DRYOUT DURING FLOW AND POWER TRANSIENTS

摘要

Six series of transient tests are reported and analysed that were aimed at testing the validity of the methods currently used to predict the onset of dryout during flow and power transients in the S.G.H.W. Prototype Reactor. The experiments were carried out with forced convection water at 1000 p.s.i.a. Four different test sections were useds uniformly heated tubes of 6 ft. and 12ft., a uniformly heated 37-rod cluster of 12 ft. heated length and a non-uniformly heated tube of 12 ft. heated length. The flow transients were initiated by tripping the circulating pump and the power transients by the use of a switching circuit and a dummy load which gave a virtually instan¬taneous increase in power. By these means very fast transients were achieved, the flow being halved in under half a second, and the power to coolant in one test rising to 130％ of its initial value in the 0.2 sec. before the onset of dryout. Reliance was placed on the thermal capacity of the tube3 to give realistic rates of change of power to coolant.