钠冷快堆蒸汽发生器腔室电加热设计

Electric Heating Scheme Design of Plenum in Sodium-cooled Fast Reactor Steam Generator

钠冷快堆启堆工况下,蒸汽发生器腔室内蒸汽温度短时间内由250℃上升到480℃,因腔室壁厚较大,存在一定热惰性,导致腔室内外壁间形成较大的温度梯度,从而引起很大的热应力。同理,在停堆阶段,腔室又会产生一个方向相反的热应力,该循环的二次应力作用易导致腔室发生蠕变棘轮失效或蠕变疲劳失效。为了降低启堆过程中腔室产生的热应力,可在腔室外壁面设置电加热装置,使外壁面与内壁面同步升温。通过合理的电加热功率设计,使得腔室最大热应力降低了约60%,提高了蒸汽发生器安全性。

During the start-up condition of the sodium-cooled fast reactor, the steam temperature in the plenum of the steam generator rises from 250 ℃ to 480 ℃ in a short time. Due to the large wall thickness of the plenum, there is a certain thermal inertia, which leads to a large temperature gradient between the inner and outer walls of the plenum, thus causing great thermal stress. In the same way, during the shutdown condition, the plenum produces a thermal stress in the opposite direction, and the circular secondary stress easily leads to creep ratchet failure or creep fatigue failure in the plenum. In order to reduce the thermal stress produced by the plenum during the start-up process, an electric heating device is set up on the outer wall surface of the plenum to make the outer wall surface and the inner wall surface heat up synchronously. Through reasonable electric heating power design, the maximum thermal stress is reduced by about 60 %,which greatly improves the safety of steam generator.