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JAEA Reports

Decommissioning of the Uranium Enrichment Laboratory

Kokusen, Junya; Akasaka, Shingo*; Shimizu, Osamu; Kanazawa, Hiroyuki; Honda, Junichi; Harada, Katsuya; Okamoto, Hisato

JAEA-Technology 2020-011, 70 Pages, 2020/10

JAEA-Technology-2020-011.pdf:3.37MB

The Uranium Enrichment Laboratory in the Japan Atomic Energy Agency (JAEA) was constructed in 1972 for the purpose of uranium enrichment research. The smoke emitting accident on 1989 and the fire accident on 1997 had been happened in this facility. The research on uranium enrichment was completed in JFY1998. The decommissioning work was started including the transfer of the nuclear fuel material to the other facility in JFY2012. The decommissioning work was completed in JFY2019 which are consisting of removing the hood, dismantlement of wall and ceiling with contamination caused by fire accident. The releasing the controlled area was performed after the confirmation of any contamination is not remained in the target area. The radioactive waste was generated while decommissioning, burnable and non-flammable are 1.7t and 69.5t respectively. The Laboratory will be used as a general facility for cold experiments.

Journal Articles

Current status of decommissioning activities in JAEA; Second midterm plan from FY2010 to FY2014

Tachibana, Mitsuo; Murata, Masato; Tasaki, Tadayuki; Usui, Hideo; Kubota, Shintaro

Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.1987 - 1996, 2015/09

230 various types of nuclear facilities were constructed in JAEA's R&D Institutes or Center until the establishment of the JAEA in 2005. The JAEA has efficiently and systematically decommissioned nuclear facilities that would no longer be required after the establishment of the JAEA. Decommissioning of nuclear facilities in each JAEA's R&D Institutes or Center was continued based on the second midterm plan of the JAEA from FY2010 to FY2014. Decommissioning of 2 nuclear facilities was completed during the second midterm. This report describes current status of decommissioning activities in the JAEA during the second midterm and outline of the decommissioning plan in the third midterm.

Journal Articles

Development in fission track- thermal ionization mass spectrometry for particle analysis of safeguards environmental samples

Lee, C. G.; Iguchi, Kazunari; Inagawa, Jun; Suzuki, Daisuke; Esaka, Fumitaka; Magara, Masaaki; Sakurai, Satoshi; Watanabe, Kazuo; Usuda, Shigekazu

Journal of Radioanalytical and Nuclear Chemistry, 272(2), p.299 - 302, 2007/05

 Times Cited Count:44 Percentile:94.37(Chemistry, Analytical)

no abstracts in English

Journal Articles

Influence of uranium enrichment on the etching rate of polycarbonate fission track detector containing uranium particles

Lee, C. G.; Iguchi, Kazunari; Esaka, Fumitaka; Magara, Masaaki; Sakurai, Satoshi; Watanabe, Kazuo; Usuda, Shigekazu

Nuclear Instruments and Methods in Physics Research B, 245(2), p.440 - 444, 2006/04

 Times Cited Count:7 Percentile:48.74(Instruments & Instrumentation)

The etching rates of fission track detectors made of polycarbonate containing uranium particles were measured after thermal neutron irradiation with fluence of 8$$times$$10$$^{14}$$ n/cm$$^{2}$$, in order to study the influence of uranium enrichment on the etching rate that was calculated from the weight loss by etching. There is a strong correlation between the etching rate of detector and the enrichment E of uranium particle: the former increases as the latter increases. Particularly, the etching rate per particle was proportional to E$$^{2/3}$$ rather than E$$^{1}$$, which is probably due to the overlapping of fission tracks. The etching behaviors of detector revealed that the existence of two different etching rate regions, a nonlinear region in the beginning of etching process and a subsequent constant region, which was explained as the opening of fission tracks and the broadening of opened tracks, respectively.

Journal Articles

Study on the etching conditions of polycarbonate detectors for particle analysis of safeguards environmental samples

Iguchi, Kazunari; Esaka, Konomi; Lee, C. G.; Inagawa, Jun; Esaka, Fumitaka; Onodera, Takashi; Fukuyama, Hiroyasu; Suzuki, Daisuke; Sakurai, Satoshi; Watanabe, Kazuo; et al.

Radiation Measurements, 40(2-6), p.363 - 366, 2005/11

 Times Cited Count:10 Percentile:59.05(Nuclear Science & Technology)

In particle analysis for safeguards environmental samples, the fission track technique is very important to detect sub-micrometer particles containing uranium. In the technique the authors developed, the particles were recovered onto the polycarbonate membrane filter. The filter was dissolved in solvent and dried to form a thin film of detector, in which the particles were confined. After thermal neutron irradiation and etching, the particles of interest in the detector were easily identified with fission tracks, and were picked up for isotope ratio analysis. It was found, however, that the particles in the vicinity of the detector surface may fall off during the etching process. Therefore, optimization of the etching condition is required. In this work, the effects of etching time and enrichment of uranium in particles were investigated. Preliminary results suggest that etching time should be shorter with the increase in the enrichment.

JAEA Reports

Proposal of new $$^{235}$$U nuclear data to improve k$$_{eff}$$ biases on $$^{235}$$U enrichment and temperature for low enriched uranium fueled lattices moderated by light water

Wu, H.; Okumura, Keisuke; Shibata, Keiichi

JAERI-Research 2005-013, 31 Pages, 2005/06

JAERI-Research-2005-013.pdf:3.29MB

The under prediction of k$$_{eff}$$ depending on $$^{235}$$U enrichment in low enriched uranium fueled systems was studied in this report. Benchmark testing was carried out with several evaluated nuclear data files, including the new uranium evaluations from preliminary ENDF/B-VII and CENDL-3.1. Another problem reviewed here was k$$_{eff}$$ underestimation vs. temperature increase, which was observed in the slightly enriched system with recent JENDL and ENDF/B uranium evaluations. Through the substitute analysis of nuclear data of $$^{235}$$U and $$^{238}$$U, we propose a new evaluation of $$^{235}$$U data to solve both of the problems. The new evaluation was tested for various uranium fueled systems including low or highly enriched metal and solution benchmarks in the ICSBEP handbook. As a result, it was found that the combination of the new evaluation of $$^{235}$$U and the $$^{238}$$U data from the preliminary ENDF/B-VII gives quite good results for most of benchmark problems.

Journal Articles

Diagnostics of pulsed plasma in laser ablation of boron compounds

Oba, Hironori; Saeki, Morihisa; Yokoyama, Atsushi

Proceedings of Plasma Science Symposium 2005/22nd Symposium on Plasma Processing (PSS-2005/SPP-22), p.331 - 332, 2005/01

A plasma produced by a XeCl laser ablation of boron compound was investigated using ion probes and a quadrupole mass spectrometer. Although the ablated neutral boron atoms had a natural abundance ratio, the isotope ratio of singly ionized boron atoms having a greatly different from the natural abundance ratio was observed. The observed isotope ratio of boron ions was different from the natural abundance.

Journal Articles

Measurement of temperature effect on low enrichment STACY heterogeneous core

Watanabe, Shoichi; Yamamoto, Toshihiro; Miyoshi, Yoshinori

Transactions of the American Nuclear Society, 91, p.431 - 432, 2004/11

Temperature effect is a main factor which affects the transient characteristics at a criticality accident. A series of reactivity effects due to changes in fuel temperatures were measured for two kinds of STACY heterogeneous lattice configurations. The core was composed of LWR-type fuel rod array and low-enriched uranyl-nitrate-solution concerning the dissolver of the reprocessing facility for LWR spent fuel. The critical solution heights at various solution temperatures were measured. From the change of the critical water height with fuel temperature, the reactivity effect was evaluated by a critical-solution-level worth method. The temperature effect was also calculated by using SRAC and the transport calculation code TWODANT. The experimental value was estimated to be -2.0 cent/$$^{circ}$$C for the case "2.1cm-pitch", and -2.5 cent/$$^{circ}$$C for the case "1.5cm-pitch". The calculated results gave agreement with the experiments within $$sim$$10%.

JAEA Reports

Measurement of coolant flow in fuel elements at the JRR-4 silicide fuel core

Yamamoto, Kazuyoshi; Watanabe, Shukichi; Nagatomi, Hideki; Kaminaga, Masanori; Funayama, Yoshiro

JAERI-Tech 2002-034, 40 Pages, 2002/03

JAERI-Tech-2002-034.pdf:1.97MB

JRR-4, a swimming-pool type research reactor with a thermal power of 3.5MW, attained criticality in July 1998, after replacing its 90% enrichment fuel with a 20% enrichment fuel under the Reduced Enrichment Program. As a part of the program, safety analysis on thermo-hydraulics of the reactor core was conducted on cases including single channel blockage accident. With the conclusion that a certain margin on thermo-hydraulics was necessary, investigation and experiments were carried out with an aim to increase the core flow rate. To increase the core flow, it was carried out to reduce the bypass flow in the core and to increase the primary coolant flow rate from 7m$$^{3}$$/min to 8m$$^{3}$$/min. After flow measurements using a mock-up fuel element, flow velocity of the fuel channel was determined as 1.45m/s as opposed to the designed value of 1.44m/s, and the ratio of core flow to total flow was 0.88, exceeding the value 0.86 used for the safety analysis.This report describes the JRR-4 core flow increase plan as well as the results of the channel flow rate measurement

Journal Articles

Comparison of JRR-4 core neutronic performance between silicide fuel and TRIGA fuel

Nakano, Yoshihiro; Ichikawa, Hiroki; Nakajima, Teruo

Proc. of the 16th Int. Meeting on Reduced Enrichment for Research and Test Reactors, 0, p.313 - 320, 1994/03

no abstracts in English

JAEA Reports

Review on JMTR safety design for LEU core conversion

; Miyazawa, Masataka; ; ; *; Yamamoto, Katsumune; Oyamada, Rokuro; Saito, Minoru

JAERI-M 93-227, 73 Pages, 1993/12

JAERI-M-93-227.pdf:2.58MB

no abstracts in English

JAEA Reports

Statistical thermodynamic properties of uranium hexafluoride

Oda, Tetsuzo

JAERI-M 93-052, 49 Pages, 1993/03

JAERI-M-93-052.pdf:1.11MB

no abstracts in English

Journal Articles

Release of fission products from silicide fuel at elevated temperatures

; Saito, Minoru; Oyamada, Rokuro; ; ; Saito, Junichi; Iwai, Takashi; ; Nakagawa, Tetsuya

Nucl. Saf., 33(3), p.334 - 343, 1992/07

no abstracts in English

Journal Articles

Dimensional stability of low enriched uranium silicide plate-type fuel for research reactors at transient conditions

Yanagisawa, Kazuaki; ; Horiki, Oichiro; Soyama, Kazuhiko; Ichikawa, Hiroki; Kodaira, Tsuneo

Journal of Nuclear Science and Technology, 29(3), p.233 - 243, 1992/03

no abstracts in English

Journal Articles

Preparation of pure tritium for a liquid D$$_{2}$$/T$$_{2}$$ target of muon-catalyzed fusion experiments

Kudo, Hiroshi; Fujie, Makoto; Tanase, Masakazu; Kato, Mineo; Kurosawa, Kiyoyuki; Sugai, Hiroyuki; Umezawa, Hirokazu; Matsuzaki, Teiichiro*; Nagamine, Kanetada*

Applied Radiation and Isotopes, 43(5), p.577 - 583, 1992/00

no abstracts in English

Journal Articles

Feasibility study of laser spectrometry for measuring uranium enrichment in gaseous UF$$_{6}$$

Oda, Tetsuzo; ; *

Proc. of the 4th Int. Conf. on Facility Operations-Safeguards Interface, p.303 - 306, 1992/00

no abstracts in English

Journal Articles

Feasibility study of laser spectrometry for measuring uranium enrichment in gaseous UF$$_{6}$$

Oda, Tetsuzo; *;

Transactions of the American Nuclear Society, 61(SUPPL.1), p.44 - 45, 1991/10

no abstracts in English

Journal Articles

Initial results of helium ash experiment in the JT-60 lower divertor

Nakamura, Hiroo; Tobita, Kenji; Hirayama, Toshio; Koide, Yoshihiko; Arai, Takashi; Kuriyama, Masaaki; Kubo, Hirotaka; Kusama, Yoshinori; Sugie, Tatsuo; Sugihara, Masayoshi; et al.

Fusion Technology, 18, p.578 - 582, 1990/12

no abstracts in English

35 (Records 1-20 displayed on this page)