サーマルサイクリング試験装置とウランによる二,三の実験結果について

ウラン燃料要素に関する研究, (1)

抄録

Woosher type thermal cycling equipment are designed and constructed in June 1957. In Japan, however, it is difficult to make it to be as same as ANL Woosher type equipment due to poorer NaK technique. Therefore, evacuated silica capsules containing uranium specimens made by grooved mill rolling at 600° and 300°C, respectively, are used in this thermal cycling equipment. Cycling was performed between room temperature and 550°C up to 1, 000 cycles in maximum and the thermal cycling growth coefficients are measured at the three stages shown in Table 2 From this experiment, the uranium rod rolled at 300°C was always found to have higher thermal cycling growth coefficient than the rod made at 600°C irrespective of the holding time at room and elevated temperature. The effects of rolling temperature of uranium rods on the thermal cycling growth coefficient are also described. The specimens after 1, 000 cycles are metallographically examined and sub-grains having crystal orientation of 2 or 3 degrees different from each other are observed. This experiment is one of the surveying test to find the best fuel element for JRR-3 reactor in which natural uranium is to be used as fissile material.