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JAEA Reports

Development of high melting temperature measurement system by laser spot heating

Iwasa, Toma; Arima, Tatsumi*

JAEA-Technology 2021-036, 23 Pages, 2022/03

JAEA-Technology-2021-036.pdf:1.35MB

Knowledge on the liquefaction (thermal decomposition and melting) temperatures of MA-bearing nitride fuels for transmutation by accelerator-driven system is essential for elucidation of the fuel behaviors under abnormal condition and for the safety analysis. A melting temperature measurement system for refractory materials was developed based on a laser spot heating method, which is expected to measure in a very short time with a small amount of sample, and demonstration tests using refractory metals and zirconium nitride were performed. As the results, it was found that this melting temperature measurement system can be applicable up to the temperatures around 3000 K which is close to the thermal decomposition temperature of nitride fuels and we confirmed the technical feasibility of this system for future application to small specimens of transuranium nitrides.

Journal Articles

Melting behavior and thermal conductivity of solid sodium-concrete reaction product

Kawaguchi, Munemichi; Miyahara, Shinya; Uno, Masayoshi*

Journal of Nuclear Science and Technology, 56(6), p.513 - 520, 2019/06

https://doi.org/10.1080/00223131.2019.1599744

Times Cited Count：2 Percentile：21.58(Nuclear Science & Technology)

This study revealed melting points and thermal conductivities of four samples generated by sodium-concrete reaction (SCR). We prepared the samples using two methods such as firing mixtures of sodium and grinded concrete powder, and sampling depositions after the SCR experiments. In the former, the mixing ratios were determined from the past experiment. The latter simulated the more realistic conditions such as the temperature history and the distribution of Na and concrete. The thermogravimetry-differential thermal analyzer (TG-DTA) measurement showed the melting points were 865-942 $^{circ}$ C, but those of the samples containing metallic Na couldn't be clarified. In the two more realistic samples, the compression moldings in a furnace were observed. The observation revealed the softening temperature was 800-840 $^{circ}$ C and the melting point was 840-850 $^{circ}$ C, which was 10-20 $^{circ}$ C lower than the TG-DTA results. The thermodynamics calculation of FactSage 7.2 revealed the temperature of the onset of melting was caused by melting of the some components such as Na $_{2}$ SiO $_{3}$ and/or Na $_{4}$ SiO $_{4}$ . Moreover, the thermal conductivity was =1-3W/m-K, which was comparable to xNa $_{2}$ O-1-xSiO $_{2}$ (x=0.5, 0.33, 0.25), and those at 700 $^{circ}$ C were explained by the equation of .

JAEA Reports

Development of sealing plug for sweep gas line

Kikuchi, Taiji; Yamada, Hirokazu*; Saito, Takashi; Nakamichi, Masaru; Tsuchiya, Kunihiko; Kawamura, Hiroshi

JAERI-Tech 2004-026, 28 Pages, 2004/03

JAERI-Tech-2004-026.pdf:2.06MB

Iirradiation capsule for irradiation test of tritium breeder and inner capsule for pebble bed of tritium breeder is inserted. Post irradiation examination of tritium breeder will be performed after irradiation test. On cutting of irradiation capsule, sweep gas line should be sealed to prevent the tritium gas release or inflow of water to sweep gas line. However, general valve and plug cannot apply to sweep gas line sealing because of the effect of neutron irradiation or limited space in irradiation capsule. Therefore, sealing plug for sweep gas line sealing has to be developed. This report shows the development of sealing plug for sweep gas line sealing and operating procedure of sealing plug in irradiation capsule.

Journal Articles

In situ observation of a first-order liquid-liquid transition in phosphorus

Katayama, Yoshinori

Journal of Non-Crystalline Solids, 312-314, p.8 - 14, 2002/10

https://doi.org/10.1016/S0022-3093(02)01641-1

Times Cited Count：29 Percentile：83.97(Materials Science, Ceramics)

Recently, we have found a sharp pressure-induced structural change between two characteristic structures of liquid phosphorus by an in-situ high-temperature high-presusre x-ray diffraction method using a JAERI beamline, BL14B1, at SPring-8. Our observations --- existence of molecular and polymeric liquids, sharp and reversible change between them and coexistence of two structures during the change --- strongly support that the structural change is a first-order liquid-liquid phase transition. It has been confirmed that the two liquid phases have different densities by a determination of melting curve by x-ray diffraction and by a density measurement by means of x-ray absorption. The structure of liquid P under high pressure resembles that of liquid arsenic.

Journal Articles

Thermal properties of pellet

Nakamura, Jinichi

Saishin Kaku Nenryo Kogaku; Kodoka No Genjo To Tembo, p.93 - 98, 2001/06

no abstracts in English

JAEA Reports

Study on melting coditions of radioactive miscellaneous solid waste (Contract research)

Fukui, Toshiki; Nakashio, Nobuyuki; Isobe, Motoyasu; Otake, Atsushi*; Wakui, Takuji*; Hirabayashi, Takakuni*; Nakashima, Mikio

JAERI-Review 2000-033, 82 Pages, 2001/02

JAERI-Review-2000-033.pdf:2.61MB

no abstracts in English

Journal Articles

New ion generation method with SF $_{6}$ plasma

Okoshi, Kiyonori; Saito, Yuichi; Tajima, Satoshi

Kagaku To Kogyo, 52(11), p.1409 - 1412, 1999/11

no abstracts in English

JAEA Reports

Melting temperature of uranium - plutonium mixed oxide fuel

; Hirosawa, Takashi

PNC TN9410 97-075, 20 Pages, 1997/08

PNC-TN9410-97-075.pdf:0.71MB

Fuel melting temperature is one of the major thermodynamical properties that is used for determining the design criteria on fuel temperature during irradiation in FBR. In general, it is necessary to evaluate the correlation of fuel melting temperature to confirm that the fuel temperature must be kept below the fuel melting temperature during irradiation at any conditions. The correlations of the melting temperature of uranium-plutonium mixed oxide (MOX) fuel, typical FBR fuel, used to be estimated and formulized based on the measured values reported in 1960's and has been applied to the design. At present, some experiments have been accumulated with improved experimental techniques. And it reveals that the recent measured melting temperatures does not agree well to the data reported in 1960's and that some of the 1960's data should be modified by taking into account of the recent measurements. In this study, the experience of melting temperature up to now are summarized and evaluated in order to make the fuel pin design more reliable. The effect of plutonium content, oxygen to metal ratio and burnup on MOX fuel melting was examined based on the recent data under the UO $_{2}$ - PuO $_{2}$ - PuO $_{1.61}$ ideal solution model, and then formulized. The correlation obtained in this work is as-follows; T = T $_{0}$ + T $_{Pu}$ + T $_{O/M}$ + T $_{Bu}$ ----(A) T $_{0}$ = 3120 T $_{Pu}$ = -5.7537PU + 1.363110 $^{-2}$ PU $^{2}$ + 1.795210 $^{-5}$ PU $^{3}$ T $_{O/M}$ = -1.41 PU (2.00 - OP)/0.39 OP : OP = /(0.01PU) T $_{Bu}$ = -5.0BU/10000 where T is the melting temperature (degree of K), PU is the weight fraction of PuO $_{2}$ in the mixed oxide fuel, OM is the oxygen to metal ratio, and BU is the burnup in the unit of MWd/MTM. respectively. T $_{Pu}$ (plutonium content), T $_{O/M}$ (O/M Ratio), ...