**2.4. ABWR (Advanced Boiling Water Reactor) passive reactor cooling system and passive containment cooling system**

The passive heat removal system (PHRS) consists of two dedicated systems (Figure 5, right) namely the passive reactor cooling system (PRCS: the same as Isolation condenser) and the passive containment cooling system (PCCS), that use a common heat sink pool above the containment allowing a one-day grace period, with a 4\*50% redundancy (Figure 5, left). These passive systems not only cover beyond DBA condition, but also provide in-depth heat removal backup for the RHR.

In addition, they provide the overpressure protection safety function, practically excluding the necessity of containment venting before and after core damage. Figure 6 shows PCCS functional schematic and an example of containment pressure transient following typical low pressure core melt scenario.

**Figure 5.** ABWR Passive heat removal system

30 Nuclear Power – Practical Aspects

**Figure 4.** Passive containment cooling condenser arrangement

**passive containment cooling system** 

removal backup for the RHR.

**2.4. ABWR (Advanced Boiling Water Reactor) passive reactor cooling system and** 

The passive heat removal system (PHRS) consists of two dedicated systems (Figure 5, right) namely the passive reactor cooling system (PRCS: the same as Isolation condenser) and the passive containment cooling system (PCCS), that use a common heat sink pool above the containment allowing a one-day grace period, with a 4\*50% redundancy (Figure 5, left). These passive systems not only cover beyond DBA condition, but also provide in-depth heat

In addition, they provide the overpressure protection safety function, practically excluding the necessity of containment venting before and after core damage. Figure 6 shows PCCS

steam in the IC/PCC pool is vented to the atmosphere. PCCS condensers are located in the large open IC/PCC pool, which are designed to allow full use of the collective water inventory.

**Figure 6.** Example of containment pressure transient following typical low pressure core melt scenario.
