Direct reactor auxiliary cooling system

DRAGS direct reactor auxiliary cooling system... 

Fig. 2.1. Schematic of the LS-VHTR. (DRAGS = direct reactor auxiliary cooling system PRACS = pool reactor auxiliary cooling system.)...

To meet the passive safety requirements of the NGNP, the AHTR uses a reactor vessel auxiliary cooling system (RVACS) similar to that of S-PRISM. It may also use a direct reactor auxiliary cooling system (DRAGS) similar to what was used in the Experimental Breeder Reactor II to supplement the RVACS and reduce the reactor vessel temperature. 

It is also possible to supplement the RVACS heat removal capacity using a direct reactor auxiliary cooling system (DRAGS) based on natural circulation of an intermediate coolant from bayonet heat exchangers in the reactor vessel to air-cooled heat exchangers. This type of DRAGS system was used in the Experimental Breeder Reactor II (EBR-II) with sodium-potasium as the intermediate coolant. There are a variety of potential intermediate coolants, several of which have been used extensively in industry for similar heat transfer applications. 

Direct reactor auxiliary cooling system (DRAGS) with immersed DHX in main vessel, intermediate sodium loop and Na-air heat exchangers. 

The secondary cooling system consists of a secondary pump, a once-through SG and piping for each loop. The reactor has two shutdown systems, the primary reactor shutdown system and the backup reactor shutdown system. Either can stop the reactor rapidly independent of the other. The decay heat removal system has four independent loops and employs a direct reactor auxiliary cooling system (DRAGS) to reduce the cost while maintaining reliability. 

Decay heat removal is by a Direct Reactor Auxiliary Cooling System(DRACS) with heat exchangers immersed in the reactor vessel, which improves reliability by a combination of forced and natural circulation, and can remove decay heat without reliance on the outer... 

A schematic of the reactor and cooling system is shown in Fig. 11.2. Two intermediate reactor auxiliary cooling systems (IRACSs) and one direct reactor auxiliary cooling system (DRAGS) have been applied as a decay heat removal system (DHRS) suitable for the two-loop cooling system and the adopted type of SG. These systems are passive type by natural circulation. 

LORL, loss of reactor level LOHS, loss of heat sink RV, reactor vessel GV, guard vessel D/2AC5, direct reactor auxiliary cooling system DHRS, decay heat removal system PRACS, primary reactor auxiliary cooling system AM, accident management. 

RVACS - Reactor vessel auxiliary cooling system DHX - Direct heat exchanger PRACS - Primary reactor auxiliary cooling system RV -Reactor vessel... 

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