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Tobita, Masahiro*; Matsui, Yoshinori
KAERI/GP-195/2002, p.87 - 95, 2002/00
In the Japan Materials Testing Reactor (JMTR) of Japan Atomic Energy Research Institute (JAERI), the temperature distribution inside of irradiation specimens and capsules structure material are evaluated in the design of irradiation capsules. For the evaluation of detailed temperature distribution, NISA (Numerically Integrated elements for System Analysis) code has been introduced, and subprograms are developed to simplify the input data of the capsules structure and the analysis conditions using the three-dimensional finite element method. By the development of subprograms, prediction of the temperature distribution inside of irradiation specimens and capsules structure material became detailed and more accurate than calculation by one-dimensional code. Also estimation of detail temperature distribution during irradiation became possible based on the indication of thermocouple.
Matsui, Yoshinori; Ide, Hiroshi; Itabashi, Yukio; Kikuchi, Taiji; Ishikawa, Kazuyoshi; Abe, Shinichi; Inoue, Shuichi; Shimizu, Michio; Iwamatsu, Shigemi; Watanabe, Naoki*; et al.
KAERI/GP-195/2002, p.33 - 40, 2002/00
Studies on the irradiation damage of the material of the RPV are inevitable for the LWR. Recently, the researches of annealing effect on the irradiation damage of RPV material were extensively carried out using specimens irradiated in the JMTR of the JAERI. As the next step, an annealing test of irradiated specimens and re-irradiation of annealed specimens were planned. The aim of the test is to evaluate the effect of annealing by comparing the damage of irradiated specimen, its recovery by annealing and the damage after re-irradiation. For the re-irradiation test of this study, JAERI developed a new capsule in which the specimens can be exchanged before and after annealing, and, re-irradiated afterward. The development of the capsule consisted of the design and fabrication of airtight connector for thermocouples and mechanical seal device which was fit to remote handling. Remote operation procedures for handling the radioactive capsule and for exchanging specimens were carefully performed. The results of the re-irradiation proved that the development was technically successful.
Nagao, Yoshiharu; Itabashi, Yukio; Komori, Yoshihiro; Niimi, Motoji; Fujiki, Kazuo
KAERI/GP-195/2002, p.49 - 55, 2002/00
An improved analysis procedure has been introduced to evaluate irradiation field at each specimen in the irradiation capsule by using the MCNP code, which is able to model the complicated structure of the capsule directly. As the verification results, it was confirmed that the calculated fast and thermal neutron flux/fluence were agreed with measured ones within 
10% and 30%, respectively, for the irradiation tests in the JMTR. Concerning gamma dose/spectrum, it was confirmed that the calculated temperature was evaluated within -3
+14% using gamma heating obtained by MCNP calculations. The evaluations of neutron flux/fluence and specimens temperature with high accuracy are therefore possible in the irradiation test of the JMTR.
Kanno, Masaru; Kitajima, Toshio; Homma, Kenzo
KAERI/GP-195/2002, p.71 - 75, 2002/00
Recent irradiation studies aiming at clarifying the detailed mechanisms of irradiation damages to the reactor materials require to maintain the specimens at constant temperature regardless of the reactor power level,in order to avoid artificial effects of temperature transient due to reactor power change. In order to deal with this problem, JMTR has adopted feed-foward control to the gas pressure based on the reactor power signal, and developed new temperature control technique in combination with feedback control of heater power.
Komori, Yoshihiro; Matsui, Yoshinori; Itabashi, Yukio; Yamaura, Takayuki; Nagao, Yoshiharu
KAERI/GP-195/2002, p.59 - 69, 2002/00
JAERI has been developing irradiation technique and facilities for irradiation tests in the JMTR to improve irradiation capability keeping up with progress of nuclear fuels and materials research. This paper summarizes recent development on irradiation technique for the JMTR. Design study and installation of the IASCC (Irradiation Assisted Stress Corrosion Cracking) irradiation test facility was main and the most urgent task of the field in the last five years since two large projects for IASCC were planned in Japan to start irradiation tests in 2002. Almost four years were devoted to preliminary design study, detail design and installation of the facility, then IASCC irradiation test started in March, 2002. Instrumentation technique and capsules development for other research purposes also have been steadily progressing during the term, and new type of off-line temperature monitor, dual re-instrumentation device and the uniform irradiation capsule became available for the irradiation tests.
Komori, Yoshihiro; Amezawa, Hiroo; Komukai, Bunsaku; Narui, Minoru*; Konashi, Kenji*
KAERI/GP-195/2002, p.3 - 10, 2002/00
The actinide-hydride(UTh
Zr
H
) fuel has been studied for transmutation of long-lived actinide contained in the high level wastes and the first irradiation test was successfully carried out in the Japan Materials Testing Reactor (JMTR) of JAERI. Fuel pellets were fabricated by alloying and hydrogenation within an expected diameter error. The fuel pellets were designed to be irradiated below 873K on the fuel surface in consideration of hydrogen dissociation. Irradiation temperature was well agreed with designed value. Fuel burnup reached 0.2%FIMA for two JMTR operation cycles.