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Journal Articles

Measurement of spent nuclear fuel burn-up using a new H$$(n,gamma)$$ method

Nauchi, Yasushi*; Sato, Shunsuke*; Hayakawa, Takehito*; Kimura, Yasuhiko; Suyama, Kenya; Kashima, Takao*; Futakami, Kazuhiro*

Nuclear Instruments and Methods in Physics Research A, 1050, p.168109_1 - 168109_9, 2023/05

https://doi.org/10.1016/j.nima.2023.168109
 Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)

Measurement of neutrons from spent nuclear fuel is performed in this study using the H$$(n,gamma)$$ method, which detects 2.223 MeV $$gamma$$ rays from neutron capture reaction of hydrogen using a highly pure germanium (HPGe) detector. The detection of the 2.223 MeV $$gamma$$ ray is affected by intense $$gamma$$ ray emission from fission products (FPs) because the emission rate of $$gamma$$ rays from the FP is seven orders of magnitude higher than the emission rate of neutrons. To shield the intense $$gamma$$ ray from the FP, the HPGe detector is placed off the axis of a collimator, whereas a polyethylene block is placed on the axis. In this geometry, the detector is shielded from the intense $$gamma$$ rays from the FP, but the detector can measure 2.223 MeV $$gamma$$ rays from the H$$(n,gamma)$$ reactions in the polyethylene block. The measured count rate of the 2.223 MeV $$gamma$$ rays is consistent with the expected rate within the statistical error, which is calculated based on the nuclide composition, which is primary $$^{244}$$Cm, estimated via depletion and decay calculations. Accordingly, the H$$(n,gamma)$$ method is considered feasible to quantify the number of neutron leakage from spent nuclear fuel assembly, which is applicable to certify burn up of the assembly.

Journal Articles

Study on identification of materials in fuel debris and waste by neutron induced gamma ray spectroscopy

Nauchi, Yasushi*; Nomi, Takayoshi; Suzuki, Risa; Kosuge, Yoshihiro*; Shiba, Tomooki; Takada, Akira*; Kaburagi, Masaaki; Okumura, Keisuke

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 4 Pages, 2022/10

Journal Articles

Preliminary measurement of prompt gamma-ray from nuclear material for the classification of fuel debris and waste

Shiba, Tomooki; Kaburagi, Masaaki; Nomi, Takayoshi; Suzuki, Risa; Kosuge, Yoshihiro*; Nauchi, Yasushi*; Takada, Akira*; Nagatani, Taketeru; Okumura, Keisuke

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR2022) (Internet), 3 Pages, 2022/10

Journal Articles

Absolute quantification of $$^{137}$$Cs activity in spent nuclear fuel with calculated detector response function

Sato, Shunsuke*; Nauchi, Yasushi*; Hayakawa, Takehito*; Kimura, Yasuhiko; Kashima, Takao*; Futakami, Kazuhiro*; Suyama, Kenya

Journal of Nuclear Science and Technology, 60(6), p.615 - 623, 2022/06

https://doi.org/10.1080/00223131.2022.2130462
 Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)

A new non-destructive method for evaluating $$^{137}$$Cs activity in spent nuclear fuels was proposed and experimentally demonstrated for physical measurements in burnup credit implementation. $$^{137}$$Cs activities were quantified using gamma ray measurements and numerical detector response simulations without reference fuels, in which $$^{137}$$Cs activities are well known. Fuel samples were obtained from a lead use assembly (LUA) irradiated in a commercial pressurized water reactor (PWR) up to 53 GWd/t. Gamma rays emitted from the samples were measured using a bismuth germinate (BGO) scintillation detector through a collimator attached to a hot cell. The detection efficiency of gamma rays with the detector was calculated using the PHITS particle transport calculation code considering the measurement geometry. The relative activities of $$^{134}$$Cs, $$^{137}$$Cs, and $$^{154}$$Eu in the sample were measured with a high-purity germanium (HPGe) detector for more accurate simulations of the detector response for the samples. The absolute efficiency of the detector was calibrated by measuring a standard gamma ray source in another geometry. $$^{137}$$Cs activity in the fuel samples was quantified using the measured count rate and detection efficiency. The quantified $$^{137}$$Cs activities agreed well with those estimated using the MVP-BURN depletion calculation code.

Journal Articles

Characterization study of four candidate technologies for nuclear material quantification in fuel debris at Fukushima Daiichi Nuclear Power Station

Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Nauchi, Yasushi*; Maeda, Makoto; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Kureta, Masatoshi; Tomikawa, Hirofumi; Okumura, Keisuke; et al.

Energy Procedia, 131, p.258 - 263, 2017/12

https://doi.org/10.1016/j.egypro.2017.09.447
 Times Cited Count：10 Percentile：98.09(Energy & Fuels)

Journal Articles

Characterization study of four candidate technologies for nuclear material quantification in fuel debris at Fukushima Daiichi Nuclear Power Station (Interim report)

Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Maeda, Makoto; Nauchi, Yasushi*; Sagara, Hiroshi*; Kosuge, Yoshihiro*; Kureta, Masatoshi; Tomikawa, Hirofumi; Okumura, Keisuke; et al.

Proceedings of INMM 57th Annual Meeting (Internet), 10 Pages, 2016/07

Journal Articles

International Conference on Nuclear Criticality Safety ICNC2015

Nauchi, Yasushi*; Takezawa, Hiroki*; Tonoike, Kotaro

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 58(4), p.247 - 252, 2016/04

no abstracts in English

Journal Articles

Development of the 4S and related technologies, 7; Summary of the FCA XXIII experiment analyses towards evaluation of prediction accuracies for the 4S core characteristics

Ueda, Nobuyuki*; Fukushima, Masahiro; Okajima, Shigeaki; Takeda, Toshikazu*; Kitada, Takanori*; Nauchi, Yasushi*; Kinoshita, Izumi*; Matsumura, Tetsuo*

Proceedings of 2009 International Congress on Advances in Nuclear Power Plants (ICAPP '09) (CD-ROM), p.9493_1 - 9493_9, 2009/05

A series of critical experiments were carried out in the JAEA fast critical facility (FCA) named FCA XXIII cores with placing emphases on the reflector reactivity worth and the sodium void reactivity which are especially important from the view point of safety features of the 4S. The analyses of those physics mockup experiments have been carried out by the neutron transport calculation methods with continuous energy Monte Carlo code MVP and 70 energy-group discrete ordinate P0-S8 transport code DANTSYS using libraries processed from JENDL-3.3 data file. The results showed that combination of the stochastic and deterministic transport calculation methods (Monte Carlo and Sn) provided good prediction bases for criticality, reflector worth, sodium void reactivity, reaction rate ratios and absorber reactivity worth for the 4S nuclear design.

Oral presentation

Measurement test of non-destructive assay for quantification of nuclear materials in fuel debris, 5; In-situ passive gamma-ray measurement for plutonium item using a CeBr$$_3$$ detector

Kaburagi, Masaaki; Shiba, Tomooki; Okumura, Keisuke; Nauchi, Yasushi*; Suzuki, Risa; Nomi, Takayoshi; Nagatani, Taketeru; Takada, Akira*; Kosuge, Yoshihiro*

no journal, , 

The passive gamma-ray spectroscopy for plutonium nuclear fuels was performed using a small volume CeBr$$_{3}$$ detector specific to high dose-rate measurements. This presentation reports that the wide energy range of gamma-ray spectra was obtained by the spectroscopy, and the energy range covered the principal gamma-decay lines of 59.5 keV emitted from $$^{241}$$Am and 2615 keV emitted from $$^{208}$$Tl, which is a descendant nuclide of $$^{236}$$Pu, comparing the measurements using HPGe.

Oral presentation

Recommendations for measurement systems for nuclear material accountancy of Fukushima Daiichi fuel debris; $$gamma$$ technologies

Tomikawa, Hirofumi; Heinberg, C.; Nauchi, Yasushi*; Vo, D.*; Carroll, C.*; Hori, Keiichiro

no journal, , 

In order to survey technologies to be developed for nuclear material quantification of fuel debris at 1F, Japan Atomic Energy Agency (JAEA) and United States Department of Energy (DOE) started collaborative research from November 2012. Under the collaborative research, three Working Groups, Neutron Working Group (NWG), Gamma Working Group (GWG) and Source Term Working Group (STWG) were established. The roles of GWG are to identify measurement systems that could be studied further for possible implementation at 1F. Candidate $$gamma$$ measurement technologies are $$gamma$$ Gross Counting, $$gamma$$ Dosimetry, $$gamma$$-ray Spectroscopy, $$gamma$$-ray Densitometry, $$gamma$$-ray Imaging, Transmission (X-ray) Radiography, Prompt Fission $$gamma$$-ray Counting and Spectroscopy, and Neutron Induced $$gamma$$-ray Spectroscopy. Taking into account system cost, system size, measurement time, development period, and potential for applicability to fuel debris, GWG members have identified recommended combinations among the $$gamma$$ technologies supplemented with neutron measurement technologies. The evaluation was carried out by literature search and simulation works. This paper provides recommendations of the GWG for measurement systems based on mainly $$gamma$$ measurement technologies for nuclear material accountancy of fuel debris at 1F.

Oral presentation

Measurement of radioactivity ratio $$^{106}$$Ru/$$^{144}$$Ce and burnup analyses

Sato, Shunsuke*; Nauchi, Yasushi*; Hayakawa, Takehito*; Kimura, Yasuhiko; Suyama, Kenya

no journal, , 

We evaluated the activity ratio of $$^{106}$$Ru to $$^{144}$$Ce by measurement of polyethylene-transmitted $$gamma$$ radiation from used nuclear fuel cooled more than 10 years. We confirmed that the ratio could be used for the burnup confirmation because we could obtain good agreement between calculation and experiment.

Oral presentation

Study on nuclear material management for fuel debris

Miyaji, Noriko; Takada, Akira*; Iwafuchi, Junichi; Tomikawa, Hirofumi; Shiba, Tomooki; Okumura, Keisuke; Nagatani, Taketeru; Nauchi, Yasushi*

no journal, , 

Nuclear materials in fuel debris need to be properly managed in order to assure to the international and national communities that no nuclear materials have been diverted. In order to provide this assurance, specific measures appropriate to the characteristics of the fuel debris are required. There is experience at managing fuel debris in similar situations, as it was the case of the partial meltdown at the TMI-2 in the US. The nuclear material in the fuel debris retrieved from the reactor was quantified in order to fulfill domestic law requirements in the US. NDA, DA, and visual observation were applied to the residual fuel in the reactor. On that specific accident, IAEA safeguards were not applied because the USA is a nuclear weapon state and therefore this power plant was not inspected by the IAEA. Nuclear material accounting (NMA)is an important measure to manage nuclear materials for states under IAEA safeguards. In this presentation a report on NMA as a measure to manage fuel debris will be discussed.

Oral presentation

Measurement test of non-destructive assay for quantification of nuclear materials in fuel debris, 4; Measurement of prompt gamma-ray emission from plutonium using LYSO detector

Shiba, Tomooki; Kaburagi, Masaaki; Kosuge, Yoshihiro*; Nauchi, Yasushi*; Takada, Akira*; Suzuki, Risa; Nomi, Takayoshi; Nagatani, Taketeru; Okumura, Keisuke

no journal, , 

no abstracts in English

Oral presentation

Measurement test of non-destructive assay for quantification of nuclear materials in fuel debris, 1; Background and purpose

Okumura, Keisuke; Nauchi, Yasushi*; Suzuki, Risa; Nomi, Takayoshi; Shiba, Tomooki; Kaburagi, Masaaki; Takada, Akira*; Kosuge, Yoshihiro*; Nagatani, Taketeru

no journal, , 

no abstracts in English

Oral presentation

Non-destructive experiments for accounting nuclear material in fuel debris, 2; Detection of gamma rays from capture reaction of plutonium

Nauchi, Yasushi*; Kosuge, Yoshihiro*; Nomi, Takayoshi; Suzuki, Risa; Nagatani, Taketeru; Shiba, Tomooki; Takada, Akira*; Kaburagi, Masaaki; Okumura, Keisuke

no journal, , 

no abstracts in English

Oral presentation

NIGS response to non-nuclear material

Nauchi, Yasushi*; Nomi, Takayoshi; Suzuki, Risa; Kosuge, Yoshihiro*; Shiba, Tomooki; Takada, Akira*; Kaburagi, Masaaki; Okumura, Keisuke

no journal, , 

no abstracts in English

Oral presentation

Measurement test of non-destructive assay for quantification of nuclear materials in fuel debris, 3; Determination of impurity in nuclear materials by using gamma-ray spectroscopy

Suzuki, Risa; Nomi, Takayoshi; Nagatani, Taketeru; Shiromo, Hideo; Shiba, Tomooki; Kaburagi, Masaaki; Okumura, Keisuke; Kosuge, Yoshihiro*; Takada, Akira*; Nauchi, Yasushi*

no journal, , 

no abstracts in English

Oral presentation

Measurement and burnup analysis of $$^{106}$$Ru/$$^{144}$$Ce activity ratio for spent fuel cooled more than 10 years

Sato, Shunsuke*; Nauchi, Yasushi*; Hayakawa, Takehito*; Kimura, Yasuhiko; Suyama, Kenya

no journal, , 

It is difficult to measure $$gamma$$-ray from short half-life nuclides such as $$^{106}$$Ru-106 and $$^{144}$$Ce in used fuel with more than 10 year cooling time. In this study, we make it possible to measure $$gamma$$ radiation of these nuclides by changing detection efficiency with install of polyethylene block. We obtained good agreement of activity ratio of $$^{106}$$Ru/$$^{144}$$Ce between measurement and calculation.

Oral presentation

Portable passive gamma-ray analysis of nuclear materials using scintillation detectors

Kaburagi, Masaaki; Shiba, Tomooki; Nomi, Takayoshi; Suzuki, Risa; Kosuge, Yoshihiro*; Nauchi, Yasushi*; Okumura, Keisuke

no journal, , 

no abstracts in English

Oral presentation

Issues of non-destructive assay technology aiming at nuclear material accountancy of fuel debris in canister

Okumura, Keisuke; Terashima, Kenichi; Nagatani, Taketeru; Komeda, Masao; Shiba, Tomooki; Nauchi, Yasushi*; Takada, Akira*; Kosuge, Yoshihiro*

no journal, , 

no abstracts in English

26 (Records 1-20 displayed on this page)