Basic design of the Hot Laboratory exhaust stack

Morita, Hisashi; Daigo, Fumihisa; Sayato, Natsuki; Watahiki, Shunsuke; Kojima, Kazuki; Nakayama, Kazuhiko; Ide, Hiroshi

JAEA-Technology 2021-030, 166 Pages, 2022/05

JAEA-Technology-2021-030.pdf:3.65MB

When the roof of the JMTR Hot Laboratory (HL) building was repaired for rain leaks in January, 2015, thinning was found at one of the anchor bolts on base of the HL exhaust stack. Moreover, the thinning of some anchor bolts and gaps between the anchor bolt nuts and flange plate was found in the later investigation for the exhaust stack. Since the possibility of the exhaust stack collapsing cannot be denied, it was removed. Therefore, it became necessary to rebuild a new exhaust stack as soon as possible. The design of the new exhaust stack was based on the measures to prevent rainwater intrusion into the base, which was the cause of the thinning of the anchor bolts found in the investigation, and on the new regulatory standards established after the accident at the Fukushima Daiichi Nuclear Power Station. Furthermore, since the new exhaust stack corresponds to buildings and structures that must undergo building confirmation, the soundness of the new exhaust stack against seismic force and wind load was evaluated based on the Building Standards Law and the Stack Structure Design Guideline. This report described the basic design of the new exhaust stack.

Improvement of plant reliability based on combining of prediction and inspection of crack growth due to intergranular stress corrosion cracking

Uchida, Shunsuke; Chimi, Yasuhiro; Kasahara, Shigeki; Hanawa, Satoshi; Okada, Hidetoshi*; Naito, Masanori*; Kojima, Masayoshi*; Kikura, Hiroshige*; Lister, D. H.*

Nuclear Engineering and Design, 341, p.112 - 123, 2019/01

https://doi.org/10.1016/j.nucengdes.2018.10.021

Improvement of plant reliability based on reliability-centered-maintenance (RCM) is going to be undertaken in NPPs. RCM is supported by risk-based maintenance (RBM). The combination of prediction and inspection is one of the key issues to promote RBM. Early prediction of IGSCC occurrence and its propagation should be confirmed throughout the entire plant systems which should be accomplished by inspections at the target locations followed by timely application of suitable countermeasures. From the inspections, accumulated data will be applied to confirm the accuracy of the code, to tune some uncertainties of the key data for prediction, and then, to increase their accuracy. The synergetic effects of prediction and inspection on application of effective and suitable countermeasures are expected. In the paper, the procedures for the combination of prediction and inspection are introduced.

Ion species/energy dependence of irradiation-induced lattice structure transformation and surface hardness of NiNb and NiTa intermetallic compounds

Kojima, Hiroshi*; Kaneno, Yasuyuki*; Ochi, Masaaki*; Semboshi, Satoshi*; Hori, Fuminobu*; Saito, Yuichi*; Ishikawa, Norito; Okamoto, Yoshihiro; Iwase, Akihiro*

Materials Transactions, 58(5), p.739 - 748, 2017/05

https://doi.org/10.2320/matertrans.MBW201612

Bulk samples of NiNb and NiTa intermetallic compounds were irradiated with 16 MeV Au, 4.5 MeV Ni, 4.5 MeV Al, 200 MeV Xe and 1.0 MeV He ions, and the change in near-surface lattice structure was investigated by means of the grazing incidence X-ray diffraction (GIXD)and EXAFS. The NiNb and NiTa lattice structures transform from the ordered structures (orthorhombic and monoclinic structures for NiNb and NiTa, respectively) to the amorphous state by the Au, Ni, Al and Xe ion irradiations. Irrespective of such heavy ion species or energies, the lattice structure transformation to the amorphous state almost correlate with the density of energy deposited through elastic collisions.

The Operation status of the superconducting cavity for CERL main linac; Toward the deep understanding inside the superconducting cavity with high current beam

Numata, Naoto*; Asakawa, Tomoyuki*; Sakai, Hiroshi*; Umemori, Kensei*; Furuya, Takaaki*; Shinoe, Kenji*; Enami, Kazuhiro*; Egi, Masato*; Sakanaka, Shogo*; Michizono, Shinichiro*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.566 - 570, 2015/09

http://www.pasj.jp/web_publish/pasj2015/proceedings/PDF/WEP0/WEP050.pdf

no abstracts in English

Design of -ray and neutron area monitoring system for the IFMIF/EVEDA accelerator building

Takahashi, Hiroki; Maebara, Sunao; Kojima, Toshiyuki; Kubo, Takashi; Sakaki, Hironao; Takeuchi, Hiroshi; Shidara, Hiroyuki; Hirabayashi, Keiichi*; Hidaka, Kosuke*; Shigyo, Nobuhiro*; et al.

Fusion Engineering and Design, 86(9-11), p.2795 - 2798, 2011/10

https://doi.org/10.1016/j.fusengdes.2011.02.074

In the IFMIF/EVEDA accelerator, the engineering validation up to 9 MeV by employing the deuteron beam of 125 mA are planning at the BA site in Rokkasho, Aomori, Japan, the personnel protection system (PPS) is indispensable. The PPS inhibit the beam by receiving the interlock signal from the -ray and neutron monitoring system. The -ray and neutron detection level which is planned to be adopted are "80 keV to 1.5 MeV (-ray)" and "0.025 eV to 15 MeV (neutron)". For the present shielding design, it is absolutely imperative for the safety review to validate the shielding ability which makes detection level lower than these -ray and neutron detector. For this purpose, the energy reduction of neutron and photon for water and concrete is evaluated by PHITS code. From the calculating results, it is found that the photon energy range extended to 10 MeV by water and concrete shielding material only, an additional shielding to decrease the photon energy of less than 1.5 MeV is indispensable.

Interlayer Josephson couplings in Hg-based multi-layered cuprates

Hirata, Yasuyuki*; Kojima, Kenji*; Uchida, Shinichi*; Ishikado, Motoyuki; Iyo, Akira*; Eisaki, Hiroshi*; Tajima, Setsuko*

Physica C, 470(Suppl.1), p.S44 - S46, 2010/12

https://doi.org/10.1016/j.physc.2009.10.120

Infrared reflectivity spectra of the multilayered HgBaCaCuO ( = 2, 3, 4, and 5) are measured. Optical plasma modes associated with the Josephson coupling between CuO planes within a multilayer appear below in the c-axis component of the reflectivity spectrum. For the bilayer and trilayer compound an optical Josephson plasma mode appears at unprecedentedly high frequency, 700-800 cm, below . The plasma frequencies appreciably decrease in four- and five-layer compounds which indicates the suppression of superconducting order in the inner CuO planes, consistent with the result of NMR experiment.

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.

Strong carrier-scattering in iron-pnictide superconductors FeAsO ( = La and Nd) obtained from charge transport experiments

Ishida, Shigeyuki*; Nakajima, Masamichi*; Tomioka, Yasuhide*; Ito, Toshimitsu*; Miyazawa, Kiichi*; Kito, Hijiri*; Lee, C.-H.*; Ishikado, Motoyuki; Shamoto, Shinichi; Iyo, Akira*; et al.

Physical Review B, 81(9), p.094515_1 - 094515_6, 2010/03

https://doi.org/10.1103/PhysRevB.81.094515

Characteristic normal-state charge transport is found in the oxygen-deficient iron-arsenides FeAsO (: La and Nd) with the highest 's among known Fe-based superconductors. The effect of "doping" in this system is mainly on the carrier scattering, quite distinct from that in high- cuprates. In the superconducting regime of the La system with maximum = 28 K, the low-temperature resistivity is dominated by a term. On the other hand, in the Nd system with higher than 40 K, the carriers are subject to stronger scattering showing -linear resistivity and small magnetoresistance. Such strong scattering appears crucial for high- superconductivity in the iron-based system.

Application of clear polymethylmethacrylate dosimeter Radix W to a few MeV electron in radiation processing

Seito, Hajime; Ichikawa, Tatsuya*; Hanaya, Hiroaki; Sato, Yoshishige*; Kaneko, Hirohisa; Haruyama, Yasuyuki; Watanabe, Hiroshi*; Kojima, Takuji

Radiation Physics and Chemistry, 78(11), p.961 - 965, 2009/11

https://doi.org/10.1016/j.radphyschem.2009.07.018

no abstracts in English

Enhancement of the superconducting critical temperature in BiSrCaCuO by controlling disorder outside CuO planes

Hobo, Hiroaki*; Ishida, Shigeyuki*; Fujita, Kazuhiro*; Ishikado, Motoyuki; Kojima, Kenji*; Eisaki, Hiroshi*; Uchida, Shinichi*

Physical Review B, 79(6), p.064507_1 - 064507_6, 2009/02

https://doi.org/10.1103/PhysRevB.79.064507

We investigate the effect of disorder at various lattice sites outside the CuO plane on the superconducting critical temperature of the cuprate superconductor BiSrCaCuO (Bi2212). The most effective disorder turns out to be that at the Sr site in the neighboring blocks, which contain apical-oxygen atoms.