Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Nagata, Takako; Maeda, Koji
Comprehensive Nuclear Materials, Vol.3, p.509 - 534, 2012/00
This article is a review of fast reactor control rod materials and is part of the Elsevier Comprehensive Nuclear Materials Series. Control rods have three primary functions; reactivity compensation during the operating cycle, start-and-stop control for normal operation, and rapid shutdown during abnormal conditions. As an absorber material, boron carbide (B
C) is mainly used in fast reactor systems, such as the Japanese experimental reactor JOYO. The current core configuration of JOYO is Mark-3 (MK-3). The control rods are inserted automatically when abnormal conditions occur. In both the MK-2 and MK-3 cores, all control rods have the same structure and functions. Every control rod assembly has seven control rod elements, and BC pellets are used as absorbers. The boron in BC includes 
B and 
B. Control rods function as safety (shutdown) rods, regulating rods, rapid shutdown rods, additional shutdown rods, absorber pins, worth of controlled rods, vertical travel of control rods, rod-drop time, and features of the drive mechanism.
Nagata, Takako; Maruyama, Tadashi; Onose, Shoji
PNC TN9470 97-001, 52 Pages, 1996/11
In order to extend life of control rods for fast reactors, development of both helium-bonded and sodium-bonded absorber pins with shroud are now under investigation. Also, in development of advanced absorber materials which are alternative materials to B4C, the materials that exhibited better properties in out of pile experiments are needed to do irradiation tests to evaluate applicability as neutron absorber in long life control rods. In irradiation tests of AMIR-8, capsules of two types of helium-bonded and three types of sodium-bonded absorber pins are to be irradiated. In designing these capsules, it is requested that the capsules must possess integrity during irradiation at burnup values of 50 
200 
10
cap/m
at maximum irradiation temperature of 1200
C. In order to satisfy above requirements, the design of capsules was done by adjusting the gap size between absorber and cladding, the loading positions and the volume of plenums. The results of design study indicated that, although a target burnup was limited in some capsules, it was confirmed that the irradiation tests are successfully carried out in the other capsules to meet the object of irradiation tests, thereby numerical values in the design of capsules were able to fix.
)Asaka, Tomomi*; Hashimoto, Chika*; Ito, Kazusa*; Yasuda, Takako*; Nagata, Kento*; Nishimaki, Toshiyuki*; Katsumura, Takafumi*; Ota, Hiroki*; Suzuki, Michiyo; Funayama, Tomoo; et al.
no journal, ,
It is thought that the irradiation to the particular area of the individual could induce the irradiation impact to the outside of the irradiated area in addition to the irradiated region. In this study, we established the procedures to conduct carbon ion irradiation on adult Medaka, which can irradiate only either dorsal or ventral side of the fish, using the broad-beam irradiation system of JAEA-Takasaki. The irradiated fish were examined heart rate before the fixation. Thereafter, the systemic alteration was evaluated by serial cross sections of the whole body of the fish. Tissues at the irradiated side were seriously injured that corresponded to the range of the beam. However, secondary gill lamella showed the characteristic edema in either the ventral or dorsal irradiated fish unless the gill located at ventral, suggesting the systemic irradiation effect. There was no alteration in the heart rate after the irradiation suggesting no severe effects in blood flow in this condition.
Asaka, Tomomi*; Ito, Kazusa*; Hashimoto, Chika*; Yasuda, Takako*; Nagata, Kento*; Nishimaki, Toshiyuki*; Katsumura, Takafumi*; Ota, Hiroki*; Suzuki, Michiyo; Funayama, Tomoo; et al.
no journal, ,
Radiotherapy has been widely used in cancer target. It is thought that the irradiation to the particular area of the individual could induce the irradiation impact to the nearby and distant tissues of the irradiated area in addition to the irradiated region. However, it is still difficult to analyze influences to the whole body using mice because of its big body size. Medaka, , is small enough to examine the acute somatic effects induced in all tissues at the cellular levels. In this study, we developed a method to conduct local irradiation on adult medaka using low energy carbon-ion beam in TIARA, JAEA-Takasaki. The irradiated fish were measured the heart rate to evaluate the impact to the heart, chemically fixed, serially sectioned and Hematoxylin/eosin stained. The results suggested that there would be the systemic effects by local irradiation in addition to the effects in the irradiated region, which is probably caused by immune system though blood.
