Reactor vessel auxiliary cooling system

RVACS reactor vessel 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. 

LOF Primary Reactor Auxiliary Cooling System (PRACS) Reactor Vessel Auxiliary Cooling System (RVACS) TOP Mechanical stop of hydraulic drive system of reflector... 

PRACS) Reactor Vessel Auxiliary Cooling System (RVACS) Passive 1 system... 

AT.MR primary sodium and reactor vessel auxiliary cooling system (RVACS) air flow circuit using for heat removal. 

For heat removal from a shutdown reactor, two independent passive systems are provided, which are the reactor vessel auxiliary cooling system (RVACS) and the intermediate reactor auxiliary cooling system (IRACS). The RVACS is completely passive and removes shutdown heat from the surfaces of the guard vessel using natural circulation of air. There is no valve, vane, or damper in the flow path of the air therefore, the RVACS is always in operation, even when the reactor operates at rated power. Two stacks are provided to obtain a sufficient draft. 

The reactor vessel auxiliary cooling system (RVACS) is a system for shutdown heat removal however, to keep the fully passive features, it is continuously operating even at normal operation of the reactor. The intermediate reactor auxiliary cooling system (IRACS) is a sodium loop with an air cooler for shutdown heat removal, arranged in series with the secondary sodium loop (Fig. XIV-2). 

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

A scheme of the 4S-LMR main heat transport system with the indication of heat removal path in normal operation and in accidents is given in Fig. XV-11. The reactor incorporates redundant passive decay heat removal systems. Specifically, a reactor vessel auxiliary cooling system (RVACS) is adopted in which the natural convection airflow removes the decay heat radiated through the guard vessel. The heat removal capability depends on the thermal radiation area. A specific (per thermal power) heat radiation area of small reactors is larger than that of medium sized or large reactors. It is expected that about 1% of the nominal power could be removed with the RVACS. 

RVACS Reactor Vessel Auxiliary Cooling System PLOHS Protected Loss Of Heat Sink... 

The SPINNOR and VSPINNOR plants adopt pool type Pb-Bi cooled fast reactors without intermediate heat exchanger. Centrifugal pump is adopted for primary circulation, which is, together with steam generator, placed inside the reactor vessel. Decay heat is removed with the use of a passive reactor vessel auxiliary cooling system (RVACS), as shown in Fig. XXVI-1. 

RVACS - reactor vessel auxiliary cooling system ULOF - unprotected loss of flow, ULOHS - unprotected loss of heat sink... 

For all designs, active systems include a reactivity control and shutdown system based on the mechanical control rods. All designs incorporate passive air-cooled reactor vessel auxiliary cooling systems (RVACSs) or equivalents. Natural circulation based passive decay heat... 

Specifically, a reactor vessel auxiliary cooling system (RVACS) is adopted that can remove 100% of the decay heat passively, even in total loss of the normal heat sink. In the RVACS, heat generated in the core is conveyed to the reactor vessel by natural circulation of the primary coolant, is conducted across the vessel and the guard vessel and is finally transferred to the atmospheric air naturally flowing on the outer surface of the guard vessel. 

A characteristic feature of the PEACER-300 is the reactor vessel auxiliary cooling system (RVACS). Figure XXIV-18 presents the schematic diagram of this system. For a reactor with an RVACS-type decay heat removal system with liquid Pb-Bi in the gap between the reactor vessel and the guard vessel, the static load is accommodated by the guard vessel, because the reactor vessel floats in the liquid Pb-Bi. 

Figure 20.16 Containment of PRISM (GE Hitachi, 2015). RVAC, reactor vessel auxiliary cooling system.

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