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Journal Articles

The Verification tests of the melting conditions for homogenization of metallic LLW at the JAEA

Nakashio, Nobuyuki; Osugi, Takeshi; Iseda, Hirokatsu; Tohei, Toshio; Sudo, Tomoyuki; Ishikawa, Joji; Mitsuda, Motoyuki; Yokobori, Tomohiko; Kozawa, Kazushige; Momma, Toshiyuki; et al.

Journal of Nuclear Science and Technology, 53(1), p.139 - 145, 2016/01

 Times Cited Count:1 Percentile:76.09(Nuclear Science & Technology)

no abstracts in English

Journal Articles

In-situ dismantling of the liquid waste storage tank in the decommissioning program of the JRTF

Mimura, Ryuji; Muraguchi, Yoshinori; Nakashio, Nobuyuki; Nemoto, Koichi; Shiraishi, Kunio

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05

The JAERI's Reprocessing Test Facility (JRTF) was the first engineering-scale reprocessing facility constructed in Japan. The JRTF was operated from 1968 to 1969 to reprocess spent fuels from the Japan Research Reactor No.3 (JRR-3). As a result of the operation (total 3 runs) by PUREX process, 200 g of highly purified plutonium (Pu) were extracted. In this operation, about 70 m$$^{3}$$ of liquid waste was generated and part of this waste, which including Pu, with relatively high radioactivity, was stored in six large tanks. After shutdown of the facility, the JRTF decommissioning program was started in 1990 to develop decommissioning technologies and to obtain experiences and data on dismantling of fuel cycle facilities. Liquid waste in the tanks was treated from 1982 to 1998. Dismantling of tanks started in 2002. The tanks were installed in narrow concrete cells and inside of the cell was high dose area. Dismantling method for the tank is important factor to decide manpower and time for dismantlement. In this paper, in-situ dismantling of the liquid waste storage tank and its preparation work are discussed.

JAEA Reports

Evaluation of void ratio of the solidified wastes containing supercompacted wastes

Sudo, Tomoyuki; Nakashio, Nobuyuki; Osugi, Takeshi; Mimura, Ryuji; Ishihara, Keisuke; Satomi, Shinichi; Myodo, Masato; Momma, Toshiyuki; Kozawa, Kazushige

JAEA-Technology 2010-041, 38 Pages, 2011/01

JAEA-Technology-2010-041.pdf:4.73MB

The super compactor in the AVRF treats compactible metal wastes mainly generated from research reactors in the Nuclear Science Research Institute of JAEA. Those wastes are compacted with the maximum about 2,000-ton force. The supercompacted wastes are packed into the container and then immobilized with cementitious materials. The solidified wastes (containing supercompacted wastes) become an object for near surface disposal with artificial barrier. For disposal, the solidified wastes must be satisfied the technical criteria. One of the important indicators is the void ratio in the solidified wastes. In this report, we manufactured the supercompacted wastes with the ordinary treatment method for actual wastes treated in the AVRF and immobilized with a mortar grout. The void ratio of the solidified wastes were evaluated in consideration for concrete vault disposal. As a result, We confirmed the integrity of the solidified wastes from a point of view of void ratio.

JAEA Reports

Verification of improvement of the casting process in metal melting system

Tohei, Toshio; Nakashio, Nobuyuki; Osugi, Takeshi; Ishikawa, Joji; Mizoguchi, Takafumi; Hanawa, Ritsu; Someya, Keita*; Takahashi, Kenji*; Iseda, Hirokatsu; Kozawa, Kazushige; et al.

JAEA-Technology 2010-008, 28 Pages, 2010/06

JAEA-Technology-2010-008.pdf:5.0MB

The Waste Volume Reduction Facility (WVRF) was constructed for volume reduction and the chemical stabilization of the low level radioactive waste in the Nuclear Science Research Institute of JAEA. The metal melting system in the WVRF treats radioactive metal waste. From the experience of trial operations, the improvement has conducted on the casting process in the metal melting system. The performance of the improved casting process was verified through the trial operations from Oct. 2008. In this report, we describe the reduction of the processing time, of the utilities consumption, of the load of maintenance on the improved casting process.

JAEA Reports

Construction, management and operation on advanced volume reduction facilities

Higuchi, Hidekazu; Osugi, Takeshi; Nakashio, Nobuyuki; Momma, Toshiyuki; Tohei, Toshio; Ishikawa, Joji; Iseda, Hirokatsu; Mitsuda, Motoyuki; Ishihara, Keisuke; Sudo, Tomoyuki; et al.

JAEA-Technology 2007-038, 189 Pages, 2007/07

JAEA-Technology-2007-038-01.pdf:15.13MB
JAEA-Technology-2007-038-02.pdf:38.95MB
JAEA-Technology-2007-038-03.pdf:48.42MB
JAEA-Technology-2007-038-04.pdf:20.53MB
JAEA-Technology-2007-038-05.pdf:10.44MB

The Advanced Volume Reduction Facilities (AVRF) is constructed to manufacture the waste packages of radioactive waste for disposal in the Nuclear Science Research Institute of the Japan Atomic Energy Agency. The AVRF is constituted from two facilities. The one is the Waste Size Reduction and Storage Facility (WSRSF) which is for reducing waste size, sorting into each material and storing the waste package. The other is the Waste Volume Reduction Facility (WVRF) which is for manufacturing the waste package by volume reducing treatment and stabilizing treatment. WVRF has an induction melting furnace, a plasma melting furnace, an incinerator, and a super compactor for treatment. In this report, we summarized about the basic concept of constructing AVRF, the constitution of facilities, the specifications of machineries and the state of trial operation until March of 2006.

Journal Articles

Trial operation of the advanced volume reduction facilities for LLW at JAEA

Nakashio, Nobuyuki; Higuchi, Hidekazu; Momma, Toshiyuki; Kozawa, Kazushige; Tohei, Toshio; Sudo, Tomoyuki; Mitsuda, Motoyuki; Kurosawa, Shigenobu; Hemmi, Ko; Ishikawa, Joji; et al.

Journal of Nuclear Science and Technology, 44(3), p.441 - 447, 2007/03

 Times Cited Count:8 Percentile:41.7(Nuclear Science & Technology)

The Japan Atomic Energy Agency (JAEA) constructed the Advanced Volume Reduction Facilities (AVRF), in which volume reduction techniques are applied and achieved high volume reduction ratio, homogenization and stabilization by means of melting or super compaction processes for low level solid wastes. It will be able to produce waste packages for final disposal and to reduce the volume of stored wastes by operating the AVRF. The AVRF consist of the Waste Size Reduction and Storage Facilities (WSRSF) and the Waste Volume Reduction Facilities (WVRF); the former have cutting installations for large size wastes and the latter have melting units and a super compactor. Cutting installations in the WSRSF have been operating since July 1999. Radioactive wastes treated so far amount to 750 m$$^{3}$$ and the volume reduction ratio is from 1.7 to 3.7. The WVRF have been operating with non-radioactive wastes since February 2003 for the training and the homogeneity investigation in the melting processes. The operation of the pretreatment system in the WVRF with radioactive wastes has partly started in FY2005.

JAEA Reports

Research and development on the melting test of low-level radioactive miscellaneous solid waste

Nakashio, Nobuyuki; Kameo, Yutaka; Hoshi, Akiko; Nakashima, Mikio

JAEA-Review 2007-005, 35 Pages, 2007/02

JAEA-Review-2007-005.pdf:2.28MB

The Nuclear Science Research Institute of the Japan Atomic Energy Agency constructed the Advanced Volume Reduction Facilities (AVRF) in February 2003 for treatment of low-level radioactive miscellaneous solid waste (LLW). The waste volume reduction is carried out by a high-compaction process or melting processes in the AVRF. In advance of operating the melting process in the AVRF, melting tests of simulated LLW with RI tracers ($$^{60}$$Co, $$^{137}$$Cs and $$^{152}$$Eu) have been conducted by using the plasma melter in pilot scale. Viscosity of molten waste, chemical composition and physical properties of solidified products and distribution of the tracers in each product were investigated in various melting conditions. In this review, experimental results of the melting tests were discussed in order to contribute to actual treatment of LLW in the AVRF.

Journal Articles

System of the advanced volume reduction facilities for LLW at JAERI

Higuchi, Hidekazu; Momma, Toshiyuki; Nakashio, Nobuyuki; Kozawa, Kazushige; Tohei, Toshio; Sudo, Tomoyuki; Mitsuda, Motoyuki; Kurosawa, Shigenobu; Hemmi, Ko; Ishikawa, Joji; et al.

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10

The JAERI constructed the Advanced Volume Reduction Facilities(AVRF). The AVRF consists of the Waste Size Reduction and Storage Facilities(WSRSF) and the Waste Volume Reduction Facilities(WVRF). By operating the AVRF, it will be able to produce waste packages for final disposal and to reduce the amount of the low level solid wastes. Cutting installations for large wastes such as tanks in the WSRSF have been operating since June 1999. The wastes treated so far amount to 600 m$$^{3}$$ and the volume reduction ratio is around 1/3. The waste volume reduction is carried out by a high-compaction process or melting processes in the WVRF. The metal wastes from research reactors are treated by the high-compaction process. The other wastes are treated by the melting processes that enable to estimate radioactivity levels easily by homogenization and get chemical and physical stability. The WVRF have been operating with non-radioactive wastes since February 2003 for the training and the homogeneity investigation in the melting processes. The operation with radioactive wastes will start in FY2005.

Journal Articles

Chemical stability of solidified products made from incombustible wastes by plasma melting

Kameo, Yutaka; Haraga, Tomoko; Nakashio, Nobuyuki; Hoshi, Akiko; Nakashima, Mikio

Nippon Genshiryoku Gakkai Wabun Rombunshi, 3(4), p.354 - 362, 2004/12

In order to investigate chemical stability of solidified products made from Low Level Radioactive Wastes (LLW) by plasma melting, a leaching test based on the MCC (Material Characterization Center)-3S Agitated Powder Leach Test Method was performed to determine Normalized Elemental Mass Loss (NL$$_{i}$$) of both main components (Na, Al, Si, Ca, and Fe) of the solidified product and radioactive tracers ($$^{60}$$Co, $$^{137}$$Cs, and $$^{152}$$Eu) incorporated into it. The results of leaching test indicated that NLi value was greatly affected by basicity defined as weight ratio of CaO to SiO$$_{2}$$ in the solidified product, while effect of FeO concentration on NL$$_{i}$$ value was small. In the case of basicity less than 0.8, logarithm of NL$$_{i}$$ linearly increased with the basicity, implying that NL$$_{i}$$ value can be estimated by chemical composition of the solidified products.

Journal Articles

Characterization of 50L-scale solidified products yielded by melting treatment of miscellaneous solid wastes and evaluation of radioisotope tracer distribution

Nakashio, Nobuyuki; Nakashima, Mikio; Hirabayashi, Takakuni*

Nippon Genshiryoku Gakkai Wabun Rombunshi, 3(3), p.279 - 287, 2004/09

Large-scale melting tests of simulated miscellaneous solid wastes were conducted to characterize solidified products (50L-drum size). Two heating modes were adopted in the tests: hybrid heating and induction heating modes. In the former, wastes were heated with both an induction furnace and a plasma torch, and in the latter, an electrically-conductive crucible was used with the induction furnace. Visual observation, chemical analysis and radioactivity measurements were conducted to the solidified products. It was found that the radioisotope distribution of solidified products was almost homogeneous. There was no remarkable deterioration in the solidified products subsequent to the leaching test.

Journal Articles

Study on plasma melting treatment of crucibles, ceramic filter elements, asbestos, and fly ash

Hoshi, Akiko; Nakashio, Nobuyuki; Nakashima, Mikio

Genshiryoku Bakkuendo Kenkyu, 10(1-2), p.93 - 101, 2004/03

The Japan Atomic Energy Research Institute (JAERI) decided to adopt an advanced volume reduction program for low-level radioactive wastes. In this program, inorganic wastes are converted to stable glassy products suitable for disposal by a plasma melting system in the Waste Volume Reduction Facilities (WVRF). In this paper, plasma melting test of crucibles,ceramic filter elements,asbestos,and simulated fly ashes were carried out as a part of technical support for WVRF. The plasma melting treatment was applicable for crucibles and asbestos because homogeneous and glassy products were obtained by controlling of waste and loading condition. It was found that an oxidizing slag is needed for effective melting condition of ceramic filter elements with a plasma torch with inert gas, and controlling of slag components have the potential to stabilize volatile metals such as Zn, Pb in a solidified product in the melting test of simulated fly ash.

Journal Articles

Effects of basicity and FeO concentration on the retention of $$^{137}$$Cs and $$^{60}$$Co in slag made from non-metallic radioactive wastes

Nakashima, Mikio; Nakashio, Nobuyuki; Kameo, Yutaka; Fukui, Toshiki*; Isobe, Motoyasu*; Otake, Atsushi*; Wakui, Takuji*; Hirabayashi, Takakuni*

Radiochimica Acta, 91(1), p.45 - 51, 2003/01

 Times Cited Count:2 Percentile:78.86(Chemistry, Inorganic & Nuclear)

no abstracts in English

Journal Articles

Plasma melting treatment of low level radioactive waste

Nakashio, Nobuyuki; Nakashima, Mikio

Dekomisshoningu Giho, (26), p.45 - 55, 2002/11

Melting treatment of low-level radioactive wastes (LLW) is considered to be a promising technology for the preparation of a stable solid that will be disposed of in near surface repositories. This is because of large reduction of waste volume and production of a stable homogeneous solidified product. In the Japan Atomic Energy Research Institute (JAERI), the construction of the Waste Volume Reduction Facilities (WVRF) has been in progress since 1999. In advance of operation of the WVRF, we have been conducting melting tests of non-metallic solid wastes with the aim of establishing the optimum melting condition for preparation of a stable solid that is suitable for disposal. We have reviewed a part of the melting test conducted in our program.

Journal Articles

Characterization of solidified products yielded by plasma melting treatment of simulated non-metallic radioactive wastes

Nakashima, Mikio; Fukui, Toshiki*; Nakashio, Nobuyuki; Isobe, Motoyasu*; Otake, Atsushi*; Wakui, Takuji*; Hirabayashi, Takakuni*

Journal of Nuclear Science and Technology, 39(6), p.687 - 694, 2002/06

 Times Cited Count:10 Percentile:40.14(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Study on melting coditions of radioactive miscellaneous solid waste (Contract research)

Fukui, Toshiki; Nakashio, Nobuyuki; Isobe, Motoyasu; Otake, Atsushi*; Wakui, Takuji*; Hirabayashi, Takakuni*; Nakashima, Mikio

JAERI-Review 2000-033, 82 Pages, 2001/02

JAERI-Review-2000-033.pdf:2.61MB

no abstracts in English

JAEA Reports

Melting behavior of low-level radioactive miscellaneous solid waste and characteristics of solidified products (Contract research)

Nakashio, Nobuyuki; Isobe, Motoyasu; Wakui, Takuji*; Iwata, Keiji*; Kibayashi, Tatsuyuki*; Kanazawa, Katsuo; Fukui, Toshiki; Otake, Atsushi*; Nakashima, Mikio; Hirabayashi, Takakuni*

JAERI-Research 2001-001, 19 Pages, 2001/02

JAERI-Research-2001-001.pdf:1.29MB

no abstracts in English

Journal Articles

Study on plasma melting of miscellaneous low-level radioactive waste

Nakashio, Nobuyuki; Wakui, Takuji*; Otake, Atsushi*; Nakashima, Mikio; Fukui, Toshiki*; Isobe, Motoyasu*

Proceedings of 8th International Conference on Radioactive Waste Management and Environmental Remediation (ICEM '01) (CD-ROM), 4 Pages, 2001/00

no abstracts in English

JAEA Reports

Performance tests of a melting system for miscellaneous solid wastes and corrosion tests of a long-life refractory material (Contract research)

Isobe, Motoyasu; Kameo, Yutaka; Nakashio, Nobuyuki; Wakui, Takuji*; Iwata, Keiji*; Kibayashi, Tatsuyuki*; Kanazawa, Katsuo; Nakashima, Mikio; Hirabayashi, Takakuni*

JAERI-Tech 2000-049, 29 Pages, 2000/09

JAERI-Tech-2000-049.pdf:2.87MB

no abstracts in English

Journal Articles

Study on treatment of miscellaneous solid waste by plasmas melting; Melting characteristics of plasma heating method

Fukui, Toshiki; Nakashio, Nobuyuki; Isobe, Motoyasu; Otake, Atsushi*; Wakui, Takuji*; Nakashima, Mikio; Hirabayashi, Takakuni*

Dai-7-Kai Doryoku Enerugi Gijutsu Shimpojiumu Koen Rombunshu (00-11), p.356 - 359, 2000/00

no abstracts in English

Journal Articles

Research and development of treatment techniques for LLW from decommissioning; Decontamination and volume reduction techniques

Hirabayashi, Takakuni; Kameo, Yutaka; Nakashio, Nobuyuki

Proceedings of International Symposium on Technologies for the Management of Radioactive Waste from Nuclear Power Plants and Back End Nuclear Fuel Cycle Activities (CD-ROM), 10 Pages, 1999/00

no abstracts in English

36 (Records 1-20 displayed on this page)