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JAEA Reports

Development of gamma camera for survey of contamination distribution; Performance demonstration of gamma camera based on survey of contamination on operating floor of the Fukushima Daiichi Nuclear Power Plant Unit 2 reactor building by $$gamma$$-eyeII

Kanayama, Fumihiko; Okada, Takashi; Fukushima, Mineo; Yoshimoto, Katsunobu*; Hanyu, Toshinori; Kawanobe, Takayuki

JAEA-Technology 2013-049, 60 Pages, 2014/03

JAEA-Technology-2013-049.pdf:25.84MB

For planning of removing fuels and debris from the Unit 2 reactor building, TEPCO has already started to measure dose rate over the floor by remotely operated vehicle. Because the measured data were widely distributed in the range of several decades to one thousand mSv/h, it is necessary for TEPCO to survey of contamination distribution on operation floor 2 for more detail planning. JAEA estimated sensitivity of developed gamma camera system named "$$gamma$$-eye II" in consistency with actual radiation condition, and carried a demonstration experiment at Fukushima Daiichi N.P.P. to confirm a strength of jamming by back ground dose. Then, JAEA surveyed contamination distribution of operating floor using $$gamma$$-eye II. At the result of survey, it was found that, - main radiation source in survey area was located on upper reactor well, - western floor in survey area was lower the margin of capacity of $$gamma$$-eye II, -there was a highly contaminated spot on the floor near the opened BOP.

Journal Articles

Proposal of healthiness confirmation procedure in electro manometer system in terms of nuclear material accountancy

Shoji, Kaoru; Mukai, Yasunobu; Nakamura, Hironobu; Yoshimoto, Katsunobu; Hayashi, Hiroyuki*

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-32-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2011/11

In general, electro manometer system for volume measurement in high concentrated Pu, U solution is used. The measurement uncertainty of volume measurement should be kept within 0.36% in the nuclear material accountancy. Not only manometer censors are calibrated periodically, but also operator should maintain the integrity of entire volume measurement system. If clogging at a tip of dip-tube is occurred, it causes measurement bias. Therefore, we studied confirmation procedure of healthiness in the system during solution storage. As result, it is confirmed that following points are effective: (1) Confirmation of consistency in the Kumar's density formula by using actual Pu, U concentration, density and acidity determined by periodical sampling and high accuracy DA. In addition, Pu, U mass is maintained within the uncertainty from the previous sampling/DA result. (2) In order to confirm the integrity of differential pressure for density that may be impacted regarding the measurement bias by clogging, comparison between measured differential pressure for density and analyzed density with high accuracy is important. In the confirmation for density, correction method between different temperatures was established by the result of evaluation of temperature effect derived by Kumar's density formula.

Journal Articles

Development for advanced solution monitoring and measurement system (ASMS)

Mukai, Yasunobu; Nakamura, Hironobu; Yoshimoto, Katsunobu; Tamura, Takayuki*; Iwamoto, Tomonori*

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-32-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2011/11

JNFL and JAEA are collaboratively developing an advanced solution monitoring and measurement system (ASMS) that is direct Pu measurement NDA system in the solution tank containing plutonium nitrate solution for the improvement of current safeguards subjects to be solved, and for next generation safeguards instrument. The target measurement uncertainty of ASMS is set less than 6% that is equivalent to detection level of partial defect at interim inventory verification by NDA. The ASMS detector was designed based on MCNPX calculation, and then manufactured. As an actual test, the detector was set in a process tank at Plutonium Conversion Development Facility, the calibration tests (known-alpha) for quantitative measurement was conducted. As a result, the total measurement uncertainty for Pu mass is about 3.4% except for the low liquid height region that is satisfied the target value. In addition, the monitoring capability of ASMS was confirmed.

Journal Articles

Development and future challenge for Advanced Solution Measurement and Monitoring System (ASMS)

Nakamura, Hironobu; Mukai, Yasunobu; Yoshimoto, Katsunobu; Tamura, Takayuki*; Iwamoto, Tomonori*

Proceedings of INMM 52nd Annual Meeting (CD-ROM), 9 Pages, 2011/07

JNFL and JAEA are collaboratively developing an Advanced Solution Measurement and monitoring System (ASMS) that is direct Pu measurement NDA system in the large scale solution tank containing purified plutonium nitrate for the improvement of current safeguards subjects to be solved, and for next generation safeguards instrument (NGSI). In this report, we summarize the first step results of ASMS development regarding quantitative measurement methodology. In order to establish quantitative measurement, accurate MCNPX modeling and calculations are very important and necessary. After calibration exercise implementation, we successfully obtained calibration constants (slope), and the total measurement uncertainty was about 3% for $$^{240}$$Pu effective mass for 2 hours measurement except for the low level region. In addition, the image of safeguards by design and collaboration of SMMS are also presented.

Journal Articles

Journal Articles

Feasibility study of neutron multiplicity assay for a heterogeneous sludge sample containing Na, Pu and other impurities

Nakamura, Hironobu; Beddingfield, D. H.*; Nakamichi, Hideo; Mukai, Yasunobu; Yoshimoto, Katsunobu

IAEA-CN-184/59 (Internet), 7 Pages, 2010/11

In order to reduce radioactivity of liquid waste generated at PCDF, a neutralization precipitation processes by sodium hydroxide precipitation is used. We call the precipitate after calcining as Sludge. The Pu amount in the sludge sample is normally determined by sampling and DA. The sludge contains many chemical components. For example, Pu, U, Am, SUS components, halogens, NaNO$$_{3}$$ (main component), residual NaOH, and moisture. They are mixed together as an impure heterogeneous sludge sample. As a result, there is a large uncertainty in the sampling and DA that is currently used at PCDF. In order to improve the material accounting in PCDF, we performed a feasibility study using neutron multiplicity assay for impure sludge samples. We have measured selected sludge samples using a commercial multiplicity counter which is called FCAS (Fast Carton Assay System) which was designed by JAEA and Canberra. For unknown samples, using 14-hour measurements, we could obtain quite low statistical uncertainty on Doublesand Triples count rate although the alpha value is extremely high and FCAS efficiency is relatively low for typical multiplicity counters. Despite the detector efficiency challenges and the material challenges, we have been able to obtain assay results that greatly exceed the accountancy requirements for retained waste materials.

Journal Articles

Evaluation of monitoring capability and sensitivity of Advanced Solution Monitoring and Measurement System (ASMS)

Mukai, Yasunobu; Nakamura, Hironobu; Hosoma, Takashi; Yoshimoto, Katsunobu; Tamura, Takayuki*; Iwamoto, Tomonori*

Proceedings of INMM 51st Annual Meeting (CD-ROM), 9 Pages, 2010/07

JNFL and JAEA are collaboratively developing an advanced solution monitoring and measurement system (ASMS) for Rokkasho Reprocessing Plant (RRP). In this study, as a second trial, we designed and fabricated a new demonstration-type detector for ASMS, then installed it to another process tank in PCDF. Using two detectors, tests for process monitoring capability were performed for several operational conditions such as sampling, bubbling, circulation, solution transfer between two tanks, followed by studies in sensitivity of monitoring and studies in stability for the duration of storage. As a result, excellent performances and advantages of ASMS compared with conventional SMMS were confirmed. It is concluded that ASMS can provide very useful information of operation status and Pu amount shared between operator and inspector. It is sure that the combination of current SMMS and the ASMS is very powerful tool to improve transparency in the future safeguards design.

Journal Articles

The Way of maintenance to keep log-term accuracy and a sign of malfunction of digiquartz differential pressure transducer used for accurate level measurement system

Mukai, Yasunobu; Koiso, Katsuya; Nakamura, Hironobu; Hosoma, Takashi; Yoshimoto, Katsunobu; Hayashi, Hiroyuki*

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-30-Kai Nenji Taikai Rombunshu (CD-ROM), 9 Pages, 2009/11

Electro manometer (ELTM) is a device to measure accurately level, density and volume in an accountability tank for the purpose of nuclear materials accountancy, safeguards and operational control. JAEA have developed and put the ELTM using digiquartz differential pressure transducer into practical use at plutonium conversion development facility since initial tank calibration in 1982. As a result of calibrations and measurements in the last 15 years, the sustainable measurement accuracy is $$pm$$2 Pa as a sigma of difference from the standard pressure and $$pm$$ 0.002 g/cm$$^{3}$$ as a sigma of difference from the solution density analytically determined. However, a drift of data we have never experienced was found in 2008. After investigations, a characteristic value T$$_{0}$$ (period of vibration at zero pressure) which is stable in normal state had changed around 7% at the drift. This was the result of aging, so it was found that monitoring of T$$_{0}$$ value was the very effective information to know the timing of replacement of the transducer. We will present the long-term measurement accuracy of ELTM practically achieved and the way of maintenance including a replacement of the transducer.

Journal Articles

Feasibility study of direct plutonium mass measurement in high-concentrated plutonium solution by a new NDA; Advanced Solution Measurement and Monitoring System (ASMS)

Nakamura, Hironobu; Takaya, Akikazu; Mukai, Yasunobu; Hosoma, Takashi; Yoshimoto, Katsunobu; Tamura, Takayuki*; Iwamoto, Tomonori*

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-30-Kai Nenji Taikai Rombunshu (CD-ROM), 9 Pages, 2009/11

JNFL and JAEA have collaboratively started to develop an ASMS for RRP since 2007. The purpose of the development is to establish direct plutonium mass measurement technique by NDA of high concentrated pure plutonium nitrate solution in a strategic process tank. If it is established, ASMS provides direct Pu mass measurement and monitoring capability, substitutes for sampling and destructive analysis at IIV, and extends process monitoring to safety purposes. The target of the measurement uncertainty is set less than 6% which is equivalent to the detection level of partial defect at IIV by NDA. The principle is similar to the one of NDA for MOX powder, but extended such as introducing variable alpha depends on solution properties. As a first trial, a simple prototype system was constructed and calibrated at PCDF (Plutonium Conversion Development Facility) using plutonium nitrate solution. Consequently, good consistency between MCNP (Monte Carlo Neutron and Photon Transport Code) calculation and measured singles/doubles count rate were obtained. As a feasibility study, it was necessary to find out subjects to be solved. We would like to present benefits of ASMS, review installation and detector setup and summarize preliminary calibration results.

Journal Articles

Innovative powder production and granulation for advanced MOX fuel fabrication

Kurita, Tsutomu; Kato, Yoshiyuki; Yoshimoto, Katsunobu; Suzuki, Masahiro; Kihara, Yoshiyuki; Fujii, Kanichi

Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.94 - 102, 2009/09

With regard to advanced MOX fuel fabrication, a new concept in which one vessel especially designed to meet microwave de-nitration is utilized also for crushing and for granulation, without organic lubricant nor powder transfer across the processes, was introduced for innovative MOX powder production. In order to realize this concept, two attempts were made: A specially designed three blade impeller coupled with auxiliary blade. A uniquely shaped mixing blade coupled with an auxiliary blade having auto-orbital hybrid rotation. The mixing blade promotes the growth of particles, whereas the auxiliary blade suppresses the overgrowth by chopping larger particles. These granulators use a little water as binder. As a result, major diameter of granule 400-1000 micron and flow-ability 82-85 was obtained with fine WO$$_{3}$$ model powder. Therefore, a prospect to satisfy both desirable powder properties and simplified nuclear material production was opened, as well as improvement of working efficiency and cut down on costs.

Journal Articles

Flowability measurement of coarse particles using vibrating tube method

Ishii, Katsunori; Suzuki, Masahiro; Yamamoto, Takuma; Kihara, Yoshiyuki; Kato, Yoshiyuki; Kurita, Tsutomu; Yoshimoto, Katsunobu; Yasuda, Masatoshi*; Matsusaka, Shuji*

Journal of Chemical Engineering of Japan, 42(5), p.319 - 324, 2009/05

 Times Cited Count:7 Percentile:31.92(Engineering, Chemical)

The flowability of coarse particles has been experimentally investigated using the vibrating tube method, to evaluate the applicability of this method to MOX (mixed oxide of PuO$$_{2}$$ and UO$$_{2}$$) particles which are nuclear fuel used for electric power production. Five sizes of non-radioactive model particles, smaller than 850 micrometers, made of ZrO$$_{2}$$ were prepared, and the experiments were carried out using vibrating tubes with an outlet diameter from 2 to 4 mm. The outlet diameter significantly affected the flowability measurements. When using the tube with a 4-mm-outlet diameter, the flowability of all the model particles was successfully measured. The inclination angle of the tube, also, affected the flowability measurements. From the advantages of high sensitivity, short measurement time, simple structure, and easy operation, the vibrating tube method is expected to be applied to the remote flowability measurement of the MOX particles.

Journal Articles

First trial to study the feasibility of direct plutonium mass measurement in a process tank by a new NDA; Advanced solution measurement and monitoring system

Nakamura, Hironobu; Takaya, Akikazu; Mukai, Yasunobu; Hosoma, Takashi; Yoshimoto, Katsunobu; Tamura, Takayuki*; Iwamoto, Tomonori*

Proceedings of INMM 50th Annual Meeting (CD-ROM), 9 Pages, 2009/00

JNFL and JAEA have collaboratively started to develop an ASMS for RRP since 2007 as a trial base. The purpose of the development is to establish quantitative plutonium mass measurement technique directly by NDA of high concentrated pure plutonium nitrate solution in a process tank. If it is established, ASMS provides direct Pu mass measurement and monitoring capability, substitutes for sampling and analysis at IIV, and extends process monitoring to safety purposes. The target of the measurement uncertainty is set less than 6% (1 $$sigma$$) which is equivalent to the detection level of partial defect at IIV by NDA. The principle is similar to the one of NDA for MOX powder, but extended such as introducing variable alpha depends on solution properties. As a first trial, a simple prototype system was constructed and tested at Plutonium Conversion Development Facility of JAEA. Prior to the installation, MCNP calculations for entire cell and tank were performed. Two detectors with a gap were installed just center of the annular tank, then we carried out calibration using plutonium nitrate solution in the range up to 52 kgPu. Consequently, good consistency between calculation and measured singles/doubles count rate were obtained. As a feasibility study, it was necessary to find out subjects to be solved. We would like to present benefits of ASMS, review installation and detector setup and summarize preliminary calibration results.

Journal Articles

Application of microwave heating to MOX fuel production and its contribution to Japanese energy strategy

Suzuki, Masahiro; Ishii, Katsunori; Yamamoto, Takuma; Kihara, Yoshiyuki; Kato, Yoshiyuki; Kurita, Tsutomu; Yoshimoto, Katsunobu; Fujii, Kanichi

Proceedings of Global Congress on Microwave Energy Applications (GCMEA 2008/MAJIC 1st), p.501 - 504, 2008/08

The natural resources, oil and uranium, would dry up around the midway of this century. FBR cycle most probably rescues this difficult situation. Mass production of MOX fuel for FBR, therefore, is the supreme subject to Japanese energy strategy. For this subject, we are attacking with Microwave heating technology. Up to present, we have succeeded to produce excellent PuO$$_{2}$$/UO$$_{2}$$ bulk, 2 kgMOX/batch, advancing toward the mass production target, 5 kgU/h for one batch.

Oral presentation

Results of basic examinations on the simplified MOX fuel fabrication process (short process), 2; The Examination on improving fluidity

Kato, Yoshiyuki; Yoshimoto, Katsunobu; Kimura, Yuichi*; Nemoto, Ryo*

no journal, , 

no abstracts in English

Oral presentation

Results of basic examinations on the simplified MOX fuel fabrication process (short process), 1; Experimental concept and the examination on Pu/U ratio control by liquid mixing

Mukai, Yasunobu; Kato, Yoshiyuki; Yoshimoto, Katsunobu; Sawa, Hideshi*; Otaka, Akihiro*

no journal, , 

no abstracts in English

Oral presentation

The Examination for realizing the simplified-pelletizing fuel fabrication method production equipment; The Experiment equipment for checking the processing procedure of conversion is installed in Plutonium Conversion Development Facility.

Kato, Yoshiyuki; Mukai, Yasunobu; Kurita, Tsutomu; Yoshimoto, Katsunobu

no journal, , 

It aims at realizing a light water reactor cycle, the safety more than equivalent, and economical efficiency in a utilization plant in FBR cycle utilization research and development (FaCT project), and the simplification pellet method was selected by the main concept with the fuel cycle institution. In order to check the enactment nature of adjustment equipment among the simplification pellet methods in the end of precursor powder, it changes to test equipment of an old beaker scale, and small-scale MOX test equipment is fixed.

Oral presentation

Introduction to a new fuel manufacturing process utilizing microwave heating for the next generation nuclear reactor; Renewal of test equipment in plutonium conversion development facility

Kato, Yoshiyuki; Mukai, Yasunobu; Kurita, Tsutomu; Yoshimoto, Katsunobu

no journal, , 

Nuclear energy is indispensable to secure long-term energy supply and to prevent global warning by taking advantage of very small CO$$_{2}$$ discharge. Current power reactor will be replaced by next generation Fast Breeder Reactor (FBR) and its fuel cycle step by step because FBR can utilize limited uranium resource to the utmost and minimize high level radioactive wastes. To achieve the target, Fast Reactor Cycle Technology Development (FaCT) project is being promoted in Japan and a simplified MOX fuel fabrication technology where microwave heating denitration is the core of manufacturing is adopted. Adjustment of plutonium/uranium mixed ratio is done just before denitration and treatment to improve powder fluidity is done continuously after the denitration, thus fuel fabrication process becomes short and economical efficiently. Current research has been examined using test equipment of a beaker scale, and it will be replaced to test equipment with capacity of 1 kgMOX/batch where practicability of the technology will be confirmed. The outline of design and schedule of the technology is introduced.

Oral presentation

Relationship between outlet diameter of tube and mesurement range of particle diameter in vibrating tube method

Ishii, Katsunori; Suzuki, Masahiro; Yamamoto, Takuma; Kihara, Yoshiyuki; Kurita, Tsutomu; Kato, Yoshiyuki; Yasuda, Masatoshi*; Matsusaka, Shuji*; Yoshimoto, Katsunobu

no journal, , 

Particle flowability test using a vibrating tube with a tapered end was carried out to evaluate the applicability of this method to the analysis of MOX particles for nuclear fuel pellet fabrication. In this experiment, zirconia particles were used as model particles, which are less than 850 micrometers in diameter. The sample particles were prepared by mixing the particles with different sizes. The experimental results showed that stable fowability evaluation is possible for particles larger than 45 micrometers and less than 850 micrometres, adjusting outlet diameter of tube and inclination angle of tube.

Oral presentation

Discussion on optimization of microwave heating for MOX fuel production

Kato, Yoshiyuki; Kurita, Tsutomu; Matsumoto, Masaki; Suzuki, Masahiro; Ishii, Katsunori; Yamamoto, Takuma; Kihara, Yoshiyuki; Yoshimoto, Katsunobu; Fujii, Kanichi

no journal, , 

An earlier accomplishment of FBR(fast breeder reactor) fuel cycle is the supreme subject from the point of view on the protection of environment by suppressing the green house effect as well as saving the oil. Microwave heating (MH) is employed as the MOX (mixed oxides U-Pu) production process in the main stream of FBR cycle. Thus, we are the optimization of MH method. We will describe the practical work of MOX fuel production which recycles the consumed nuclear fuel containing both U and Pu. The MH is employed to solidify the mixed solution by evaporating nitric acid and water. We call this processing de-nitration. The physical, mechanical, and chemical characteristics of the products are analyzed, being thereby discussed the contribution of the MH technology to the MOX fuel production. And, optimization of MH is discussed from the view point of design of MH oven, regulation of MH power, and combination with several auxiliary heating sources.

46 (Records 1-20 displayed on this page)