Development of technologies of cutting and decontamination employing high power fiber laser

Toyama, Shinichi; Minehara, Eisuke*

Dekomisshoningu Giho, (56), p.55 - 65, 2017/09

Development of the steel cutting technology which employs high power fiber laser for the industrial applicability of the laser technology has been carried out at The Wakasa Wan Energy Research Center (WERC). At present, the laser technologies for dismantling and decontamination are concurrently being developed to the application measure of nuclear dismantling for domestic nuclear power plants in the future. Dismantling of nuclear facilities is now under the development in the world. The necessity of the technology is increasing and the development is strongly expected. Beside the relative easiness to handle compared with other laser system, suppression of production of secondary radioactive waste and dose exposure can be realized by the dramatic improvement by excelled thermal density of fiber laser. This paper provides recent results from cutting technology for thick steels aiming disassembling nuclear pressure vessel, and decontamination machine technology which works under high radiation dose, explaining the results from cutting experiment of steels and the actual equipment and from the radiation resistance experiment for component devices.

Frequency-resolved optical gating system with a tellurium crystal for characterizing free-electron lasers in the wavelength range of 10-30 m

Iijima, Hokuto; Nagai, Ryoji; Nishimori, Nobuyuki; Hajima, Ryoichi; Minehara, Eisuke*

Review of Scientific Instruments, 80(12), p.123106_1 - 123106_5, 2009/12

https://doi.org/10.1063/1.3265318

Nondestructive detection of heavily shielded materials by using nuclear resonance fluorescence with a laser-Compton scattering -ray source

Kikuzawa, Nobuhiro; Hajima, Ryoichi; Nishimori, Nobuyuki; Minehara, Eisuke; Hayakawa, Takehito; Shizuma, Toshiyuki; Toyokawa, Hiroyuki*; Ogaki, Hideaki*

Applied Physics Express, 2(3), p.036502_1 - 036502_3, 2009/03

https://doi.org/10.1143/APEX.2.036502

Nondestructive detection and assay of nuclear material by laser Compton -rays from energy-recovery linacs

Hajima, Ryoichi; Kikuzawa, Nobuhiro; Hayakawa, Takehito; Minehara, Eisuke

Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/10

Nondestructive assay of nuclear materials is one of the most urgent research issues for the management of nuclear waste. We apply nuclear resonant fluorescence (NRF), a fingerprint of each isotope, to the nondestructive detection. Detection of NRF signals from objectives irradiated by quasi-monochromatic -rays enables one to make quantitative assay of nuclear materials in a nondestructive manner. In order to obtain high-flux -rays for the above purpose, we propose to utilize an energy-recovery linac (ERL), which produces a high-brightness electron beam with high-average current. A design study of high-flux -ray source based on an ERL shows that a -ray flux of ph/sec/keV is obtained and detection of U-238 of 1 Bq/g in a concrete drum is possible within 1 second. In this paper, we present a design of the assay system and results of Monte Carlo simulations of NRF.

Proposal of nondestructive radionuclide assay using a high-flux -ray source and nuclear resonance fluorescence

Hajima, Ryoichi; Hayakawa, Takehito; Kikuzawa, Nobuhiro; Minehara, Eisuke

Journal of Nuclear Science and Technology, 45(5), p.441 - 451, 2008/05

https://doi.org/10.3327/jnst.45.441

A nondestructive assay system for radioactive waste management is proposed. The system utilizes nuclear resonance fluorescence triggered by a quasi-monochromatic high-flux -ray generated from Compton scattering of laser photons by relativistic electrons. We employ an energy-recovery linac as an electron source and a mode-locked fiber laser followed by a laser supercavity as a photon source. The combination of these novel technologies realizes a -ray flux much higher than existing sources using electron storage rings. The proposed -ray source produces a quasi-monochromatic ray with a flux of /s/keV, which is high enough for industrial applications such as nondestructive analysis of radionuclides in nuclear waste and interrogation of fissile material in cargoes. The nuclear resonance fluorescence triggered by quasi-monochromatic -rays provides a versatile method of nondestructive analysis of both radioactive and stable nuclides.

Feasibility of laser decommissioning for nuclear power reactor plants

Minehara, Eisuke

Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 4 Pages, 2007/04

https://doi.org/10.1299/jsmeicone.2007.15._ICONE1510_347

Recent industrial lasers and newly-developed high performance lasers will open new possibilities of laser decommissioning that we can clean-up quickly every facility of the nuclear power reactors, decontaminate each piece of the disassembled devices and sharply cut without producing a large amount of radioisotope (RI)-contaminated dusts during the decommissioning operation. In the conference, we plan to report recent results of laser decommissioning trials and basic performances for cold materials using several laser types, and to discuss finally about feasibility of the laser decommissioning for Fugen Nuclear Power Station.

Estimation of HOM-BBU threshold current for an energy recovery linac

Nagai, Ryoji; Hajima, Ryoichi; Sawamura, Masaru; Nishimori, Nobuyuki; Iijima, Hokuto; Kikuzawa, Nobuhiro; Minehara, Eisuke

Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.637 - 639, 2007/00

A collaborative project towards an ERL light source has been launched in Japan. In this project, the superconducting cavity is optimized for a high-average current beam. The latest design is a 9-cell cavity of 1.3 GHz with enlarged beam pipes and on-axis HOM absorbers. In this paper, beam breakup instabilities for the newly designed cavity is investigated. Threshold current of beam breakup at a 5-GeV ERL and possible extention to multi-turn configuration is presented.

Emittance compensation solenoid of a DC photo-cathode electron gun

Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki; Iijima, Hokuto; Sawamura, Masaru; Kikuzawa, Nobuhiro; Minehara, Eisuke

Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.673 - 675, 2007/00

An emittance compensation solenoid magnet is designed for a DC photo-cathode electron gun. The DC gun is now in fabrication at JAEA for an energy-recovery linac (ERL) light-source. The ERL light-source requires very low emittance electron beam to generate coherent X-rays. In order to produce the very low emittance electron beam from the DC gun, a focusing lens is indispensable to compensate the linear emittance growth. A solenoid magnet is employed for the emittance compensation lens. The solenoid magnet consists of a main coil, pure iron yoke, and a backing coil. The compensated emittance is estimated less than 0.6 mm-mrad in the bunch charge of 77 pC by PARMELA simulation.

An Interrogation method for radioactive waste by using an ERL-based high-flux -ray source

Kikuzawa, Nobuhiro; Hajima, Ryoichi; Hayakawa, Takehito; Minehara, Eisuke

Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.577 - 579, 2007/00

Laser-Compton-backscattered photons from an energy-recovery linac (ERL) and a high power laser realize a high-efficiency, high-flux and tunable monochromatic -ray source. A non-destructive interrogation method by using nuclear resonance fluorescence (NRF) make possible to measure the discrimination of clearance levels of a concrete solidification radioactive waste. The purpose of our work is to design and evaluation of the NRF-based detection system. For this evaluation, we are developing a GEANT4-based Monte Carlo simulation code. Some simulations have been performed with simple models of a concrete solidification radioactive waste cask and detectors. We present a recent result of the simulation.

Performance of a conventional analog -A type low-level RF controller

Nagai, Ryoji; Hajima, Ryoichi; Iijima, Hokuto; Kikuzawa, Nobuhiro; Minehara, Eisuke; Nishimori, Nobuyuki; Nishitani, Tomohiro; Sawamura, Masaru

Proceedings of 28th International Free Electron Laser Conference (FEL 2006) (CD-ROM), p.316 - 318, 2006/08

For an FEL application and an ERL light source, high-stability of accelerator RF amplitude and phase is required. A low-level RF controller (LLC) of the JAEA-ERL has been improved to ensure high-stability accelerating RF field. The LLC performance is tested for a 499.8MHz superconducting cavity and a 1300MHz copper cavity. The phase and amplitude stabilities of the 499.8MHz superconducting cavity within a 1ms macro-pulse are 0.0055deg-rms and 7.6410, respectively. For the 1300MHz copper cavity, pulse mode and CW mode were tested. In the case of pulse mode, the phase and amplitude stabilities are 0.011deg-rms and 7.6410, respectively. In the case of CW mode, the phase and amplitude stabilities are 0.011deg-rms and 6.6810, respectively.