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Journal Articles

Study on optimizing microwave heating denitration method and powder characteristics of uranium trioxide

Segawa, Tomoomi; Kawaguchi, Koichi; Kato, Yoshiyuki; Ishii, Katsunori; Suzuki, Masahiro; Fujita, Shunya*; Kobayashi, Shohei*; Abe, Yutaka*; Kaneko, Akiko*; Yuasa, Tomohisa*

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 9 Pages, 2019/05

A solution of plutonium nitrate and uranyl nitrate is converted into a mixed oxide by microwave heating denitration method. In the present study, for improving the efficiency of microwave heating and achieving high-temperature uniformity to produce homogeneous UO$$_{3}$$ powder, the microwave heating test of potassium chloride and uranyl nitrate solution, and numerical simulation analysis were conducted. The potassium chloride agar was adjusted to the dielectric loss, which is close to that of the uranyl nitrate solution and the optimum support table height was estimated to be 50 mm for denitration of the uranyl nitrate solution by microwave heating. The adiabator improved the efficiency of microwave heating denitration. Moreover, the powder yield was improved by using the adiabator owing to ease of scraping of the denitration product from the bottom of the denitration vessel.

Oral presentation

Stabilizing and solidifications for Pu nitrate solution at TRP, 3; Preparation for the operation of solidification and stabilization for Pu nitrate solution and the operation result

Nishimura, Kazuaki; Tanaka, Hideki; Kobayashi, Daisuke; Suzuki, Shohei; Numata, Shinji; Nakamichi, Hideo; Kurita, Tsutomu; Iida, Masayoshi*; Tajiri, Kazuma*; Sukegawa, Katsumi*

no journal, , 

no abstracts in English

Oral presentation

Study on influence of radioactive contamination derived from nuclear power plant accident on building space, 2; Study on measurement method of direction radiation dose rate intended for field survey

Yamamori, Ryo*; Kobayashi, Hikaru*; Honta, Shohei*; Yoshino, Hiroshi*; Nozaki, Atsuo*; Ichijo, Yusuke*; Yoshida, Hiroko*; Furuta, Takuya

no journal, , 

Understanding radiation field is important to predict radiation dose rate in newly constructing buildings in an area widely contaminated by radioactive nuclei. Radiation dose rate at the site is not sufficient, and directional spectra of the radiations are important to consider the shielding effect of the building. Radiation directional spectra can be measured by scintillator partially shielded by lead collimators but the angle of view highly depends on the combination of the scintillator and the collimators. We adopts a method to measure the directional spectra by adopting 3 inch scintillator with placing a plate of lead collimator in front of the scintillator and subtract the values from the spectra measured without lead collimator. We simulates the optimal size of the lead collimator and found that the 15 cm diameter plate placing at 3 cm from the scintillator is the best for our purpose, 90 degree angle of view.

Oral presentation

Development of $$gamma$$-ray directional radiation dose detector with good efficiency for field survey

Yamamori, Ryo*; Kobayashi, Hikaru*; Honta, Shohei*; Yoshino, Hiroshi*; Nozaki, Atsuo*; Ichijo, Yusuke*; Hijikata, Yoshio*; Yoshida, Hiroko*; Furuta, Takuya

no journal, , 

Understanding radiation field is important to predict radiation dose rate in newly constructing buildings in an area widely contaminated by radioactive nuclei. Directional spectra of the radiations are important to consider the shielding effect of the building. We adopts a method to measure the directional spectra by adopting a plate of lead collimator in front of the scintillator and subtract the values from the spectra measured without lead collimator. We investigated a possible weight saving detection system having sufficient detection efficiency. The investigation was carried out for the condition of the collimator radius ($$phi$$ = 10, 15, 20 cm) and the distance between collimator and detector ($$ell$$ = 1, 3, 5 cm). We found that three combinations satisfied the 90$$^{circ}$$ field view and the detection efficiency became better with larger collimator radius. On the other hand, larger collimator radius indicate heavier detection system. Therefore, we developed an optimum detection system for field survey with the 15 cm diameter plate (10kg), the scintillator (3.4kg), and the folder (1.0kg).

Oral presentation

Effect of permittivity on microwave heating characteristics

Kobayashi, Shohei*; Fujita, Shunya*; Abe, Yutaka*; Kaneko, Akiko*; Yuasa, Tomohisa*; Segawa, Tomoomi; Kato, Yoshiyuki; Kawaguchi, Koichi; Ishii, Katsunori

no journal, , 

The microwave heating denitration method is used in the spent fuel reprocessing process. In order to develop the mass production of denitrification technology for the future, it is necessary to fully grasp the operating conditions to avoid flashing and overflow phenomena of solution. In this research, the conditions of the generation of flashing are evaluated using the potassium chloride aqueous solution as the simulated solution, and the concentration of potassium chloride and the microwave output as parameters. It is found that it is difficult to occur the flashing phenomenon as the concentration of potassium chloride increases.

Oral presentation

Effect of high dielectric solution on microwave heating characteristics

Kobayashi, Shohei*; Abe, Yutaka*; Kaneko, Akiko*; Futsuta, Akihiro*; Fujiwara, Kota*; Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori

no journal, , 

To investigate the influence of the dielectric properties of a solution or a spacer on the heating process of the solution, a low dielectric Teflon or an airogel having a very low dielectric property almost equivalent to air was placed as a spacer directly below the vessel. And the influence of the geometry and the dielectric properties of the sample and the spacer on the heating properties of the sample were evaluated. The heating efficiency obtained by the experiment tended to decrease as the spacer height increased. It was confirmed that the heating efficiency obtained by the electromagnetic analysis almost agreed with the experimental results by a support height of 50 mm. When Teflon was used as a spacer, microwaves entered from the bottom of the solution, whereas when airogel was used as a spacer, microwaves tended to enter from the top of the solution, and it was clarified that the dielectric characteristics of the spacer were the heating characteristics of the sample.

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