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Yamane, Ikumi; Takahashi, Nobuo; Sawayama, Kengo; Nishiwaki, Hiroki; Matsumoto, Takashi; Ogawa, Jumpei; Nomura, Mitsuo; Arima, Tatsumi*
JAEA-Technology 2021-038, 18 Pages, 2022/02
JAEA-Technology-2021-038.pdf:1.61MB
We have dismantled uranium enrichment facilities in Ningyo-toge Environmental Engineering Center since their operation finished in 2001, and the total amount of metallic wastes is estimated to be about 130 thousand tons. Eighty percent of them can be disposed as nonradioactive waste (NR), but there are some steel parts possibly uranium-contaminated. We need removing painted surface of such steels and radiologically surveying to dispose them as NRs. Though painted surfaces have been conventionally removed through hand working with grinders, this manual work requires installation of green house, protective clothing, and full-face mask, in order to prevent dispersion and inhalation of airborne dusts. We desire further developments of surface cleaning techniques to reduce time, cost, workload, and secondary waste generation caused by excessive grinding. Therefore, in this study, we focused on the laser cleaning technology used for the separation and removal of paint films at construction sites. In order to improve the coating separation and removal technology for NR objects, we evaluated the coating separation and removal performance of NR steel surface by laser cleaning system, observed the coating scattering behavior by high-speed camera and investigated the coating recovery method, evaluated the laser separation and removal performance of steel surface powder, and thermodynamically evaluated the uranium compounds on steel surface. We additionally evaluated the feasibility of laser cleaning techniques in our works basing on these results, and discussed future work plans for further developments of laser cleaning techniques.
La-Ce-
Ce nuclear cosmochronometer of supernova neutrino process'"Hayakawa, Takehito; Shizuma, Toshiyuki; Kajino, Toshitaka*; Ogawa, Kengo*; Nakada, Hitoshi*
Physical Review C, 79(5), p.059802_1 - 059802_2, 2009/05
Times Cited Count：0 Percentile：1.45(Physics, Nuclear)We have proposed a new nuclear cosmochronometer La(T
=102 Gyr)-Ce-Ce for measuring the time elapsed from a supernova 
process episode. La is synthesized by the process. If a 1
excited state exists at energy lower than 72 keV, the 1 state may be a 
unstable isomer and La synthesized by the process is destroyed via the isomer. Recently, Byelikov et al. have measured Gamow-Teller strength distributions in La. It has been presented that this experiment shows that the existence of a low-energy 1 state in La is extremely unlikely. Our calculated result is consistent with their result and we conclude that there is no evidence that suggests the existence of the 1 isomer in La.
La-Ce-Ce nuclear cosmochronometer of supernova neutrino processHayakawa, Takehito; Shizuma, Toshiyuki; Kajino, Toshitaka*; Ogawa, Kengo*; Nakada, Hitoshi*
Physical Review C, 77(6), p.065802_1 - 065802_5, 2008/06
Times Cited Count：14 Percentile：64.91(Physics, Nuclear)no abstracts in English
Ba populated by deep inelastic collisionsShizuma, Toshiyuki; Gan, Z. G.*; Ogawa, Kengo*; Nakada, Hitoshi*; Oshima, Masumi; Toh, Yosuke; Hayakawa, Takehito; Hatsukawa, Yuichi; Sugawara, Masahiko*; Utsuno, Yutaka; et al.
European Physical Journal A, 20(2), p.207 - 210, 2004/04
Times Cited Count：13 Percentile：71.74(Physics, Nuclear)Excited states in Ba, populated in deep-inelastic collisions by the interaction of 450-MeV 
Se ions with a 
La target, have been studied by means of in-beam 
-ray spectroscopy. A new isomer with 
has been identified at an excitation energy of 
MeV. The half-life was determined as 
ns. The extracted 
value is much smaller than those in 
Te and 
Xe. This hindrance is investigated by a shell model calculation.
for the 
doublet in 
CuHou, L.; Ishii, Tetsuro; Asai, Masato; Hori, Junichi; Ogawa, Kengo*; Nakada, Hitoshi*
Physical Review C, 68(5), p.054306_1 - 054306_6, 2003/11
Times Cited Count：4 Percentile：33.69(Physics, Nuclear)Lifetimes of excited states in Cu were measured by the --
coincidence with two BaF
detectors through the decay of Cu
produced by the (
,
) reaction. The halflife of the 2
state at 84~keV was obtained as 7.84(8)~ns, corresponding to the 
value of 0.00777(8)~
. A shell model calculation with a minimum model space of 
gives a good prediction of this value by using experimental g-factors of neighboring nuclei. This small value can be explained by a shell model calculation with the 
model space.
Tsuzuki, Kazuhiro; Kimura, Haruyuki; Kawashima, Hisato; Sato, Masayasu; Kamiya, Kensaku; Shinohara, Koji; Ogawa, Hiroaki; Hoshino, Katsumichi; Bakhtiari, M.; Kasai, Satoshi; et al.
Nuclear Fusion, 43(10), p.1288 - 1293, 2003/10
Times Cited Count：39 Percentile：74.23(Physics, Fluids & Plasmas)no abstracts in English
Tsuzuki, Kazuhiro; Sato, Masayasu; Kawashima, Hisato; Ogawa, Hiroaki; Kimura, Haruyuki; Okano, Fuminori; Suzuki, Sadaaki; Komata, Masao; Sawahata, Masayuki; Shinohara, Koji; et al.
Journal of Nuclear Materials, 313-316, p.177 - 181, 2003/03
Times Cited Count：9 Percentile：53.35(Materials Science, Multidisciplinary)no abstracts in English
Tsuzuki, Kazuhiro; Sato, Masayasu; Kawashima, Hisato; Isei, Nobuaki; Kimura, Haruyuki; Ogawa, Hiroaki; Miyachi, Kengo; Yamamoto, Masahiro; Shibata, Takatoshi
Journal of Nuclear Materials, 307-311(Part2), p.1386 - 1390, 2002/12
Times Cited Count：15 Percentile：67.86(Materials Science, Multidisciplinary)no abstracts in English
Ninomiya, Hiromasa; Kitsunezaki, Akio; Shimizu, Masatsugu; Kuriyama, Masaaki; JT-60 Team; Kimura, Haruyuki; Kawashima, Hisato; Tsuzuki, Kazuhiro; Sato, Masayasu; Isei, Nobuaki; et al.
Fusion Science and Technology, 42(1), p.7 - 31, 2002/07
Times Cited Count：13 Percentile：27.27(Nuclear Science & Technology)In order to establish scientific basis for the sustainment of highly integrated performance required in the advanced steady-state operation, JT-60U has been optimizing the discharge control scenarios of improved confinement plasmas and expanding the operation regions. Promising results toward the steady-state tokamak were obtained. The detail of such results is reported. JFT-2M has performed advanced and basic research for the development of high performance tokamak plasma as well as the structural material for a fusion reactor. The toroidal ripple reduction with ferritic steel plates outside the vacuum vessel was successfully demonstrated. No adverse effects were observed in the pre-testing on compatibility between ferritic steel plates, covering ~20% of the inside wall of the vacuum vessel, and plasma. The results of TRIAM-1M is also reported.
Tsuzuki, Kazuhiro; Isei, Nobuaki; Kawashima, Hisato; Sato, Masayasu; Kimura, Haruyuki; Ogawa, Hiroaki; Miura, Yukitoshi; Ogawa, Toshihide; Shibata, Takatoshi; Akiyama, Takashi*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 78(5), p.455 - 461, 2002/05
no abstracts in English
Kimura, Haruyuki; Sato, Masayasu; Kawashima, Hisato; Isei, Nobuaki; Tsuzuki, Kazuhiro; Ogawa, Hiroaki; Ogawa, Toshihide; Miura, Yukitoshi; Yamamoto, Masahiro; Shibata, Takatoshi; et al.
Fusion Engineering and Design, 56-57, p.837 - 841, 2001/10
Times Cited Count：14 Percentile：68.97(Nuclear Science & Technology)no abstracts in English
Hayakawa, Takehito; Shizuma, Toshiyuki; Kajino, Toshitaka*; Ogawa, Kengo*; Nakada, Hitoshi*
no journal, ,
no abstracts in English
Hayakawa, Takehito; Shizuma, Toshiyuki; Kajino, Toshitaka*; Ogawa, Kengo*; Nakada, Hitoshi*
no journal, ,
no abstracts in English
Hayakawa, Takehito; Shizuma, Toshiyuki; Kajino, Toshitaka*; Ogawa, Kengo*; Nakada, Hitoshi*
no journal, ,
no abstracts in English
Hayakawa, Takehito; Shizuma, Toshiyuki; Kajino, Toshitaka*; Ogawa, Kengo*; Nakada, Hitoshi*
no journal, ,
no abstracts in English
Hayakawa, Takehito; Shizuma, Toshiyuki; Kajino, Toshitaka*; Ogawa, Kengo*; Nakada, Hitoshi*
no journal, ,
no abstracts in English
Matsubara, Shinichiro*; Imaoka, Kengo*; Ikarimoto, Iwao*; Ogawa, Shinta*; Eto, Masao*; Kawasaki, Nobuchika
no journal, ,
Core assemblies installed in the core vessel deform during the normal operation due to swellings and irradiation creep. Insertability of core assemblies during fuel exchanges was studied with consideration of this deformation.
Kondo, Toshiki; Ogawa, Kengo*; Nakagawa, Takeshi*; Kikuchi, Shin; Seino, Hiroshi
no journal, ,
In this study, as a first step to understand the formation behaviour of gaseous iodine under Sodium-cooled fast reactor sever accident condition, gas evolution from sodium iodide (NaI) in an inert atmosphere was investigated using a Temperature Programmed Desorption-Mass Spectrometry (TPD-MS) apparatus. NaI is expected to be formed by reacting iodine as the fission product with sodium as the coolant. The result was suggested that thermal behaviour of NaI over about 660 Celsius degree was apparently phase change from solid to liquid/gas and formation of gaseous iodine was negligible in an inert atmosphere.
