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Kawaguchi, Munemichi
Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08
In decommissioning sodium-cooled fast reactors, the operators can be exposed to radiation during dismantling of the cold trap equipment (C/T). The C/T has higher dose equipment because the C/T trapped the tritium of the fission product during the operation to purify the sodium coolant. In this research, the thermal decomposition temperature and rate of sodium hydride were measured as the fundamental research for improvement of the thermorlysis method prior to the dismantling. We measured the thermal decomposition temperature and rate using sodium hydride powder (95.3%, Sigma-Aldrich) in Al
O
crucible with TG-DTA (STA2500, NETASCH Japan). The heating rates were set to 
= 2.0, 5.0, 10.0, 20.0 K/min, and the weight decrease was measured. The thermal decomposition temperature and rate were obtained from the temperature of the onset of the weigh decrease and the Kissinger plot, respectively. Furthermore, we set to the thermal decomposition temperature of around 600 K, and the weight decreasing rates were measured. The change of the chemical composition of the sodium hydride with heating (from NaH to Na) was measured with X-Ray Diffraction (XRD) analysis. As a result, the thermal decomposition occurred at around 600 K, and the almost all hydrogen in the sodium hydride released within 1 h. The thermal decomposition rate strongly depended on the heating temperature.
JNC TN9410 2000-003, 52 Pages, 1999/12
JNC-TN9410-2000-003.pdf:3.51MB
In May, 1999, disassembly and cleansing of sodium residues contained in the large cold trap (50MWSG) were carried out. Two cold trap units, one from the primary sodium loop and the other from the for the secondary sodium loop were disassembled and cleaned. This report describes the procedures, methods, and tasks under taken in the clean-up effort, including countermeasures for safe handling of sodium. The disassembly of the cold trap was based an information regarding similar cleansing activities external to JNC. There was also same a priori knowledge of the type and amount of sodium-laden residues. As this result, we conducted disassembly and cleansing task as provisionally planned. In fact we learned that disassembly methods for the specific components could be conducted in an aerated atmosphere. We thus gained additional disassembly and sodium cleansing experience under manageable and safe conditions.
Shiotsu, Masahiro*; Hata, Koichi*; *; Shirai, Yasuyuki*; *; Sakai, Takaaki
PNC TY9604 97-002, 15 Pages, 1997/03
no abstracts in English
Hayashi, Takumi; Nakamura, Hirofumi; Konishi, Satoshi; Inoue, Masahiko*; Hirata, Kazuhiro*; Okuno, Kenji; Naruse, Yuji; Barnes, J. W.*; W.Harbin*; Bartlit, J. R.*; et al.
JAERI-M 93-082, 32 Pages, 1993/03
no abstracts in English
*; *; *
PNC TN941 85-127, 92 Pages, 1985/08
RECT-II (the Removal test of reaction products by cold trap) was conducted by use of SWAT-3 (the Steam Generator Safety Test Facility) at PNC in order to construct the post-accident operation of steam generators of the prototype FBR Monju and a larger plant following it. In prior to the test, some amount of the sodium-water reaction products (SWRP) generated in the water injection test (Run 18) was remained in the sodium system. An objective of the test is to confirm the purifying method to remove SWRP by hot sodium circulating through a cold trap (CT). A meshless type cold trap was selected to avoid choking by impurities and to enable efficient SWRP removal. RECT-II started on April 4, 1984 and terminated on April 26 when the plugging temperature decreased to 187
C. Major results obtained in the test are as follows: (1)Post-test observation revealed that the SWRP having remained at the bottom of the evaporator and the sodium outlet pipe were completely removed through the purification operation. (2)Hence, it is concluded that after the hot draining the SWRP of 14 kg-H
0 remained in the sodium system out of that generated by the 42 kg-H0 injection and that almost all of the former was removed through the operation. (3)However, some amount of the hydrocarbon-oxide and SWRP in the slit articles simulating crevice and stagnant region still remained after the operation. Then it is concluded that it is insufficient to remove SWRP in crevice and stagnant region by the circulation of hot sodium. (4)A mass transfer coefficient of oxygen is evaluated as 2 
10
[g/(mm H ppm)] if the cross section of the evaporator and inner surface of the 8 inch horizontal pipe are assumed to be the entire surface area of SWRP. (5)Since the choking of the cold trap degrades the efficient SWRP removal, it is essential to develop a cold trap which hardly chokes and easily regenerates even after choking; one of answers for this request is a ...
JAERI-M 6405, 19 Pages, 1976/02
no abstracts in English
Furukawa, Tomohiro; Kondo, Hiroo; Kanemura, Takuji; Hirakawa, Yasushi; Iijima, Minoru; Wakai, Eiichi
no journal, ,
The purification performance of lithium by a cold trap which was installed in the EVEDA lithium test loop has been done under the validation activities in the IFMIF/EVEDA. The chemical analysis was conducted for the lithium sampled during the experiment, and the performance was evaluated.
Sato, Takeshi; Okawachi, Yasushi; Nakamura, Yoshihide; Sawazaki, Hiromasa
no journal, ,
In the Monju, before expanding accident in the unlikely event of a water leak from the steam generator tubes, capturing the hydrogen concentration changes in the secondary sodium, it is important to early detect the corresponding water leak. Its detection sensitivity, the amount of hydrogen diffused from the water side to the secondary sodium in through the heat exchanger tube during normal operation, depends on the performance of the cold trap to remove it. So, this time was carried out to confirm the purification efficiency derived by using the operating data of the actual machine of purification efficiency and about 20 years was expected in the design of the secondary sodium purification system cold trap.
Sato, Takeshi; Sawazaki, Hiromasa; Morioka, Tatsuya; Uchida, Takenobu; Nakamura, Yoshihide; Shiotani, Hiroki; Okawachi, Yasushi
no journal, ,
In Monju, it is important to detect and respond to hydrogen concentration changes in secondary sodium at an early stage, before any water leakage from the steam generator heat transfer tube expands. For that purpose, it is necessary to understand the hydrogen concentration during normal operation. In this report, we estimated, using the purification efficiency evaluation of the cold trap reported at the fall programs of 2016, the amount of diffused hydrogen from the characteristic test data of 1995 and evaluated the hydrogen concentration in the secondary sodium during normal operation.
Kawaguchi, Munemichi
no journal, ,
In decommissioning sodium-cooled fast reactors, the thermal decomposition behavior of tritium is important from the viewpoint of reducing the exposed radiation for the operators during dismantling of the cold trap equipment. In this study, the thermal decomposition temperature and rate of sodium hydride (95.3%, Sigma-Aldrich) were estimated from the TG-DTA measurements. The change of the chemical composition for the thermal decomposition was measured with X-Ray Diffraction analysis.
