Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

https://doi.org/10.1080/00223131.2022.2038301

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Droplet generation during liquid jet impingement onto a horizontal plate

Zhan, Y.*; Oya, Naoki*; Enoki, Koji*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Takata, Takashi

Experimental Thermal and Fluid Science, 98, p.86 - 94, 2018/11

https://doi.org/10.1016/j.expthermflusci.2018.05.022

Production of droplets during liquid jet impingement onto a flat plate

Yi, Z.*; Oya, Naoki*; Enoki, Koji*; Okawa, Tomio*; Ohno, Shuji; Aoyagi, Mitsuhiro; Takata, Takashi

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 7 Pages, 2016/11

It is important to set the amount of sodium droplet mechanistically for appropriate numerical evaluations of sodium leak and fire behavior in a sodium-cooled fast reactor plant. In the present work, fundamental experiments were performed to measure the splash ratio during the vertical water jet impact onto a horizontal wall. It was shown that the splash ratio can be correlated well as a function of the impact Weber number, the Strouhal number and the Ohnesorge number of the droplets impinging the liquid film.

Development of image-analysis method of plutonium samples by imaging plate; Measurement of plutonium samples in mixed oxide fuel fabrication facility

Takasaki, Koji; Sagawa, Naoki; Kurosawa, Shigeyuki*; Shioya, Satoshi; Suzuki, Kazunori; Horikoshi, Yoshinori; Mizuniwa, Harumi

JAEA-Technology 2008-028, 73 Pages, 2008/03

JAEA-Technology-2008-028.pdf:5.88MB

Recently, an imaging plate (IP) was developed. Pu analysis by an IP was studied in the JAEA Cooperative Research Scheme on the Nuclear Fuel Cycle, and the availability about detection of Pu and discrimination with radon progenies was shown. In order to apply these results to the radiation control, this research aims at evaluation of radioactivity, discrimination with radon progenies, and evaluation of AMAD by an IP. In the conventional autoradiography (ARG) by a ZnS and Polaroid film, Contamination of Pu can only be grasped by viewing. Since the digital data of the radiation and location is obtained by an IP, Pu can be detected quantitatively and radioactivity can be evaluated. As a result of this research, the image of alpha emitter on an IP is the same as that of the conventional ARG, and can be applied also to the ARG of beta and emitter. In measurement of Pu, the function of Image J (image-analysis software) was very available. Pu radioactivity was evaluated by an IP.

None

Takeuchi, Sukune*; Okada, Shigeru*; Kobayash, Naoki*; *; Oya, Naohiko*; *

PNC TJ7552 96-002, 328 Pages, 1996/03

PNC-TJ7552-96-002.pdf:8.15MB

None

Study on droplet generation at the time of a water jet, the liquid film collision

Oya, Naoki*; Okawa, Tomio*; Ohno, Shuji; Aoyagi, Mitsuhiro

no journal, , 

It is important to set the diameter of leakage sodium droplet mechanistically for appropriate numerical evaluations of sodium leak and fire behavior in a sodium-cooled fast reactor plant. We performed a fundamental experiment with water in order to clarify mechanism of droplet generation in this study. Impinging water jet on a flat plate was tested for various cases of jet velocity, nozzle diameter and nozzle height. The impinging behavior was visualized by means of a high-speed video camera. We measured the amount of generated droplet and the maximum droplet diameter. Observed jet flow was categorized into following three modes: drop mode which is droplet state flow, jet mode which is straight flow and lump mode which is partially constricted flow. Both the amount of generated droplet and the maximum droplet diameter increased in the following order: jet, drop and lump modes.

Splashing during liquid jet impact onto a horizontal wall

Okawa, Tomio*; Oya, Naoki*; Yi, Z.*; Enoki, Koji*; Ohno, Shuji; Aoyagi, Mitsuhiro

no journal, , 

It is important to set the amount of sodium droplet mechanistically for appropriate numerical evaluations of sodium leak and fire behavior in a sodium-cooled fast reactor plant. In the present work, fundamental experiments were performed to measure the rate of splashing during the vertical water jet impact onto a horizontal wall. It was found that the splashing rate is negligibly small when the water jet is continuous at the impact point. Whilst, the splashing rate increased rapidly with an increase in the jet velocity when the jet was broken into droplets at the impact point. Therefore, when the fall height is longer than the breakup length, it was suggested that the dimensionless splashing rate scaled by the liquid jet flow rate can be expressed as a function of the modified Weber number of the primary droplets impacting the target. A semi-empirical method to estimate the splashing rate during liquid jet impact onto a horizontal wall was proposed based on linear stability theory.

Droplet generation during liquid jet collision onto solid surface

Oya, Naoki*; Zhan, Y.*; Okawa, Tomio*; Enoki, Koji*; Aoyagi, Mitsuhiro; Ohno, Shuji; Takata, Takashi

no journal, , 

This study aims improvement of safety analysis for sodium fire accidents in sodium-cooled fast reactors. In the experiment, droplets were generated by collision of downward liquid jet onto a horizontal solid surface. We studied the mechanism of droplet generation and the empirical correlation of droplet amount.

Study on splashing phenomenon of liquid jet collision

Zhan, Y.*; Oya, Naoki*; Enoki, Koji*; Okawa, Tomio*; Aoyagi, Mitsuhiro; Ohno, Shuji; Takata, Takashi

no journal, , 

This study aims improvement of safety analysis for sodium fire accidents in sodium-cooled fast reactors. In the experiment, droplets were generated by collision of downward liquid jet onto a horizontal solid surface. We studied the mechanism of droplet generation and the empirical correlation of droplet amount.