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Journal Articles

The Effects of plutonium content and self-irradiation on thermal conductivity of mixed oxide fuel

Ikusawa, Yoshihisa; Morimoto, Kyoichi; Kato, Masato; Saito, Kosuke; Uno, Masayoshi*

Nuclear Technology, 205(3), p.474 - 485, 2019/03

 Percentile:100(Nuclear Science & Technology)

This study evaluated the effects of plutonium content and self-irradiation on the thermal conductivity of mixed-oxide (MOX) fuel. Samples of UO$$_{2}$$ fuel and various MOX fuels were tested. The MOX fuels had a range of plutonium contents, and some samples were stored for 20 years. The thermal conductivity of these samples was determined from thermal diffusivity measurements taken via laser flash analysis. Although the thermal conductivity decreased with increasing plutonium content, this effect was slight. The effect of self-irradiation was investigated using the stored samples. The reduction in thermal conductivity caused by self-irradiation depended on the plutonium content, its isotopic composition, and storage time. The reduction in thermal conductivity over 20 years' storage can be predicted from the change of lattice parameter. In addition, the decrease in thermal conductivity caused by self-irradiation was recovered with heat treatment, and recovered almost completely at temperatures over 1200 K. From these evaluation results, we formulated an equation for thermal conductivity that is based on the classical phonon-transport model. This equation can predict the thermal conductivity of MOX fuel thermal conductivity by accounting for the influences of plutonium content and self-irradiation.

Journal Articles

Separation technique using column chromatography for safeguards verification analysis of uranium and plutonium in highly-active liquid waste by isotope dilution mass spectrometry

Yamamoto, Masahiko; Taguchi, Shigeo; Horigome, Kazushi; Kuno, Takehiko

Proceeding IAEA Symposium on International Safeguards; Building Future Safeguards Capabilities (Internet), 8 Pages, 2018/11

In this study, the single-column extraction chromatographic separation has been developed for analysis of U and Pu in highly active liquid waste by isotope dilution mass spectrometry (IDMS). The commercially available TEVA$$^{textregistered}$$ resin is selected as an extraction chromatography resin. The U is chromatographically separated from fission products (FP) elements by nitric acid while Pu(IV) is adsorbed on the resin. After that, Pu is eluted by reducing to Pu(III). The method has been successfully achieved the separation with yielding the enough recovery and sufficient decontamination factors for subsequent IDMS analysis. The column dose rate after the FP removal is decreased to the background. The analytical results obtained by the developed method are in a good agreement with those of the conventional method. It provides simple and rapid separation and expected that the method can be applied to join IAEA/Japan on-site analytical laboratory.

Journal Articles

Trace analysis for nuclear non-proliferation and security

Esaka, Fumitaka

Bunseki, 2018(10), p.408 - 411, 2018/10

Recent development of analytical techniques for identification of particles containing nuclear materials, isotope ratio analysis of uranium and plutonium using mass spectrometry, and age determination is described in this paper. These techniques are successfully applied to the trace analysis for nuclear non-proliferation.

JAEA Reports

Development of separation technique of Pu, Am, Np using solid phase extraction resin for the determination of impurity metal elements in plutonium nitrate solution by inductivity coupled plasma optical emission spectrometry

Taguchi, Shigeo; Yamamoto, Masahiko; Furuse, Takahiro*; Masaki, Yuji*; Kuno, Takehiko

JAEA-Technology 2018-005, 14 Pages, 2018/06

JAEA-Technology-2018-005.pdf:0.94MB

The method to remove Pu, Am and Np from plutonium nitrate solution recovered from spent nuclear fuel prior to ICP-OES measurement has been developed for the determination of 18 impurity metal elements (Fe, Cr, Ni, Mn, Al, Cd, V, Cu, Si, Zn, Mo, Sn, Ca, Mg, Na, Ag, Pb, B). In this method, two TRU resin packed columns were used for separation. In the first column, Pu and Am were mainly removed by adsorption. The recovered solution from the fist column was added to the second column after reduction of Np, and Am(III) and Np(IV) were removed by adsorption. The Pu nitrate solution (22g/L) of 2mL were treated by proposed method. The alpha emission nuclide was decreased to $$<$$5.8 Bq/mL in a solution diluted to 100mL. As a result of ICP-OES measurement, the recoveries of impurity metals separated by proposed method were almost 100%. This separation scheme can apply to the metal impurity elemental analysis in Pu nitrate solution recovered from spent nuclear fuel.

Journal Articles

Safety and economics of uranium utilization for nuclear power generation

Fukaya, Yuji

Uranium; Safety, Resources, Separation and Thermodynamic Calculation, p.22 - 48, 2018/05

Safety and economics of uranium utilization for nuclear power generation were investigated and discussed. In order to sustain energy supply with nuclear power generation, uranium resources should be abundant. From the viewpoint of depletion of the resources, FBR, which is breeder reactor of plutonium, has been developed, but that has been not diffused as a commercial reactor yet. Instead of obtaining inexhaustible resources by breeding plutonium, it is known that the inherent safety feature becomes weak in the fast neutron spectrum. As the result of the investigation, it is confirmed with concrete FBR designs that the inherent safety feature and breeding ability are related to the transactions. The amount of uranium resources and electricity generation cost with the resources were investigated. It is concluded that the semi-permanently sustainable energy supply can be established with reasonable cost by using seawater uranium. In addition, the significance of P&T, which is one of the advantages of FBR, was also discussed from the viewpoint of environmental burden from radioactive waste.

JAEA Reports

Investigative report on the PVC bag burst in the contamination incident at Plutonium Fuel Research Facility; Radiolysis of organic materials and raising of internal pressure

Cause Investigation Team for the PFRF Contamination Incident

JAEA-Review 2017-038, 83 Pages, 2018/03

JAEA-Review-2017-038.pdf:11.37MB

The contaminated accident occurred at Plutonium Fuel Research Facility on June, 2017. The PVC bag packaging in a fuel storage container burst when a worker opened the lid, and a part of contents (uranium and plutonium) was spattered over the room. In order to clarify the cause of the burst, the Cause Unfolding Team collected information concerning characteristics of the contents from any past records and interview. And then we observed and analyzed the contents in a glove box. We also performed experiments on radiolysis of organic materials, degradation of PVC bag by $$gamma$$ radiation, and PVC bag burst. Based on fault tree analysis, finally we concluded that the main gas generation source was alpha radiolysis of the epoxy resin mixed with the fuel powder. We hope that the calculation procedures for the gas generation and the inner pressure transition described in this report can be useful reference for the management of fuel storage in other facilities.

Journal Articles

Laser ablation absorption spectroscopy for isotopic analysis of plutonium; Spectroscopic properties and analytical performance

Miyabe, Masabumi; Oba, Masaki; Jung, K.; Iimura, Hideki; Akaoka, Katsuaki; Kato, Masaaki; Otobe, Haruyoshi; Khumaeni, A.*; Wakaida, Ikuo

Spectrochimica Acta, Part B, 134, p.42 - 51, 2017/08

 Times Cited Count:5 Percentile:22.02(Spectroscopy)

Spectroscopic properties of atomic species of plutonium were investigated by combining laser ablation and resonance absorption techniques for the analysis of a plutonium oxide sample. For 17 transitions of Pu atoms and ions, the absorbance, isotope shift, and hyperfine splitting were determined via Voigt profile fitting of the recorded absorption spectra. Three transitions were selected as candidates for analytical use. Using these transitions, we investigated the analytical performance that was attainable and determined a correlation coefficient R2 between the absorbance and plutonium concentration of 0.9999, a limit of detection of 30-130 ppm, and a relative standard deviation of approximately 6% for an abundance of $$^{240}$$Pu of 2.4%. These results demonstrate that laser ablation absorption spectroscopy is applicable to the remote isotopic analysis of highly radioactive nuclear fuels and waste materials containing multiple actinide elements.

JAEA Reports

Application of controlled-potential coulometry as a primary method for the characterization of plutonium nitrate solutions being used for reference materials (Joint research)

Yamamoto, Masahiko; Holland, M. K.*; Cordaro, J. V.*; Kuno, Takehiko; Surugaya, Naoki

JAEA-Technology 2017-014, 63 Pages, 2017/06

JAEA-Technology-2017-014.pdf:4.38MB

In this study, the controlled-potential coulometry has been applied as a primary method for characterizing the Pu master solutions being used as alternative source material for IDMS spikes. The coulometry system compliance with ISO12183 has been used for measurement. It has been calibrated using equipment traceable to the SI units. Plutonium standard samples have been measured to confirm the accuracy. The relative standard deviation is below 0.05%. The results agree with the reference value within $$pm$$0.05%. It is found that the Pu can be precisely analyzed by the coulometry system. Then, the Pu nitrate solution, which has been purified from mixed oxide powder containing relatively high $$^{239}$$Pu, has been measured. The relative standard deviation is below 0.05%. The relative expanded uncertainty is less than 0.074% at the 95% confidence interval (k=2). It is indicated that coulometric assay of Pu is fit for the purpose of characterizing reference materials.

JAEA Reports

Report on analytical activities in potentially hazardous materials mitigation measures at the Plutonium Conversion Development Facility; 2015.12 $$sim$$ 2016.10

Horigome, Kazushi; Taguchi, Shigeo; Ishibashi, Atsushi; Inada, Satoshi; Kuno, Takehiko; Surugaya, Naoki

JAEA-Technology 2017-008, 14 Pages, 2017/05

JAEA-Technology-2017-008.pdf:1.15MB

The plutonium solution had been converted into MOX powder to mitigate the potential hazards of storage plutonium solution such as hydrogen generation at the Plutonium Conversion Development Facility. The plutonium conversion operations had been started in April, 2014, and had been finished in July, 2016. With respect to the samples taken from the conversion process, about 2,200 items of plutonium/uranium solutions and MOX powders had been analyzed for the operation control in the related analytical laboratories at the Tokai Reprocessing Plant. This paper describes the reports on analytical activities and related maintenance works in the analytical laboratories conducted from December, 2015 to October, 2016.

Journal Articles

Analysis of plutonium isotope ratios including $$^{238}$$Pu/$$^{239}$$Pu in individual U-Pu mixed oxide particles by means of a combination of alpha spectrometry and ICP-MS

Esaka, Fumitaka; Yasuda, Kenichiro; Suzuki, Daisuke; Miyamoto, Yutaka; Magara, Masaaki

Talanta, 165, p.122 - 127, 2017/04

 Times Cited Count:4 Percentile:47.81(Chemistry, Analytical)

The isotope ratios of $$^{238}$$Pu/$$^{239}$$Pu, $$^{240}$$Pu/$$^{239}$$Pu, $$^{241}$$Pu/$$^{239}$$Pu, and $$^{242}$$Pu/$$^{239}$$Pu were measured for individual Pu and U-Pu mixed oxide particles by a combination of alpha spectrometry and inductively coupled plasma mass spectrometry (ICP-MS). As a consequence, we were able to determine the $$^{240}$$Pu/$$^{239}$$Pu, $$^{241}$$Pu/$$^{239}$$Pu, and $$^{242}$$Pu/$$^{239}$$Pu isotope ratios with ICP-MS after particle dissolution and chemical separation of uranium, plutonium and americium with UTEVA resins. Furthermore, $$^{238}$$Pu/$$^{239}$$Pu isotope ratios were able to be calculated by using both the $$^{238}$$Pu/( $$^{239}$$Pu+$$^{240}$$Pu) activity ratios that had been measured through alpha spectrometry and the $$^{240}$$Pu/$$^{239}$$Pu isotope ratios determined through ICP-MS. Therefore, the combined use of alpha spectrometry and ICP-MS is useful in determining plutonium isotope ratios, including $$^{238}$$Pu/$$^{239}$$Pu, in individual U-Pu mixed oxide particles.

JAEA Reports

Preliminary missions for the decommissioning of the laboratory building No.1 for the plutonium research program

Segawa, Yukari; Horita, Takuma; Kitatsuji, Yoshihiro; Kumagai, Yuta; Aoyagi, Noboru; Nakada, Masami; Otobe, Haruyoshi; Tamura, Yukito*; Okamoto, Hisato; Otomo, Takashi; et al.

JAEA-Technology 2016-039, 64 Pages, 2017/03

JAEA-Technology-2016-039.pdf:5.24MB

The laboratory building No.1 for the plutonium research program (Bldg. Pu1) was chosen as one of the facilities to decommission by Japan Atomic Energy Agency Reform in September, 2013. The research groups, users of Bldg. Pu1, were driven by necessity to remove used equipment and transport nuclear fuel to other facilities from Bldg. Pu1. Research Group for Radiochemistry proactively established the Used Equipment Removal Team for the smooth operation of the removal in April, 2015. The team classified six types of work into the nature of the operation, removal of used equipment, disposal of chemicals, stabilization of mercury, stabilization of nuclear fuel, transportation of nuclear fuel and radioisotope, and survey of contamination status inside the glove boxes. These works were completed in December, 2015. This report circumstantially shows six works process, with the exception of the approval of the changes on the usage of nuclear fuel in Bldg. Pu1 to help prospective decommission.

Journal Articles

Application of controlled-potential coulometry for the characterization of plutonium nitrate solutions being used for reference materials

Yamamoto, Masahiko; Holland, M. K.*; Cordaro, J. V.*; Kuno, Takehiko; Surugaya, Naoki

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

Precise and accurate determination of plutonium is necessary. The high reliability is required for standard materials used in the plutonium determination. In this study, JAEA and SRNL have collaborated on a mission to apply controlled-potential coulometry as a primary method for characterizing the plutonium master solution being used for reference materials of isotope dilution mass spectrometry. The measurement cell and electrodes were upgraded and optimized compliance with ISO12183. The instruments were calibrated traceable to the SI. The samples of plutonium standard solution were measured to confirm the accuracy of the method. The results have been in good agreement with the reference values. Therefore, the plutonium solution which were purified from MOX powder have been characterized. The total measurement uncertainty was less than 0.07%. The results indicated that coulometry assay of plutonium are fit for the purpose of characterizing reference material.

JAEA Reports

Report on analytical activities in potentially hazardous materials mitigation measures at the Plutonium Conversion Development Facility; 2014.4 $$sim$$ 2015.12

Horigome, Kazushi; Suzuki, Hisanori; Suzuki, Yoshimasa; Ishibashi, Atsushi; Taguchi, Shigeo; Inada, Satoshi; Kuno, Takehiko; Surugaya, Naoki

JAEA-Technology 2016-026, 21 Pages, 2016/12

JAEA-Technology-2016-026.pdf:1.14MB

In order to mitigate potential hazards of storage plutonium in solution such as hydrogen generation, conversion of plutonium solution into MOX powder has been carried out since 2014 in the Plutonium Conversion Development Facility. With respect to the samples taken from the conversion process, about 3500 items of plutonium/uranium solutions and MOX powders have been analyzed for the operation control in the related analytical laboratories at the Tokai Reprocessing Plant. This paper describes the reports on analytical activities and related maintenance works in the analytical laboratories conducted from April 2014 to December 2015.

Journal Articles

Uranium and plutonium extraction by ${it N,N}$-dialkylamides using multistage mixer-settler extractors

Ban, Yasutoshi; Hotoku, Shinobu; Tsutsui, Nao; Suzuki, Asuka; Tsubata, Yasuhiro; Matsumura, Tatsuro

Procedia Chemistry, 21, p.156 - 161, 2016/12

 Percentile:100

A continuous counter-current experiment was carried out to demonstrate the validity of a process using ${it N,N}$-dialkylamides for recovering U and Pu. This process consisted of two cycles, and the 1st cycle and the 2nd cycle employed ${it N,N}$-di(2-ethylhexyl)-2,2-dimethylpropanamide and ${it N,N}$-di(2-ethylhexyl)butanamide as extractants, respectively. The feed solution for the 1st cycle was 5.1 mol/dm$$^{3}$$ (M) nitric acid containing 0.92 M U, 1.6 mM Pu, and 0.6 mM Np. The raffinate collected in the 1st cycle was used as the feed for the 2nd cycle. The ratios of U recovered in the U fraction and U-Pu fraction were 99.1% and 0.8%, respectively. The ratio of Pu recovered in the U-Pu fraction was 99.7%. The concentration ratio of U with respect to Pu in the U-Pu fraction was 9, and this indicated that Pu was not isolated. The decontamination factor of U with respect to Pu in the U fraction was obtained as 4.5$$times$$10$$^{5}$$. These results supported the validity of the proposed process.

Journal Articles

Automatic sequential separation with an anion-exchange column for ultra-trace analysis of Pu, U, Th, Pb, and lanthanides in environmental samples

Miyamoto, Yutaka; Yasuda, Kenichiro; Magara, Masaaki

Journal of Radioanalytical and Nuclear Chemistry, 309(1), p.303 - 308, 2016/07

 Times Cited Count:1 Percentile:76.09(Chemistry, Analytical)

The technique of sequential separation for U, Th, Pb, lanthanides and Pu using a single anion-exchange column and mixed acids media were developed. An automatic system utilizing a small column and pressurized gas was assembled for this sequential separation. By adjusting the eluent chemical composition for Pu separation, this separation technique has been achieved. Some pieces of tree ring sample were digested, and ultra-trace U and Pu in the samples were separated by this system. The analytical results of U and Pu measured by mass spectrometry will be mentioned.

Journal Articles

Development of Pu standard material preparation and characterization technique in Japan

Okazaki, Hiro; Shibano, Koya; Abe, Katsuo; Sumi, Mika; Kayano, Masashi; Kageyama, Tomio; Mason, P.*

Proceedings of INMM 57th Annual Meeting (Internet), 7 Pages, 2016/07

The reference materials used for accountancy analysis by IDMS, referred to as LSD spikes allows to obtain accurate measurement results for a variety of nuclear materials under potentially difficult handling or measurement conditions. Because of expected difficulties in a stably long term supply of plutonium reference materials, which are the main source of plutonium for LSD spikes preparation, the JAEA's PFDC decided to evaluate the possibility of using domestically available MOX powders as a plutonium source material for LSD spikes. Therefore, PFDC started to separate, purify and characterize plutonium in MOX powders for plutonium reference materials (MOX-Pu) preparation that are suitable for source of LSD spikes in cooperation with the US DOE's NBL. The detailed preparation procedure of the latest MOX-Pu standard material and results of intercomparison for verification are presented.

Journal Articles

Application of controlled-potential coulometery as a primary method for the characterization of plutonium nitrate solutions being used for large-size dry spike reference materials; Collaboration between JAEA and SRNL

Holland, M. K.*; Cordaro, J. V.*; Morales-Arteaga, M. E.*; Yamamoto, Masahiko; Kuno, Takehiko; Surugaya, Naoki

Proceedings of INMM 57th Annual Meeting (Internet), 10 Pages, 2016/07

Since 2007, the laboratory at the Japan Atomic Energy Agency (JAEA) and Savannah River National Laboratory (SRNL) have collaborated on a new mission to apply controlled-potential coulometry as a primary method for characterizating plutonium master solutions. Measurement results are being used to prepare traceable and certifiable large-size dry (LSD) spike standards for safeguards measurements by isotope dilution mass spectrometry. The collaboration activities performed by JAEA and SRNL were authorized and funded under the JAEA & United States NNSA/DOE Permanent Coordinating Group. This report will chronicle the collaboration activities of JAEA and SRNL, and provide the detail on the periodic coulometer component calibration, the coulometric plutonium measures and measure practices, including the uncertainty propagation for the most recent plutonium master solution used for LSD Spike preparation.

Journal Articles

Distribution behavior of neptunium by extraction with ${it N,N}$-dialkylamides (DEHDMPA and DEHBA) in mixer-settler extractors

Ban, Yasutoshi; Hotoku, Shinobu; Tsutsui, Nao; Tsubata, Yasuhiro; Matsumura, Tatsuro

Solvent Extraction and Ion Exchange, 34(1), p.37 - 47, 2016/01

 Times Cited Count:3 Percentile:80.3(Chemistry, Multidisciplinary)

The extraction properties of ${it N,N}$-di(2-ethylhexyl)-2,2-dimethylpropanamide (DEHDMPA) and ${it N,N}$-di(2-ethylhexyl)butanamide (DEHBA) for Np(V) and Np(VI) were studied by a batch method using various nitrate ion concentrations. The distribution ratios of Np(VI) obtained with DEHDMPA and DEHBA exceeded unity when the nitrate ion concentration was $$>$$3 mol/L. DEHDMPA and DEHBA barely extracted Np(V), and the maximum distribution ratios were 0.4 and 0.2 when DEHDMPA and DEHBA were used as extractants, respectively. A continuous counter-current experiment was performed to evaluate the behavior of Np in a process comprising two cycles. The ratio of Np recovered to the U fraction and U-Pu fraction were 63.7% and 29.1%, respectively. The behavior of Np suggested that the valence state of Np changed from Np(V) to Np(IV) or Np(VI) after the 1st experimental cycle. The recoveries of U and Pu to the U fraction stream and the U-Pu fraction stream were 99.9% and 99.8%, respectively.

Journal Articles

Determination of plutonium isotope ratios in individual uranium-plutonium mixed particles with inductively coupled plasma mass spectrometry

Esaka, Fumitaka; Suzuki, Daisuke; Miyamoto, Yutaka; Magara, Masaaki

Journal of Radioanalytical and Nuclear Chemistry, 306(2), p.393 - 399, 2015/11

 Times Cited Count:4 Percentile:43.49(Chemistry, Analytical)

An analytical technique was developed by a combination of single particle dissolution, chemical separation of uranium, plutonium and americium with extraction chromatography using UTEVA resins and measurement with inductively coupled plasma mass spectrometry (ICP-MS). This method was applied to plutonium isotope ratio analysis of individual U-Pu particles with U/Pu ratios ranging from 1 to 70. Consequently, $$^{240}$$Pu/$$^{239}$$Pu, $$^{241}$$Pu/$$^{239}$$Pu and $$^{242}$$Pu/$$^{239}$$Pu isotope ratios were successfully determined, while it was impossible to determine $$^{238}$$Pu/$$^{239}$$Pu ratios due to the high process blank values on m/z 238.

Journal Articles

Chemical separation of ultra-trace multi-elements in environmental samples

Miyamoto, Yutaka; Yasuda, Kenichiro; Magara, Masaaki

KEK Proceedings 2015-4, p.44 - 48, 2015/11

We developed an automatic system for sequential separation with an anion-exchange column to simply and quickly separate less than pico-grams of ultra-trace U, Th, Pb, the lanthanide, and Pu in an environmental sample without foreign contamination. The objective sequential separation of ultra-trace multi-elements succeeded by choosing the HCl-HF mixture based acetic acid for Th separation and the HCl-diluted HF mixture for Pu separation. The objective elements in a multi-elements mixture were completely separated for 6 h 15 min by use of the automatic system and the optimized separation condition.

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