Control blade degradation test under temperature gradient in steam atmosphere

Shibata, Hiroki; Tokushima, Kazuyuki; Sakamoto, Kan*; Kurata, Masaki

Proceedings of Annual Topical Meeting on LWR Fuels with Enhanced Safety and Performance (TopFuel 2016) (USB Flash Drive), p.1033 - 1042, 2016/09

To understand the degradation process of control blade channel, control blade degradation tests using sim-materials were performed under various atmospheres with the temperature increase and temperature gradient conditions. In the steam atmosphere with a flow rate of 0.0125 g/s/rod, control blade, channel box, and fuel rods were degraded, especially at the upper part of the test piece, which was similar to that observed in argon atmosphere test. However, the observed degradation was rather different at a flow rate of 0.0417 g/s/rod. At the upper part of the test piece, only the control blade was degraded preferentially and did not react with channel box wall. In contrast, the eutectic reaction of S.S./BC-melt and Zry occurred at the lower part. These observations suggested the existence of a threshold condition for the control rod degradation between 0.0125 and 0.0417 g/s/rod which is significantly affected by the thickness of the oxide layer on Zry.

Current status and problems of computer codes for nuclear safety evaluation

Suyama, Kenya; Hirao, Yoshihiro*; Sakamoto, Hiroki*

Nihon Genshiryoku Gakkai-Shi ATOMO, 57(12), p.787 - 791, 2015/12

In the measures to pursue the world's highest level of safety of the nuclear installations, it is required to maintain the technical revel of the safety analyses codes as higher as possible. Because many of them were introduced from US at the initial phase of the nuclear energy introduction, development of computer codes and relevant tools in Japan have not been continued successfully. Accordingly, many old US-oriented code has been used. This manuscript presents the current status and the problems of computer codes for nuclear safety evaluation, and a scheme to introduce the computer codes of Japan, which in-cooperate the latest knowledge, in the scene of nuclear safety regulation and practical purpose.

Progress of the high current Prototype Accelerator for IFMIF/EVEDA

Okumura, Yoshikazu; Ayala, J.-M.*; Bolzon, B.*; Cara, P.*; Chauvin, N.*; Chel, S.*; Gex, D.*; Gobin, R.*; Harrault, F.*; Heidinger, R.*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.203 - 205, 2015/09

http://www.pasj.jp/web_publish/pasj2015/proceedings/PDF/FROL/FROL08.pdf

Under the framework of Broader Approach (BA) agreement between Japan and Euratom, IFMIF/EVEDA project was launched in 2007 to validate the key technologies to realize IFMIF. The most crucial technology to realize IFMIF is two set of linear accelerator each producing 125mA/CW deuterium ion beams up to 40MeV. The prototype accelerator, whose target is 125mA/CW deuterium ion beam acceleration up to 9MeV, is being developed in International Fusion Research Energy Center (IFERC) in Rokkasho, Japan. The injector developed in CEA Saclay was delivered in Rokkasho in 2014, and is under commissioning. Up to now, 100keV/120mA/CW hydrogen ion beams and 100keV/90mA/CW duty deuterium ion beams are successfully produced with a low beam emittance of 0.21 .mm.mrad (rms, normalized). Delivery of RFQ components will start in 2015, followed by the installation of RF power supplies in 2015.

Experimental study on control blade degradation and its modeling

Kurata, Masaki; Shibata, Hiroki; Sakamoto, Kan*; To, Takehiko*

Proceedings of 2014 Water Reactor Fuel Performance Meeting/ Top Fuel / LWR Fuel Performance Meeting (WRFPM 2014) (USB Flash Drive), 8 Pages, 2014/09

Control blade degradation is predicted to occur at the early stage of severe accident of boiling water reactor. Simulation tests and modeling are being performed by collaboration among JAEA, Hitachi-GE Nuclear Energy (Hitachi-GE), Nippon Nuclear Fuel Development (NFD), and Nippon Steel & Sumitomo Metal Corporation (NSSMC). Preliminary simulation tests under inert atmosphere indicated that complicated chemical reactions progressed and that finally the mixture of degraded control blade and the channel box separated into two parts. The first part rich in Zr had low melting temperature and flowed down from the high temperature region like candling. The second part rich in steel, B, and C mechanically collapsed down at temperatures higher than approximately 1673K. The interaction between the control blade and the channel box was highly exothermic. Preliminary model for control blade degradation is being developed using VOFFLUENT, which successfully simulates the early stage ofthe control blade degradation.

Development of a calculation system for the estimation of decontamination effect

Satoh, Daiki; Kojima, Kensuke; Oizumi, Akito; Matsuda, Norihiro; Iwamoto, Hiroki; Kugo, Teruhiko; Sakamoto, Yukio*; Endo, Akira; Okajima, Shigeaki

Journal of Nuclear Science and Technology, 51(5), p.656 - 670, 2014/05

https://doi.org/10.1080/00223131.2014.886534

A calculation system for the estimation of decontamination effect (CDE) has been developed to support planning a rational and effective decontamination. The method calculates the dose-rate distribution before and after decontamination, according to the distribution of radioactivity and the decontamination factor (DF), and uses a dose rate reduction factor (DRRF) to estimate the decontamination effect. The results that were calculated by using the CDE were compared with the results of measurements as well as with the results of calculations that were performed using a Monte Carlo particle transport code PHITS. It was found that the CDE successfully reproduced the measured as well as the calculated dose-rate distributions, requiring less than several seconds of calculation time.

Result of study on storage plan for irradiated components generated at MLF in J-PARC

Kinoshita, Hidetaka; Wakui, Takashi; Matsui, Hiroki; Maekawa, Fujio; Kasugai, Yoshimi; Haga, Katsuhiro; Teshigawara, Makoto; Meigo, Shinichiro; Seki, Masakazu; Sakamoto, Shinichi; et al.

JAEA-Technology 2011-040, 154 Pages, 2012/03

JAEA-Technology-2011-040.pdf:8.08MB

In the MLF, relatively high level irradiated components will be generated. Therefore, these components can not be kept in standard facilities. For the irradiated components at the MLF, the storage plan using the facilities in the Nuclear Science Research Institute has been studied, but the concrete plan is not decided yet. In this report, outline of the components, prehistory of the studying for storage, schedule of the component generation and status of the possible facility, which is a hot laboratory, are described. Resulting from the comparison between the generation schedule and the plan of the hot laboratory, the difference is very large. Present status of the hot laboratory and the cost estimation of the modification to use for storage of the MLF components were studied. Using the hot laboratory seems not to have advantage from the view point of cost and modification method. Therefore, the study on a new storage facility construction will be started as soon as possible.

Steady state high discharges and real-time control of current profile in JT-60U

Suzuki, Takahiro; Isayama, Akihiko; Sakamoto, Yoshiteru; Ide, Shunsuke; Fujita, Takaaki; Takenaga, Hidenobu; Luce, T. C.*; Wade, M. R.*; Oikawa, Toshihiro; Naito, Osamu; et al.

Proceedings of 20th IAEA Fusion Energy Conference (FEC 2004) (CD-ROM), 8 Pages, 2004/11

http://www-naweb.iaea.org/napc/physics/fec/fec2004/datasets/EX_1-3.html

no abstracts in English

Introduction of calculation system for decontamination effect

Satoh, Daiki; Kojima, Kensuke; Oizumi, Akito; Matsuda, Norihiro; Iwamoto, Hiroki; Kugo, Teruhiko; Sakamoto, Yukio; Endo, Akira; Okajima, Shigeaki

no journal, , 

Calculation system for decontamination effect was developed to help decision about removal work plans of radiological materials which were deposited in soil after the Fukushima Dai-ichi NPP accident. In this presentation, the system's outline and operation method will be introduced with demonstration.

Development of a calculation system for decontamination effect

Satoh, Daiki; Kojima, Kensuke; Oizumi, Akito; Matsuda, Norihiro; Iwamoto, Hiroki; Kugo, Teruhiko; Sakamoto, Yukio; Endo, Akira; Okajima, Shigeaki

no journal, , 

A computer software, named CDE (Calculation system for Decontamination Effect), has been developed to support planning the decontamination. CDE is programed with VBA (Visual Basic for Applications), and runs on Microsoft Excel with a user friendly graphical interface. It calculates dose rate distributions in a target area before and after the decontamination from a radioactivity distribution and DF (Decontamination Factor), which is a ratio of original radioactivity to remaining one after the decontamination. DRRF (Dose Rate Reduction Factor) is also derived to express the decontamination effect. All the calculation results are visualized on an image of the target area with color map. Owing to its quick calculation speed, CDE is able to investigate the decontamination effect in various cases for a short period. This is very useful to establish a rational decontamination plan before an action.

Degradation test using control blade applied for BWRs in Japan

Shibata, Hiroki; Tokushima, Kazuyuki; Sakamoto, Kan*; Kurata, Masaki

no journal, , 

In this study, control blade degradation test under the conditions of axial temperature gradient and high temperature increase rate in Ar-atmosphere was performed as preliminary test in steam atmosphere to investigate the relocation of control blade melt and interaction with channel box under the conditions. It was found that the molten products redistribute to axial direction and interaction between S.S./BC-melt and Zry-4 progresses significantly in the condition that a few micron oxide layer exists on Zry-4. Moreover, as preliminary test in steam atmosphere, reaction test between the materials of control blade and channel box was carried out to investigate the effect of oxide layer formed on the surface of Zry-4 in steam atmosphere. It was found that in the condition of supplying oxygen continuously, the liquefaction interaction between Zry and S.S./BC-melt is considered to be prevented.