| 摘要 |
<p>PURPOSE:To enable shortening of solving time and improve work efficiency and economy by keeping fuel pellets at higher temperature than a solvent liquid temperature in advance and then dropping into the solving liquid to quench. CONSTITUTION:Unirradiated fuel pellets are heated to a determined temperature for a predetermined time and then dropped into room temperature water. With this heating and quenching method, pellet temperature difference of 200 deg.C(a) or 500 deg.C(b) causes fine cracks due to thermal shock. The number of thermal shock cracks 2 in this situation is found larger for (b) than for (a) and also the inside cracks are finer. This effect appears suddenly when the thermal shock temperature difference(heated temperature-solving temperature) exceeds 100 deg.C. For the temperature difference of 200 deg.C, the solving time becomes 1/2, and for the temperature difference of 500 deg.C, it becomes 1/10. For the temperature difference of 1000 deg.C, the solving time will be further shortened.</p> |
