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Journal Articles

Work hardening behavior of dual phase copper-iron alloy at low temperature

Yamashita, Takayuki*; Koga, Norimitsu*; Kawasaki, Takuro; Morooka, Satoshi; Tomono, Shohei*; Umezawa, Osamu*; Harjo, S.

Materials Science & Engineering A, 819, p.141509_1 - 141509_10, 2021/07

 Times Cited Count:3 Percentile:68.56(Nanoscience & Nanotechnology)

Journal Articles

Change in mechanical properties by high-cycle loading up to Gigacycle for 316L stainless steel

Naoe, Takashi; Harjo, S.; Kawasaki, Takuro; Xiong, Z.*; Futakawa, Masatoshi

JPS Conference Proceedings (Internet), 28, p.061009_1 - 061009_6, 2020/02

At the J-PARC, a mercury target vessel made of 316L SS suffers proton and neutron radiation environment. The target vessel also suffers cyclic impact stress caused by the proton beam-induced pressure waves. The vessel suffers higher than 4.5$$times$$10$$^8$$ cyclic loading during the expected service life of 5000 h. We have investigated fatigue strength 316L SS up to gigacycle in the previous studies. The cyclic hardening and softening behavior were observed. In this study, to evaluate the cyclic hardening/softening behavior, the dislocation densities of specimens were measured using the neutron diffraction method at the MLF BL-19. The result showed that the dislocation density of a 316L SS was increased with increasing the number of loading cycles. By contrast, in the case of cold-rolled 316L SS, annihilation and re-accumulation of dislocation by cyclic loading were observed. In the workshop, result of neutron diffraction measurement will be introduced with the progress of fatigue test.

Journal Articles

Contribution by incorporation of laser technology and robotics technology for Fukushima Daiichi Nuclear Power Plants decommissioning

Kawatsuma, Shinji

Reza Kenkyu, 45(7), p.413 - 417, 2017/07

Inside and surrounding area of reactor buildings of Fukushima Daiichi Nuclear Power Plants became high radiation condition because of radioactive materials release by the accidents caused by earthquake of Pacific coast on eastern and northern Japan. In the stage of emergency response to the accidents, more than 20 robots had been deployed, and some of them had equipped with laser technologies like as laser range finder. In the following decommissioning stage of the plans, operations under higher radiation condition will be required, so that varied laser technologies will be needed to fuse with robot technologies. Laser checker laser analysis would be expected besides laser range finder. However those technologies will be deployed under higher radiation condition, so radiation hardening and control stabilizing should be solved.

Journal Articles

Improved cavitation resistance of structural materials in pulsed liquid metal targets by surface hardening

Koppitz, T.*; Jung, P.*; M$"u$ller, G.*; Weisenburger, A.*; Futakawa, Masatoshi; Ikeda, Yujiro

Journal of Nuclear Materials, 343(1-3), p.92 - 100, 2005/08

 Times Cited Count:7 Percentile:46.25(Materials Science, Multidisciplinary)

Cavitation damage of structural materials due to pressure waves is expected to be one of the majior life-time limiting factors in high power liquid metal spallation targets under pulsed operation. Two methods are developed for the European Spallation Source (ESS) to mitigate this damage: Introduction of gas bubbles to surpress the pressure pulse and surface-hardening of structural materials. Surface-hardening of four 8-13%Cr martenstic steels was examined by thermal treatment with pulsed or scanned electron- and laser-beams as well as by nitriding in plasma. A specimens of the 12%Cr steel were tested in liquid mercury under pulsed proton irradiation, and under mechanical pulsed-loading. Surface damage was analysed by optical, confocal-laser, or scanning-electron microscopy, showing in both tests much better resistance of the hardened material compared to standard condition.

Journal Articles

Effects of helium production and heat treatment on neutron irradiation hardening of F82H steels irradiated with neutrons

Wakai, Eiichi; Taguchi, Tomitsugu; Yamamoto, Toshio*; Tomita, Hideki*; Takada, Fumiki; Jitsukawa, Shiro

Materials Transactions, 46(3), p.481 - 486, 2005/03

 Times Cited Count:7 Percentile:52.75(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Hardening of Fe-Cu model alloys induced by electron irradiation and neutron irradiation

Tobita, Toru; Aizawa, Kazuya; Suzuki, Masahide; Iwase, Akihiro*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(4), p.331 - 339, 2004/12

Nevertheless, there is a possibility that $$gamma$$-ray induces embrittlement more efficiently than fast neutron, the irradiation effect of $$gamma$$-ray has not been fully clarified. Comparative experiments on irradiation hardening by 2.5MeV electron irradiation for the purpose of $$gamma$$-ray irradiation and neutron irradiation were performed to the Fe-Cu model alloys. We obtained the dose dependence and the temperature dependence on irradiation induced hardening. The growth of Cu clusters with increase in irradiation dose was confirmed by the small angle neutron scattering measurements. Although the differences in hardening between electron and neutron irradiations were very small on a displacement-per-atom (dpa) basis, the electron irradiation hardening initiated slightly earlier than the neutron. The growth of Cu clusters with increase in irradiation dose was the principal cause of hardening. The present results suggested that, from an engineering point of view, both the $$gamma$$-ray induced and neutron induced hardening can be well scaled by using dpa.

JAEA Reports

Report of Examination of the Samples from Core Shroud (2F3-H6a) at Fukushima Dai-ni Nuclear Power Station Unit-3 (Contract Research)

The Working Team for Examination Operation of Samples From Core Shroud at Fukushima Dai-ni Unit-3

JAERI-Tech 2004-044, 92 Pages, 2004/05

JAERI-Tech-2004-044.pdf:15.18MB

The present examination has been performed with the objective to ensure the transparency of the examination as the third-party organization by providing technical basis for identifying the causes of cracking through examination of the sample taken from the cracked region of outer H6a welding portion of the core shroud at Fukushima Dai-ni Nuclear Power Station Unit-3, which was a part of sample stored in the Nippon Nuclear Fuel Development Co., Ltd. in the examination of Tokyo Electric Power Company in 2001. The present examination of the sample was conducted at the post irradiation examination facilities of JAERI. The following findings were obtained from the result of the present examination. (1)Three cracks were observed at the portion 3 to 9mm apart from the weld metal and the maximum depth was about 8mm. (2)Intergranular cracking was observed in almost whole fracture surface. The transgranular cracking was partially observed within the depth of about 300$$mu$$m from the surface. (3)Hardening layer over Hv400 at its maximum was found from the surface to the depth of about 500$$mu$$m. Based on the examination results concerning presence of tensile residual stress by welding and relatively high dissolved oxygen contents in core coolant, it is concluded that the cracks were mainly initiated in the hardening layer by transgranular stress corrosion cracking and propagated along the grain boundaries.

JAEA Reports

Report of Examination of the Sample from Core Shroud (O1-H2) at Onagawa Nuclear Power Station Unit-1 (Contract research)

The Working Team for Examination of the Sample from Core Shrouds and Primary Loop Recirculation Pipi

JAERI-Tech 2004-012, 62 Pages, 2004/02

JAERI-Tech-2004-012.pdf:16.4MB

At Onagawa Nuclear Power Station Unit-1 of the Tohoku Electric Power co., inc., cracks were confirmed near welded joints of core shroud in 15th periodical inspection. Tohoku Electric Power co., inc. has conducted a material examination with Nippon Nuclear Fuel Development Co., Ltd.. To investigate independently, a JAERI's own evaluation report was provided. The results are as follows; (1) Hardening layer was detected at the depth of about 150-250$$mu$$m from outer surface of the sample. (2) Corrosion products were observed on inner surface of the cracks and some of them penetrated into grains. (3) Transgranular cracking and intergranular cracking were observed at the region within about 100$$mu$$m and the deeper region more than about 200$$mu$$m in depth from outer surface of the sample, respectively. (4) Distinct chromium depletion was not detected at the grain boundaries. (5) Chemical compositions of the sample corresponded to type 304L stainless steel in Japanese Industrial Standard. From the above, it is concluded that the cracks are stress corrosion cracking.

JAEA Reports

Report of Examination of the Sample from Core Shroud (K1-H4) at the Kashiwazaki-Kariwa Nuclear Power Station Unit-1 (Contract research)

The Working Team for Examination of the Sample from Core Shrouds and Primary Loop Recirculation Pipi

JAERI-Tech 2004-011, 64 Pages, 2004/02

JAERI-Tech-2004-011.pdf:14.65MB

At the Kashiwazaki-Kariwa Nuclear Power Station Unit-1 of the TEPCO, cracks were confirmed at the weld joint (H4) in the middle of core shroud, by the visual inspection test for the weld joint of core shroud during the 13th periodic examination by a direction of the Nuclear and Industrial Agency. TEPCO has conducted a material examination with NFD on the specimen including cracks sampled from the core shroud. The present research has been performed with the objective to independently investigate and evaluate the materials by jointly attending the examination with NFD from the planning stage, receiving the final data given by the examination and providing JAERI's own evaluation report as a third-party organization for assuring the transparency. As a result, the consideration of residual stress induced with welding process and dissolved oxygen concentration in core cooling water, it was concluded that the cracks were initiated by SCC and propagated three-dimensionally through grains, and some cracks reached weld metal.

JAEA Reports

Report of Examination of the Sample from Core Shroud (1F4-H4) at Fukushima Dai-ichi Nuclear Power Station Unit-4 (Contract research)

The Working Team for Examination of the Sample from Core Shrouds and Primary Loop Recirculation Pipi

JAERI-Tech 2004-004, 74 Pages, 2004/02

JAERI-Tech-2004-004.pdf:31.62MB

During the 12th periodical inspection in Fukushima Dai-ichi Nuclear Power Station Unit-4 (BWR, 784MW) of Tokyo Electric Power Company (TEPCO), which has been held from September 1993 to February 1994, cracks were found at welded joints No.H4 in the core shroud middle shell. TEPCO has conducted a material examination with Nippon Nuclear Fuel Development Co. Ltd. (NFD) on the SUS304L specimen including cracks sampled from the inner surface of welded joints (H4) of the middle shell of the core shroud. The present examination has been performed with the objective to independently investigate and evaluate the materials by jointly attending the examination with NFD, receiving the final data given by the examination and providing a JAERI's own evaluation report as a third-party organization for assuring the transparency. Based on the research results described above, presence of tensile residual stress by welding and relatively high dissolved oxygen contents in core coolant, it is concluded that the cracks observed were caused by the stress corrosion cracking (SCC).

Journal Articles

Triple ion beam irradiation tests on window materials of spallation targets

Futakawa, Masatoshi; Kurata, Yuji; Henry, J.*; Ioka, Ikuo; Saito, Shigeru; Naito, Akira

FZKA-6876, p.166 - 171, 2003/12

A report at MEGAPIE(Megawatt Pilot Experiment) Technical R & D Meeting is collected into an FZK report. Triple ion beam irradiation tests on T91 specimens were conducted under MEGAPIE condition using TIARA facility at JAERI. Results of triple ion beam irradiation up to 15dpa, 1400appm He, 10000appm H at 320$$^{circ}$$C were compared with those of single or dual beam irradiation of Fe or He ions by use of a micro-indentation method. Hardsness increase was mainly attributed to displacement damage by Fe ions. A little effect on hardness was found on simultaneous implantation of He and H ions. An analysis method to predict mechanical characterization form micro-indentation test results was developed on ion irradiated materials.

Journal Articles

Localized-impact damage caused by proton bombarding in mercury target

Futakawa, Masatoshi; Kogawa, Hiroyuki; Ishikura, Shuichi*; Kudo, Hisaaki*; Soyama, Hitoshi*

Journal de Physique, IV, 110, p.583 - 588, 2003/09

A liquid-mercury target system for the MW-scale target is being developed in the world. The moment the proton beams bombard the target, pressure waves will be generated in the mercury by the thermally shocked heat deposition. Provided that the negative pressure generates through its propagation in the mercury target and causes cavitation in the mercury, there is the possibility for the cavitation bubbles collapse to form pits on the interface between the mercury and the target vessel wall. In order to estimate the cavitation erosion damage, Split Hopkinson Pressure Bar (SHPB) tests impact tests were performed to impose the impact pressure to the interface between mercury and solid metals. In particular, the surface hardening treated samples: Kolsterising, some coatings are investigated. As results, it is confirmed that the pitting damage is suppressed by surface hardening treatments and relative hardness appeared to be a good correlating parameter on impact erosion resistance.

Journal Articles

Effect of hardening treatment on impact erosion of liquid/solid metal interface

Koyama, Tomofumi*; Futakawa, Masatoshi; Kogawa, Hiroyuki; Ishikura, Shuichi*

Nihon Kikai Gakkai Kanto Shibu Ibaraki Koenkai (2002) Koen Rombunshu, p.5 - 6, 2002/09

no abstracts in English

Journal Articles

Irradiation embrittlement of 2.25Cr-1Mo steel at 400$$^{circ}$$C and its electrochemical evaluation

Nishiyama, Yutaka; Fukaya, Kiyoshi; Suzuki, Masahide; Eto, Motokuni

Journal of Nuclear Materials, 258-263, p.1187 - 1192, 1998/00

 Times Cited Count:4 Percentile:39.38(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Effect of neutron irradiation on deformation behavior of a Ti-Ni shape memory alloy

Hoshiya, Taiji; *; Ando, Hiroei

Nihon Kinzoku Gakkai-Shi, 56(7), p.741 - 746, 1992/00

no abstracts in English

Journal Articles

Radiation effects in pure silica core and ge-doped silica core fibers

; ; *; *; *; *; *; *

Fujikura Densen Giho, 66, p.42 - 50, 1983/00

no abstracts in English

Journal Articles

Seismic response of high temperature gas-cooled reactor core with block-type fuel, 2; Three-dimensional vibration characteristices of stacked blocks column

; *

Journal of Nuclear Science and Technology, 17(9), p.655 - 667, 1980/00

 Times Cited Count:5 Percentile:53.82(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Journal Articles

Electron irradiation hardening of copper and copper alloys at 78K and 300K

; *;

Phys.Status Solidi A, 18(1), p.377 - 386, 1973/01

 Times Cited Count:7

no abstracts in English

Journal Articles

The Role of some alloying elements on radiation hardening in pressure vessel steels

*; ; *

ASTM Special Technical Publication 529, p.63 - 74, 1973/00

no abstracts in English

22 (Records 1-20 displayed on this page)