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Maeda, Shigetaka; Ito, Chikara; Okawachi, Yasushi; Sekine, Takashi; Aoyama, Takafumi
Reactor Dosimetry State of the Art 2008, p.474 - 482, 2009/00
In 2003 the Joyo reactor upgrade to the MK-III core was completed to increase the irradiation testing capability. This study describes the detail distributions of neutron flux and reaction rate in the MK-III core were experimentally obtained by characterization test during the first two operating cycles. Accuracy of the calculated methods in fast reactor was evaluated by comparing results of DORT, TORT and MCNP. The all calculated reaction rates of U(n,f) agreed well with the measured values about 5% in the fuel region and less than 10% in the reflector region and BC shielding subassembly. However, a large discrepancy more than 10% was observed in the central non-fuel irradiation test subassembly and radial reflector region by DORT and TORT. The MCNP can reduce this discrepancy to 6%. Specific areas of difference, such as uranium fission reaction in non-fuel subassemblies, are understood and correction methods were identified.
Maeda, Shigetaka; Sekine, Takashi; Aoyama, Takafumi; Suzuki, Soju
Reactor Dosimetry State of the Art 2008, p.607 - 615, 2009/00
The experimental fast reactor Joyo is the first sodium-cooled fast reactor in Japan. One of the primary missions of it is to perform irradiation tests of fuel and structural materials to support the development of fast reactors. The MK-III high performance core upgrade to enhance the irradiation testing capabilities was completed in 2003. In order to expand Joyo's capabilities for innovative irradiation testing applications, neutron spectrum tailoring, lower irradiation temperature, sample movable devices and fast neutron beam holes are being considered. By this program, the latent core performance is sufficiently drawn. It accurately responds to existing irradiation needs and aims at further various irradiations.
Ito, Chikara; Maeda, Shigetaka; Sekine, Takashi; Aoyama, Takafumi
no journal, ,
The high accurate and precise measurement of Nb(n,n')Nb reaction rate was established for fast reactor dosimetry. The effect of self-absorption on measuring X-rays emitted by Nb was decreased by the solution and evaporation to dryness of niobium dosimeter. The high precision number of Nb atoms was obtained by measuring niobium solution concentration using the inductively coupled plasma mass spectrometry. X-rays of Nb were measured accurately by means of comparing an X-rays intensity of irradiated niobium solution with the intensity of the solution to which stable Nb was added. The measurement error of Nb(n,n')Nb reaction rate was improved to be less than 3 %, which was equivalent to the other reaction rate error of dosimeters for the Joyo dosimetry.