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Marufuji, Takato; Sato, Takumi; Ito, Hideaki; Suzuki, Hisashi; Fujishima, Tadatsune; Nakano, Tomoyuki
JAEA-Technology 2019-006, 22 Pages, 2019/05
JAEA-Technology-2019-006.pdf:2.84MB
Radioactive contamination incident occurred at Plutonium Fuel Research Facility (PFRF) in Oarai Research and Development Institute, Japan Atomic Energy Agency on June 6, 2017. During inspection work of storage container containing nuclear fuel materials, the PVC bag packaging in the storage container ruptured when a worker opened the lid in the hood, and a part of contents was spattered over the room. The cause of the increase of internal pressure of the storage container was gas generation by alpha radiolysis of the epoxy resin mixed with nuclear fuel materials. Opening inspection of about 70 similar containers stored in PFRF has been planned to confirm the condition of the contents and to stabilize the stored materials containing organic compounds. For safe and reliable open inspection of the storage containers with high internal pressure in the glove box, it is necessary to develop a pressure-resistant chamber in which the storage containers are opened and the contents are inspected under gastight condition. This report summarizes the concerns and countermeasures of the chamber design and the design results of the chamber.
Yamamoto, Takahiro; Ito, Chikara; Maeda, Shigetaka; Ito, Hideaki; Sekine, Takashi
JAEA-Technology 2017-036, 41 Pages, 2018/02
JAEA-Technology-2017-036.pdf:7.86MB
In the experimental fast reactor Joyo, the damaged upper core structure (UCS) was retrieved into the cask in May 2014 The dose rate on UCS surface was quite high due to the activation for over 30 years operation. In order to attain the optimum safety design, manufacture and operation of equipment for UCS replacement, the method to evaluate UCS surface dose rate was developed on the basis of C/E obtained by the in-vessel dose rate measurement in Joyo. In order to verify the evaluation method, the axial gamma-ray distribution measurement on the surface of the cask, which contained UCS, was conducted using a plastic scintillating optical fiber (PSF) detector. This paper describes the comparison results between calculation and measurement as follows. (1) The measured axial gamma-ray distribution on the cask surface had a peak on proper location with considering the cask shielding structure and agree well with the calculated distribution. (2) The C/E of axial gamma-ray distribution on the cask surface was ranged from 1.1 to 1.7. It was confirmed that the calculation for UCS replacement equipment design had a margin conservatively. Then, the results showed that the developed evaluation method for UCS replacement equipment design was sufficiently reliable.
Ashida, Takashi; Nakamura, Toshiyuki*; Ito, Hideaki
JAEA-Technology 2017-024, 198 Pages, 2017/11
JAEA-Technology-2017-024.pdf:55.8MB
JAEA-Technology-2017-024-appendix(CD-ROM)-1.zip:298.09MBJAEA-Technology-2017-024-appendix(CD-ROM)-2.zip:210.77MB
In the experimental fast reactor Joyo, the disconnecting of an irradiation test subassembly MARICO-2 (Material Testing Irradiation Rig with Temperature Control) from its holding mechanism was conducted in May 2007. After the operation, the rotating plug was rotated despite the fact that the test subassembly was not disconnected completely. Consequently, top of wrapper tube of the MARICO-2 subassembly was bent onto the in-vessel storage rack. Since the overhanging part of the subassembly was in the height in which contacts with the upper core structure, it had damaged the bottom surface of the upper core structure. As the result, it was necessary to replace the damaged upper core structure and to retrieve the bent MARICO-2 subassembly for Joyo restart. Retrieval devices for MARICO-2 subassembly consist of a gripper mechanism to lift subassembly together with transfer pot, a guide tube built-in a pantograph mechanism to adjust lifting axis and safety mechanisms to prevent or mitigate falling of MARICO-2 subassembly, a retrieval cask and so on. Design of the retrieval devices have been verified in ex-vessel partial or full-scale mock-up tests and in-vessel function tests. In 2014, MARICO-2 subassembly was successfully retrieved from the reactor vessel by applying these retrieval devices. Then, retrieved subassembly was transported to a hot-cell facility for post-irradiation examinations. Devices have demonstrated expected performance under the actual environmental conditions of a sodium cooled fast reactor. This is a synthetic report about the retrieval work of the deformed and irradiated test subassembly in Joyo. This report includes the detail design and fabrication of the special retrieval device, results of tests for confirmation including the mock-up tests in manufacturer's factory, and results of MARICO-2 retrieval work from the reactor vessel.
Ashida, Takashi; Ito, Hideaki; Miyamoto, Kazuyuki*; Nakamura, Toshiyuki; Koga, Kazuhiro*; Ohara, Norikazu*; Ino, Hiroichi*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 15(4), p.210 - 222, 2016/12
In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test sub-assembly of material testing rig named "MARICO-2" had been broken and bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). As the result, for Joyo restart, it was necessary to replace the damaged UCS and to retrieve the bent sub-assembly. This paper describes in-vessel repair techniques performed in the retrieval work of the obstacle inside of the reactor vessel. The devices which were prepared for this work demonstrated expected performance under the environmental conditions of an SFR such as high temperature and radiation dose, and the work was completed in 2014. The successful operation of this retrieval work of the damaged component inside of a reactor vessel will contribute to the development of in-service inspections and repair technics in an SFR.
Koga, Kazuhiro*; Ohara, Norikazu*; Ino, Hiroichi*; Kondo, Katsumi*; Ito, Hideaki; Ashida, Takashi; Nakamura, Toshiyuki
FAPIG, (190), p.3 - 8, 2015/07
no abstracts in English
Ashida, Takashi; Miyamoto, Kazuyuki; Okazaki, Yoshihiro*; Ito, Hideaki
JAEA-Technology 2012-047, 106 Pages, 2013/06
JAEA-Technology-2012-047.pdf:11.09MBJAEA-Technology-2012-047-appendix(CD-ROM).zip:15.46MB
In the experimental fast reactor Joyo, failure of disconnecting the irradiation test subassembly MARICO-2 (Material Testing Irradiation Rig with Temperature Control) was occurred and top of the MARICO-2 test subassembly was bent onto the in-vessel storage rack. As a result of this incident, the operation area of rotating plug for the fuel exchange in Joyo is limited. The replacement of the damaged UCS and retrieving the bent MARICO-2 are required to Joyo restoration. This report describes about investigations and some tests to know the status of MARICO-2 test subassembly and the optimized detail design of retrieval device reflecting those results.
Takamatsu, Misao; Ashida, Takashi; Kobayashi, Tetsuhiko; Kawahara, Hirotaka; Ito, Hideaki; Nagai, Akinori
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Safe Technologies and Sustainable Scenarios (FR-13) (USB Flash Drive), 10 Pages, 2013/03
In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test Sub-Assembly (S/A) of "MARICO-2" (material testing rig with temperature control) had bent onto the in-vessel storage rack (IVS) as an obstacle and had damaged the Upper Core Structure (UCS). This incident necessitates the replacement of the UCS and the retrieval of MARICO-2 S/A for Joyo re-start. Along with four stages involving jack-up and retrieval of the existing damaged UCS (ed-UCS), retrieval of the MARICO-2 S/A, and installation of the new UCS (n-UCS) in the restoration work plan, current conditions at Joyo are being carefully investigated, and the results are applied to the designs of special handling equipment, which is being manufactured and scheduled for operation in 2014.
Ito, Hideaki; Ashida, Takashi; Takamatsu, Misao
UTNL-R-0483, p.6_1 - 6_10, 2013/03
no abstracts in English
Ito, Chikara; Ito, Hideaki; Ishida, Koichi; Aoyama, Takafumi
JAEA-Technology 2011-007, 56 Pages, 2011/06
JAEA-Technology-2011-007.pdf:9.2MB
In the experimental fast reactor Joyo, measurement for characterizing and predicting the deposition condition and the condition change of the corrosion product (CP) that is the major radiation source in equipments and piping of primary cooling system has been carried out regularly from early period of reactor operation. Cooling system modification work with the shift to the MK-III core was carried out after the last measurement that was carried out, and the main equipments such as intermediate heat exchangers were replaced. This measurement in this report was carried out at after the 2nd cycle operation of the MK-III core which started formal operation.
Ito, Hideaki; Maeda, Shigetaka; Naito, Hiroyuki; Akiyama, Yoichi; Miyamoto, Kazuyuki; Ashida, Takashi; Noguchi, Koichi; Ito, Chikara; Aoyama, Takafumi
JAEA-Technology 2010-049, 129 Pages, 2011/03
JAEA-Technology-2010-049.pdf:6.99MB
The in-vessel gamma dose rate was measured in the experimental fast reactor Joyo to evaluate the activation of reactor structural components and the radiation exposure of the fiber scope used for in-vessel visual inspection. The measurement system, which requires a wide sensitivity range and high durability in a high-temperature environment, was specifically developed for use in the sodium cooled fast reactor. Using this system, the in-vessel gamma dose rate with cooling times of 450 and 720 days after reactor shutdown was measured in Joyo, which has been operated for 71,000 hours over approximately 30 years. The gamma dose rate was calculated using QAD-CGGP2 code with the gamma source intensity obtained by the ORIGEN2 code. The neutron flux used as input to the ORIGEN2 was evaluated by the Joyo dosimetry method. The ratio between the calculated and experimental values ranged from 1.1 to 2.4, confirming the accuracy of gamma dose rate and component activation calculation.
Tanaka, Hirokazu*; Hashimoto, Takeji; Koizumi, Satoshi; Ito, Hideaki*; Naka, Kensuke*; Chujo, Yoshiki*
Macromolecules, 41(5), p.1815 - 1824, 2008/03
Times Cited Count：8 Percentile：26.86(Polymer Science)We have investigated the self-assembly formed by palladium acetate (Pd(OAc)
) and polyamidoamine dendrimers (GN-NH) in a mixed solvent of methanol and N, N-dimethylformamide. We aim to explore effects of the generation number (GN) and concentration of the dendrimers, [GN-NH], on the self-assembly of the dendrimers (defined hereafter as "templates") and the Pd nanoparticles inside the templates in order to clarify physical factors controlling the self-assembling mechanisms. We found that the templates are formed only when [GN-NH] falls below a critical value and thereby a sufficient amount of Pd(OAc) exists as the binders between the dendrimers. Otherwise dendrimers are molecularly dispersed in solution.
Tanaka, Hirokazu*; Koizumi, Satoshi; Hashimoto, Takeji; Ito, Hideaki*; Sato, Masahide*; Naka, Kensuke*; Chujo, Yoshiki*
Macromolecules, 40(12), p.4327 - 4337, 2007/06
Times Cited Count：32 Percentile：67.9(Polymer Science)We reported the reduction process of palladium(II) acetate, Pd(OAc), and self-assembling process of the resulting palladium atoms, Pd(0)'s, into nanoparticles in the presence of the first-generation polyamidoamine dendrimer (G1-NH) in non-aqueous solution. The process was induced by mixing the following two solutions: (A) Pd(OAc) dissolved in N,N-dimethylformamide (DMF) and (B) the G1-NH dissolved in methanol, under a specific condition of 
[Pd(OAc)]/[-NH] = 3.3 where [-NH] is mole concentration of the amine groups in the dendrimer in the reaction solution. The reaction and reaction-induced self-assembling process were explored in-situ by means of a combined time-resolved method of small-angle neutron scattering and small-angle X-ray scattering. The method revealed time-evolution of a series of self-assembling processes occurring in the system.
Ito, Chikara; Ito, Hideaki; Ishida, Koichi; Hatoori, Kazuhiro; Oyama, Kazuhiro; Sukegawa, Kazuya*; Murakami, Takanori; Kaito, Yasuaki; Nishino, Kazunari; Aoyama, Takafumi; et al.
JNC TN9410 2005-003, 165 Pages, 2005/03
JNC-TN9410-2005-003.pdf:12.66MB
At experimental fast reactor JOYO, appraisal of detection efficiency of behavior and FFD and FFDL of the fission product which is discharged inside the furnace as one of safety research of the country, is carried out. In MK-II core, the slit in the gas plenum part of the test sub-assembly, the test which irradiates this(1985 April, FFDL in-pile test(I)), providing the slit in the fuel column part of the test sub-assembly, the test which it irradiates(1992 November, FFDL in-pile test(II)) were carried out.MK-III reactor core replacement was completed and started in 2004. That the behavior in the system of FP with the reactor core replacement and so on changes in the MK-III reactor core and to have an influence on the sensitivity and the replying of FFD and FFDL are thought of. Therefore, behavior of FP in the fuel failure in the MK-III reactor core, the performance of FFD and FFDL must be confirmed beforehand. Moreover, to prepare for the fuel failure and the RTCB test which is doing a future plan, and to confirm a plant operation procedure in the fuel failure in MK-III reactor core operation and to attempt for the correspondency to improve are important.Therefore, in the period from 2004 November 11th to November 29th, it carried out the FFDL in-pile(III). It did a series of plant operation to stop a nuclear reactor after loading a reactor core center with the fuel element for the test which provided an artificial slit for the fuel cladding in the MK-III reactor core and irradiating it and detecting fuel damaging and to take out fuel. And it confirmed the operation procedure of the fast reactor in the fuel failure.Also, the improvement items such as the improvement of the operation and the procedure and the remodeling and the service of the facilities could be picked up. In the future, it attempts these compatible, and it prepares for the MK-III reactor core operation and it incorporates a final examination result by the improvement of the safety of FBR.
Karube, Koji; Akagi, S.; Terano, Toshihiro; Onuki, Osamu; Ito, Hideaki; Aoki, Hiroshi; Odo, Toshihiro
JNC TN9430 2004-004, 36 Pages, 2004/03
JNC-TN9430-2004-004.pdf:1.03MB
This paper describes the results of primary auxiliary cooling system,which were done as a part of JOYO MK-III function test. The aim of the tests was to confirm the operational performance of primary auxiliary EMP and the protection system including siphon breaker of primary auxiliary cooling ststem. The items of the tests were:(1) Test No.:SKS-117/Test item/EMP start up test (2) Test No.:SKS-118-1/Test item:EMP start up test when pony mortor running (3) Test NO.:SKS-121/Test item:Function test of siphon breaker The results of the tests satisfied the required performance,and demonstrated succeccful operation of primary auxiliary cooling system.
Terakado, Tsuguo; Morimoto, Makoto; Izawa, Osamu; Ishida, Koichi; Hoshino, Katsuaki; Suzuki, Shinya; Ito, Hideaki; Aoki, Hiroshi; Odo, Toshihiro
JNC TN9430 2004-003, 87 Pages, 2004/03
JNC-TN9430-2004-003.pdf:2.86MB
This paper describes the results of Secondary Cooling System main pumps test ,which were done as a part of JOYO MK-3 function test. The function tests were cexcuted to get the operating characteristics of secondary cooling system, after the Intermediate Heat Exchangers, Dump Heat Exchangers, secondary main pump motors, pump speed control board and rheostat were replaced in the MK-3 conversion. These tests are composed of six items. These tests purpose are confirmed in the function of the Main pumps, sodium purification system and argon cover gas pressure control system in Secondary Cooling System. (1) SKS-205-1: flow control test, (2) SKS-205-2: flow coast down characteristics test, (3) SKS-205-3: running operation test, (4) SKS-205-4: pump vibration measurement test, (5) SKS-212: secondary sodium purification system electromagnetic-pump flow control test, (6) SKS-213: argon cover gas pressure in secondary cooling system pressure control test function tests are satisfied the design criteria. We have confirmed the system performance of the main pump, secondary sodium purification system and argon cover gas pressure control system in the Secondary Cooling System after the MK-3 conversion.
Morimoto, Makoto; Suto, Masayoshi; Ito, Yoshio; Ito, Hideaki; Aoki, Hiroshi; Odo, Toshihiro
JNC TN9430 2004-002, 60 Pages, 2004/03
JNC-TN9430-2004-002.pdf:2.28MB
This paper describes the result of the sodium purity measurement test on MK-III function tests. This test meant cold traps caught impurity which was carried into the primary and the secondary cooling system by MK-III modification work of the heat transport system, and the amount of impurity was evaluated by plugging temperature before and after the primary and secondary purification operation. Then the following two tests were practiced. Test number and name was shown. (1)SKS-122 Measurement test of purity on primary sodium purification system (2)SKS-211 Measurement test of purity on secondary sodium purification system As the cold traps could catch impurity which made with MK-III modificatlon work, impurity concentrations of sodium in the both of systems were generally within the reference limits of JOY0, while the function tests took in practice for Mk-III. As a result, the amount of impurity Oxygen caught by cold traps calculated approximately 400g in the primary sodium cooling system and approximately 1100g in the secondary one.
Michino, Masanobu; Suzuki, Toshiaki; Aita, Tsuyoshi; Suto, Masayoshi; Saito, Takakazu; Kawahara, Hirotaka; Isozaki, Kazunori; Ito, Hideaki; Inoue, Setsunari; Aoki, Hiroshi; et al.
JNC TN9430 2004-001, 103 Pages, 2004/03
JNC-TN9430-2004-001.pdf:4.06MB
This report describes the results of the primary and secondary cooling system interlock test and the fuel handling system function test, which were done as a part of JOYO MK-3 function test. The items of the test are: (1) Primary and secondary cooling system interlock test (SKS-106,210) (2) Loss of electric power supply test (SKS-116) (3) In-vessel and ex-vessel automatic fuel transportation test (SKS-501,502) As the interlock of the primary and secondary cooling system was changed, the interlock test by the reactor scram and the loss of electric power supply was carried out. The function of the remote automatic fuel handling system was confirmed before the handling of the fuel for MK-3 core configuration. The results of the test satisfied the required performance, and it was confirmed that operation of the primary and secondary cooling system interlock and operation of the fuel handling system in JOYO MK-3 were normal.
Terakado, Tsuguo; Hoshino, Katsuaki; Suzuki, Shinya; Ito, Hideaki; Aoki, Hiroshi; Odo, Toshihiro
JNC TN9410 2004-008, 55 Pages, 2004/03
JNC-TN9410-2004-008.pdf:1.82MB
The automatic control rod operation system was developed to control the JOYO reactor power automatically in all operation modes(critical approach, cooling system heat up, power ascent and power descent), development began in 1989. Prior to applying, we are examined possibility of apply to the automatic control rod operation guide system which developed in MK-2 operation to get the control rod operation guide data in MK-3 performance tests. The main results are as follows: (1).Critical approach mode in control rod operation guide function will be need tuning of fuzzy algorisms structure for changed MK-3 reactor critical point. (2).Cooling system heet up mode, power ascent mode and power descent mode will be supply to good guidance at MK-3 reactor operation. Because, power change rate and cooling system heet up rate same MK-2 reactor operation. (3).Plant operation guide function will be need change, based on MK-3 reactor operation manual. (4).The automatic control rod operation guide system will be need renewal for system maintainability.
; Aita, Tsuyoshi; Murakami, Takanori; Ito, Hideaki; Aoki, Hiroshi; Odo, Toshihiro
JNC TN9410 2004-006, 36 Pages, 2004/03
Joyo Plant Operation Management Expert Tool system named JOYPET has developed with the aim of confirming the stable and safety operation of JOYO and improving operational reliability in future FBR plants.New JOYPET system was designed and manufactured in 2002, and began or operation in 2003, because the former system, which was designed in 1988 and operated from 1991 to 2002, was superannuated, and it was difficult to obtain alternative hardwares and replace parts.The difference between the former one and the later new one was adopted the web-online system to use lan(Lacal area network) instead of the host and the terminal computer processing system.Then the new system enabled to take unitary document management for reactor operation, and each person in one's rost was able to search, refer and wake document on line directly.This document reported new JOYPET system design, manufacturing, system constitution and operation actual result.
; Ito, Hideaki; Odo, Toshihiro; Suzuki, Soju
FNCA Genshiryoku Anzen Bunka Wakushoppu, 0 Pages, 2004/00
Focusing on the cover layer materials (as the Radon Barrier Materials), which could have the effect to restrain the radon from scattering into the air and the effect of the radiation shielding, we produced the radon barrier materials with crude bentonite on an experimental basis, using the rotary type comprehensive unit for grinding and mixing, through which we carried out the evaluation of the characteristics thereof.
