Document collection of the 39th Technical Special Committee on Fugen Decommissioning

Sato, Yuji; Miyamoto, Yuta; Awatani, Yuto; Yamamoto, Kosuke; Hatakeyama, Takumi

JAEA-Review 2023-002, 59 Pages, 2023/08

JAEA-Review-2023-002.pdf:8.75MB

"Fugen Decommissioning Engineering Center", in planning and carrying out our decommissioning technical development, organizes "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 domestic and international, as the central place in research and development base of Fukui prefecture, and to utilize the outcome in our decommissioning to the technical development effectively. This report consists of presentation paper are "Achievements and Considerations for Sampling and Analysis of Reactor Core Components", "Treatment of liquid scintillator waste liquid" and "Results and issues of rationalization of decontamination related to the clearance and considerations related to surface contamination monitoring" which is presented in the 39th Technical Special Committee on Fugen Decommissioning.

Preparation of the particles containing isotope reference uranium for the determination of the low abundant U isotope ratios

Tomita, Jumpei; Tomita, Ryohei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka

KEK Proceedings 2022-2, p.154 - 158, 2022/11

Precise determination of minor U isotopes (U and U) of particles from the safeguard environmental samples is powerful method for detecting the undeclared nuclear activities. In this study, preparation method of U particle was examined to utilize for the minor U isotope determination. The porous silica particles were used as the particle matrix and lutetium was mixed to the impregnation solution as U impregnation indicator for the particle picking. The result of the Scanning Electron Microscope indicated that the contacting the solution with Si particles overnight gently could produce the impregnated particles effectively rather than the mixing them with PFA stick.

Improvement of the return mapping algorithm based on the implicit function theorem with application to ductile fracture analysis using the GTN model

Mano, Akihiro; Imai, Ryuta*; Miyamoto, Yuhei*; Lu, K.; Katsuyama, Jinya; Li, Y.

International Journal of Pressure Vessels and Piping, 199, p.104700_1 - 104700_13, 2022/10

https://doi.org/10.1016/j.ijpvp.2022.104700

Elastic-plastic analyses based on finite element methods are widely applied to simulate the nonlinear behaviors of materials. When the analysis is conducted by an implicit method, the stress values are generally updated with a time increment by using the so-called return mapping algorithm. This algorithm requires solving simultaneous nonlinear equations related to a constitutive model. In the present paper, we proposed a general method to reduce the number of equations in the return mapping algorithm based on the implicit function theorem. In addition, the proposed method was applied to the Gurson-Tvergaard-Needleman (GTN) model that considers the influence of damage due to nucleation and growth of microscopic void in materials in the simulation of the nonlinear behaviors. By using the GTN model with the proposed method, an elastic-plastic analysis was performed by the implicit method for a 4-point bending test of pipe with a through-wall crack. The numerical solution of the variation of the load-load line displacement from the analysis agreed with experimental result. Thus, we concluded that the proposed method is useful for simulating nonlinear behaviors, including void nucleation and growth in materials.

Optimization of SIMS-APM for high enrichment uranium particles including higher uranium hydride

Tomita, Ryohei; Tomita, Jumpei; Yomogida, Takumi; Suzuki, Daisuke; Yasuda, Kenichiro; Esaka, Fumitaka; Miyamoto, Yutaka

KEK Proceedings 2021-2, p.146 - 150, 2021/12

no abstracts in English

Age determination analysis of a single uranium particle for safeguards

Suzuki, Daisuke; Tomita, Ryohei; Tomita, Jumpei; Esaka, Fumitaka; Yasuda, Kenichiro; Miyamoto, Yutaka

Journal of Radioanalytical and Nuclear Chemistry, 328(1), p.103 - 111, 2021/04

https://doi.org/10.1007/s10967-021-07626-x

An analytical technique was developed to determine the age of uranium particles for safeguards. After the chemical separation of uranium and thorium, the Th/U ratio was measured using single-collector inductively coupled plasma mass spectrometry and a U-based reference material comprising a certain amount of Th as a progeny nuclide of U. The results allowed us to determine the purification age of two certified materials, i.e., U-850 and U-100, which was in good agreement with the reference purification age (61 y). Moreover, the age of a single U-850 particle was determined with a difference of -28 to 2 years from the reference date.

Technology demonstration of sampling from reactor core structure of FUGEN Decommissioning Engineering Center

Iwai, Hiroki; Soejima, Goro; Takiya, Hiroaki; Awatani, Yuto; Aratani, Kenta; Miyamoto, Yuta; Tezuka, Masashi

Dekomisshoningu Giho, (61), p.12 - 19, 2020/03

http://www.randec.or.jp/publish/documents/gihou/Decommissioning%20gihou_61.pdf

FUGEN Decommissioning Engineering Center received the approval of the decommissioning plan in 2008, and we have been progressing the decommissioning. The first phase of decommissioning (Heavy Water and Other System Decontamination Period) finished in March 2018, and FUGEN has entered into the second phase of decommissioning (Reactor Periphery Facilities Dismantling Period). This report outlines the technology demonstration of sampling from reactor core structure of FUGEN that to prepare for reactor dismantlement in the third phase.

Anion-exchange separation of americium and the lanthanides using a single column

Miyamoto, Yutaka; Yasuda, Kenichiro

Journal of Nuclear and Radiochemical Sciences (Internet), 18, p.13 - 15, 2018/07

http://www.radiochem.org/en/paper/JN181/jn18104.pdf

A sequential separation technique using an anion-exchange column developed in the previous works have the potential to completely separate picograms of Am from the lanthanides using mixtures of acetic acid, hydrochloric acid, and nitric acid as the eluents, without any functional ligands or special columns. This experimental result implies that ultra-trace actinides, including Am, Pu, U, and Th in environmental samples can be sequentially separated by combination of these mixed-media eluents and an anion exchange column.

Analysis of plutonium isotope ratios including Pu/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

https://doi.org/10.1016/j.talanta.2016.12.041

The isotope ratios of Pu/Pu, Pu/Pu, Pu/Pu, and Pu/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 Pu/Pu, Pu/Pu, and Pu/Pu isotope ratios with ICP-MS after particle dissolution and chemical separation of uranium, plutonium and americium with UTEVA resins. Furthermore, Pu/Pu isotope ratios were able to be calculated by using both the Pu/(Pu+Pu) activity ratios that had been measured through alpha spectrometry and the Pu/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 Pu/Pu, in individual U-Pu mixed oxide particles.

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

https://doi.org/10.1007/s10967-015-4113-6

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, Pu/Pu, Pu/Pu and Pu/Pu isotope ratios were successfully determined, while it was impossible to determine Pu/Pu ratios due to the high process blank values on m/z 238.

Accurate purification age determination of individual uranium-plutonium mixed particles

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

Analytical and Bioanalytical Chemistry, 407(23), p.7165 - 7173, 2015/09

https://doi.org/10.1007/s00216-015-8880-2

Age of individual uranium-plutonium mixed particles with various U/Pu atomic ratios were determined by inductively-coupled plasma mass spectrometry. Micron-sized particles were prepared from U and Pu certified reference materials. The Pu reference was stored for 4-6 years since the last purification. The Pu purification age was obtained from the Am/Pu ratio which was calculated from the product of three measured ratios of Pu and Am isotopes in the eluted fractions. Am, U and Pu in a sample solution were sequentially separated a small anion-exchange column. The Am/Pu ratio was accurately determined by spiking pure Am to the sample solution. The determined age of particles with various U/Pu ratios was in good agreement with the expected age with high accuracy and high precision.