Application of probability generating function to the essentials of nondestructive nuclear materials assay system using neutron correlation

Hosoma, Takashi

JAEA-Research 2016-019, 53 Pages, 2017/01

JAEA-Research-2016-019.pdf:5.71MB

Application of probability generating function for nondestructive nuclear materials assay system was studied. First, high-order neutron correlations were derived algebraically up to septuplet and basic characteristics of the correlations were investigated. It was found that higher-order correlation increases rapidly in response to the increase of leakage multiplication, crosses and leaves lower-order correlations behind, when leakage multiplication is 1.3 that depends on detector efficiency and counter setting. Next, fission rates and doubles count rates by fast neutron and by thermal neutron in their coexisting system were derived algebraically. It was found that the number of induced fissions per unit time by fast neutron and by thermal neutron, the number of induced fissions ( 1) by one source neutron, and individual doubles count rates were possible to be estimated from Rossi-alpha combined distribution and measured ratio of each area obtained by differential die-away self-interrogation and conventional assay data.

Numerical calculation of axisymmetric fluid-liquid interfaces by polar coordinate system and examples associated with U-Pu co-conversion technology

Hosoma, Takashi

JAEA-Research 2012-033, 66 Pages, 2013/01

JAEA-Research-2012-033.pdf:13.1MB

An exquisite shape of gas-liquid interface, that is a bubble/drop/liquid bridge, is the result of continuous pressure balance along vertical axis between the pressure due to difference of density and the pressure due to surface tension and curvature of interface. However, there have been surprisingly a little papers arguing the accurate shape, curvatures and volume. Regarding the research and development of U-Pu co-conversion technology, some phenomena were well understood by obtaining the accurate shape and/or volume. A numerical solving method by polar coordinate system with a switched-origin algorithm applicable to the shape that includes multiple tangential planes both in horizontal and in vertical was derived through such experiences, although static physical conditions and axisymmetrical property are assumed. The real interface shape is actualized or selected as a part of the calculated curve, which depends on physical conditions. A bubble at the tip of dip-tube used for density/level measurement, a bubble nucleates in the cylindrical shape of liquid heated by microwave and an estimated liquid bridge in the granule after co-conversion were described as actual examples. Interfaces between water and air under normal temperature and atmospheric pressure were described as numerical examples for systematic investigation. Contact angle, internal/external pressure difference, volume, surface energy and wavelength of periodically deforming shape are physical conditions actualizing the calculation.

Volume measurement system for plutonium nitrate solution and its uncertainty to be used for nuclear materials accountancy proved by demonstration over fifteen years

Hosoma, Takashi

JAEA-Research 2010-033, 47 Pages, 2010/10

JAEA-Research-2010-033.pdf:3.45MB

An accurate volume measurement system for plutonium nitrate solution stored in an accountability tank with dip-tubes has been developed and demonstrated over fifteen years at Plutonium Conversion Development Facility of Japan Atomic Energy Agency. It was proved, as a result of calibrations during the demonstration, that measurement uncertainty practically achieved and maintained was less than 0.1% (systematic character) and 0.15% (random) as one sigma which was half of the current target uncertainty admitted internationally. It was also proved that discrepancy between measured density and analytically determined density was less than 0.002 gcm as one sigma. These uncertainties include effects by long term use of the accountability tank where plutonium throughput is six ton. The system consists of high precision differential pressure transducers and a dead weight tester, sequentially controlled valves for periodical zero adjustment, dampers to reduce pressure oscillation and a procedure to correct measurement biases. The sequence was also useful to carry out maintenances safely without contamination. Longevity of the transducer was longer than 15 years. Principles and essentials to determine solution volume and weight of plutonium, measurement biases and corrections, accurate pressure measurement system, maintenances and diagnostics, operational experiences, evaluation of measurement uncertainty are introduced.

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 2 Pa as a sigma of difference from the standard pressure and 0.002 g/cm 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 (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 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.

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 ) 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.

A Practical approach to reduce measurement uncertainty of Pu isotopic composition by high resolution spectrometry applied to product MOX powder

Hosoma, Takashi; Nakamura, Hironobu; Mukai, Yasunobu; Fujisaku, Sakae

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-28-Kai Nenji Taikai Rombunshu (CD-ROM), 8 Pages, 2007/00

For verification of MOX powder produced daily in a MOX conversion plant, it is expected to reduce uncertainty of NDA which enables bias defect verification and improves compatibility with plant operation. JAEA had studied conceptual design of such NDA in 2000 with DOE and there was a proposal to utilize analytical results of isotopic composition of the sources (plutonium nitrate) which were entirely verified by IAEA. The idea to determine weighing coefficients of the combination of the sources reproducing the peak ratios of measurable isotopes by HRGS was developed and confirmed using data obtained at PCDF and simulated HRGS data. It is possible to reduce uncertainty of HRGS to 1/2-1/3. For example, around 0.7% uncertainty of effective Pu ratio is realized, if HRGS achieves 2% uncertainty. It is sufficient to pick simply the latest four lots as the sources which were received to the facility at the time of measuring or verifying product MOX powder.

History of 20 Years Demonstration of Pu-U Co-Conversion Process using a Microwave Heating Direct Denitration Method; Operational Experiences and Developments at the Plutonium Conversion Development Facility

Hosoma, Takashi; Ichige, Koji; Yoshiharu, Takahashi,

Saikuru Kiko Giho, (24), p.11 - 26, 2004/00

https://rdreview.jaea.go.jp/gihou/pdf2/n24-02.pdf

The application of the fluoride volatility process in the reprocessing of fuel from the fast breeder reactor is regarded as one of the economical methods. Plutonium hexafluoride (PuF6), however, reacting with fluorine (F2) and plutonium dioxide (PuO2) as the raw material, is in an unstable condition and tends to remain as a solid compound in the process after decomposing into plutonium tetrafluoride (PuF4). Suitable conditions should be established for the practical use of this process. One of them is to enhance the stability of PuF6. The behaviour of plutonium fluorination and relevant chemical reactions were investigated by referring to sundry literature and by thermodynamic calculation. It was then compared with recent data from laboratory scale experiments for this paper. Results from the theoretical analysis agreed with experimental observation that PuF6 could be formed stably under a high temperature condition (approx.1000 K) with over supply of figher concentration of F2.

DESIGN OF GEOMETRICAL DETECTOR ARRANGEMENT FOR EXTENSIVE HOLDUP MEASUREMENT

; ; Hosoma, Takashi

Proceedings, 0 Pages, 2002/00

None

DESIGN OF GEOMETRICAL DETECTOR ARRANGEMENT FOR EXTENSIVE HOLDUP MEASUREMENT

; ; Hosoma, Takashi

P292, 292 Pages, 2001/00

None

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; Hosoma, Takashi; D'Agraives, B. C.*; ;

Donen Giho, (95), p.27 - 31, 1995/09

https://jopss.jaea.go.jp/pdfdata/PNC-TN1340-95-003.pdf

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