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JAEA Reports

Report on cause investigation and countermeasure of leakage trace from the drum

Shimomura, Yusuke; Sato, Takuya; Fukui, Yasutaka; Kudo, Kenji; Yoshioka, Tatsuji

JAEA-Review 2018-023, 220 Pages, 2019/01

JAEA-Review-2018-023.pdf:15.6MB

On September 11, 2015, leaky traces of bituminized wastes were confirmed from four drums filled with bituminization in waste packages storage yard (II) of waste management facility in Oarai Research and Development Center. Moreover, even after the subsequent investigation, a leakage trace was found from one bituminous drum on November 10, 2015. Furthermore, on December 2, 2015, there was no a leakage trace in one bituminous drum, however the upper lid was found to be intensely corroded. To investigate the causes and the countermeasures for leakages of bituminized wastes from the drums, we have set up a Work Group to investigate the causes and the countermeasures to leakage traces from the drums. This report is based on "Report on Cause Investigation and Countermeasure of Leakage Trace from the Drum" summarized by this working group, the report was reconstructed including the contents clarified in the subsequent document investigation.

Journal Articles

Outline of Oarai Waste Reduction Treatment Facility and volume reduction processing

Sakauchi, Hitoshi; Kikuchi, Yuki; Imaizumi, Haruki; Fukui, Yasutaka

Dekomisshoningu Giho, (57), p.34 - 42, 2018/03

OWTF (Oarai Waste Reduction Treatment Facility) is constructed for volume reduction processing and stabilization treatment of radioactive solid waste, which generate from hot facilities in Oarai Research and Development Center of Japan Atomic Energy Agency, using in-can type high frequency induction heating by remote control. In this report, we describe the outline of OWTF under construction and treatment technologies, in which incinerating and melting.

Journal Articles

Probing surface distributions of $$alpha$$ clusters in $$^{20}$$Ne via $$alpha$$-transfer reaction

Fukui, Tokuro; Taniguchi, Yasutaka*; Suhara, Tadahiro*; Kanada-En'yo, Yoshiko*; Ogata, Kazuyuki*

Journal of Physics; Conference Series, 863(1), p.012036_1 - 012036_3, 2017/07

 Times Cited Count:0 Percentile:0.08

Journal Articles

Probing surface distributions of $$alpha$$ clusters in $$^{20}$$Ne via $$alpha$$-transfer reaction

Fukui, Tokuro; Taniguchi, Yasutaka*; Suhara, Tadahiro*; Kanada-En'yo, Yoshiko*; Ogata, Kazuyuki*

Physical Review C, 93(3), p.034606_1 - 034606_9, 2016/03

AA2015-0612.pdf:0.54MB

 Times Cited Count:13 Percentile:75.95(Physics, Nuclear)

JAEA Reports

Development of dismantling technology for nuclear fuel facility; Discussion of dismantling method for Old Waste Treatment Facility for JOYO

Morita, Kenji; Morimoto, Makoto; Hisada, Masaki; Fukui, Yasutaka

JAEA-Technology 2015-038, 30 Pages, 2016/02

JAEA-Technology-2015-038.pdf:14.65MB

The Old Waste Treatment Facility for JOYO (Old JWTF) has been operated to treat radioactive liquid waste from the experimental fast reactor JOYO and post irradiation examination facilities. Operation of Old JWTF stopped in 1995, and dismantling & decontamination method has discussed. As a response to discussion results of remote and dismantling method in high dose environment on 2013, its concept examination was discussed on 2014. Results are follows. As a cutting tool for Old JWTF equipment, wire saw is selected from cutting ability (speed and thickness of objects). Discussed the component technology of wire saw remote operation system (handling, monitoring, collection method of secondary waste, else).

JAEA Reports

Deuterium Critical Assembly (DCA) Decommissioning work in 2013

Morita, Kenji; Morimoto, Makoto; Hisada, Masaki; Fukui, Yasutaka

JAEA-Technology 2015-037, 28 Pages, 2016/01

JAEA-Technology-2015-037.pdf:8.44MB

Deuterium Critical Assembly (DCA) achieved first critically in 1969 and used for research and development program of Advanced Thermal Reactor. To achieved the aim of facility, DCA decommissioning work started in 2002. Decommissioning schedule consists of 4 stages. The third stage, which is the main work (To dismantle and remove reactor vessel and main equipment), was started in 2008 and will be finished at 2023. This report describes DCA decommissioning work and data (Ability of cutting tools and Man-hours) in 2013.

JAEA Reports

Development of a cutting technique of core structural materials and fuel debris; Applicability test of the plasma jet cutting technique

Shoji, Tsugio; Fukui, Yasutaka; Ueda, Takiho

JAEA-Technology 2015-035, 70 Pages, 2016/01

JAEA-Technology-2015-035.pdf:8.07MB

The plasma jet cutting technology (Max output current is 250A) is developed for the dismantling of nuclear facilities in Oarai Research and Development Center. The plasma jet cutting technology is applicable to take out the debris. The plasma jet torch (Max output current is 600A) was produced for this application. This torch is available for the cutting of thick core internal materials in water. The ability of taking out debris and core internal material has been confirmed.

Journal Articles

The Development of thermal and mechanical cutting technology for the dismantlement of the internal core of Fukushima Daiichi NPS

Tezuka, Masashi; Nakamura, Yasuyuki; Iwai, Hiroki; Sano, Kazuya; Fukui, Yasutaka

Journal of Nuclear Science and Technology, 51(7-8), p.1054 - 1058, 2014/07

 Times Cited Count:8 Percentile:60.89(Nuclear Science & Technology)

The cutting technologies for removing the fuel debris and the internal core structure in 1F are needed in consideration of the situation in the core and so on. On the other hand, JAEA has been carrying out the decommissioning of the nuclear facilities ending the R&D, has several technologies and knowledge to dismantle the nuclear facilities. In particular, the cutting technologies of the plasma arc, the laser, and the abrasive water jet (AWJ) and the plasma jet have been developed. Therefore, based on the above, JAEA has carried out the cutting test for investigating the applicability of those cutting technologies to propose the method for removing the fuel debris and the internal core structure to the national project. In this paper, it is outlined on the test results of the plasma arc and the AWJ cutting technologies, and the future plan of the test of those technologies and the plasma jet cutting technology.

Journal Articles

Measurement, decontamination and dismantlement technology that applies to decommissioning

Hirokawa, Katsunori; Hisada, Masaki; Fukui, Yasutaka; Inoue, Setsunari

Dekomisshoningu Giho, (44), p.33 - 42, 2011/09

In Japan Atomic Energy Agency, facilities where the mission was finished and superannuation facilities are decommissioned systematically for rationalization and efficiency improvement of business. It is necessary to execute safe and economically by making good use of the technology according to the kind of facilities and the feature of the dismantlement object. In this report, it reports on the radiation measurement, decontamination and dismantling technology that develops in the Waste Treatment Technology Section O-ARAI Research and Development Center JAEA.

JAEA Reports

Development of laser decontamination technique (VII); The pollution distribution check examination of the test piece after laser decontamination

; Fukui, Yasutaka; ; Tanimoto, Kenichi

JNC TN9410 2001-028, 62 Pages, 2001/12

JNC-TN9410-2001-028.pdf:6.96MB

On irradiating laser ray to surface of metal, the surface is rapidly heated, melted, and evaporated. Laser decontamination technique has been developed by using the transpire process to radionuclides contaminated machine surface. The decontamination experiments using normal pulse YAG laser and hot sample were carried out. In the experiments, it was understood that even if the surface is ground by 150$$mu$$m or more, radioactivities could not be completely removed. 0n this account, for the purpose of study the depth where a radioactivities merges in the metal by the laser irradiation, surveys using the hot test specimen were per拓rmed. Results are as follows. (1) Observation of topographic profile suggested that the depth of irregularity by laser irradiation were from 200$$mu$$m to 500$$mu$$m, and there were crud on the surface, which seems reattached melting crud by laser irradiation. (2) Metallic composition analysis with fluorescent X-ray analysis device suggested that there was the segregation of Cr in the test specimen that used Air for the assistance gas, and there were not the segregation that used Ar for the assistance gas. (3) The radioactivity analysis of the test specimen that uses the imaging plate and the radio autograph could not clear the distribution of radioactivities. However, it could be confirmed that a radioactive nuclide exited in a range of 500 $$mu$$m or less. (4) Grounding the test specimen and measurement of the doses of radiation with Ge measuring tool suggested that there were radioactivities up to the depth of 300$$mu$$m in the test specimen which used Air for the assistance gas, and 120$$mu$$m in the test specimen which used Ar for the assistance gas.

JAEA Reports

Development of laser decontamination technique (VI); Normal pulse laser decontamination test

Fukui, Yasutaka; ; Kondo, Hitoshi; Tanimoto, Kenichi

JNC TN9410 2000-015, 83 Pages, 2000/09

JNC-TN9410-2000-015.pdf:3.06MB

By irradiating the material surface with the laser beam, it is possible that the surface is rapidly heated, melted and transpired. Laser decontamination technique which applies this process to the removal of the material surface layer contaminated in the radionuclide has been developed. In this report, factual waste laser decontamination experiment using the piping of the old Joyo Waste Treatment Facility was carried out for the purpose of applying laser decontamination technique to decommissioning of nuclear fuel cycle facility. And, secondary product splash prevention test of a normal pulse YAG laser was carried out. Main results are as follows. (1)Factual wast decontamination test It is necessary to decontaminate with the aim of 0.15mm removal depth in order to obtain the decontamination effect to B.G.level, when the pollution piping is decontaminated using a normal pulse YAG laser. Conditions for efficiently obtaining 0.15mm removal depth and l.3kJ/cm$$^{2}$$ irradiation energy density in the irradiation of 2 times with 364W oscillator are 30Hz frequency, duty ratio 50 % in irradiation energy density 1.3kJ/cm$$^{2}$$, and test piece mobile speed 30mm/s. (2)The splash prevention of the secondary product test For the purpose of the splash prevention of the secondary product, the small hood for splash prevention installed in the decontamination nozzle was made. As a result of the test, the following were confirmed : That it does not scatter for the high position almost, though it horizontally scatters in the wide angle, and that the part of the secondary product scatters in the hood outside by reflecting in the hood. It is necessary to make the hood with wedged structure and attraction mechanism for the purpose of shatter-resistant of secandary products.

JAEA Reports

Development of laser decontamination(5); Decontanination test of the hot samples

Fukui, Yasutaka; ; ; Tanimoto, Kenichi

JNC TN9410 99-016, 77 Pages, 1999/08

JNC-TN9410-99-016.pdf:2.82MB

Process of laser decontamination system is as follows. As the material is irradiated by laser beam, its surface is instantaneously heated and ablated. Laser decontamination system is able to decontaminate thoroughly. In this work, the characteristics of laser beam transmission by optical fibers, and decontamination effect of laser beam irradiation to test pieces which are cut down of pipe in the hot facility, are experimented for apply laser decontamination technique to radioactive wastes treatment and decommissioning of nuclear fuel facilities. The results are as follows. (1)Beam transmission. Transmission of Q switch pulse YAG laser's beam by optical fibers are examined. Transmission energy is in proportion to incident energy to fiber. Transmission energy of bundled fiber is 168mJ to 406mJ of incident energy. In the case of incident energy was 425mJ, transmission energy was decrease, because some fibers of bundled fiber were damaged by laser beam. (2)Decontamination test of the hot samples. Counting rate of pipe test piece were decreased more than 90% by first irradiation of Q switch pulse YAG laser. Counting rate of pipe test piece were decreased no more than 4% by on and after second irradiation of Q switch pulse YAG laser. To move the test piece slowly, and to raise the density of irradiation energy, and to use the helium gas for auxiliary gas are effective to increase decontamination effect.

JAEA Reports

Development of laser decontamination(4); Test of beam transmission by fibers and the most suitable condition

Fukui, Yasutaka; ; ; Tanimoto, Kenichi

JNC TN9410 99-014, 99 Pages, 1999/07

JNC-TN9410-99-014.pdf:3.43MB

In this work, the characteristics of laser beam transmission by optica1 fibers and decontamination speed by the most suitable condition and improvement of the characteristics of secondary products are experimented for apply laser decontamination technique to radioactive wastes treatment and deco㎜issioning of nuclear fuel facilities. The results are as follows. (1)Beam transmission. For Q switch pulse YAG laser, beam transmission by optical fibers were examined. Transmission energy increase in proportion to diameter of fiber. The maximum transmission energy of optical fiber was 61mJ, which was not damaged. The transmission energy of bundle fiber was more plenty than the energy of single fibers at same numbers. It is able to apply bundle fiber to transmission system of Q switch pulse YAG laser beam. (2)Improvement of decontamination speed. Imitation contaminants were removed perfectly on the condition that, the irradiation frequency was 2 times, move speed of test piece was 3.0mm/sec, beam diameter was 1.2㎜, repetition speed was 10Hz. At this time, the number of beam shots were more 4 in the unit area. The case of fluence is constant, the number of beam shots were increased by spread of beam diameter in the unit area. (3)Measurement of secondary products. Particle diameters of more than 50% secondary products by Q switch pulse YAG laser were less than 0.1$$mu$$m. Particle diameters of more than 50% secondary products by normal pulse YAG laser were from 0.1$$mu$$m to 1$$mu$$m.

JAEA Reports

Development of laser decontamination technique(3); Experiments of laser beam transmission

Fukui, Yasutaka; ; ; Tanimoto, Kenichi

JNC TN9410 99-008, 157 Pages, 1999/04

JNC-TN9410-99-008.pdf:4.32MB

Laser decontamination system is able to decontaminate thoroughly, and it is able to mitigate the secondary waste quantity, and the system is able to operate by remote control. It is advantageously method compared with other decontamination methods. Irradiation by YAG laser beam is competent for decontamination of stainless steel surface. In this paper, using normal and Q switch pulse YAG laser, Experiments to confirm transmission efficiency using mirror and optical fiber, shape dependency at decontamination, and secondary waste size distribution were performed. The results of the work are as follows. (1) The beam energy of normal pulse YAG laser is able to transmit using optical fiber. The beam energy of Q switch pulse YAG laser is difficult to transmit using a single optical fiber. (2) Normal pulse YAG laser has 10$$^{2}$$ Decontamination Factor (DF) on L-shaped, bolt-shaped, and cylindrical-shaped waste. Q switch pulse YAG laser has over 10$$^{2}$$ DF on L-shaped and cylindrical-shaped waste, but on the other hand, under 10 DF on bolt-shaped waste. (3) In the case of using the argon gas as auxiliary gas, almost particles of secondary products are dropped as dross. In the case, scattering area is within 1m. On the other hand, in the case of using the atmosphere gas as auxiliary gas, almost particles of secondary products are floated in the air, its diameter are under 3$$mu$$m.

Journal Articles

None

Fukui, Yasutaka; Tanimoto, Kenichi

Dekomisshoningu Giho, (19), p.13 - 22, 1998/12

None

Journal Articles

None

Fukui, Yasutaka; ;

Donen Giho, (104), 155 Pages, 1997/12

None

Journal Articles

None

Fukui, Yasutaka; Terunuma, Seiichi

Proceedings of International Conference on Evaluation of Emerging Nuclear Fuel Cycle Systems (GLOBAL'95), 0 Pages, 1995/00

None

JAEA Reports

Development of laser decontamination; Research and fundamental experiment

Fukui, Yasutaka; ; Tanimoto, Kenichi; Terunuma, Seiichi

PNC TN9410 95-041, 171 Pages, 1994/12

PNC-TN9410-95-041.pdf:11.32MB

As the material is irradiated by laser beam, its surface is instataneously heated and ablation. the contaminant in surface layer of radioactive wastes will be decontaminated, provided that such the physical phenomenon is used of decontamination technique. The applicability with decommissioning of laser decontamination technique are investigated by the research of the associated laser techniques and the removing test with metal surface. The results of the research and the test is as follows. (1)The research of laser decontamination. On the YAG and the eximer laser beam, there were some study reports of the decontamination, with the metal and the concrete. The structural material. the biological shield, and the waste strage vessel, these objects were regarded as the objects of the laser decontamination. (2)The removing test of the metal surfacc by lascr beam. The removing performance was examined by irradiating line forcused YAG laser beam with the stainless steel surface. The average removal depth rose, in proportion the product of the energy beam density and the number of beam pulse in He atomosphere. The removal depth was obtained more than 1$$mu$$m, in condition of the laser beam energy was 400mJ and the moving velocity of the test piece was 0.25mm/sec. About 65% of the ablation products were collected, by the simple absorbing system of the open type. (3)Future plan. It is necessary, Examining the removing performance and the variable property of the removal surface, investigating the decontamination technique of the large area and the collecting technique of the ablation products, and so. Thereafter the application to the decontamination will be studied.

JAEA Reports

Development of high-pressure ice brasting method (II) (Confirmation of most auitable condition for decontamination)

Fukui, Yasutaka; ; Tanimoto, Kenichi; Terunuma, Seiichi

PNC TN9410 94-033, 86 Pages, 1994/01

PNC-TN9410-94-033.pdf:33.14MB

It is must deceasse the pool risk for the radio active wastes. So it is necessary to decontaminate the wastes low level $$alpha$$ ($$<$$500$$mu$$Sv/h) during control the secendry wastes. Exfoliation velocity (aria of exfoliated paint per unit time) was measured on various cndition changed parameter brasting pressure, feed rate, stand off distance between nozzle and waste surface, angle of nozzle, therefore most suitable condition for decontamination was decide on high-pressure ice brasting method, results are as follows. (1)Feeding dry-ice pellets of most suitable condition was decided on that brasting pressure is 15Kgf/cm$$^{2}$$, feed rate is 30%. Same exfolation ability was gained on condition that brasting pressure is 15Kgf/cm$$^{2}$$, feed rate is 50%. (2)Brasting dry-ice flow of most suitable condition was dicided on that stand off distance is between 50㎜ and 100㎜ angle of nozzle is 30$$^{circ}$$ with vertical. (3)In case of a pipe form, exfolation ability was gained on condition that angle of nozzle is 60$$^{circ}$$ with vertical after the waste was settled on the turn-table and turning. In case of angle iron form, on condition that angle of nozzle was 0$$^{circ}$$ or 60$$^{circ}$$ with vertical. In case of inner can on condition that angle of nozzle was 45$$^{circ}$$ with axis. When these were such small parts as bolts in the barrel basket which leand 30$$^{circ}$$ with vertical and turned 120rpm, exfolation ability was gained on condition that angle of nozzle was vertical. (4)In decontamination hood designing, negative pressure was maintaind in the cell, and freeze preventing heat capacity of ventilation filter (-78$$^{circ}$$C) was calculated at 73kw.

Journal Articles

None

; Fukui, Yasutaka; ; ; Terunuma, Seiichi

SPECTRUM'94, , 

None

23 (Records 1-20 displayed on this page)