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Journal Articles

Corrigendum; Study of the neutron multiplication effect in an active neutron method [J Nucl Sci Technol. 2017;54(11):1233-1239]

Komeda, Masao; Ozu, Akira; Mori, Takamasa; Nakatsuka, Yoshiaki; Maeda, Makoto; Kureta, Masatoshi; Toh, Yosuke

Journal of Nuclear Science and Technology, 55(8), P. 962, 2018/08

We correct the derivation of equations in the derivation of equations in the paper of "Study of the neutron multiplication effect in an active neutron methods [J Nucl Sci Technol. 2017;54(11):1233-1239]". Although the derivations are not correct, the obtained equations are correct. Therefore, the results and discussions of the paper remain the same.

Journal Articles

Study of the neutron multiplication effect in an active neutron method

Komeda, Masao; Ozu, Akira; Mori, Takamasa; Nakatsuka, Yoshiaki; Maeda, Makoto; Kureta, Masatoshi; Toh, Yosuke

Journal of Nuclear Science and Technology, 54(11), p.1233 - 1239, 2017/11

 Times Cited Count:2 Percentile:42.02(Nuclear Science & Technology)

The previous active neutron method cannot remove the influence of the multiplication effect of neutrons produced by second- and subsequent fission reactions, and it might overestimate the amount of nuclear material if an item contains large amounts. In this paper, we discussed the correction method for the neutron multiplication effect on the measured data in the fast neutron direct interrogation (FNDI) method, one of the active neutron methods, supposing that the neutron multiplication effect is caused mainly by third-generation neutrons from the second-fission reactions under the condition that the forth-generation neutrons are much fewer. This paper proposed a correction method for the neutron multiplication effect in the measured data. Moreover we have shown a possibility that this correction method gives rough estimates of the effective neutron multiplication factor and the subcriticality.

Journal Articles

Development of non-destructive assay system using fast neutron direct interrogation method for actual uranium waste drums

Ozu, Akira; Komeda, Masao; Kureta, Masatoshi; Zaima, Naoki; Nakatsuka, Yoshiaki; Nakashima, Shinichi

Nippon Genshiryoku Gakkai Wabun Rombunshi, 15(2), p.115 - 127, 2016/06

A non-destructive assay system using the fast neutron direct interrogation method has been developed to put its method into practical use for the determination of uranium ($$^{235}$$U) mass contained in actual uranium-contaminated waste drums. The method is capable of measuring the fissile mass in a drum by counting the number of fission neutrons resulting from nuclear fission reactions between the fissile materials contained in a drum and thermal neutrons generated by 14 MeV fast neutrons irradiated from outside the drum. The performance test employing simulated metal waste drums demonstrated that a natural uranium mass of as low as 10 g could be detected within an error of $$pm$$20% regardless of the distribution of uranium samples in the drum. A demonstration test employing actual waste drums could determine the uranium mass by using a newly developed correction method for deriving the fissile mass in a drum. It has been proved by the experimental validation tests that the assay system equipped with the correction method is very useful for the accountancy of the waste drums.

Journal Articles

Analytical study on uranium measurement in uranium waste drums by the fast neutron direct interrogation method

Komeda, Masao; Ozu, Akira; Haruyama, Mitsuo; Takase, Misao*; Kureta, Masatoshi; Nakatsuka, Yoshiaki; Zaima, Naoki; Nakashima, Shinichi; Otsuka, Yoshimasa

Proceedings of INMM 55th Annual Meeting (Internet), 9 Pages, 2014/07

We have researched and developed the FNDI method for a long time through experiments in NUCEF in JAEA Tokai. Referred from the pilot machine, we designed a demonstrator, called as JAWAS-N, for applying to non-destructive assay tools for uranium waste drums in JAEA Ningyo. In this paper, we present the modeling and the simulations concerning JAWAS-N's characteristics, and discuss for practical use compared analytical results with obtained some experimental data.

JAEA Reports

On performance experience and measurements with Ningyo Waste Assay System (NWAS), 3

Zaima, Naoki; Nakashima, Shinichi; Nakatsuka, Yoshiaki; Fujiki, Naoki*; Kado, Kazumi

JAEA-Technology 2013-050, 39 Pages, 2014/03

JAEA-Technology-2013-050.pdf:3.56MB

A uranium mass assay system NWAS, for 200-litter wastes drums applied by NDA method was developed and accumulated the data of the actual uranium bearing wastes drums. The system consists of the 16 pieces of Helium-3 proportional counters for neutron detection generated from U-234($$alpha$$,n) reaction or U-238 spontaneous fissions with polyethylene moderation and a Germanium solid state detector for $$gamma$$ ray detection as to determine uranium enrichment. The satisfactory works had been continued and the uranium determination data of 850 drums had been accumulated approximately. On the other hand several considerable problems on the system or methodology had been revealed technically or analytically through the measurements experiences. Furthermore as the next improvement plans, the active neutrons assay for uranium bearing wastes drums are now progressing. The results of complications will lead us to the progressive next steps.

Journal Articles

Analysis of dismantling activities of rotary kiln for benchmark tests

Tachibana, Mitsuo; Izumo, Sari; Sugitsue, Noritake; Park, S.-K.*

DYNATOM (Internet), 2013(4), p.31 - 35, 2013/04

JAEA has the Uranium Refining & Conversion Plant. KAERI has the Uranium Conversion Plant. These CFs have been under decommissioning after their missions completed. Each organization has been developing decommissioning engineering systems to develop effective decommissioning plans and to implement dismantling activities effectively. Therefore, benchmark tests were started in order to verify mutual decommissioning engineering systems. Each organization compared mutual decommissioning engineering system, and compared specification and dismantling procedure of the rotary kiln and management data for dismantling the rotary kiln. Management data for dismantling the rotary kiln in KAERI was calculated by using DENESYS of JAEA. This report describes results of comparisons of dismantling activities of the rotary kiln in JAEA and KAERI, and calculated results by JAEA.

JAEA Reports

Log of refining and conversion facility dismantling; Progress in 2011FY

Editorial Committee of Refining and Conversion Facility Decommissioning Results

JAEA-Data/Code 2012-026, 78 Pages, 2013/01

JAEA-Data-Code-2012-026.pdf:26.08MB

The Refining and Conversion Facility located in the Ningyo-toge Environmental Engineering Center had the natural uranium conversion process and reprocessed uranium conversion process. The construction of this facility was started in 1979 and completed in October 1981. Dismantling of equipments in radiation controlled area of this facility was started from 2008. Equipments in radiation controlled area (excluding ventilating equipment and liquid waste treatment equipment) will be dismantled by the 2011 fiscal year, and ventilating equipment and liquid waste treatment equipment will be dismantled by the 2014 fiscal year. This report is a record of the dismantlement situation of the Refining and Conversion Facility in 2011 fiscal years. Concretely, dismantlement logs, dismantlement material, and secondary waste are published.

Journal Articles

Analysis of dismantling activities of rotary kiln for benchmark tests

Tachibana, Mitsuo; Izumo, Sari; Sugitsue, Noritake; Park, S.-K.*

Proceedings of American Nuclear Society Embedded Topical on Decommissioning, Decontamination and Reutilization and Technology Expo (DD&R 2012) (DVD-ROM), p.107 - 110, 2012/06

JAEA has the Uranium Refining & Conversion Plant. KAERI has the Uranium Conversion Plant. These facilities have been under decommissioning after their missions completed. Each organization has been developing decommissioning engineering systems to develop effective decommissioning plans and to implement dismantling activities effectively. Therefore, benchmark tests were started in order to verify mutual decommissioning engineering systems. This report describes results of comparisons of dismantling activities of the rotary kiln in JAEA and KAERI, and calculated results by JAEA.

JAEA Reports

On performance experience and measurements with Ningyo Waste Assay System (NWAS)

Zaima, Naoki; Nakashima, Shinichi; Kaneda, Koji; Kado, Kazumi

JAEA-Technology 2010-046, 31 Pages, 2011/02

JAEA-Technology-2010-046.pdf:2.84MB
JAEA-Technology-2010-046(errata).pdf:0.05MB

The uranium mass assay systems for 200-litter wastes drums applied neutron and $$gamma$$ measurements by NDA method had been developed. The measurement systems and trial data are described in this preliminary report. The systems are composed of the 16 pieces of helium-3 proportional counters for neutron detection and a large sized NaI(Tl) scintillation detector for $$gamma$$ ray detection. The extensive testing trials using the calibrated uranium sources with different enrichment and some kinds of matrices in drums were performed. Through the one year testing the useful experiences of this system concerning neutron and $$gamma$$ ray measurements for uranium mass were obtained. Almost all instruments and software were so good performance as is designed. As the next step we are scheduled to try measurements for actual wastes that are stored in the Uranium Refining and Conversion Plant at Ningyo-toge, and put practical uses near future. Our research was accomplished with the support of LANL.

JAEA Reports

Log of refining and conversion facility dismantling; Progress in 2009FY

Editorial Committee of Refining and Conversion Facility Decommissioning Results

JAEA-Data/Code 2010-024, 168 Pages, 2011/01

JAEA-Data-Code-2010-024.pdf:25.76MB

The schedule which will finish dismantling of all equipment in a radiation controlled area is by the 2011 fiscal year. This report is a record of the dismantlement situation of the Refining and Conversion Facility in 2009 fiscal years. Concretely, dismantlement logs, dismantlement material, and secondary waste are published.

Journal Articles

Uranium refining and conversion plant decommissioning project

Zaima, Naoki; Morimoto, Yasuyuki; Sugitsue, Noritake; Kado, Kazumi

Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.311 - 320, 2010/10

JAEA Reports

Present status of refining and conversion facility dismantling; Progress in latter half of 2009FY

Editorial Committee of Refining and Conversion Facility Decommissioning Results

JAEA-Technology 2010-032, 115 Pages, 2010/09

JAEA-Technology-2010-032.pdf:29.72MB

The Refining and Conversion Facility located in the Ningyo-toge Environmental Engineering Center had the natural uranium conversion process and reprocessed uranium conversion process. The construction of this facility was started in 1979 and completed in October 1981. Dismantling of equipments in radiation controlled area of this facility was started from 2008, and all equipments in radiation controlled area will be dismantled by the 2011 fiscal year. This report describes the master plan of this decommissioning and shows as the progress in latter half year of 2009FY, the actual time schedule, the method of decommissioning, the decommissioning progress appearance with photographs, work rates of each room / each worker class, and the quantity of dismantled materials and secondary wastes.

JAEA Reports

Radiation environment account before dismantling the conversion facilities; Evaluation of the uranium inventory and air dose rate in the dismantling facilities, 2

Takahashi, Nobuo; Yokoyama, Kaoru; Morimoto, Yasuyuki; Shimaike, Masamitsu; Ikegami, Sohei; Sugitsue, Noritake

JAEA-Technology 2010-003, 92 Pages, 2010/06

JAEA-Technology-2010-003.pdf:10.76MB

At the reprocessed uranium conversion facilities, Hydration and Conversion room-1,2,3, Dehydration and Conversion room-1,2, Dry process filter room have been dismantled according to the schedule, in 2009 fiscal year. The $$gamma$$-ray measurement had been carried out before dismantlement to evaluate the radioactivity inventory. As a result, the uranium recovery work was forecasted for reasonable dismantlement. In addition, the feature nuclide affecting the results of the measurement on the air dose was evaluated. Additionally, as the waste data, $$gamma$$-ray analysis results are shown.

JAEA Reports

Present status of Refining and Conversion Facility dismantling; Progress in first half of 2009FY

Editorial Committee of Refining and Conversion Facility Decommissioning Results

JAEA-Technology 2010-002, 66 Pages, 2010/05

JAEA-Technology-2010-002.pdf:19.73MB

The Refining and Conversion Facility located in the Ningyo-toge Environmental Engineering Center had the natural uranium conversion process and reprocessed uranium conversion process. The construction of this facility was started in 1979 and completed in October 1981. Dismantling of equipments in radiation controlled area of this facility was started from 2008, and all equipments in radiation controlled area will be dismantled by the 2011 fiscal year. This report describes the master plan of this decommissioning and shows as the progress in first half year of 2009FY, the actual time schedule, the method of decommissioning, the decommissioning progress appearance with photographs, work rates of each room/each worker class, and the quantity of dismantled materials and secondary wastes.

JAEA Reports

Present status of Refining and Conversion Facility Dismantling; Progress in 2008 first half of the fiscal year

Editorial Committee of Refining and Conversion Facility Decommissioning Results

JAEA-Technology 2009-024, 101 Pages, 2009/06

JAEA-Technology-2009-024.pdf:60.55MB

The Refining and Conversion Facility located in the Ningyo-toge Environmental Engineering Center. Process of natural uranium conversion facility (PNC Process) and reprocessed uranium conversion facility (two-stage dry fluorination system) is in a Refining and Conversion Facility. This building started construction in 1979 and was completed in October 1981. The PNC process operated from March 1982 to March 1991. As a result, uranium hexafluoride of about 385 tonU was manufactured. Also, the reprocessed uranium conversion process operated from December 1982 to July 1999. As a result, uranium hexafluoride of about 338 tonU was manufactured. The demonstration of the demolition method was done using the PNC process after the end of operation. The schedule which will finish dismantling of all equipment in a radiation controlled area is by the 2011 fiscal year. This report summarized the present situation by the first half of the 2008 fiscal year of a Refining and Conversion Facility decommissioning.

JAEA Reports

Radiation environment account before dismantling the conversion facilities; Evaluation of the uranium inventory and air dose rate in the dismantling facilities

Shimaike, Masamitsu; Yokoyama, Kaoru; Ikegami, Sohei; Takahashi, Nobuo; Sugitsue, Noritake

JAEA-Technology 2009-020, 55 Pages, 2009/06

JAEA-Technology-2009-020.pdf:2.0MB

At the conversion facility, 48Y homogenization treatment equipment (cylinder processing room), UO$$_{3}$$ pneumatic dispatch equipment (fluoride precipitation process room), gas trapping and filling equipment (cold trap room and UF$$_{6}$$ filling room) and the second grade UF$$_{4}$$ drying equipment (UF$$_{4}$$ feed chamber and UF$$_{4}$$ treatment room) are scheduled to be dismantled, in 2008 fiscal year. The $$gamma$$-ray measurement intended for the equipment was done before dismantlement and the radioactivity inventory was evaluated. As a result, the part that the uranium recovery had to be executed was forecast for reasonable dismantlement. Additionally, the reprocessed uranium was used at the conversion facility, so the feature nuclide affecting the air dose was evaluated. In addition, $$gamma$$-ray analysis results are organized for using as the waste data and the radionuclide distribution data in the process.

Oral presentation

Decommissioning project of uranium conversion plant, 2; Evaluation of the nuclide composition in the spent bed material and the external exposure

Takahashi, Nobuo; Shimaike, Masamitsu; Morimoto, Yasuyuki; Ikegami, Sohei; Sugitsue, Noritake

no journal, , 

no abstracts in English

Oral presentation

Decommissioning project of uranium conversion plant, 1; Master plan

Morimoto, Yasuyuki; Ikegami, Sohei; Sugitsue, Noritake

no journal, , 

no abstracts in English

Oral presentation

Decommissioning project of uranium conversion plant, 3; Evaluation of the nuclide composition in the cold trap and the external exposure

Shimaike, Masamitsu; Takahashi, Nobuo; Morimoto, Yasuyuki; Ikegami, Sohei; Sugitsue, Noritake

no journal, , 

no abstracts in English

Oral presentation

Decommissioning project of uranium conversion plant, 4; Dismantling operation data management

Tokuyasu, Takashi; Morimoto, Yasuyuki; Ikegami, Sohei; Sugitsue, Noritake; Tachibana, Mitsuo; Tanimoto, Masataka; Ishigami, Tsutomu

no journal, , 

no abstracts in English

53 (Records 1-20 displayed on this page)