Secondary circulation system

The process at Three Mile Island involved nuclear fission and subsequent reactor cooling using circulating water. The primary water was kept under pressure to prevent boiling. Heat was transferred to a secondary water system that supplied power to a steam generator. Upon completion of this step, steam condensate was recovered and recycled. All radioactive materials, including primary water, were enclosed in a lined concrete containment building to prevent their escape to the atmosphere. 

Local anesthetics are frequently coadministered with vasoconstrictor molecules such as epinephrine. Normally, they are applied or injected locally and then taken up by local blood vessels into the systemic circulation, ultimately leading to their metabolic breakdown. The co-administration of a vasoconstrictor decreases the systemic absorption of the local anesthetic, thereby increasing its effective half-life in the area of administration and decreasing the probability of systemic toxicity (i.e., cardiac toxicity) secondary to systemic distribution. 

Secondary Circulation Loop Temperature Control Systems... 

This is the simplest system for temperature control of a reactor only the jacket temperature is controlled and maintained constant, leaving the reaction medium following its temperature course as a result of the heat balance between the heat flow across the wall and the heat release rate due to the reaction (Figure 9.9). This simplicity has a price in terms of reaction control, as analysed in Sections 6.7 and 7.6. Isoperibolic temperature control can be achieved with a single heat carrier circuit, as well as with the more sophisticated secondary circulation loop. 

Figure 9.8 Heating cooling system with secondary circulation loop.

Secondary sampling port/valves should be installed on various circulating systems. 

The organism eliminates toxic substances or their metabolites through the kidneys, bile, lungs, saliva, stools and skin. The excretion by the kidneys is of the main importance. This mechanism is the same as that during the excretion of final products of primary and secondary metabolic pathways. Substances absorbed in the gastrointestinal tract are eliminated from the blood by the liver. These substances can be removed by the liver prior to reaching the circulation system. Substances which enter the body by inhalation are also eliminated from the lung (carbon monoxide, alcohol, volatile substances). The excretion system is not specialized and it operates on the basis of a simple diffusion [7-9]. 

Constant pressure water inlet device and filter device are built up at a time in secondary circulating water system. 

Using an oil/gas heat-exchanger This is similar to the above system but more expensive because of the need for a secondary cooling system. The heat-exchanger is generally cooled with a circulation of mineral oil. Cooling with a water/gas heat-exchanger is not (or only very rarely) practised... 

The HCIHX for the HTTP is a vertical helically-coiled counter flow type heat exchanger in which the primary helium gas flows on the shell side and the secondary in the tube side as shown in Fig.2. The major specification is shown in Table 1. The primary helium gas of the maximum 950°C enters the HCIHX through the inner tube In the primary concentric hot gas duct. It is deflected under a hot header and discharged around the heat transfer tubes to transfer primary heat to the secondary cooling system. It flows to the primary circulator via an upper outlet nozzle and returns between the inner and outer shell in order to cool the outer shell. 

A shell and tube type IHX integrated with heat transfer tubes for the decay heat removal system is used Considering their contribution to the simplification of the head access area, sodium immersed EM pumps are employed as both primary and secondary circulating pumps Cold traps are integrated with the primary EM pumps... 

Two medium-voltage buses supplied from the secondary windings of the two transformers on the Class IV primary medium-voltage buses, which supply power to the pumps in the service water system, ECCS, moderator circulation system, shutdown cooling system, HTS feed lines, steam generator auxiliary feed line, and the air compressors and chillers. 

If it is undesirable to circulate the coolant at the regular rate when the tube is deenergized, a secondary circulating pump can be used to move the coolant at a lower rate to purge any air that might enter the system and to prevent stagnation. Typical recommended minimum circulation rates within the coolant Hnes are as follows ... 

The last-ditch backup involves the use of raw water for once-through reactor cooling This system will operate even If the circulating water system the secondary coolant system and parts of the primary system (except for Inlet piping) are out of service,... 

In addition to the main cooling system there is an auxiliary cooling system to remove decay heat from the core when the reactor is shut down for refueling, or in an emergracy. The auxiliary cooling system which is separated from the secondary sodium system, has an air cooler in parallel with the steam generator. When it is operating, the primary and secondary sodium are circulated by the primary and secondary main circulation pumps driven by pony motors. 

The system is the union of two old ideas enhanced by new technology. The old ideas are singlepipe distribution and primarysecondary pumping. The new technology consists of the use of maintenance-free wet rotor circulators. The primary distribution system is a single-pipe loop the secondary distribution system is a decoupled secondary piping loop for each terminal unit in the system. 

Refrigeration system. Refrigeration is required in the HRE-2 for operation of freeze plugs and cold traps. The refrigeration system consists of a primary loop, which is not irradiated, and a secondary liquid circulating system which enters the shield. 

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