Gunji; *; *; *; Sugiyama, Toshihide*; et al.
Nihon Genshiryoku Gakkai-Shi, 33(4), p.318 - 328, 1991/04
no abstracts in English
; ; ; *; *; *; *; *; *
JAERI-M 8546, 107 Pages, 1979/11
no abstracts in English
; ; ; ; ; ; ; ; ; ; et al.
JAERI-M 6895, 170 Pages, 1976/12
no abstracts in English
; ; ; *; *; *; *
JAERI-M 6714, 39 Pages, 1976/09
no abstracts in English
Matsumoto, Toshiyuki; Yoshida, Eiichi; Suzuki, Shigeaki*; Yasu, Tomohisa*
no journal, ,
no abstracts in English
Shimoyama, Kazuhito; Hayakawa, Masato; Suzuki, Shigeaki*; Miyakoshi, Hiroyuki; Ara, Kuniaki
no journal, ,
We are conducting dismantling inspection of large-scale sodium component that we have been using in sodium environment for a long time. It was found from the operation history etc. that the sodium compound adhesion behavior on the inner surface of each device exposed to the sodium environment for several decades from the start of use affects sodium purity. In dismantling large sodium equipment, it is important to reduce the residual sodium in the equipment as much as possible, and proposing to carry out high temperature refining operation effective for removal of these attached impurities at the end of plant operation.
Hayakawa, Masato; Suzuki, Shigeaki*; Shimoyama, Kazuhito; Umeda, Ryota; Yoshida, Eiichi; Miyakoshi, Hiroyuki
no journal, ,
no abstracts in English
Suzuki, Shigeaki*; Hayakawa, Masato; Shimoyama, Kazuhito; Umeda, Ryota; Yoshida, Eiichi; Miyakoshi, Hiroyuki
no journal, ,
We are conducting dismantling inspection of large-scale sodium component that we have been using in sodium environment for a long time. We got the cover gas area sodium deposition rate of the large tank used for several decades. As a result of examination based on the data and past findings, it was possible to derive the recommended value "1.0e-10 g/cm/s" for the cover gas region sodium adhesion rate of the plant operating in the low temperature range (150 to 200C). For disassembling large sodium equipment, it is possible to estimate and evaluate sodium adhesion amount based on this recommended value and operation history. With this evaluation, it became possible to increase the reliability of disassembly technology for safety measures and safety management related to sodium fires etc.