Coolant circulation

Nuclear Radiation Effects. Components of a nuclear reactor system that require lubrication include control-rod drives, coolant circulating pumps or compressors, motor-operated valves, and fuel handling devices, and, of course, are exposed to varying amounts of ionising (14). 

In extremely cold environments, engines can quickly become difficult, sometimes nearly impossible, to start. If ordinary gasoline- or diesel-oil-fired heaters are used, the coolant circulation pump, air fan, etc, must be powered from the vehicle s batteries, thus curtailing the time the system can be used, especially at very low temperatures when it is needed the most. By adding PbTe thermoelectrics to such heater systems, about 2% of their thermal output can be turned into electricity to mn the heater s electronics, fuel pump, combustion fan, and coolant circulation pump, with stiH sufficient power left over to keep the vehicle s battery fliUy charged. The market for such units is in the hundreds of thousands if manufacturing costs can be reduced. 

To slow down and control the rate of reaction, a moderator is also required. Typically, the moderator is boric acid, graphite, or heavy water (D20) and is present in the high-purity water, which also serves as a primary coolant for the fuel and the reactor vessel. The tremendous heat generated by nuclear fission is transferred to this closed-loop coolant, which is contained within a reactor primary-coolant circulation system. The high-purity water coolant also contains a suitable pH buffer such as lithium hydroxide, which has the additional effect of limiting the corrosion of fuel-cladding and other components. 

The remaining reactors are of similar design as shown in Fig. 22. These are bottom fed, completely filled vessels. There is a central upward pumping screw surrounded by a draft tube through which coolant circulates. The reactant syrup descends in the annular space between the draft tube and the jacketed reactor wall. In this annular space is a circular rank of manifolded vertical tubes with circulating coolant... 

Fig. 1. Flow diagram of production of sulfur dioxide from oleum 1, 30% oleum exchanger 2, S03 vaporizer 3, reactor 4, coolant surge tank 5, coolant circulating pump 6, coolant exchangers 7, sludge and acid pump 8, scmbber 9, S02 cooler 10, gas cleaner 11, S02 compressor 12, pulsation damper and 13, S02 condenser. CM is the condensate FRC, flow recording controller PIC, pressure indicating controller SM, steam TC, temperature recorder ...

FIGURE 22.9 A nuclear power plant. Heat produced in the reactor core is transferred by coolant circulating in a closed loop to a steam generator, and the steam then drives a turbine to generate electricity. 

Transformation of make-up and recycle methacrolein, previously vaporized, to which air and steam are added, and then raised to the required temperature. The operation takes place in a multi-tube reactor with shell-side coolant circulation and the production of low-pressure steam. It.operates at about 300°C and 03.10 Pa absolute. The catalyst contained in the tubes must be regenerated periodically by controlled combustion of coke deposits. 

Accident sequences investigated were decay heat removal without / with main cooling system. In the former case, both core and reformer are cutoff from the coolant circulation and a gradual temperature balance is obtained by heat conduction, radiation zind small internal convection. The activation of the main cooling system delayed by 1 h encounters a merely changed temperature distribution allowing for a smooth and gentle restart. 

This calorimetric principle makes use of the fact that the heat produced by the process must be equivalent to the heat accumulation in the coolant circulating in the jacket in order to ensure a constant internal temperature. 

The mold for thermoplastics receives the molten plastic in its cavity and cools it to solidity to the point of ejection. The most is provided with cooling channels. The mold temperature is controlled by regulating the temperature of the cooling fluid and its rate of flow through the channels. Proper cooling or coolant circulation is essential for uniform repetitive mold cycling. 

Primary coolant circulation is provided by main coolant pumps (MCP) with canned asynchronous motors that are installed on the reactor cover. As an additional benefit, simple configuration and short length of the primary circuit path permit to sustain high flow rate of... 

Both mechanical upright pumps with a turbine or electric driver and electromagnetic pumps may be used for coolant circulation. 

This defect is met in commercial BWR designs by additional circulation of the coolant around the reactor core, over and above the coolant removed as steam through the turbines. Controllers link the flow rate to the power demand as felt on the turbine, so that the increased coolant input sweeps out the steam bubbles and compensates for the void effect. The RBMK has a similar additional coolant circulation which is necessary, perhaps, for its satisfactory operation with a negative water void coefficient but would exacerbate the disadvantage of a positive coefficient. This again was a feature of the Chernobyl accident. 

I Using liquid sodium metal as the coolant, circulated at an average linear rate of 10 meters per second in a channel 2 mm. wide between reactor plates, which are 2 ram. thick and covered by a protective metal, ... 

In 1992 -1993 almost at all WWER-1000 of Ukraine, Russia and then in Bulgaria incomplete RCCA insertion (i.e. RCCA stuck in intermediate position), RCCA drop time exceeds 4s (design time) have been revealed. The program of additional quarterly measurements of RCCA drop time was developed and implemented. In the case of RCCA operation violation (and when there was no chance to cease one) the unit had been transferred to the operational mode with three loops coolant circulation and with preliminary power reduction to 67% of... 

---