B. Tsuchiya

J. Ukai

K. Toh

L.L. Snead

M. Itoh

M. Narui

S. Nagata

S. Onose

S.J. ZinkIe

T. Muroga

T. Shikama

T. Yano

National Institute for Fusion Science (NIFS-Repository)

6.•Linear Dimension Change in JMIR, JOYO, HFIR•••..•................2.5 ---.........................................,................,.....,"'""T""...........,....,..........,.....,.....,o L.....................L....&..........................-'-...........J...&....................L...l...................Io 1000 2000 3000 4000 5000Fast Neutron Fluence(E>O.lMeV) (XIOI\13nfmI\2)Figure 1 Linear dimension change in three differentreactors tabulated in Table 2, as a function of fast neutronfluence.The prepared specimens were irradiated in two fissionreactors which have different neutron spectra: JOYO, asodium cooled fast reactor, in Oarai Engineering Center ofInstitute of Japan Nuclear Fuel Cycle Development (JNe),has a hard neutron spectrum and, HFIR, a water-cooledhigh-flux isotope reactor of Oak Ridge National Laboratory,has a typical mixed neutron spectrum. The HFIR irradiationwas carried out under the Japan/USA collaboration calledJUPITER-II program. The present results shown in Fig. I,in comparison with accumulated data obtained in JOYO andin JMTR (Japan Materials Testing Reactor in OaraiResearch Establishment in Japan Atomic Energy ResearchInstitute), are clearly demonstrating that there will bedefinite gas nuclear transmutation effects in the aluminumnitride. The high hydrogen gas formation rate in the HFIR isenhancing the linear expansion about twice, namely theswelling rate will be six times larger than that in theirradiation environments not associated with gas production.This is rather unexpected since the irradiationtemperature is high enough for hydrogen atoms to makelong-distant diffusion. Also, it was unexpected that thelinear expansion rate showed good linear dependence on thefast neutron fluence, irrespective of reactors used andirradiated temperatures. Detailed examinations ofmicrostructures of irradiated Aluminum nitride specimensare planned. Also, isotope tailored Aluminum oxide (Ah03)specimens, irradiated in HFIR, will reveal effects oftransmuted helium. These will reveal effects of transmutinggasses on evolution of radiation induced microstructures andperformance of aluminum nitride (AIN) near burning fusionplasma in fusion reactors.Table 1. PropertIes 0 smtere anAl1SN AI l4NDensitv (% TO) 97.3 93.5Onen Porosity (%) 0.8 6.8Comnosition (mass%)C 0.17 0.230 1.14 1.13Y 1.20 0.02Fe <n.OOI <0.001Si n.042 0.068Ca 0.nn2 0.002§ 4. Gas Nuclear Transmutation Effects InAluminum Nitride (AIN)Shikama, T., Narui, M., Nagata,S., Tsuchiya, B.,Toh, K. (Inst. for Materials Res., Tohoku Univ.)Yano, T. (Tokyo Inst. Technol.)Ukai, J., Onose, 5., Itoh, M. (JNC, Oarai)Muroga, T.ZinkIe, S.J., Snead, L.L. (ORNL, USA)Gas transmutation effects were studied by theisotope tailoring method in aluminum nitride (AIN). Thealuminum nitride is a good electrical-insulator, has highthermal conductivity and is a candidate for substrates ofelectrical circuits to be used in a high nuclear heatingenvironments in fusion devices such as InternationalThermonuclear Experimental Reactor (ITER). Also, as oneof refractory insulating nitride, aluminum nitride has goodcompatibility with liquid lithium, and it is one of candidatesfor MHD-coatings on vanadium structural materials inburning fusion devices.Fine powders of aluminum nitride (AIN) wereprepared by nitriding highly pure aluminum powder(99.98mass% manufactured by Toyo aluminum Co.) withhighly pure nitrogen-15 isotope gas. (ISN!,4N99.7at%/O.3at%, impurity concentrations of 02' CH4, andCO2 were less than 20/volppm, manufactured by NihonSanso Co.) Also, conventional pure Al 14N powders wereprepared with nitrigen-14 gas. Obtained AIN fine powderswere then sintered at 2100K Small amount of Y203 finepowders were added as a sintering agent. Sintering wascarried out in an argon environment. Except for a densityand an open porosity, Al 14N and Al 15N have about the sameproperty-parameters as shown in Table 1. The final N-15enrichment ratio was 99.2at%. A small amount of N-15 wasreplaced by N-14 in the process of sintering in an argon gasenvironment.402

Gas Nuclear Transmutation Effects in Aluminum Nitride (AlN)

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Gas Nuclear Transmutation Effects in Aluminum Nitride (AlN)

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