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Journal Articles

Isotope and plasma size scaling in ion temperature gradient driven turbulence

Idomura, Yasuhiro

Physics of Plasmas, 26(12), p.120703_1 - 120703_5, 2019/12

 Times Cited Count:2 Percentile:27.41(Physics, Fluids & Plasmas)

This Letter presents the impacts of the hydrogen isotope mass and the normalized gyroradius $$rho^*$$ on L-mode like hydrogen (H) and deuterium (D) plasmas dominated by ion temperature gradient driven (ITG) turbulence using global full-f gyrokinetic simulations. In ion heated numerical experiments with adiabatic electrons, the energy confinement time shows almost no isotope mass dependency, and is determined by Bohm like $$rho^*$$ scaling. Electron heated numerical experiments with kinetic electrons show clear isotope mass dependency caused by the isotope effect on the collisional energy transfer from electrons to ions, and the H and D plasmas show similar ion and electron temperature profiles at an H to D heating power ratio of $$sim 1.4$$. The normalized collisionless ion gyrokinetic equations for H and D plasmas become identical at the same $$rho^*$$, and collisions weakly affect ITG turbulence. Therefore, the isotope mass dependency is mainly contributed by the $$rho^*$$ scaling and the heating sources.

Journal Articles

Fracture toughness evaluation of reactor pressure vessel steels by master curve method using miniature compact tension specimens

Tobita, Toru; Nishiyama, Yutaka; Otsu, Takuyo; Udagawa, Makoto; Katsuyama, Jinya; Onizawa, Kunio

Journal of Pressure Vessel Technology, 137(5), p.051405_1 - 051405_8, 2015/10

 Times Cited Count:7 Percentile:42.22(Engineering, Mechanical)

We conducted a series of fracture toughness tests based on the Master curve method for several specimen size and shapes, such as 0.16T-CT, pre-cracked Charpy type, 0.4T-CT and 1T-CT specimens, in commercially manufactured 5 kinds of A533B class1 steels with different impurity contents and fracture toughness levels. The reference temperature ($$T_{o}$$) values determined from the 0.16T-CT specimens were overall in good agreement with those determined from the 1T-CT specimens. The scatter of the 1T-equivalent fracture toughness values obtained from the 0.16T-CT specimens was equivalent to that obtained from the other larger specimens. The higher loading rate gave rise to a slightly higher $$T_{o}$$, and this dependency was almost the same for the larger specimens. We suggested an optimum test temperature on the basis of the Charpy transition temperature for determining $$T_{o}$$ using the 0.16T-CT specimens.

Journal Articles

VEGA; An Experimental study of radionuclides release from fuel under severe accident conditions

Kudo, Tamotsu; Hidaka, Akihide*; Fuketa, Toyoshi

Proceedings of 2005 Water Reactor Fuel Performance Meeting (CD-ROM), p.883 - 889, 2005/10

The VEGA program have been performed at Japan Atomic Energy Research Institute (JAERI). The program was comprised of series of experiments on radionuclides release from fuel under severe accident conditions and post-test evaluation with numerical calculations. Effects on the release of ambient pressure, fuel temperature, inert or steam environment and MOX-effect were studied in the program. These effects had been hardly investigated in previous studies due to difficulties in experiments with high temperature and pressure conditions. Release of cesium was mitigated at elevated pressure in comparison with atmospheric pressure. Cesium release was enhanced in the temperature region where fuel foaming occurred below the melting point of UO$$_{2}$$. Release of cesium and ruthenium under steam condition was greater than that under the inert helium condition. Released mass of plutonium above 2800 K was higher by nearly three orders of magnitude than that in lower temperature than 2800 K.

JAEA Reports

An Irradiation test of heat-resistant ceramic composite materials, 2; Interim report on post-irradiation examinations of the second and third preliminary test, 98M-41A, 99M-30A

Baba, Shinichi; Nemoto, Makoto*; Sozawa, Shizuo; Yamaji, Masatoshi*; Ishihara, Masahiro; Sawa, Kazuhiro

JAERI-Tech 2005-055, 157 Pages, 2005/09

JAERI-Tech-2005-055.pdf:19.06MB

The Japan Atomic Energy Research Institute (JAERI) has been carrying out the research on radiation damage mechanism of heat-resistant ceramics composite materials, as one of the subjects of the innovative basic research on high temperature engineering using the High Temperature Engineering Test Reactor (HTTR). A series of preliminary irradiation tests is being made using the Japan Materials Testing Reactor (JMTR). The present report describes results of post-irradiation examinations so far on specimens irradiated in the second and third capsule, designated 98M-41A and 99M-30A, to fast neutron fluences of 1.0$$times$$10$$^{25}$$m$$^{-2}$$(E$$>$$1MeV) at temperatures of 973K-1173K and 1273K-1473K. The PIE were conducted as the fundamental statistics index of the diametral dimensions for irradiated specimen, irradiation induced dimensional change rate and thermal expansion rate.

Journal Articles

Temperature evaluation of core components of HTGR at depressurization accident considering annealing recovery on thermal conductivity of graphite

Sumita, Junya; Shibata, Taiju; Nakagawa, Shigeaki; Hanawa, Satoshi; Iyoku, Tatsuo; Ishihara, Masahiro

Transactions of 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT-18), p.4822 - 4828, 2005/08

Graphite materials are used for structural components in High Temperature Gas-Cooled Reactor (HTGR) core because of their excellent thermo/mechanical properties. Thermal conductivity of graphite components is reduced by neutron irradiation in reactor operation. The reduced conductivity is expected to be recovered by thermal annealing effect when irradiated graphite component is heated above irradiated temperature. In the present study, temperature analyses considering the annealing effect of the HTGR core at a depressurization accident were carried out and influence of annealing effect on maximum fuel temperature was investigated. The analyses show that the annealing effect can reduce the fuel temperature about 100$$^{circ}$$C at the maximum, and it is possible to evaluate the maximum fuel temperature more appropriately. It was also shown that the core-temperature of High Temperature Engineering Test Reactor (HTTR) at the safety demonstration tests can be analyzed with the developed evaluation method considering annealing effect.

Journal Articles

Measurement of temperature effect on low enrichment STACY heterogeneous core

Watanabe, Shoichi; Yamamoto, Toshihiro; Miyoshi, Yoshinori

Transactions of the American Nuclear Society, 91, p.431 - 432, 2004/11

Temperature effect is a main factor which affects the transient characteristics at a criticality accident. A series of reactivity effects due to changes in fuel temperatures were measured for two kinds of STACY heterogeneous lattice configurations. The core was composed of LWR-type fuel rod array and low-enriched uranyl-nitrate-solution concerning the dissolver of the reprocessing facility for LWR spent fuel. The critical solution heights at various solution temperatures were measured. From the change of the critical water height with fuel temperature, the reactivity effect was evaluated by a critical-solution-level worth method. The temperature effect was also calculated by using SRAC and the transport calculation code TWODANT. The experimental value was estimated to be -2.0 cent/$$^{circ}$$C for the case "2.1cm-pitch", and -2.5 cent/$$^{circ}$$C for the case "1.5cm-pitch". The calculated results gave agreement with the experiments within $$sim$$10%.

JAEA Reports

Preliminary investigation of annealing effect on thermal conductivity of graphite and investigation of annealing test method (Contract research)

Sumita, Junya; Nakano, Masaaki*; Tsuji, Nobumasa*; Shibata, Taiju; Ishihara, Masahiro

JAERI-Tech 2004-055, 25 Pages, 2004/08

JAERI-Tech-2004-055.pdf:4.25MB

Neutron irradiation remarkably reduces the thermal conductivity of graphite, and the reduced thermal conductivity is recovered by annealing effect if the graphite is heated above the irradiation temperature. Therefore, it is expected that the reduced thermal conductivity of graphite components in the HTGR could be recovered by the annealing effect in accidents, such as a depressurization accident. Then, an analytical investigation of the annealing effect on thermal performance of a HTGR core was carried. The analysis showed that the annealing effect reduces the maximum fuel temperature about 70$$^{circ}$$C, and it is important to introduce the annealing effect appropriately in the temperature analysis of the core components and reactor internals. In addition, an annealing test method was investigated to evaluate the effect quantitatively, and the test plan was made.

Journal Articles

Correlation between cleavage fracture toughness and charpy impact properties in the transition temperature range of reactor pressure vessel steels

Onizawa, Kunio; Suzuki, Masahide

JSME International Journal, Series A, 47(3), p.479 - 485, 2004/07

In the structural integrity assessment of reactor pressure vessel, fracture toughness values are estimated by assuming that the radiation effect on fracture toughness is equivalent to that on Charpy properties. Therefore, it is necessary to establish the correlation between both properties especially on irradiation embrittlement. In this paper, we present the fracture toughness data obtained by applying the master curve approach that was adopted recently in the ASTM test method. Materials used in this study are five ASTM A533B class 1 steels and one weld metal. Neutron irradiation for Charpy-size specimens as well as standard Charpy-v specimens was carried out at the Japan Materials Testing Reactor. The shifts of the reference temperature on fracture toughness due to neutron irradiation are evaluated. Correlation between the fracture toughness reference temperature and Charpy transition temperature is established. Based on the correlation, the optimum test temperature for fracture toughness testing and the method to determine a lower bound fracture toughness curve are discussed.

Journal Articles

Multichordal charge exchange recombination spectroscopy on the JT-60U tokamak

Koide, Yoshihiko; Sakasai, Akira; Sakamoto, Yoshiteru; Kubo, Hirotaka; Sugie, Tatsuo

Review of Scientific Instruments, 72(1), p.119 - 127, 2001/01

 Times Cited Count:37 Percentile:84.49(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Study on reactivity feedback effects in the TRACY transient experiments

Nakajima, Ken; ;

Proceedings of 6th International Conference on Nuclear Criticality Safety (ICNC '99), 3, p.1286 - 1292, 1999/00

no abstracts in English

Journal Articles

Temperature effects on radiation induced phenomena in polystyrene having atactic and syndiotactic structures

*; *; *; Seguchi, Tadao; Tabata, Yoneho*

Radiation Physics and Chemistry, 55(4), p.399 - 408, 1999/00

 Times Cited Count:14 Percentile:71.72(Chemistry, Physical)

no abstracts in English

Journal Articles

Alanine-polystyrene dosimeters prepared by injection moulding

Kojima, Takuji; Kashiwazaki, Shigeru*; Zhang, Y.*

Applied Radiation and Isotopes, 48(7), p.965 - 968, 1997/07

no abstracts in English

Journal Articles

Irradiation and ESR analysis temperature dependence of the gamma-ray response of alanine-polystyrene dosimeters

Kojima, Takuji; Morishita, Norio; Ito, Hisayoshi; S.Biramontri*

Applied Radiation and Isotopes, 47(4), p.457 - 459, 1996/00

 Times Cited Count:4 Percentile:40.53(Chemistry, Inorganic & Nuclear)

no abstracts in English

Journal Articles

Temperature effect on critical mass and kinetic parameter $$beta$$$$_{eff}$$/$$wedge$$ of VHTRC-4 core

Yamane, Tsuyoshi; Akino, Fujiyoshi;

PHYSOR 96: Int. Conf. on the Physics of Reactors, 2, p.E290 - E299, 1996/00

no abstracts in English

Journal Articles

Effect of low irradiation temperature on the gamma-ray response of dyed and undyed PMMA dosimeters

S.Biramontri*; ; Tachibana, Hiroyuki; Kojima, Takuji

Radiation Physics and Chemistry, 48(1), p.105 - 109, 1996/00

 Times Cited Count:15 Percentile:77.34(Chemistry, Physical)

no abstracts in English

Journal Articles

Temperature effects on radiation induced phenomena in polymers

Tabata, Yoneho*; *; *; Seguchi, Tadao

Radiation Physics and Chemistry, 48(5), p.563 - 568, 1996/00

no abstracts in English

Journal Articles

Effects of cryogenic reactor irradiation on organic insulators

Kato, Teruo

Teion Kogaku, 30(11), p.510 - 518, 1995/00

no abstracts in English

Journal Articles

Fading characteristics of an alanine-polystyrene dosimeter

Kojima, Takuji; L.Chen*; Haruyama, Yasuyuki; Tachibana, Hiroyuki; Tanaka, Ryuichi

Applied Radiation and Isotopes, 43(7), p.863 - 867, 1992/00

no abstracts in English

Journal Articles

Future potential of nuclear heat utilization in energy, economy and environment

; Sato, Osamu; ; *

Nucl. Eng. Des., 136, p.211 - 217, 1992/00

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Development of functional ceramics for nuclear fusion devices and their property measurements in radiation environment

Ono, Hideo; Kondo, Tatsuo

Proc. 1st Japan Int. SAMPE Symp., p.1622 - 1627, 1989/00

no abstracts in English

47 (Records 1-20 displayed on this page)