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Journal Articles

Effect of spacer in microwave oven cavity to heat uniformly Pu/U mixed nitrate solution for producing MOX Fuels

Imai, Suguru*; Taguchi, Kenji*; Kashiwa, Tatsuya*; Kitazawa, Toshihide*; Kato, Yoshiyuki; Segawa, Tomomi; Suzuki, Masahiro

Denki Gakkai Rombunshi, A, 133(5), p.271 - 272, 2013/05

As a part of the nuclear fuel cycle in Japan, the mixed oxide (MOX) fuels are produced through the microwave heating of the Pu/U mixed nitrate solution obtained from spent fuels. In this work, we investigate the effect of a spacer between the bottom of cavity and solution dish in microwave oven cavity to heat unifomly Pu/U mixed nitrate solution for making MOX fuels. As a result, we show the effectiveness of inserting the spacer for a uniform heating of the solution by evaluating the top-to-bottom ratio.

Journal Articles

Microwave heating of solid Pu/U mixed nitrate medium in cylindrical cavity for nuclear fuel cycle

Imai, Suguru*; Nakajima, Yuki*; Taguchi, Kenji*; Kashiwa, Tatsuya*; Kitazawa, Toshihide*; Suzuki, Masahiro; Segawa, Tomomi; Fujii, Kanichi

Proceedings of 2011 International Symposium on Antennas and Propagation (ISAP 2011) (USB Flash Drive), 4 Pages, 2011/10

As a part of the nuclear fuel cycle in Japan, the mixed oxide (MOX) fuels are produced through the microwave heating of the Pu/U mixed nitrate solution obtained from spent fuels. This paper investigated the electric power absorption of the solid Pu/U mixed nitrate medium in a cylindrical oven cavity and the effect of the input polarized waves. The numerical simulations have revealed that the incidence of the circularly polarized wave improves the uniformity of the absorbed power of the medium placed in the cylindrical cavity.

Oral presentation

Study on microwave heating of Pu/U mixed nitrate medium in solid state on denitration process

Imai, Suguru*; Taguchi, Kenji*; Kashiwa, Tatsuya*; Kawaguchi, Koichi; Segawa, Tomomi

no journal, , 

In the nuclear cycle system, reprocessing solutions (plutonium and uranium mixed nitrate solution) produced from spent nuclear fuel is converted to Mixed Oxide (MOX) by a microwave heating (MH) method in Japan. The electric constant of the reprocessing solution is varied by its phase state on heating and denitration reaction and affects the microwave heating property. It is important to understand the property of the microwave heating for improving the efficiency. Therefore the temperature distribution of the solid state of the reprocessing solution is investigated by the electromagnetic analysis and thermal analysis using FDTD method and thermal analysis method. As a result, the absorbed power of the solid-state Pu-U mixed nitrate are concentrated at upper surface and periphery, and generated heat flows to below.

Oral presentation

Evaluation on the denitration characteristics heated by the circular polarized microwave

Segawa, Tomomi; Tanigawa, Masafumi; Kato, Yoshiyuki; Kawaguchi, Koichi; Ishii, Katsunori; Suzuki, Masahiro; Kitazawa, Toshihide*; Taguchi, Kenji*; Kashiwa, Tatsuya*

no journal, , 

For the purpose of improving the microwave heating denitration technology, the denitration characteristics of cobalt nitrate aqueous solutions as a simulated materials were analyzed and evaluated by using the microwave heating equipment whichi was controlled to circular polarized wave. Numerical simulation confirmed that the circular polarized wave controlled microwave irradiation uniformed the absorbed power distribution in the circumferential direction. Moreover, it was confirmed that the denitration proceeded uniformly even in the radial direction by the microwave heating denitration experiments of cobalt nitrate aqueous solutions. From these results, it was revealed that favorable heating and denitration characteristics can be obtained by the circularly polarized wave controlled microwave heating equipment.

Oral presentation

Electromagnetic field analysis for the development of the microwave heating equipment capable of uniform heating of a metal nitrate aqueous solution and the metal oxide powder with circular polarization control

Segawa, Tomomi; Tanigawa, Masafumi; Kato, Yoshiyuki; Kawaguchi, Koichi; Ishii, Katsunori; Suzuki, Masahiro; Kitazawa, Toshihide*; Kashiwa, Tatsuya*

no journal, , 

To improve the handling and sinterability of raw powder of a uranium and plutonium mixed oxide produced in the reprocessing process of spent fuels, the microwave heating equipment has been developed considering the microwave property of linear polarization and circularly polarization that contribute to the uniformization of the microwave heating denitration by JAEA. The electromagnetic field simulation analysis was carried out by the Finite-Difference Time-Domain method, and the experimental results were evaluated. An analysis model was developed based on the obtained physical property data which were measured by the cylindrical cavity resonator method. The liquid phase state, microwave was concentrated on the upper surface and bottom surface due to the high loss of the cobalt nitrate aqueous solution, while in the solid phase state, microwave energy was absorbed inside. The absorption electric power distribution became uniform in the circumferential direction.

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