ECC performance in the semiscale geometry

Semiscale Mod-1 system response during the ECC baseline test series (design of the Mod-1 baseline ECC test). [PWR]

“…The different system depressurization rates in Tests S-04-1 and S-04-2 affected the duration of the Mod-1 downcomer countercurrent flow [3] and the time at which the downcomer hot wall delay time [3] began. The time at which the pressure near the cold leg break in Tests S-04-1 and S-04-2 reached the simulated containment pressure was 48 and 42 sec, respectively, as shown in Figures 6 and 7.…”

Analysis of Semiscale Mod-1 integral test with asymmetrical break (Test S-29-1). [PWR]

“…in establishing the time ECC begins flowing into the lower plenum. Past analyses [ 6] have shown •that as the system pressure reaches the simulated cunlaimm:ul pressure, the high velocity upward flow of steam in the downcomer (termed countercurrent flow) diminishes and the ECC is no longer _restricted from flowing down the downcomer. The downcomer hot wall delay time then begins, followed within 10 to IS sec by the initiation of lower plenum refill and shortly afterwards by core reflood.…”