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Arai, Yoichi; Watanabe, So; Ono, Shimpei; Nomura, Kazunori; Nakamura, Fumiya*; Arai, Tsuyoshi*; Seko, Noriaki*; Hoshina, Hiroyuki*; Hagura, Naoto*; Kubota, Toshio*
Nuclear Instruments and Methods in Physics Research B, 477, p.54 - 59, 2020/08
Times Cited Count：5 Percentile：45.45(Instruments & Instrumentation)Arai, Yoichi; Watanabe, So; Ono, Shimpei; Nakamura, Masahiro; Shibata, Atsuhiro; Nakamura, Fumiya*; Arai, Tsuyoshi*; Seko, Noriaki*; Hoshina, Hiroyuki*; Hagura, Naoto*; et al.
International Journal of PIXE, 29(1&2), p.17 - 31, 2019/00
The spent PUREX solvent containing U and Pu is generated from the reprocessing process of spent nuclear fuel. The nuclear material removal is important for the safe storage or disposal of the spent solvent. Our previous study revealed that the adsorbent with the iminodiacetic acid (IDA) functional group is one of the most promising materials for designing the nuclear material recovery process. Accordingly, an IDA-type adsorbent was synthesized by using graft polymerization technology or a chemical reaction to improve the adsorption rate and capacity. The synthesized IDA-type adsorbent was characterized by micro particle-induced X-ray emission (PIXE) and extended X-ray absorption fine structure (EXAFS) analyses. The micro-PIXE analysis revealed that Zr was adsorbed on the whole synthesized adsorbents and quantified the microamount of adsorbed Zr. Moreover, EXAFS suggested that Zr in the aqueous solution and solvent can be trapped by the IDA group with different mechanisms.
Okumura, Keisuke; Kojima, Kensuke; Okamoto, Tsutomu; Hagura, Hiroyuki; Suyama, Kenya
JAEA-Conf 2013-002, p.15 - 20, 2013/10
Three-dimensional nuclide inventory and decay heat analysis were performed for the Fukushima Dai-ichi Power Plants (1F1, 1F2, 1F3) by using MOSRA system with JENDL-4.0 library. In the analysis, nuclide inventory for approximately 1400 nuclides were estimated in consideration of radial and axial burn-up and void distributions. Total decay heat and its distribution in each plant were estimated by the sum of all nuclide contributions. The obtained decay heat was compared with the results of simple evaluation formulas used in severe accident analyses. The results of the simple evaluation formulas agree with our results within 20%. For future decommissioning of commercial nuclear power plants, new activation cross-sections library for ORIGEN-S is also under development in the cooperative study program between JAEA and JAPCO. The present status and future plan are shown from view points of nuclear data and method.
Okamoto, Tsutomu; Okumura, Keisuke; Kojima, Kensuke; Hagura, Hiroyuki; Suyama, Kenya; Nagase, Fumihisa
no journal, ,
Three-dimensional nuclides inventory evaluation was carried out for each core of unit-1, 2, 3 in the Fukushima Dai-ichi Nuclear Power Station at the time of the nuclear accident. In the evaluation, the modular system for reactor analyses (MOSRA) and the latest Japanese nuclear data library JENDL-4.0 were employed. The obtained inventory data is useful for the assessment of the broken core situation, planning of future disposal of radioactive wastes, such as fuel debris, polluted rubble, and so on.
Hagura, Hiroyuki; Okumura, Keisuke; Iwamoto, Yosuke; Nagase, Fumihisa
no journal, ,
We developed neutron, photon and electron transport libraries based on JENDL-4.0 for PHITS code. A motivation for the development is to contribute the analysis of the severe accident at Fukushima Dai-ichi Plant. To verify the developed libraries, we carried out test calculations which demonstrate transport of neutron, photon and electron using the libraries. As for the revised Kerma coefficients, we compared them with an ACE-format library based on ENDF/B-VII.1, and checked them visually. The developed photon and electron libraries were compared with MCNPDATA libraries by comparative transport calculations, and bremstrahlung photon spectrum are shown to be consistent with each other.
Okumura, Keisuke; Okamoto, Tsutomu; Kojima, Kensuke; Hagura, Hiroyuki; Suyama, Kenya
no journal, ,
In order to confirm the prediction accuracy of I-129 inventory in the nuclear spent fuels of light water reactors, the post irradiation examination analysis was performed for the fuel samples irradiated in a Japanese PWR (Mihama-3) and for the samples irradiated in a foreign PWR, by using recent nuclear data libraries such as JENDL-4.0 and the lattice burnup calculation module of the MOSRA system. As a result, it was found that the fission yield data of JENDL-4.0 and ENDF/B-VII.0 give underestimation of the I-129 inventory by about 20% compared with the assay data. On the other hand, the fission yield data of JNDC/V-2 and JEFF-3.1 give better results although they still give underestiomation (about 7%). Then, we made a simple evaluation formula to predict the I-129 inventory from the assay data.
-ray detection efficienciesFurutaka, Kazuyoshi; Okumura, Keisuke; Kojima, Kensuke; Hagura, Hiroyuki; Okamoto, Tsutomu
no journal, ,
We are developing a system to estimate the radioactivity of the contaminated debris produced from the TEPCO's Fukushima Daiichi NPS accident to facilitate their reasonable and efficient managements and disposal. The system uses a radiation transport code PHITS to calculate detection efficiencies of the -rays emitted from the debris with finite volumes. As its first step, information on a Ge -ray detector such as its size and shape were input and the full-energy peak efficiencies were calculated in a energy range between 50-1450 keV. The efficiencies were also measured experimentally using several standard -ray sources and compared to the results of the calculation. The comparison shows that the experimentally observed efficiencies were well reproduced throughout the energy range by applying a single bias factor irrespective of the distance and the direction of the sources from the detector.
Okumura, Keisuke; Hagura, Hiroyuki; Kojima, Kensuke; Yamamoto, Kento; Tanaka, Kenichi*
no journal, ,
A method of the activation sensitivity analysis was developed for the optimization of the inventory evaluation of radionuclides in the waste generated in the decommissioning of LWR plants. By applying the method to a BWR plant, we clarified the impurity nuclides in the structural materials and their nuclear reactions contributing the generation of about fifty radioactive nuclides important for the processing and disposal of radioactive wastes.
Okumura, Keisuke; Kojima, Kensuke; Hagura, Hiroyuki*; Ito, Takashi*; Miyoshi, Katsumasa*
no journal, ,
In order to contribute to the removal of fuel debris from Fukushima Daiichi Nuclear Power Station (1F), an efficient estimation method of the dose rate distribution in the primary containment vessel of 1F, by using photon transport calculations with a Monte Carlo calculation code and information on the radiation sources obtained from computations for fuel burnup, activation of structural materials, severe accident analysis, etc.
Nagaya, Yasunobu; Hagura, Hiroyuki*
no journal, ,
Careful criticality management must be required for the removal of fuel debris generated at the accident in the Fukushima Daiichi Nuclear Power Station; the uncertainties in fuel debris properties such as amount, composition, location, densities, etc. must be taken into account. For determining the policy of such criticality management, it is important to build the fundamental criticality safety database (criticality maps) for as many fuel debris conditions as possible. In order to contribute the building of the database, the development of a novel Monte Carlo solver has been initiated to perform criticality calculations of fuel debris with flexible randomized models. In this work a model of collision analysis with the ACE formatted nuclear data has been implemented and verified with criticality calculations for simple spherical geometries.
Nagaya, Yasunobu; Hagura, Hiroyuki*
no journal, ,
In order to build the criticality safety database for fuel debris, a Monte Carlo Solver Solomon has been under development. The probability table method has been implemented into Solomon to treat the self-shielding effect in the unresolved resonance region correctly. The implementation has been verified with the calculation of effective multiplication factors for simple geometry systems.
