Introduction of application examples of ultrasonic simulation in the development of nuclear reactor measurement technology

Abe, Yuta; Otaka, Masahiko; Sekiya, Naoki*; Makuuchi, Etsuyo*

Hihakai Kensa, 71(2), p.69 - 74, 2022/02

no abstracts in English

Dry cleaning process test for fuel assembly of fast reactor plant system, 1; Pilot scale test for fuel pin bundle

Kudo, Hideyuki*; Otani, Yuichi*; Hara, Masahide*; Kato, Atsushi; Ishikawa, Nobuyuki; Otaka, Masahiko; Nagai, Keiichi; Saito, Junichi; Ara, Kuniaki; Ide, Akihiro*

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 10 Pages, 2019/05

A next generation SFR in Japan has adopted an advanced dry cleaning system which consists of the argon gas blowing process to reduce the amount of metallic residual sodium remaining on spent fuel assemblies. This paper describes experimental and analytical work focusing on the amount of residual sodium remaining on a fuel pin bundle before and after the argon gas blowing process. The experiments were conducted using a sodium test loop and a short specimen consisting of a 7 pin bundle. The effects of the blowing gas velocity and the blowing time were quantitatively analyzed in the experiments. On the basis of these experimental results, evaluation models predicting the amount of the residual sodium were constructed.

A New measuring method for elemental ratio and Vickers hardness of metal-oxide-boride materials based on Laser-Induced Breakdown Spectroscopy (LIBS)

Abe, Yuta; Otaka, Masahiko; Okazaki, Kodai*; Kawakami, Tomohiko*; Nakagiri, Toshio

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 7 Pages, 2019/05

Since the hardness of fuel debris containing boride from BC pellet in control rod is estimated to be two times higher as that of oxide, such as UO and ZrO, it is necessary to select the efficient and appropriate operation for removal of fuel debris formed in the severe accident of nuclear power plants. We focused on the characteristics of LIBS, an innovative rapid chemical in-situ analysis technology that enables simultaneous detection of B, O, and other metal elements in fuel debris. Simulated solidified melt specimens were obtained in the plasma heating tests (CMMR-0/-2, performed by JAEA) of simulated fuel assembly (ZrO is used to simulated UO pellet, other materials such as stainless steel, BC are same as fuel assembly). The LIBS signals of (B/O)/Zr ratio showed good linear relationship with Vickers hardness. This technique can be also applied as in-situ assessment tool for elemental composition and Vickers hardness of metal-oxide-boride materials.

Dry cleaning process test for fuel assembly of fast reactor plant system

Kato, Atsushi; Nagai, Keiichi; Ara, Kuniaki; Otaka, Masahiko; Oka, Nobuki*; Tanaka, Masako*; Otani, Yuichi*; Ide, Akihiro*

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 8 Pages, 2017/04

In a fuel handling system (FHS) of a sodium-cooled fast reactor, it is necessary to reduce residual sodium on a spent fuel subassembly before storing at a spent fuel water-pool (SFP) in order to minimize design loads. Although the wet cleaning process adopted on MONJU could eliminate almost all of residual sodium, a large amount of radioactive liquid waste occurs and it needs long duration of cleaning treatment and large plant commodities. On the other hand, Japan sodium-cooled fast reactor adopted an advanced dry cleaning system which consists of roughly blowing massive sodium on the fuel subassembly out by 300C argon gas, inactivation of residual sodium to NaOH by moist argon gas and directly immersion into the SFP to achieve economic competitiveness and waste reduction. This paper reports current status of recent R&D activities to demonstrate a performance of the dry cleaning process in Japan which are for improvement of the cleaning performance and optimizing the FHS design.

Current status of the technology development on lithium safety handling under IFMIF/EVEDA

Furukawa, Tomohiro; Hirakawa, Yasushi; Kato, Shoichi; Iijima, Minoru; Otaka, Masahiko; Kondo, Hiroo; Kanemura, Takuji; Wakai, Eiichi

Fusion Engineering and Design, 89(12), p.2902 - 2909, 2014/12

https://doi.org/10.1016/j.fusengdes.2014.07.010

For the irradiation test of the candidate materials for the fusion DEMO reactor, Engineering Validation and Engineering Design Activities (EVEDA) of the International Fusion Materials Irradiation Facility (IFMIF) are performed under the Broader Approach Activities. As a major Japanese activity on the target facility of the IFMIF, the engineering validation using the EVEDA Lithium Test Loop which is the largest scale liquid lithium test loop has been started in 2012. In parallel with the design and fabrication, the research on the technology establishment for the lithium safety handling was started in 2008, as one of the related technologies under the IFMIF-EVEDA. In the research, experiments of lithium chemical reaction, experiments on lithium fire, establishment of chemical analysis of impurities in lithium and experiments on advanced lithium leak detection system were carried out. This paper describes the results of these experiments.

Progress of design study on fuel handling system in JSFR against design extension conditions

Otaka, Masahiko; Kato, Atsushi; Chikazawa, Yoshitaka; Uzawa, Masayuki*; Ide, Akihiro*; Kaneko, Fumiaki*; Hara, Hiroyuki*

Proceedings of 2014 International Congress on the Advances in Nuclear Power Plants (ICAPP 2014) (CD-ROM), p.607 - 615, 2014/04

Responding to the TEPCO's Fukushima Dai-ichi Nuclear Power Station accident, the design study was carried out to enhance cooling function of fuel handling system for Japan sodium-cooled fast reactor (JSFR). Design measures to maintain an FHS cooling function even in case of Design Extension Conditions are studied; such as alternative cooling systems which are independent and diversified from design basis cooling systems. Based on effectiveness evaluations, it was confirmed that these measures have adequate availability against the postulated design extension conditions.

Simulation study on unfolding methods for diagnostic X-rays and mixed rays

Hashimoto, Makoto; Otaka, Masahiko; Ara, Kuniaki; Kanno, Ikuo; Imamura, Ryo*; Mikami, Kenta*; Nomiya, Seiichiro*; Onabe, Hideaki*

Journal of Nuclear Science and Technology, 46(1), p.76 - 82, 2009/01

https://doi.org/10.3327/jnst.46.76

A photon detector for unfolding X-ray energy distribution has been previously reported. Simulation studies on the unfolding method for this detector are discussed for diagnostic X-rays and mixed-source rays of Cs/Co. Response functions for diverse diagnostic X-rays are almost indistinguishable and an unfolding using error reduction method is not sufficiently worked. The spectrum surveillance method is effective in this case. However, a simple error reduction method is useful for mixed rays. For both techniques, the neural network method is promising.

Feasibility study of in-sodium imaging technique employing -ray emission

Otaka, Masahiko; Hirabayashi, Masaru; Ara, Kuniaki

Proceedings of 13th International Conference on Nuclear Engineering (ICONE-13) (CD-ROM), P. (50439), 2005/05

In order to enhance the maintenance performance of Sodium-Cooled Fast Reactor (SFR), a novel in-sodium imaging technique was proposed for monitoring a deformation or a displacement of in-sodium components or assemblies in primary cooling systems. This technique based on computed tomography using high-energy gamma photons emitted from radioisotopes of sodium (22Na, 24Na) in the primary coolant. Feasibility studies have been performed in order to explore the applicability to typical piping (or vessels). Preliminary analyses exploring measuring time and imaging capability were performed. The results showed that the proposed technique was feasible as a monitoring system of in-sodium components.

Study on sodium viewing technique applying sodium gamma-rays emission tomography; Verification of basic principle by analytical investigation

Hirabayashi, Masaru; Otaka, Masahiko; Hayashida, Hitoshi; Ara, Kuniaki

JNC TN9400 2003-016, 35 Pages, 2003/04

JNC-TN9400-2003-016.pdf:1.45MB

To confirm structural integrity of a primary cooling system and in-vessel components in a sodium-cooled fast breeder reactor, monitoring and inspection technique applying Gamma-rays emitted from sodium are proposed. The basic principle is as follows. As radioisotope Na decays, photons are emitted and a fraction of these photons penetrate materials. If the number of these photons is counted by radiation detectors, an image of gamma-rays source is reconstructed by a computed tomography technique. In this report, Applicability and problems concerned with the technique are investigated. Main results are as follows: (1)To verify applicability, the technique was analytically investigated based on gamma-rays emitted from sodium coolant in a typical pipe of a primary cooling system. As a result, it was confirmed that the image of gamma-rays source could be reconstructed. (2)A required time to measure in a spatial resolution of about 1mm was investigated in the detection efficiency of 20%. The time was about 4 minutes per section by a thousand detectors in the typical pipe of a primary cooling system. And in a typical steam generator, the time was about 2 days per section by ten thousand detectors. (3)To realize a fluoroscopic inspection system, it is necessary that the principle should be verified by experimental researches. Main equipments of the system are a collimator, radiation detector, scanner, signal processing device and image processing device. As a spatial resolution is decide by the collimator, the shape must be evaluated by experimental researches and analytical investigation.

Development of computer program for whole core thermal-hydraulic analysis of fast reactors

Ohshima, Hiroyuki; Otaka, Masahiko

Proceedings of 10th International Conference on Nuclear Engineering (ICONE-10), 0 Pages, 2002/00

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