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Maruyama, Shuhei; Endo, Tomohiro*; Yamamoto, Akio*
Journal of Nuclear Science and Technology, 61(1), p.31 - 43, 2024/01
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)This study investigated the feasibility of reducing the uncertainty associated with fast-reactor-core design by sharing an experimental database between different fields (e.g., reactor physics and radiation shielding) using data assimilation techniques. As the first step in this study, we focused on the ORNL sodium shielding experiment and investigated the possibility of using the experimental data to reduce the uncertainty in sodium void reactivity (SVR), which is the most important safety parameter for sodium-cooled fast reactors. A sensitivity analysis based on the Generalized Perturbation Theory was performed for the sodium shielding experiment. Using the sensitivity coefficients evaluated here and those of the sodium void reactivity previously evaluated by the JAEA, we showed that sodium shielding experimental data can contribute to the uncertainty reduction of SVR by adopting the cross-section adjustment method. Based on this study, the uncertainty reduction effect is expected to be significant, especially for SVR dominated by neutron-leakage phenomena. Although new reactor physics experimental data on SVR may be difficult to obtain, the results of this study suggest that data from sodium shielding experiments can partially substitute for this role. This study demonstrated the value of the mutual use of integral experimental data in fast reactor designs.
Kawaguchi, Maho*; Shiba, Shigeki*; Iwahashi, Daiki*; Okawa, Tsuyoshi*; Gunji, Satoshi; Izawa, Kazuhiko; Suyama, Kenya
Proceedings of 12th International Conference on Nuclear Criticality Safety (ICNC2023) (Internet), 8 Pages, 2023/10
The Nuclear Regulation Authority (NRA) has been working on an experimental approach for evaluating the criticality of fuel debris produced by the Fukushima Daiichi Nuclear Power Plant (FDNP) accident since 2014, collaborating with the Japan Atomic Energy Agency (JAEA). As part of the approach, JAEA has modified the STAtic experiment Critical facilitY (STACY) for critical experiments to evaluate characteriscs of pseudo-fuel debris. As the preliminary analyses, we verified critical characteristics with major nuclear data libraries for the proposed core configuration patterns. The three-dimensional continuous-energy Monte Carlo neutron and photon transport code, SERPENT-V2.2.0 was used with the latest JENDL, JENDL-5. As a result, larger multiplication factors of JENDL-5 across the modified STACY core configuration patterns were evaluated in comparison to the other libraries. And, 
H scattering and 
U fission sensitivity coefficients of JENDL-5 were different from those of the other libraries. Comparing among analyses with those libraries, the updated S(
, 
) of JENDL-5 might affect the result of critical characteristics in the critical analyses for the modified STACY core configuration.
Tada, Kenichi; Kondo, Ryoichi; Endo, Tomohiro*; Yamamoto, Akio*
Journal of Nuclear Science and Technology, 60(6), p.624 - 631, 2023/06
Times Cited Count：2 Percentile：48.47(Nuclear Science & Technology)The sensitivity analysis and the uncertainty quantification have an important role in improving the evaluated nuclear data library. The current computational performance enables us to the sensitivity analysis and uncertainty quantification using the continuous energy Monte Carlo calculation code. The ACE file perturbation tool was developed for these calculations using modules of FRENDY. This tool perturbs the microscopic cross section, the number of neutrons per fission, and the fission spectrum. The uncertainty quantification using the random sampling method is also available if the user prepares the covariance matrix. The uncertainty of the k-effective using the perturbation tool was compared to the current sensitivity analysis codes SCALE/TSUNAMI and MCNP/KSEN. The comparison results indicated that the random sampling method using this tool accurately estimates the uncertainty of k-effective.
Hirouchi, Jun; Takahara, Shogo; Komagamine, Hiroshi*
Journal of Radiological Protection, 42(4), p.041503_1 - 041503_12, 2022/12
Times Cited Count：1 Percentile：27.23(Environmental Sciences)Sheltering is one of the countermeasures against radiation exposure during nuclear accidents. The effectiveness of sheltering for inhalation exposure is often expressed by the reduction factor, which is defined as the ratio of the indoor to the outdoor cumulative radioactivity concentrations or doses. The indoor concentration is mainly controlled by the air exchange rate, penetration factor, and indoor deposition rate. Meanwhile, the air exchange rate depends on surrounding environmental conditions: the wind speed, leakage area normalized by the floor area of the house, and gross building coverage ratio. In this study, the ranges of the uncertainty of the reduction factors for particles and I
were investigated under various environmental conditions, and sensitivity analyses were conducted to understand the parameter with the most influence on the uncertainty of the reduction factor. From the results of the uncertainty analyses, the calculated reduction factor was highly variable depending on the environmental condition and the airtightness of the houses. The uncertainty ranges of the reduction factor for particles and I were up to 0.9 and 0.3, respectively, and were smaller for newer houses. From the results of the sensitivity analyses, the wind speed was the most influential parameter on the reduction factor. Additionally, the wind speed was less influential for the reduction factor in newer houses.
Okumura, Keisuke
Hoshasen Shahei Handobukku; Oyohen, p.78 - 83, 2020/03
no abstracts in English
Iwamoto, Hiroki; Stankovskiy, A.*; Fiorito, L.*; Van den Eynde, G.*
Journal of Nuclear Science and Technology, 55(5), p.539 - 547, 2018/05
Times Cited Count：9 Percentile：66.49(Nuclear Science & Technology)The applicability of Monte Carlo techniques, namely the Monte Carlo sensitivity method and the random-sampling method, for uncertainty quantification of the effective delayed neutron fraction 
is investigated using the continuous-energy Monte Carlo transport code, MCNP, from the perspective of statistical convergence issues. This study focuses on the nuclear data as one of the major sources of uncertainty. For validation of the calculated , a critical configuration of the VENUS-F zero-power reactor was used. It is demonstrated that Chiba's modified 
-ratio method is superior to Bretscher's prompt -ratio method in terms of reducing the statistical uncertainty in calculating not only but also its sensitivities and the uncertainty due to nuclear data. From this result and a comparison of uncertainties obtained by the Monte Carlo sensitivity method and the random-sampling method, it is shown that the Monte Carlo sensitivity method using Chiba's modified -ratio method is the most practical for uncertainty quantification of . Finally, total uncertainty due to nuclear data for the VENUS-F critical configuration is determined to be approximately 2.7% with JENDL-4.0u, which is dominated by the delayed neutron yield of 
U.
Hemmi, Ko; Yamaguchi, Tetsuji; Takeda, Seiji; Kimura, Hideo
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 24(1), p.3 - 14, 2017/06
Conditions of contaminated sources and ranges of forest decontamination that significantly reduce the air dose rate in residential areas were investigated by means of a sensitivity analysis related to the decontamination of the forest contaminated by radiocesium deriving from the accident at Fukushima Daiichi Nuclear Power Station. The contaminated sources including 
Cs and 
Cs were assumed to be a layer of sedimented organic matter (the A
layer) and surface soils (the A
layer). The air dose rates were calculated using the three-dimensional Monte Carlo transport code MCNP. A slope number of the forest, angles, state of contaminant distribution, radiocesium content in the forest soils, decontamination ranges, distance from the forest boundary to an evaluation point, and height at the evaluation point were adopted as the parameters. The decontamination of a litter (A) layer within the distance of 20 m from the forest boundary was revealed to be effective in reducing the air dose rate when the source distribution was homogeneous. The air dose rates were significantly reduced by the decontamination of the A layer within a distance of 40 m from the forest boundary on condition that the radiocesium content of the A layer was larger than that of the A layer and the source distribution was non-homogeneous, such as the forest areas beyond 20 m from the forest boundary, which were more heavily contaminated than those within 20 m.
Choi, B.; Nishida, Akemi; Nakajima, Norihiro
Kozo Kogaku Rombunshu, B, 63B, p.325 - 333, 2017/03
The Japan Atomic Energy Agency promotes research and development of three-dimensional vibration simulation technologies for nuclear facilities. In this paper, we report a seismic response analysis of the Tohoku Pacific Coast Earthquake using three-dimensional models of the High-Temperature Engineering Test Reactor (HTTR) building. We conducted a sensitivity study using input parameters with uncertainty. Furthermore, we examined the variation of the seismic response results against the input parameters.
Shimada, Taro; Nishimura, Yuki; Takeda, Seiji
MRS Advances (Internet), 2(12), p.687 - 692, 2017/01
A disposal measure for fuel debris generated at the accident in the Fukushima Daiichi Nuclear Power Station has been studied so far. However, physical and chemical properties of the fuel debris have not yet investigated in reactor containment vessels. In order to investigate the safety function of barriers required for disposal of fuel debris, sensitivity analyses for radionuclide migration were carried out, considering with uncertainty of the properties. As a result, it is indicated that it was important for evaluation of fuel debris disposal to obtain the physical and chemical properties of 
C and 
I during release to groundwater, in addition to U.
Sakai, Takuro; Yasuda, Ryo; Iikura, Hiroshi; Matsubayashi, Masahito
JPS Conference Proceedings (Internet), 11, p.020005_1 - 020005_6, 2016/11
Iwamoto, Hiroki; Nishihara, Kenji; Katano, Ryota*; Fukushima, Masahiro; Tsujimoto, Kazufumi
JAEA-Research 2014-033, 82 Pages, 2015/03
JAEA-Research-2014-033.pdf:6.53MB
The effect of experiments using Transmutation Physics Experimental Facility (TEF-P) is analysed from the viewpoint of the reduction of uncertainties in reactor physics parameters (criticality and coolant void reactivity) of an accelerator-driven system (ADS). The analysis is conducted by the nuclear-data adjustment method using JENDL-4.0 on the assumption that ve types of reactor physics experiments (a total of 44 experiments) are performed in TEF-P: (1) criticality experiment, (2) lead void reactivity experiment, (3) reaction rate ratio experiment, (4) sample reactivity experiment, and (5) fuel replacement reactivity experiment. As the result, 1.0% of uncertainty in criticality is found to be reduced to approximately 0.4%, and effective experiments for the reduction of uncertainty in criticality and coolant void reactivity are shown to be fuel replacement reactivity experiments and lead void reactivity experiments, respectively. Although these effects depend largely on the composition and amount of minor-actinide (MA) fuels, it is found that a combination of different types of experiments and database of existing experiments is effective in reducing the uncertainties.
Hatsukawa, Yuichi; Toh, Yosuke; Oshima, Masumi; Kimura, Atsushi; Gharaie, M. H. M.
Journal of Radioanalytical and Nuclear Chemistry, 271(1), p.43 - 45, 2007/01
Times Cited Count：3 Percentile：25.42(Chemistry, Analytical)
- coincidence of multiple -rays from the radioisotopes produced by neutron capture reactions was measured with a array of 19-Ge detectors with BGO Compton suppressors, GEMINI-II. Using multiparameter spectrometry, high sensitive determination of iridium in geological samples and I-129 in environmental samples were carried out at GEMINI.
Hayashi, Takumi; Suzuki, Takumi; Yamada, Masayuki; Nishi, Masataka
Fusion Science and Technology, 48(1), p.317 - 323, 2005/07
Times Cited Count：10 Percentile：56.58(Nuclear Science & Technology)no abstracts in English
Shinohara, Kazunori; Okuda, Hiroshi*; Ito, Satoshi*; Nakajima, Norihiro; Ida, Masato
Keisan Kogaku Koenkai Rombunshu, 10(2), p.629 - 632, 2005/05
To obtain optimal designed shape effectively, a parallel computing method of determining Armijo's line-search step size of the adjoint variable method is proposed. The adjoint valiable method is based on the Lagrange multiplier method (a conditional variational principle), and consists of the state equation, the adjoint equation and the sensitivity equation. The equations for decreasing the fluid drag of shaped surface under a constant volume condition are formulated. To solve the equations effectively by the steepest descent method, the parallel algorithm that finds the Armijo's line-search step size is implemented by using ITBL (the grid system of Japan's shared super computers attached to the network). Using this parallel method, the calculation cost can be reduced.
Ekins-Daukes, N. J.*; Lee, H. S.*; Sasaki, Takuo*; Yamaguchi, Masafumi*; Khan, A.*; Takamoto, Tatsuya*; Agui, Takaaki*; Kamimura, Kunio*; Kaneiwa, Minoru*; Imaizumi, Mitsuru*; et al.
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.87 - 91, 2004/10
no abstracts in English
laser collective thomson scattering system in JT-60ULee, S.; Kondoh, Takashi; Miura, Yukitoshi
Japanese Journal of Applied Physics, Part 1, 41(11A), p.6574 - 6576, 2002/11
Times Cited Count：1 Percentile：5.59(Physics, Applied)no abstracts in English
Yasuda, Kenichiro; Sakurai, Satoshi; Gunji, Hideho; Usuda, Shigekazu
Journal of Nuclear Science and Technology, 39(Suppl.3), p.552 - 555, 2002/11
In order to contribute to the strengthened safeguards system based on the Program 93+2 of the IAEA, Japan Atomic Energy Research Institute (JAERI) constructed the CLEAR facility (Clean Laboratory for Environmental Analysis and Research) and is developing analytical technology for ultra trace amounts of nuclear materials in environmental samples. To avoid cross-contamination among the samples and contamination of the clean rooms, radioactive materials in the samples to be introduced into the CLEAR facility will be limited to a certain amount. For this purpose the authors have examined the feasibility of Imaging-plate method, which is a kind of autoradiography and is suitable for determination on distribution of low-level radioactivity in the samples. Preliminary examination with -ray (K-40), the linearity was obtained in the range of 0.01 - 0.2 Bq. The experiments with -ray (Sm-147) suggested the detection limit of 0.01 Bq, which was equivalent to 2 
g of natural uranium. At the presentation, the results on actual environmental samples will be reported.
-ray detectionOshima, Masumi; Toh, Yosuke; Hatsukawa, Yuichi; Hayakawa, Takehito; Shinohara, Nobuo
Journal of Nuclear Science and Technology, 39(4), p.292 - 294, 2002/04
Times Cited Count：18 Percentile：73.04(Nuclear Science & Technology)no abstracts in English
InGaP solar CellsDharmarasu, N.*; Khan, A.*; Yamaguchi, Masafumi*; Takamoto, Tatsuya*; Oshima, Takeshi; Ito, Hisayoshi; Imaizumi, Mitsuru*; Matsuda, Sumio*
Journal of Applied Physics, 91(5), p.3306 - 3311, 2002/03
Times Cited Count：25 Percentile：66.9(Physics, Applied)3MeV proton irradiation effects on InGaP single junction and InGaP/GaAs two junction cells were studied. The degradation of electrocal properties for InGaP cells was smaller than that for InGaP/GaAs cells. The results of the measurement of spectral response showed the large degradation in long wavelength. This indicates that GaAs cell degrades. The Damage coefficient of minority carrier diffusion length was estimated to be 7.9
10
for InGaP and 1.610
for GaAs. These values of the damage coefficient for InGaP and GaAs are 580 times and 280 times larger than those for InGaP and GaAs irradiated with 1MeV electrons.
-PIXEOnuki, Toshihiko; Kozai, Naofumi; Samadfam, M.; Yasuda, Ryo; Kamiya, Tomihiro; Sakai, Takuro; Murakami, Takashi*
Nuclear Instruments and Methods in Physics Research B, 181(1-4), p.586 - 592, 2001/07
Times Cited Count：14 Percentile：68.89(Instruments & Instrumentation)no abstracts in English
