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Mizuno, Mineo; Haga, Tetsuya; Sudo, Katsuo; Takeuchi, Kentaro; Okita, Takatoshi; Kihara, Yoshiyuki
JAEA-Technology 2011-009, 100 Pages, 2011/06
JAEA-Technology-2011-009.pdf:32.59MB
Crystalline cellulose granulated to sizes from 70 to 100 micron was previously used as pore former (PF) to fabricate low density MOX pellets for MONJU. When sale of Avicel was discontinued, it became necessary to find a substitute PF. Then, small scale fabrication tests of MOX pellets with candidate PFs were conducted. Three candidate PFs, cellulose beads, CEOLUS and CELPHERE, were examined in the tests. The results are summarized below. (1) The CELPHERE gave MOX pellets with almost same density depression performance as pellets using Avicel, and standards deviation of the sintered densities of pellets was the smallest. (2) MOX pellets with CELPHERE had lower incidence of observable defects. (3) MOX pellets with CELPHERE had almost the same O/M as pellets with Avicel. (4) MOX pellets with CELPHERE had lower incidence of micro cracks. (5) The densification amount of pellets with CELPHERE was almost the same as that of pellets with Avicel. It was concluded CELPHERE was a suitable substitute for Avicel.
Mizuno, Mineo*; Kosaka, Yuji*; Ogawa, Shinta*
JNC TJ8430 2005-002, 136 Pages, 2005/02
JNC-TJ8430-2005-002.pdf:30.86MB
The measurement method of the thermal conductivity has been studied on the sintered UO
particles bed to investigate the necking effects on the thermal conductivity of the Vibro-packed fuel. In the years from 2002 to 2004, the experimental study was carried out in order to survey the sintering condition of UO particles fuel bed, and it was certified that the effective thermal conductivity of the sintered UO2 particles bed could be measured by the apparatus which was constructed based on the Guarded-Comparative Longitudinal Heat Flow Technique. In this work, improvement of the apparatus in order to decrease heat loss from the sample in radial direction in the measurement of the thermal conductivity in high temperature region is carried out. Furthermore, the relation between necking ratio and the thermal conductivity of the sintered ZrO spherical particles bed are surveyed to apply this apparatus to the thermal conductivity measurements of UO spherical particle bed with high sphericity in next stage of study. The results indicate that necking ratio of particles can be controlled easily by the usage of spherical particles, and the relation between necking ratio and sintering strain can be applicable to low necking ratio region. The characteristics of the measurement apparatus are surveyed using quarts glass disc as a standard sample, and the error of the thermal conductivity measurements is estimated 3%(95% confidence limit) in 600~900deg. C , which is smaller than 8% estimated in the measurement of the thermal conductivity carried out in 2002. The thermal conductivity of the sintered ZrO spherical particle bed depends on necking ratio of particles. This result is due to the homogeneity of necking in the particle bed by the usage of spherical particles and the improvement of accuracy of measured thermal conductivity using the advanced apparatus.
Mizuno, Mineo*; Kosaka, Yuji*; Mori, Yukihide*; Shimada, Takashi*
JNC TJ8410 2004-006, 85 Pages, 2004/03
JNC-TJ8410-2004-006.pdf:3.05MB
/The process (the UPRISE method) of dissolving uranium and plutonium selectively and separating from oxide fuel using the amide system extraction solvent have been investigated. By the cold test which used Nd oxide so far, the dissolving of Nd with about 0.2 mol to the solvent of 250mL is confirmed. In this work, the investigations of the dissolving tendency of uranium to the amide system extraction solvent and decontamination factor (DF) of the typical fission product (FP) such as Nd were carried out, and following results are obtained. (1)In the test of the same dissolving conditions, the uranium dissolving rate to extraction solvent DOBA was approximately equivalent to the case of the DOiBA. (2)Three kinds of extraction solvent were examined in the same dissolving condition, the difference of the uranium dissolving rate was observed. The results of the dissolving rates indicated the order of NN'-hexyl-2, ethyl-hexan-amid-1.6 mol/L nitric acid complex 
NN'-dibutyl-butyl-amid-1.7 mol/L nitric acid complex NN'-di-isobutyl-isobutyl-amid-1.5 mol/L nitric acid complex. (3)In the case of DOBA extraction solvent, the dissolving rate increased by about 2 order with the increase of the nitric acid concentration from 1mol/L up to 3.5mol/L and strong influence of the nitric acid concentration was confirmed to the dissolving rate. (4)In the tests with the NN'-dibutyl-butyl-amid-1.7 mol/L nitrie acid complex and NN'-di-isobutyl-isobutyl-amid-1.5 mol/L nitric acid complex, the DF values of Zr, Ru and Ce increased with the elapse of the test duration and exceeded 100 after 150 hours of test duration. On the other hand, the DF value indicated around 1 for Sr, Mo and Pd, and around 0.1 for Nd. (5)In the test with the NN'-hexyl-2-ehyl-hexan-amid-1.6 mol/L nitric acid complex, significant difference wasn't observed in the tendency of the elapsed change among the DF values of the FP elements. The DF values of all FP elements except Nd and Pd exceeded 100 after 100 ...
Mizuno, Mineo*; Kosaka, Yuji*; Ogawa, Shinta*
JNC TJ8430 2004-001, 93 Pages, 2004/02
JNC-TJ8430-2004-001.pdf:7.42MB
Measurement of thermal conductivity of sintered UO2 particle bed was performed to investigate the necking effect on thermal conductivity. Test samples were prepared with high temperature creep test equipment. Plate comparison method was applied to the measurement. Thermal conductivity measurements were done for two neck ratio samples (0% and 37%) under the temperature from 600 to 800 Celsius degrees.
Mizuno, Mineo*; Kosaka, Yuji*; Ogawa, Shinta*
JNC TJ8430 2003-001, 73 Pages, 2003/02
JNC-TJ8430-2003-001.pdf:5.66MB
no abstracts in English
complexMori, Yukihide*; Shimada, Takashi*; Kosaka, Yuji*; Mizuno, Mineo*
JNC TJ8400 2003-013, 69 Pages, 2002/12
JNC-TJ8400-2003-013.pdf:3.53MB
As a head end process for the pulverization of the spent fuel, the mechanical method (the shredder method) and the pyro-chemical method (oxidization heat-treatment) have been examined. UO is a main ingredient of Uranium oxide powder by the mechaical method, and UO
is that by the pyro-chemical method. Moreover, the particle size of the pulverized powder depend on the conditions of the pulverizing process. As it was considered that the difference of dissolution rates of samples was caused by the difference of sample chemical forms and dissolution temperature, parametric surveys on chemical form and particle size of powder and dissolution temperature were carried out, and the following results were obtained. (1)The remarkable difference of dissolution rate between U3O powder(average particle size 3.7
m) and UO powder (average particle size 2.4m) which have comparatively similar particle size was not observed. (2)It was confirmed that the dissolution rate became lower according to the particle size increase (average particle size 2.4m
1mm) And it was considered that dissolution rate had strong dependency on particle size, according to the results that the powder with 1mm particle size did not dissolute completely after 5 hours test. (3)The temperature dependency of the dissolution rate was confirmed by dissolution test with UO powder (average particle size 2.4m 1mm). The higher dissolution rate was obtained in the higher dissolution temperature, and 11 kcal/mol was obtained as activation energy of dissolution. (4)In the dissolution test of UO powder, the nitric acid concentration started to change earlier than that of UO powder and concentration change range became larger compared with that in the dissolution test of UO powder. It was considered that those differences were caused by difference in mole ratio of Uranium and nitric acid which are consumed in the ...
Nakamura, Masahiro; Mizuno, Mineo*; Kosaka, Yuji*; Ogawa, Shinta*
JNC TJ8440 2002-003, 55 Pages, 2002/02
JNC-TJ8440-2002-003.pdf:13.04MB
no abstracts in English
Mizuno, Mineo*; *
JNC TJ9440 99-011, 74 Pages, 1999/03
For the driver fuel of the FBR Safety Engineering Reactor (SERAPH), a well-controlled pellet-to-cladding heat transfer to fulfill the the requirements is necessary so that some mechanism to regulate heat transfer through the gap is indispensable. Inthis study, following experiments were performed aiming at clarification of heat transfer characteristics through the pellet-cladding gaps filled with alumina cloth or filled only with gas. (1)Measurement of center-line temperature of the test piece, in which alumia cloth sleeve in the gap is compressed simulating the real fuel element, during a rapid cooling or heating from outside. (2)Measurement of center-line temperature of the test piece, in which a constant-width gas gap is maintained along the circumference, during a rapid cooling from outside. In addition to the above experiments, a study on alternative gap concepts, which could fulfill the requirements for the SERAPH driver fuel, has been carried out. These experiments clarified that heat transfer through the alumina-cloth-filled gap is dependent on the compression level of the cloth layer. However, these experimental results with different compression levels showed that the heat transfer is much lower compared with the former experiments where pure alumina cloth layer has been tested. There are some possible elements, which could explain the difference, such as difference of the cloth type. Information on heat transfer through the gas gap has also been obtained using test elements with 20 to 100 microns of gap width. Furthermore, based on survey of existing material technology and experience, which could be utilized for realization of alternative gap concepts besides the alumina-cloth gap, potential of such alternatives to fulfill the requirements was studied.
*; Mizuno, Mineo*; *; Ito, Kunihiro*; *; *
PNC TJ9678 95-003, 195 Pages, 1995/03
In preceding years, as the method of TRU transmutation (TRU means Minor Actinide such as Np, Am and Cm in this report) in FBR, we have evaluated core characteristics and TRU transmuting characteristics for two TRU loading methods : homogeneous TRU-loading method where the TRU fuel is dispersed uniformly throughout the core; and heterogeneous TRU-loading method where a few number of subassemblies with concentrated TRU fuel (target S/As) are loaded in the core. Also, as the research on the TRU transmutation by FBR plant, the survey have been conducted for the effect upon the core characteristics and the TRU transmuting characteristics affected by RE(Rare Earth) which is entrapped when TRU is separated from the high level waste. At the same time, the effect have been surveyed in the case where the TRU recycle was executed in FBR. In this fiscal year, the investigation have been conducted for a core concept in which TRU are loaded separately between the group of Np and the group of Am + Cm + RE , according to the results of advancement of nuclear fuel reprocessing technology. The core concepts with excellent TRU transmuting characteristic have been investigated for the separate loading method of Np and Am + Cm by adding only Np in the core region and adding Am, Cm and RE in the target assemblies located at radial blanket location of the core periphery. As the result of investigation, it has been found that the total amount of TRU up to around 20 % is possible in the case of loading 72 target assemblies composed of 271 pins with the pin diameter almost equal to that of the core fuel, and the TRU amount transmuted per cycle becomes 580 kg which is 3 4 times higher than the conventional TRU loading methods such as homogeneous loading and heterogeneous loading. The main core characteristics of this core concept are as follows, and the core design is feasible, : ...
Nakamura, Masahiro; Kase, Takeshi; Koizumi, Tsutomu; Mizuno, Mineo*; Kosaka, Yuji*; Ogawa, Shinta*; Sekine, Nobuyuki*
no journal, ,
Particles in the sphere-pac fuel will sinter together due to high temperature and high pressure during an irradiation. Interparticle sintering will improve the effective thermal conductivity of the particle bed. Necking ratio is introduced to take the development of it to a fuel design code. Accuracy of the necking ratio measurement with the ceramography in a post irradiation examination was evaluated by the comparison of the results of ceramography measurement and fracture surface measurement.
Mizuno, Mineo; Sudo, Katsuo; Takeuchi, Kentaro; Okita, Takatoshi; Kihara, Yoshiyuki
no journal, ,
The short process is considered to be a main concept which has high feasibility in Fast Reactor Cycle Technology Development (FaCT). In this study, a small-scale fabrication test was carried out to investigate characteristic of MOX pellet made of granulated MOX powder blended with dry-route recycle powder, for the first time, as a basic test concern with the short process. As the results, it was found that the sintered density of the pellet clearly depends on the preparing conditions and content of recycle powder. The results is intended to be utilized in the investigation of engineering-scale test conditions.