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JAEA Reports

Impact assessment for internal flooding in HTTR (High temperature engineering test reactor)

Tochio, Daisuke; Nagasumi, Satoru; Inoi, Hiroyuki; Hamamoto, Shimpei; Ono, Masato; Kobayashi, Shoichi; Uesaka, Takahiro; Watanabe, Shuji; Saito, Kenji

JAEA-Technology 2021-014, 80 Pages, 2021/09


In response to the new regulatory standards established in response to the accident at TEPCO's Fukushima Daiichi Nuclear Power Station in March 2011, measures and impact assessments related to internal flooding at HTTR were carried out. In assessing the impact, considering the characteristics of the high-temperature gas-cooled reactor, flooding due to assumed damage to piping and equipment, flooding due to water discharge from the system installed to prevent the spread of fire, and flooding due to damage to piping and equipment due to an earthquake. The effects of submersion, flooding, and flooding due to steam were evaluated for each of them. The impact of the overflow of liquids containing radioactive materials outside the radiation-controlled area was also evaluated. As a result, it was confirmed that flooding generated at HTTR does not affect the safety function of the reactor facility by taking measures.

Journal Articles

High-spin states in $$^{35}$$S

Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Aoi, Nori*; Azaiez, F.*; Furutaka, Kazuyoshi; Hatsukawa, Yuichi; Kimura, Atsushi; Kisamori, Keiichi*; Kobayashi, Motoki*; et al.

Physical Review C, 103(3), p.034327_1 - 034327_8, 2021/03

 Times Cited Count:2 Percentile:46.35(Physics, Nuclear)

Journal Articles

Vertical distribution of $$^{90}$$Sr and $$^{137}$$Cs in soils near the Fukushima Daiichi Nuclear Power Station

Sasaki, Takayuki*; Matoba, Daisuke*; Dohi, Terumi; Fujiwara, Kenso; Kobayashi, Taishi*; Iijima, Kazuki

Journal of Radioanalytical and Nuclear Chemistry, 326(1), p.303 - 314, 2020/10

 Times Cited Count:1 Percentile:23.17(Chemistry, Analytical)

Journal Articles

How different is the core of $$^{25}$$F from $$^{24}$$O$$_{g.s.}$$ ?

Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri, A.*; Hwang, S. H.*; et al.

Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05

 Times Cited Count:11 Percentile:78.03(Physics, Multidisciplinary)

The structure of a neutron-rich $$^{25}$$F nucleus is investigated by a quasifree ($$p,2p$$) knockout reaction. The sum of spectroscopic factors of $$pi 0d_{5/2}$$ orbital is found to be 1.0 $$pm$$ 0.3. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus, and the core consists of $$sim$$35% $$^{24}$$O$$_{rm g.s.}$$, and $$sim$$65% excited $$^{24}$$O. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus. The result may infer that the addition of the $$0d_{5/2}$$ proton considerably changes the neutron structure in $$^{25}$$F from that in $$^{24}$$O, which could be a possible mechanism responsible for the oxygen dripline anomaly.

Journal Articles

Upgrade of the 3-MeV linac for testing of accelerator components at J-PARC

Kondo, Yasuhiro; Hirano, Koichiro; Ito, Takashi; Kikuzawa, Nobuhiro; Kitamura, Ryo; Morishita, Takatoshi; Oguri, Hidetomo; Okoshi, Kiyonori; Shinozaki, Shinichi; Shinto, Katsuhiro; et al.

Journal of Physics; Conference Series, 1350, p.012077_1 - 012077_7, 2019/12

 Times Cited Count:0 Percentile:0.07

We have upgraded a 3-MeV linac at J-PARC. The ion source is same as the J-PARC linac's, and the old 30-mA RFQ is replaced by a spare 50-mA RFQ, therefore, the beam energy is 3 MeV and the nominal beam current is 50 mA. The main purpose of this system is to test the spare RFQ, but also used for testing of various components required in order to keep the stable operation of the J-PARC accelerator. The accelerator has been already commissioned, and measurement programs have been started. In this paper, present status of this 3-MeV linac is presented.

Journal Articles

Structural change of borosilicate glass by neutron irradiation

Nagai, Takayuki; Kobayashi, Hidekazu; Okamoto, Yoshihiro; Akiyama, Daisuke*; Sato, Nobuaki*; Uehara, Akihiro*; Fujii, Toshiyuki*; Sekimoto, Shun*

KURNS Progress Report 2018, P. 105, 2019/08

To understand this structural change of a borosilicate glass by a neutron irradiation in detail, the irradiation test was carried out in KUR in 2017FY. The glass structure was estimated by using Raman spectrometry in 2018FY. Comparing with the Raman spectra of glass samples before and after irradiation, it could be observed the change of peak height of Si-O bridging structure by the irradiation.

Journal Articles

Study on loss-of-cooling and loss-of-coolant accidents in spent fuel pool, 4; Investigation of fuel loading effects in BWR spent fuel rack

Tojo, Masayuki*; Kanazawa, Toru*; Nakashima, Kazuo*; Iwamoto, Tatsuya*; Kobayashi, Kensuke*; Goto, Daisuke*; Nemoto, Yoshiyuki; Kaji, Yoshiyuki

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 13 Pages, 2019/05

In this study, fuel loading effects in BWR spent fuel rack accidents are widely investigated using three-dimensional analysis methods from both nuclear and thermal hydraulics viewpoints, including: (a) Decay heat of spent fuel after discharge, (b) The maximum temperature of spent fuel cladding in the spent fuel rack depending on heat transfer phenomena, and (c) Criticality of the spent fuel rack after collapsing of the fuel due to a severe accidents in the BWR spent fuel pool (SFP).

Journal Articles

Evaluation of uranium chemical state in borosilicate glasses by using XAFS measurement

Nagai, Takayuki; Kobayashi, Hidekazu; Okamoto, Yoshihiro; Akiyama, Daisuke*; Sato, Nobuaki*

Photon Factory Activity Report 2017, 2 Pages, 2018/00

no abstracts in English

Journal Articles

Completion of solidification and stabilization for Pu nitrate solution to reduce potential risks at Tokai Reprocessing Plant

Mukai, Yasunobu; Nakamichi, Hideo; Kobayashi, Daisuke; Nishimura, Kazuaki; Fujisaku, Sakae; Tanaka, Hideki; Isomae, Hidemi; Nakamura, Hironobu; Kurita, Tsutomu; Iida, Masayoshi*; et al.

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 8 Pages, 2017/04

TRP has stored the plutonium in solution state for long-term since the last PCDF operation in 2007 was finished. After the great east Japan earthquake in 2011, JAEA had investigated the risk against potential hazard of these solutions which might lead to make hydrogen explosion and/or boiling of the solution accidents with the release of radioactive materials to the public when blackout. To reduce the risk for storing Pu solution (about 640 kg Pu), JAEA planned to perform the process operation for the solidification and stabilization of the solution by converted into MOX powder at PCDF in 2013. In order to perform PCDF operation without adaption of new safety regulation, JAEA conducted several safety measures such as emergency safety countermeasures, necessary security and safeguards (3S) measures with understanding of NRA. As a result, the PCDF operation had stared on 28th April, 2014, and successfully completed to convert MOX powder on 3rd August, 2016 for about 2 years as planned.

Journal Articles

Effect of magnetism on lattice dynamics in SrFe$$_2$$As$$_2$$ using high-resolution inelastic X-ray scattering

Murai, Naoki*; Fukuda, Tatsuo; Kobayashi, Tatsuya*; Nakajima, Masamichi*; Uchiyama, Hiroshi*; Ishikawa, Daisuke*; Tsutsui, Satoshi*; Nakamura, Hiroki; Machida, Masahiko; Miyasaka, Shigeki*; et al.

Physical Review B, 93(2), p.020301_1 - 020301_5, 2016/01

 Times Cited Count:7 Percentile:38.57(Materials Science, Multidisciplinary)

Journal Articles

Superdeformation in $$^{35}$$S

Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Kobayashi, Motoki*; Kisamori, Keiichi*; Takaki, Motonobu*; Miya, Hiroyuki*; Ota, Shinsuke*; Michimasa, Shinichiro*; Shimoura, Susumu*; et al.

JPS Conference Proceedings (Internet), 6, p.030005_1 - 030005_4, 2015/06

Journal Articles

Effect of heavy ion irradiation to the silkworm eggs at before fertilization and at nuclear cleavage stage

Ueda, Daisuke*; Shirai, Koji*; Funayama, Tomoo; Sakashita, Tetsuya; Yokota, Yuichiro; Kobayashi, Yasuhiko

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 84, 2015/03

In this study, we investigated the effects of irradiation to the silkworm eggs at various developmental stages. First, we tried the irradiation to the unfertilized eggs (at 1.5 hour after oviposition). At this stage, the female pronucleus and the sperm nucleus are observed in the eggs, but not fertilized. After irradiation, the irradiated eggs stopped the development after fertilization. About 2 hours after, the egg restarted the nuclear cleavage. This result indicates the DNA damage on pronuleus cannot prevent the fertilization. We also investigated the effects of irradiation to the egg at the nuclear cleavage stage (at 6 hour after oviposition). The egg also stopped the development after irradiation, but the duration time of the developmental arrest was almost two times longer (about 4 hours) than that of the egg irradiated at fertilization.

Journal Articles

Performance evaluation of the European Committee Standardization Method EN1785 for the detection of irradiated processed food

Tsutsumi, Tomoaki*; Adachi, Rika*; Takatsuki, Satoshi*; Nei, Daisuke*; Kameya, Hiromi*; Todoriki, Setsuko*; Kikuchi, Masahiro; Kobayashi, Yasuhiko; Matsuda, Rieko*; Teshima, Reiko*

Shokuhin Shosha, 49(1), p.9 - 15, 2014/12

no abstracts in English

Journal Articles

Factors controlling the spatiotemporal variation of $$^{137}$$Cs in seabed sediment off the Fukushima coast; Implications from numerical simulations

Misumi, Kazuhiro*; Tsumune, Daisuke*; Tsubono, Takaki*; Tateda, Yutaka*; Aoyama, Michio*; Kobayashi, Takuya; Hirose, Katsumi*

Journal of Environmental Radioactivity, 136, p.218 - 228, 2014/10

 Times Cited Count:21 Percentile:56.59(Environmental Sciences)

Major controls on spatiotemporal variations of $$^{137}$$Cs activity in seabed sediments derived from the Fukushima Dai-ichi Nuclear Power Plant accident during the first year after the accident were investigated by using numerical simulations. The model successfully reproduced major features of the observed spatiotemporal variations of $$^{137}$$Cs activity in sediments. The spatial pattern of $$^{137}$$Cs in sediments, which mainly reflected the history of $$^{137}$$Cs activity in the bottom water overlying the sediment and the sediment particle size distribution, became established during the first several months after the accident. Taking $$^{137}$$Cs activities in sediments in the coastal area and in the vicinity of the power plant into account, increased the simulated total inventory of $$^{137}$$Cs in sediments off the Fukushima coast to a value on the order of 10$$^{14}$$ Bq.

Journal Articles

Deformation-driven $$p$$-wave halos at the drip-line; $$^{31}$$Ne

Nakamura, Takashi*; Kobayashi, Nobuyuki*; Kondo, Yosuke*; Sato, Yoshiteru*; Tostevin, J. A.*; Utsuno, Yutaka; Aoi, Nori*; Baba, Hidetada*; Fukuda, Naoki*; Gibelin, J.*; et al.

Physical Review Letters, 112(14), p.142501_1 - 142501_5, 2014/04

 Times Cited Count:51 Percentile:90.3(Physics, Multidisciplinary)

no abstracts in English

JAEA Reports

Survey of radiation protection creiteria following the accident at the Fukushima Dai-ichi Nuclear Power Plant

Yamada, Katsunori; Fujii, Katsutoshi; Kanda, Hiroshi; Higashi, Daisuke; Kobayashi, Toshiaki; Nakagawa, Masahiro; Fukami, Tomoyo; Yoshida, Keisuke; Ueno, Yumi; Nakajima, Junya; et al.

JAEA-Review 2013-033, 51 Pages, 2013/12


After the accident at Fukushima Dai-ichi Nuclear Power Plant, various numerical criteria relevant to radiation protection were defined. We surveyed these criteria through internet. As a result of survey, the following 13 items were identified: (1) criteria for taking stable iodine tablets, (2) criteria for the screening of surface contamination, (3) evacuation area, sheltering area, etc., (4) activity concentrations in food, drinking water, etc., (5) dose limit for radiation workers engaged in emergency work, (6) guideline levels of radioactive substances in bathing areas, (7) criteria for use of school buildings and schoolyards, (8) restriction on planting rice, (9) acceptable activity concentrations in feedstuff, (10) acceptable activity concentrations in compost, (11) criteria for export containers and ships, (12) criteria for contaminated waste, (13) standards for radiation workers engaged in decontamination work. In this report, the basis of and issues on these criteria are summarized.

Journal Articles

Experimental study on radiation tolerance of SOI-PLLs

Hoshino, Eijiro*; Kobayashi, Daisuke*; Makino, Takahiro; Oshima, Takeshi; Hirose, Kazuyuki*

Proceedings of 10th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-10) (Internet), p.130 - 133, 2012/12

Single event effects on phase locked loops (PLLs) are experimentally investigated. Test chips of the PLLs are fabricated in a 0.2-$$mu$$m fully-depleted silicon-on-insulator technology. The PLL architecture is designed in conjunction with hardening techniques such as the triple modular redundancy and a stacked transistor design approach. A heavy-ion beam test confirms that the hardened PLL exhibits higher radiation tolerance than non-hardened one for 7.5-MeV Ne irradiation: The accelerated ions have the linear energy transfer of 7.3 MeV/cm$$^2$$/mg in Si.

Journal Articles

Oceanic dispersion simulations of $$^{137}$$Cs released from the Fukushima Daiichi Nuclear Power Plant

Masumoto, Yukio*; Miyazawa, Yasumasa*; Tsumune, Daisuke*; Tsubono, Takaki*; Kobayashi, Takuya; Kawamura, Hideyuki; Estournel, C.*; Marsaleix, P.*; Lanerolle, L.*; Mehra, A.*; et al.

Elements, 8(3), p.207 - 212, 2012/06

 Times Cited Count:77 Percentile:93.74(Geochemistry & Geophysics)

Present status of oceanic dispersion simulations of cesium 137 ($$^{137}$$Cs) directly discharged from Fukushima Daiichi Nuclear Power Plant are reviewed using five model outputs and other available informations, focusing on estimations of discharged amount of $$^{137}$$Cs and subsequent dispersion in a region off Fukushima during March and April, 2011. Common aspects and discrepancies among the simulated results are described. While the discharged amount spreads from about 1 to 27 P Bq of $$^{137}$$Cs among the estimates, the values obtained from the five models indicate 2 to 4 P Bq. With these total amounts and time evolutions of the discharge rate, mimicking observed $$^{137}$$Cs concentration near FDNPP, as a source for the dispersion calculation, all the five models simulated the $$^{137}$$Cs dispersion in the ocean reasonably well corresponding to the observed distributions.

Journal Articles

Tolerance of anhydrobiotic eggs of the tardigrade ${it Ramazzottius varieornatus}$ to extreme environments

Horikawa, Daiki*; Yamaguchi, Ayami*; Sakashita, Tetsuya; Tanaka, Daisuke*; Hamada, Nobuyuki*; Yukuhiro, Fumiko*; Kuwahara, Hirokazu*; Kunieda, Takekazu*; Watanabe, Masahiko*; Nakahara, Yuichi*; et al.

Astrobiology, 12(4), p.283 - 289, 2012/04

 Times Cited Count:23 Percentile:70.77(Astronomy & Astrophysics)

We examined the hatchability of hydrated and anhydrobiotic eggs of the tardigrade ${it Ramazzottius varieornatus}$ to hatch after ionizing irradiation (helium ions), extremely low and high temperatures, and high vacuum. Anhydrobiotic eggs (50% lethal dose; 1690 Gy) were substantially more radioresistant than hydrated ones (50% lethal dose; 509 Gy). Anhydrobiotic eggs also have a broader temperature resistance compared with hydrated ones. Over 70% of the anhydrobiotic eggs treated at high and low temperatures, but all of the hydrated eggs failed to hatch. After exposure to high vacuum conditions, the hatchability of the anhydrobiotic eggs was comparable to that of untreated control eggs.

JAEA Reports

Consideration on the earthquake-resistant margin of equipment base-bolts receiving the shearing load during seismic movements

Sakaguchi, Shinobu; Tachibana, Ikuya; Koshino, Katsuhiko; Shirozu, Hidetomo; Shirai, Nobutoshi; Imamoto, Nobuo; Tomita, Tsuneo; Tobita, Hiroo; Yamanaka, Atsushi; Kobayashi, Daisuke; et al.

JAEA-Technology 2011-006, 24 Pages, 2011/03


In the Niigataken Chuetsu-oki Earthquake on 2007, observed earthquake motion exceeded design base at the Kashiwazaki Kariwa nuclear plant. However, there was no earthquake damage in safety important equipments to stop reactor, to cool reactor, and to contain radioactive materials. One of this reason is said that many safety margin are included in the design and the permissible value. To know more accurate safety margin, shearing force examinations for the base bolts were conducted. In examinations, delegate test-bolts were made; the test bolts were selected from heavier equipment in Tokai Reprocessing Plant. In this report, the shearing strength obtained from the examinations shows more accurate safety margin.

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