Monte Carlo N-Particle eXtended (MCNPX) simulation for passive neutron measurement of fuel debris at Fukushima Daiichi Nuclear Power Plants

Nagatani, Taketeru; Nakajima, Shinji; Kosuge, Yoshihiro*; Shiromo, Hideo; Asano, Takashi

Proceedings of INMM 55th Annual Meeting (Internet), 10 Pages, 2014/07

Meltdown of the reactor cores of Units 1-3 occurred at Fukushima Daiichi Nuclear Power Plants (1F). Fuel debris at 1F contains minor actinides and fission products and neutron absorber. These materials make it difficult to quantify fertile nuclear materials in fuel debris by the conventional passive neutron technique. We consider that DDSI and PNAR which focused on fissile material are promising techniques to quantify the nuclear materials in the fuel debris. A concept of application of these techniques to fuel debris measurement was investigated and presented at the last INMM annual meeting. In order to evaluate the applicability of these techniques to fuel debris measurement, we investigated the neutron behavior in the fuel debris by using MCNPX simulation code. Because property of fuel debris is not clear, source term data used were prepared by referring TMI data. This paper provides results of MCNPX simulation for fuel debris measurement at 1F with passive neutron techniques.

Performance test results of the Advanced Verification for Inventory Sample System (AVIS), 2

Nakajima, Shinji; Nagatani, Taketeru; Asano, Takashi; Kawasue, Akane*; Iso, Shoko*; Kumakura, Shinichi*; Watanabe, Takehito*; Marlow, J. B.*; Swinhoe, M. T.*; Menlove, H. O.*; et al.

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-34-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2013/10

The Advanced Verification for Inventory Sample System (AVIS) is a nondestructive assay (NDA) system in order to verify the plutonium mass in the small MOX samples at Japan Nuclear Fuel Limited (JNFL) MOX fuel fabrication plant (J-MOX) under construction. The AVIS is required the high measurement performance because the AVIS will be used as a verification tool to substitute destructive analysis for a part of the samples which needs the bias defect verification. Therefore, the AVIS will fulfill an important role in the safeguards approach for J-MOX. Japan Atomic Energy Agency (JAEA) conducted the performance test of the AVIS under the contract with NMCC. As the results of these tests, we confirmed that the AVIS could almost satisfy the required performance by IAEA.

Formation and growth of image crystals by helium precipitation

Serizawa, Hiroyuki; Matsunaga, Junji*; Haga, Yoshinori; Nakajima, Kunihisa; Akabori, Mitsuo; Tsuru, Tomohito; Kaji, Yoshiyuki; Kashibe, Shinji*; Oishi, Yuji*; Yamanaka, Shinsuke*

Crystal Growth & Design, 13(7), p.2815 - 2823, 2013/07

https://doi.org/10.1021/cg4001335

Since the shape of the negative crystal closely relates to the morphology of the crystal habits, the formation and the growth mechanism is important subject in a field of the physical science. Whereas, the negative crystal formed in a large single crystal mass has been arousing interest as an expensive jewelry because of its mysterious appearance and rarity. However, it is difficult to control the shape of this polyhedral cavity embedded in a solid medium arbitrary. Here we report the recent discovery on the growth process of the negative crystal. We found that precipitated helium forms the negative crystal in UO; the shape changes drastically with the condition of the helium precipitation. The transformation mechanism was discussed in this article. Our investigation implies that the shape of the negative crystal can be arbitrary controlled by controlling the precipitation condition.

Performance test results of the advanced verification for inventory sample system (AVIS)

Nakajima, Shinji; Nagatani, Taketeru; Asano, Takashi; Marlow, J. B.*; Swinhoe, M. T.*; Menlove, H. O.*; Rael, C. D.*; Kawasue, Akane*; Iso, Shoko*; Kumakura, Shinichi*; et al.

Proceedings of INMM 54th Annual Meeting (CD-ROM), 10 Pages, 2013/07

The advanced verification inventory system (AVIS) is a nondestructive assay (NDA) system developed by Los Alamos National Laboratory (LANL) to measure small samples of bulk plutonium and uranium mixed oxide (MOX) powder and pellets at the Japan Nuclear Fuel Limited (JNFL) mixed oxide fuel fabrication plant (J-MOX). In order to mitigate the workload on the Rokkasho On-Site Laboratory (OSL), it is intended that the AVIS measurement will be substituted for a part of the Destructive Assay (DA) for J-MOX. Based on the commission from Office for Nuclear Non-Proliferation and Safeguards (JSGO) of Ministry of Education, Culture, Sports, Science and Technology (MEXT) and Nuclear Material Control Center (NMCC), Japan Atomic Energy Agency (JAEA) has conducted the performance test of the AVIS in order to confirm the system performance before installation at the J-MOX site. The performance test consists of two phases. In the phase 1 test, detector parameters such as detector efficiency and die-away time were evaluated by using a californium-252 neutron source. These results agreed well with design value and were reported at the 53rd INMM annual meeting. JAEA conducted the phase 2 test by using MOX materials in order to evaluate the total measurement uncertainty (TMU). In the test, influence of sample density, plutonium concentration and organic additives in samples were also evaluated. Consequently, it is expected that AVIS can achieve the target TMU of 0.5% required in user requirement of IAEA by optimizing measurement condition and by using well-characterized standards. This paper provides a summary of the results of comprehensive performance test of AVIS.

Study on helium behavior in oxide fuel, 1; Deformation of microstructure induced by precipitation of helium (Joint research)

Serizawa, Hiroyuki; Matsunaga, Junji*; Haga, Yoshinori; Nakajima, Kunihisa; Kashibe, Shinji*; Iwai, Takashi

JAEA-Research 2011-025, 32 Pages, 2011/11

JAEA-Research-2011-025.pdf:10.17MB

This report deals with the precipitation of helium in UO matrix to deform the microstructure. The examination was performed using single and polycrystalline UO sample. The helium-treated samples under 900 atm at 1473 K were reheat-treated at much more high temperature, 1573 K or 1973 K to release the infused helium. The microstructure of the sample was examined by FIB, FE-STEM and FE-TEM. It was confirmed that precipitated helium atoms form a negative crystal in the grain or the matrix of the single crystal. At 1573 K, helium can be released without formation of intergranular tunnel since the surface diffusion coefficient of helium is large. However, some open grain boundaries were observed in the sample heat-treated at 1973 K. This might be related to the activity of helium in the grain boundary region. The structure of the negative crystal was analyzed from the view point of the thermodynamics of the surface growth.

Evaluation of application effect of the integrated safeguards approach for MOX fuel fabrication facilities from the operator's viewpoint

Ninagawa, Junichi; Asano, Takashi; Nagatani, Taketeru; Nakajima, Shinji; Nomi, Takayoshi; Fujiwara, Shigeo

Proceedings of INMM 52nd Annual Meeting (CD-ROM), 8 Pages, 2011/07

Japan was transferred to the Integrated Safeguards (IS) scheme in September 2004. The IS approach for JNC-1 site, including PFPF, was developed to improve the efficiency of safeguards while maintaining the effectiveness and has been implemented since August 2008. JAEA has evaluated the validity of the IS approach for PFPF based on the historical performance over about three-year period. As the result of evaluation, JAEA confirmed the improvement of efficiency of inspection activities and the reduction of the impact of inspection activities on plant operation. On the other hand, the IAEA has also evaluated the validity of IS approach and considered to modify based on the result of its evaluation. In order to maintain or improve the validity of the IS approach, JAEA thinks that it will be necessary to work very closely and honestly with the inspectorate to address this modification process.

An Analysis of composition distributions for 2 liquid phase separation solution composed of HI, HSO, I and HO by 3-dimensional visualization

Nakajima, Hayato*; Imai, Yoshiyuki; Kubo, Shinji

JAEA-Technology 2009-082, 35 Pages, 2010/08

JAEA-Technology-2009-082.pdf:2.74MB

Concerning the thermochemical water-splitting Iodine-Sulfur process, understanding of solution compositions on 2 liquid phase separation is essential for making good choices of operating conditions and for accurate estimations of thermal efficiency. The compositions of 4-component system composed of HI, HSO, I and HO were examined experimentally and were analysed by a 3-dimensional visualization technique. A chemical titration method was adapted to determine the mole fractions of the solutions at 293 K and 363 K, and the fraction were represented by scattered points in an equilateral tetrahedron. Two valuable features were found from a visualized shape viewed as an aggregate of the points, which were difficult to find out by 2-dimensional presentations.

An Estimation technique for compositions of bunsen reaction solutions on thermochemical water splitting is process

Kubo, Shinji; Nakajima, Hayato; Imai, Yoshiyuki; Kasahara, Seiji; Tanaka, Nobuyuki; Okuda, Hiroyuki; Miyashita, Reiko*; Onuki, Kaoru

Proceedings of 17th World Hydrogen Energy Conference (WHEC 2008) (CD-ROM), 4 Pages, 2008/06

A new technique was developed to estimate compositions of Bunsen reaction solution in liquid-liquid phase separation which was targeted on the two solutions in phase equilibrium. In this technique, just two densities measured in the two solution are employed to estimate compositions of two solutions consisting of HI, HSO, I, HO. The fundamental equations underlying this estimation is relations between densities and compositions. To formulate the relations, densities of simulated Bunsen reaction solutions were measured and regression expressions were formulated. Moreover, relational equations for both phases were set up from measured values by the regression procedure. Through estimations of both compositions from both densities, the calculated values are approximately consistent with titrated values. Because of easily and simply execution, this technique is useful for practical use, especially for plant operation and equipment design.

Effect of sulfur dioxide partial pressure on the reaction of iodine, sulfur dioxide and water

Nakajima, Hayato; Imai, Yoshiyuki; Kasahara, Seiji; Kubo, Shinji; Onuki, Kaoru

Kagaku Kogaku Rombunshu, 33(3), p.257 - 260, 2007/05

https://doi.org/10.1252/kakoronbunshu.33.257

Effect of sulfur dioxide partial pressure on the reaction of iodine, sulfur dioxide and water, which is a unit reaction of thermochemical hydrogen production IS process, was studied experimentally at 323K under iodine saturated condition. Quasi-equilibrium state was observed in the presence of sulfur dioxide gas of constant pressure. The composition of the poly-hydriodic acid solution was discussed assuming an ideal desulfurization using the reverse reaction of the Bunsen reaction. The value of HI/(HI+HO) of the desulfurized solution was high in great sulfur dioxide pressure and reached the maximum of 15.70.3 mol%.

Advanced fusion technologies developed for JT-60 superconducting Tokamak

Sakasai, Akira; Ishida, Shinichi; Matsukawa, Makoto; Akino, Noboru; Ando, Toshinari*; Arai, Takashi; Ezato, Koichiro; Hamada, Kazuya; Ichige, Hisashi; Isono, Takaaki; et al.

Nuclear Fusion, 44(2), p.329 - 334, 2004/02

https://doi.org/10.1088/0029-5515/44/2/015

no abstracts in English