Two-loop cooling system

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. 

Yamano, H., et al., 2010. Technological feasibility of two-loop cooling system in JSFR. Nuclear Technology 170, 159. 

The case in Figure 8 represents a reactor with two different cooling systems. In the not recommended case (right) the cooling system presents a feedback loop between a reactor heat rise and the rise in the coolant temperature, which should be avoided. On the left is the recommended system, where the coolant temperature does not depend on the reactor temperature. 

Three steps eliminate these odor problems. The first is a distillate recovery system that recovers most of the fatty acid as a byproduct and many of the associated odors in the deodorizer vapor discharge. The second is a closed-loop cooling system that keeps the fat-laden hot well water out of the cooling tower. The third is a vapor scrubbing or oxidation system to eliminate volatile organic compounds that are not removed in the previous two steps. 

Figure 99 is an example of modern ammonia synthesis loop (Krupp-Uhde) with a two-vessel converter system and three indirectly cooled catalyst beds producing 1500 t/d NH3 at 188 bar. 

A combination of two cooling systems may sometimes be found as well, for instance in plants which have both a number of smaller process coolers and large turbine waste steam condensers installed. Whereas the latter are operated with sea water wherever possible, the former are normally combined into a small open or closed loop. 

Six-control rod subassemblies made of 90% enriched B4C were used in JOYO MK-II and were located symmetrically in the third row. In 1994, one control rod was moved to the fifth row to provide a position for irradiation test assemblies with on-line instrumentation. Since then, the control rod subassemblies have been loaded asymmetrically. The JOYO cooling system has two primary sodium loops, two secondary loops and an auxiliary cooling system. The cooling system uses approximately 200 tons of sodium. In the MK-II core, sodium enters the core at 370°C at a flow rate of 1 100 tons/h/loop and exits the reactor vessel at 500°C. The maximum outlet temperature of a fuel subassembly is about 570 C. An intermediate heat exchanger (IHX) separates radioactive sodium in the primary system from non-radioactive... 

Ifoter supplies and treatment. Two deep wells are located on the site each one is capable of delivering the normal site demands. Water passes through reservoir tanks and is pumped from there to the Demineralizer Building. Here one portion is demineralized, another chlorinated, and a third softened and chlorinated. The reactor uses demineralized water in a recirculating cooling system. An overhead working reservoir in this loop provides the flow... 

The cooling system, which is shown in Fig. 9.5, consists of two loops, the coolant tank (1), two redundant pumps in each loop (PIA, PIB and P2A, P2B), and the heat exchanger (2). The latter is connected to a refrigerating unit. In one of the loops the coolant, whose temperature is —5 °C, is pumped by one of the pumps P2A or P2B from the cold side of the coolant tank to the consumers of the production process. After removing heat from the consumers the coolant is pumped back into the warm side of the coolant tank. 

The passive system for residual heat removal is intended to remove residual heat from the core foUowing complete loss of power supply when the reactor operates at any power level. The system consists of two loops and operates without power sources to complete cool down without operator intervention. 

It comprises two 100% independent trains, each one including a Primary Safety Cooling System (PSC) an Intermediate Safety Cooling loop (ISC)... 

The function of the reactor water recirculation system (Figure 3.8) is to circulate the required coolant through the reactor core. The system consists of two loops external to the reactor vessel, each containing a pump with a directly coupled water-cooled (air-water) motor, a flow control valve, and two shutoff valves. 

Being put into operation with the HTS at full temperature and pressure The shutdown cooling system consists of two independent circuits, one located at each end of the reactor. Each circuit consists of a pump and a heat exchanger, connected between the inlet and outlet headers of both HTS loops. The system is normally full of D2O and isolated from the HTS by power-operated valves. 

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