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JAEA Reports

Document collection of the 37th Technical Special Committee on Fugen Decommissioning

Nakamura, Yasuyuki; Koda, Yuya; Yamamoto, Kosuke; Soejima, Goro; Iguchi, Yukihiro

JAEA-Review 2020-002, 40 Pages, 2020/05

JAEA-Review-2020-002.pdf:8.78MB

Fugen Decommissioning Engineering Center, in planning and carrying out our decommissioning technical development, has been establishing "Technical special committee on Fugen decommissioning" which consists of the members well-informed, aiming to make good use of Fugen as a place for technological development which is opened inside and outside the country, as the central point in the energy research and development base making project of Fukui prefecture, and to utilize the outcome in our decommissioning to the technical development effectively. This report compiles presentation materials "The Current Situation of Fugen Decommissioning", "Development of Dismantling Mon-hours Estimated system by Achieved Data in Fugen", "Future Plan Based on the Operational Status of Clearance System" and "The Result and Future Plan of the Sampling work from Core Internal of Fugen", presented in the 37th Technical special committee on Fugen decommissioning which was held on December 2, 2019.

Journal Articles

Laser cutting underwater is carried out in the Fukui Smart Decommissioning Technology Demonstration Base

Soejima, Goro; Iwai, Hiroki; Nakamura, Yasuyuki; Kuwamuro, Naotoshi*; Shimazu, Tadashi*

Eneken Nyusu (Internet), 131, P. 1, 2019/04

We investigated the behavior of the dust generated by Laser cutting underwater aimed at the simulant material of reactor components (SUS304) and the pressure and calandria tube (Zr-2.5%Nb, Zry-2) of the prototype reactor. This test was carried out in the water tank as large as the reactor of FUGEN.

Journal Articles

Investigation for dust behavior of cutting in air and cutting underwater by thermal cutting methods

Soejima, Goro; Iwai, Hiroki; Nakamura, Yasuyuki; Tsuzuki, Satoshi*; Yasunaga, Kazushi*; Kume, Kyo*

Heisei-29-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 20, P. 80, 2018/11

We investigated the behavior of the dust generated by Laser and Plasma-arc cutting underwater and in air aimed at the simulant material of reactor components (SUS304) and the pressure and calandria tube (Zr-2.5%Nb, Zry-2) of the prototype reactor "FUGEN".

Journal Articles

Study of the dust behavior on the laser and plasma cutting

Soejima, Goro; Iwai, Hiroki; Kadowaki, Haruhiko; Nakamura, Yasuyuki; Tsuzuki, Satoshi*; Yasunaga, Kazushi*; Nakata, Yoshinori*; Kume, Kyo*

Heisei-28-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 19, P. 9, 2017/10

no abstracts in English

Journal Articles

Technology development on reactor dismantling and investigation of contamination in FUGEN

Soejima, Goro; Iwai, Hiroki; Nakamura, Yasuyuki; Hayashi, Hirokazu; Kadowaki, Haruhiko; Mizui, Hiroyuki; Sano, Kazuya

Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 5 Pages, 2017/07

no abstracts in English

Journal Articles

Operator's contribution on the improvement of inspection scheme for the PCDF operation

Shimizu, Yasuyuki; Makino, Risa; Mukai, Yasunobu; Ishiyama, Koichi; Kurita, Tsutomu; Nakamura, Hironobu

Dai-37-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu (CD-ROM), 9 Pages, 2017/02

no abstracts in English

Journal Articles

Operator's contribution on the improvement of RII scheme against the process operation at PCDF

Nakamura, Hironobu; Shimizu, Yasuyuki; Makino, Risa; Mukai, Yasunobu; Ishiyama, Koichi; Kurita, Tsutomu; Ikeda, Atsushi*; Yamaguchi, Katsuhiro*

Proceedings of INMM 57th Annual Meeting (Internet), 9 Pages, 2016/07

Regarding the Integrated Safeguards (IS) in Japan, the implementation of IS has been started on September 2004, and the concept has been introduced to the JNC-1 facilities since August 2008. Then, random interim inspection with short notice and reducing person-days of inspection (PDI) was introduced instead of traditional scheduled IIV in order to improve deterrence of the nuclear material diversion with timeliness goal. And it was agreed that it should be evaluated and reviewed because RII was designed when inter-campaign. In JAEA, we decided to restart PCDF campaign to reduce potential safety risks of reprocessing facilities. To adopt the RII scheme to the process operation in campaign, JAEA proposed a new scheme to JSGO and IAEA without increasing PDI and reducing detection probability. As a result of the discussion, it was agreed and successfully introduced since March 2014. The new scheme for PCDF consists of scheduled inspection (fixed-day RII), reduction of estimated material for the verification, implementation of remote monitoring with data provision, improvement of operational status check list, introduction of NRTA and MC&A data declaration with timeliness. Though the operator's workloads for information provision were increased, we could manage to balance IS requirement with implementation of our operation successfully. This contribution was helped to safeguards implementation and our operation for 2 years.

Journal Articles

Feasibility study of technology for Pu solution monitoring including FP; Overview and research plan

Sekine, Megumi; Matsuki, Takuya; Tanigawa, Masafumi; Tsutagi, Koichi; Mukai, Yasunobu; Shimizu, Yasuyuki; Nakamura, Hironobu; Tomikawa, Hirofumi

Proceedings of INMM 57th Annual Meeting (Internet), 9 Pages, 2016/07

The International Atomic Energy Agency (IAEA) has proposed in its long-term research and development plan, development of a real-time measurement technology to monitor and verify nuclear material movement continuously as part of an advanced approach to effectively and efficiently conduct safeguards for reprocessing facilities. In the reprocessing plant, since solutions containing both Pu and FP exist, a new detector development project to monitor Pu with FP is being carried out from 2015 to 2017. This project is mainly conducted in the High Active Liquid Waste Storage (HALWS) in Tokai Reprocessing Plant (TRP). In this paper, an overview of the technology development, simulation results of preliminary evaluation of the characteristics of radiation emitted from the HALW tank at TRP, and the future research plan are presented.

JAEA Reports

Applicability test of abrasive water jet cutting technology for dismantling of the core internals of Fukushima Daiichi NPS

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

JAEA-Technology 2015-055, 89 Pages, 2016/03

JAEA-Technology-2015-055.pdf:17.54MB

It was reported that Fukushima Daiichi Nuclear Power Station (1F) had lost the cooling function of the reactor by the Tohoku Earthquake. It is assumed that the core internals became narrow and complicated debris structure mixed with the molten fuel. In consideration of the above situations, the AWJ cutting method, which has features of the long work distance and little heat effect for a material, has been developed for the removal of the molten core internals through cutting tests for 3 years since FY 2012. And it was confirmed that AWJ cutting method is useful for the removal of the core internals etc. The results in FY 2012 were reported in "R&D of the fuel debris removal technologies by abrasive water jet cutting technology (JAEA-Technology 2013-041)" and this report summarizes the results of FY 2012, 2013 and 2014 in this report. It was confirmed the possibility to apply the removal work of the fuel debris and the core internals.

JAEA Reports

Applicability test of plasma cutting technology for dismantling of the core internals of Fukushima Daiichi NPS

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

JAEA-Technology 2015-047, 114 Pages, 2016/03

JAEA-Technology-2015-047.pdf:46.17MB

It was reported that Fukushima Daiichi Nuclear Power Plant had been lost the function of cooling the reactor by the Tohoku Earthquake. It is assumed that the original shapes of the internal core are not kept and the inside of the reactor makes so narrow in the space, however the fuel debris and the molten internal core will have to be removed for the decommissioning of 1F. We concerned the suppression of dross by optimization of cutting conditions, in using some moderated test pieces. And we can improve the cutting capability by heating the objects in advance. Moreover, it's possible that plasma arc cutting can cut off the mixed material the fuel debris and the molten internal core by using the cooperation cutting technique both the plasma arc and the plasma jet cutting. From these results, we have got the prospect that plasma cutting method can apply the removal of the fuel debris and the molten internal core.

JAEA Reports

The Development of the basic dismantling procedure of the reactor of FUGEN

Iwai, Hiroki; Nakamura, Yasuyuki; Mizui, Hiroyuki; Sano, Kazuya

JAEA-Technology 2015-046, 110 Pages, 2016/03

JAEA-Technology-2015-046.pdf:85.22MB

Advanced Thermal Reactor (ATR) FUGEN is a proto-type heavy water moderated, boiling light water cooled, pressure tube-type reactor with the thermal power of 557 MW and the electrical power of 165 MW. The reactor of FUGEN is classified into the core region and the shielding region. The core region is highly activated owing to the long term operation, and characterized by its tube-cluster construction that contains 224 fuel channels arranging both the pressure and the calandria tubes coaxially in each channel closely. And the shielding region surrounding the core region has the laminated structure composed of up to 150 mm thickness of carbon steel. The reactor is planning to be dismantled under water remotely in order to shield the radiation around the core and prevent airborne dust generated by the cutting, and firing of zirconium material. This paper reports on the result of development of the basic dismantling procedure of the reactor of FUGEN.

JAEA Reports

The Selection of the cutting technologies for dismantling the FUGEN reactor

Nakamura, Yasuyuki; Iwai, Hiroki; Mizui, Hiroyuki; Sano, Kazuya

JAEA-Technology 2015-045, 137 Pages, 2016/03

JAEA-Technology-2015-045.pdf:27.77MB

FUGEN is 9 m outer-diameter and 7m height, and characterized by its tube-cluster construction that contains 224 fuel channels arranging both the pressure and the calandria tubes coaxially in each channel. And the periphery part of the core has the laminated structure composed of up to 150 mm thickness of carbon steel for radiation shielding. The structure of the reactor, which is made of various materials such as stainless steel, carbon steel, zirconium alloy and aluminum. The reactor is planning to be dismantled under water in order to shield the radiation ray around the core and prevent airborne dust generated by the cutting, the temporary pool structure and the remote-operated dismantling machines needs to be installed on the top of reactor. In consideration of above the structure of Fugen reactor, the cutting method was selected for dismantling the reactor core in order to shorten the dismantling term and reduce the secondary waste.

Journal Articles

The Study on application of laser technology for the reactor core dismantling

Iwai, Hiroki; Nakamura, Yasuyuki; Mizui, Hiroyuki; Sano, Kazuya; Morishita, Yoshitsugu

Proceedings of 7th International Congress on Laser Advanced Materials Processing (LAMP 2015) (Internet), 4 Pages, 2015/08

The reactor of FUGEN is characterized by its tube-cluster construction that contains 224 channels arranging both the pressure and the calandria tubes coaxially in each channel. And the periphery part of the core has the laminated structure of up to 150 mm thickness of carbon steel for radiation shielding. Method for dismantling the reactor core is also being studied with considering processes of dismantlement by remote-handling devices under the water for the radiation shielding. In order to shorten the term of the reactor dismantlement work and reduce the secondary waste, some cutting tests and literature research for various cutting methods had been carried out. As the result, the laser cutting method, which has feature of the narrow cutting kerf and the fast cutting velocity, was mainly selected for dismantling the reactor. In this presentation, current activities of FUGEN decommissioning and R&D of laser cutting tests are introduced.

Journal Articles

Improvement of INVS measurement uncertainty for Pu nitrate solution

Makino, Risa; Swinhoe, M. T.*; Suzuki, Hisanori; Ikeda, Atsushi*; Menlove, H. O.*; Shimizu, Yasuyuki; Nakamura, Hironobu

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-35-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2015/01

The Inventory Verification Sample system (INVS) is a non-destructive assay system for samples to quantify the Pu amount in Pu nitrate solutions and MOX with 31.3% of counting efficiency. It has been used for IAEA verification measurement for many years at the Plutonium Conversion Development Facility for the samples taken at the timing of PIV etc. as a partial defects verification system (uncertainty: about 3-5%). If the measurement uncertainty can be improved (to $$sim$$1%), it is expected that the usage can be extended to the operator's own measurements in MC&A to reduce the number of destructive analyses. In order to improve the measurement uncertainty for solution samples, after optimization of detector parameter and sample position, we conducted 3 different types of calibration method that is passive calibration curve, known-$$alpha$$ and multiplicity method to achieve the target uncertainty. To perform calibration and control the measurement quality, MOX fuel pellets with known Pu amount are fabricated and used. In the range of concentration of typical solution samples, we could confirm good correlations between measured doubles and $$^{240}$$Pu effective mass in the three methods. Especially, it was confirmed that the conventional calibration curve method could meet our target uncertainty ($$sim$$1%).

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

Utilization status at TIARA facility

Haruyama, Yasuyuki; Takizawa, Haruki; Hosono, Masakazu; Mizuhashi, Kiyoshi*; Nakamura, Yoshiteru*; Kaneya, Satoshi*; Asai, Takahiro*; Kawabata, Michiko*; Imai, Koji*

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 177, 2014/03

Cyclotron use in FY 2012, was 2243.5 hours beam time. Among them, the use time of Bio technology and Medical application relationship most, I occupy the time spent for the Quarter of the total. Use offer to the outside utilization was 17%. Use the number of days in Electrostatic Accelerators was 490 days. Among them, Basic technology is accounted for using the percentage of 46%, but the use of irradiation Reactor materials and irradiation of Material for space even more, I accounted for 18 percent utilization rate, respectively, of 15%. Use offer to the outside utilization was 8%.

JAEA Reports

R&D of the fuel debris removal technologies by abrasive water jet cutting technology

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

JAEA-Technology 2013-041, 57 Pages, 2014/02

JAEA-Technology-2013-041.pdf:7.01MB

It was reported that Fukushima Daiichi Nuclear Power Plant (1F) had been lost the function of cooling the reactor by the Tohoku Earthquake. It is assumed that the original shapes of the internal core are not kept and the inside of the reactor makes so narrow in the space, however the fuel debris and the molten internal core will have to be removed for the decommissioning of 1F. The cutting methods for those removal works will have to be selected depending on the situation of the inside of the reactor. In consideration of above situations, the abrasive water jet cutting method, Fugen has much data of underwater cutting for the reactor dismantling and there are experiences of the reactor maintenance and dismantling in both domestic and international, will be being developed for the fuel debris removal works and so on. In the fiscal year 2012, in order to confirm the cutting performance of the cutting machine, the cutting tests were carried out to acquire the fundamental data.

JAEA Reports

R&D of the fuel debris removal technologies by plasma arc cutting technology

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

JAEA-Technology 2013-040, 80 Pages, 2014/02

JAEA-Technology-2013-040.pdf:4.29MB

It was reported that Fukushima Daiichi Nuclear Power Plant (1F) had been lost the function of cooling the reactor by the Tohoku Earthquake. It is assumed that the original shapes of the internal core are not be kept and the inside of the reactor make so narrow in the space, however the fuel debris and the molten internal core will have to be removed for the decommissioning of 1F. The cutting methods for those removal works will have to be selected depending on the situation of the inside of the reactor. In consideration of above situations, the plasma-arc cutting method, Fugen has much data of underwater cutting for the reactor dismantling and there are experiences of the reactor dismantling in both domestic and international, will be being developed for the fuel debris removal works and so on.

JAEA Reports

Document collection of the 28th Technical Special Committee on Fugen Decommissioning

Kutsuna, Hideki; Iwai, Hiroki; Mizui, Hiroyuki; Kadowaki, Haruhiko; Nakamura, Yasuyuki

JAEA-Review 2013-049, 49 Pages, 2014/02

JAEA-Review-2013-049.pdf:5.59MB

Fugen Decommissioning Engineering Center has been establishing "Technical special committee on Fugen decommissioning" which consists of the members well-informed, aiming to make good use of Fugen as a place for technological development which is opened inside and outside the country. This report compiles presentation materials "The Current Situation of Fugen Decommissioning", "The Current Status of the Cutting Test toward the Practical Use of Laser Cutting Technology and the Future Plan", "Study on Radioactive Substance Osmosis for Basis Concrete of Equipment", "Verification Tests of the Room-Temperature Vacuum Drying and the Evaluation Method of Residual Amount of Heavy Water in the Tritium Removal" and "Applicability Test of Thermal and Mechanical Cutting Technology for the Dismantlement of the Internal Core of Fukushima Daiichi NPS", presented in the 28th Technical special committee on Fugen decommissioning which was held on September 24, 2013.

Journal Articles

Utilization of process monitoring data in the Tokai Reprocessing Plant for future nuclear security

Kimura, Takashi; Shimizu, Yasuyuki; Yamazaki, Katsuyuki; Endo, Yuji; Nakamura, Hironobu

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-34-Kai Nenji Taikai Rombunshu (Internet), 8 Pages, 2013/10

no abstracts in English

106 (Records 1-20 displayed on this page)