Analysis of two forms of radioactive particles emitted during the early stages of the Fukushima Dai-ichi Nuclear Power Station accident

Satou, Yukihiko; Sueki, Keisuke*; Sasa, Kimikazu*; Yoshikawa, Hideki; Nakama, Shigeo; Minowa, Haruka*; Abe, Yoshinari*; Nakai, Izumi*; Ono, Takahiro*; Adachi, Koji*; et al.

Geochemical Journal, 52(2), p.137 - 143, 2018/00

https://doi.org/10.2343/geochemj.2.0514

Irradiation test of semiconductor components on the shelf for nuclear robots based on Fukushima Accidents

Kawatsuma, Shinji; Nakai, Koji; Suzuki, Yoshiharu; Kase, Takeshi

QST-M-2; QST Takasaki Annual Report 2015, P. 81, 2017/03

https://repo.qst.go.jp/records/73804

Radiation Tolerance of semiconductor components on the shelf, utilized on the robots for emergency response or decommissioning in nuclear facilities, should be estimated. Just after the Fukushima Daiichi NPPs accidents occurred, a guideline, of irradiation tolerance estimation and management method of semiconductor components on the shelf, was tried to be made based on the old database developed in the course of Bilateral Servo Manipulator under the high radiation and high contamination environments. The estimation was conservative, because the data in the database were old and mainly based on the test results of silicon semiconductors. Ga-As Semiconductors are coming major recently, and expected to be higher radiation tolerance. For those reason, present semiconductor devices have irradiated and the irradiation tolerance have estimated.

Measurements of electron-induced neutrons as a tool for determination of electron temperature of fast electrons in the task of optimization laser-produced plasma ions acceleration

Sakaki, Hironao; Nishiuchi, Mamiko; Maeda, Shota; Sagisaka, Akito; Pirozhkov, A. S.; Pikuz, T.; Faenov, A.*; Ogura, Koichi; Fukami, Tomoyo; Matsukawa, Kenya*; et al.

Review of Scientific Instruments, 85(2), p.02A705_1 - 02A705_4, 2014/02

https://doi.org/10.1063/1.4825154

High intensity laser-plasma interaction has attracted considerable interest for a number of years. The laser-plasma interaction is accompanied by generation of various charged particle beams. Results of simultaneous novel measurements of electron-induced photonuclear neutrons (photoneutron), which are a diagnostic of the laser-plasma interaction, are proposed to use for optimization of the laser-plasma ion generation. The proposed method is demonstrated by the laser irradiation with the intensity os 110 W/cm on the metal foil target. The photoneutrons are measured by using NE213 liquid scintillation detectors. Heavy-ion signal is registered with the CR39 track detector simultaneously. The measured signals of the electron-induced photoneutrons are well reproduced by using the Particle and Heavy Ion Transport code System (PHITS). The results obtained provide useful approach for analyzing the various laser based ion beams.

Development of Level 2 PSA methodology for sodium-cooled fast reactors; Overview of evaluation technology development

Suzuki, Toru; Nakai, Ryodai; Kamiyama, Kenji; Seino, Hiroshi; Koyama, Kazuya*; Morita, Koji*

NEA/CSNI/R(2012)2, p.381 - 391, 2012/07

http://www.oecd-nea.org/html/nsd/docs/2012/csni-r2012-2.pdf

For the probabilistic safety assessment (PSA) of sodium-cooled fast reactors (SFRs), JAEA consolidated the analytical methodologies and technical basis for all phases/sequences to be evaluated in the Level 2 PSA. In addition to the existing computational codes such as SAS4A, SIMMER-III, DEBNET, ARGO and APPLOHS, JAEA newly developed MUTRAN and SIMMER-LT in order to evaluate the long term behaviors of the material-relocation in the degraded core. These tools enabled the systematic assessment for the in-vessel accident sequences. For the ex-vessel accident sequences, JAEA also improved CONTAIN/LMR taking into account the feature of SFRs and verified the analytical models utilizing the new experiments such as sodium-concrete reaction test. In addition, the technical basis for constructing event trees was compiled, in which the dominant factors having significant effects on the event progression were corresponded to the related experiments and analytical results.

In-cell maintenance by manipulator arm with 3D workspace information recreated by laser rangefinder

Kitamura, Akihiro; Nakai, Koji; Namekawa, Takashi; Watahiki, Masatoshi

Nuclear Engineering and Design, 241(7), p.2614 - 2623, 2011/07

https://doi.org/10.1016/j.nucengdes.2011.04.044

We developed a remote control system to display recreated three dimensional information of workspace from measured data obtained by laser rangefinder and to operate manipulator arm remotely. In order to evaluate the effectiveness and usefulness of developed system, we implemented remote handling experiments using mock up equipment and compared the performances of remote operation conducted by the present control system with that by the usual camera based control system. Impressions of operator on the performance of each system are collected and NASA TLX tests are conducted. It was observed that the present system reduced workload stresses and reinforced visual information during remote operation.

Development of level 2 PSA methodology for sodium-cooled fast reactors, 1; Overview of evaluation technology development

Nakai, Ryodai; Suzuki, Toru; Kamiyama, Kenji; Seino, Hiroshi; Koyama, Kazuya*; Morita, Koji*

Proceedings of 8th International Topical Meeting on Nuclear Thermal-Hydraulics, Operation and Safety (NUTHOS-8) (CD-ROM), 12 Pages, 2010/10

The evaluation technology of Level-2 PSA for Sodium-Cooled Fast Reactors (SFRs) was established in order to systematically assess the core damage sequences. In addition to the existing computational tools for Level-2 PSA, the computational tools, MUTRAN and SIMMER-LT were developed for core material relocation phase. Also the analytical models, CORCON and VANESA, were improved based on newly performed experiments for the ex-vessel phase taking into account the feature of SFRs. The technical information was compiled as technical database used in the construction and quantification of level-2 PSA event trees for SFRs. The technical basis was established for the Level-2 PSA for SFRs.

Development of a prototype module for the ERL superconducting main linac at KEK

Furuya, Takaaki*; Hara, Kazufumi*; Hosoyama, Kenji*; Kojima, Yuji*; Nakai, Hirotaka*; Nakanishi, Kota*; Sakai, Hiroshi*; Umemori, Kensei*; Sawamura, Masaru; Shinoe, Kenji*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2923 - 2925, 2010/05

http://accelconf.web.cern.ch/AccelConf/IPAC10/papers/wepec015.pdf

A prototype module including a couple of 1.3 GHz superconducting 9-cell cavities has been designed as the main linac of cERL which is the test facility to establish the basic ERL technology at KEK. The shape of 9-cell Nb structure is optimized to accelerate a CW beam of 100 mA with sufficiently damped higher order modes (HOM) which is achieved by adopting an eccentric fluted beam pipe and a cylindrical beam pipe of a large diameter of 120 mm. Extracted HOMs are absorbed by the ferrite cylinders bonded on the copper beam pipes by HIP process. A power coupler with double disk-ceramics has been developed to transfer an RF of 20 kW CW to the cavity in full reflection. The test results of fabrication, cooling and RF performance for these components are integrated as the prototype module of the main linac for cERL facility.

A New measurement of the Li(,n)B reaction for astrophysical interest

Das, S. K.*; Fukuda, Tomokazu*; Mizoi, Yutaka*; Ishiyama, Hironobu*; Miyatake, Hiroari*; Watanabe, Yutaka*; Hirayama, Yoshikazu*; Tanaka, Masahiko*; Yoshikawa, Nobuharu*; Jeong, S.-C.*; et al.

AIP Conference Proceedings 847, p.374 - 376, 2006/07

https://doi.org/10.1063/1.2234430

no abstracts in English

MK-III Function Tests in JOYO; Primary main Cooling Pump

Isozaki, Kazunori; Saito, Takakazu; Sumino, Kozo; Yamazaki, Yuji*; Karube, Koji; Terano, Toshihiro; Sakaba, Hideo; Nakai, Satoru

JNC TN9410 2004-014, 162 Pages, 2004/06

JNC-TN9410-2004-014.pdf:48.0MB

This technical report describes MK-III function tests on the primary main cooling pump. MK-III function tests (SKS-1) before MK-III core configuration completed from October 17, 2001 to October 23, 2001. MK-III function tests (SKS-2) after MK-III core configuration completed from January 27, 2003 to February 13, 2003. The results of function tests were shown as follows; (1) The primary main pump was confirmed to do stable control on both CAS (cascade) mode and MAN (manual) mode in the flow control system. And also this was confirmed no-emanation trend both flow and revolution per minute against flow step response, too. (2) The main motor was shifted run-back operation in about 54 seconds after scram. Run-back operation of the main motor (A) was 167m3/h with 117 rpm. 185 m/h with 118 rpm was the main motor (B). And they were controlled within the limit of run-back operational revolution 122 rpm 8 rpm. The flow was confirmed to maintain in 10 percent and over of the rated flow. (3) Succeeding operation to the pony motor was confirmed to do in about 39 seconds after the primary main pump trip. The pony motor (A) operation was 180m3/h with 124rpm. 190 m/h with 123 rpm was the pony motor (B). They were enough satisfied with the forgiven revolution per minute which was 93 rpm and over. And the flow was confirmed to maintain in 10 percent and over of the rated flow. (4) Free flow coast down characteristic of the primary main pump was confirmed that time constant was 10 seconds at both the trip and run-back operation time of the primary main pump. (5) Over flow column sodium level of the main pump duty operation was NL-1,550 mm Na by column (A), NL-1,468mm Na by column (B). They were smaller than NL-1,581 mm Na by the design value. Pressure loss value of the new IHX had more conservative value than the design value. (6) The primary main pump was confirmed which the rated flow could be restored no-scram by the instantaneous power loss within 0.6 second.

Basic and clinical studies for application of epithermal neutron beam for neutron capture therapy

Nose, Tadao*; Matsumura, Akira*; Yamamoto, Tetsuya*; Shibata, Yasushi*; Yoshida, Fumiyo*; Akutsu, Hiroyoshi*; Yasuda, Susumu*; Matsushita, Akira*; Nakai, Kei*; Yamada, Takashi*; et al.

UTRCN-G-29, p.114 - 123, 2001/00

no abstracts in English