Decay Heat Removal in GEN IV Gas-Cooled Fast Reactors

Table 5

Timing of significant events for case  32.

0s	10 sq. in break initiated.
169.3s	Reactor tripped on low-pressure. Generator tripped off line and turbine bypass is opened.
234.92s	Turbine bypass reclosed when PCU flow dropped below 20% of rated value.
382.92s	Compressors replaced by dummy volumes when PCU flow again dropped below 20% of rated value.
420s	Blower turned on with a flow velocity of 3.5 m/s.
1250s	Helium accumulator connected to guard containment to maintain pressure at 800 kPa. Accumulator is modeled by a time-dependent volume of constant pressure (800 kPa) and constant temperature (303.15 K)
9000s	Case restarted by defining reactor power as a function of time in the form of a table. Reactor power decayed linearly from 26.2589 MW at 𝑡=9000 seconds to 13.9748 MW at 𝑡=15000 seconds. The later power level is equivalent to the decay power 24-hours after a shutdown.
9050s	Trip valve located at the junction between the PCU outlet and the reactor downcomer was closed. This was used to simulate the action of a check valve that would have prevented flow from entering the PCU via the reactor downcomer.
15000s	Blower speed reduced to zero in 5 seconds. Reactor power was maintained constant at the 24-hour decay heat level.
25000s	Case ended.