Emergency power supply system

Increase of reliability of normal and emergency power supply systems of the primary pumps and other measures increasing reactor safety. 

At the first stage, number of modifications of schemes was made, with the purpose to prevent boron dilution in primary circuit, to reduce the single failure and common mode failure probability. The effectiveness of primary circuit emergency supply systems and spring system was increased. The reliability and effectiveness of the SG emergency feed water systems are increased. Reliability of the emergency power supply systems and control systems is increased. 

The SCS does not utilize any pneumatically operated valves. The instrumentation, controls, and electric equipment pertaining to the SCS is designed to applicable portions of IEEE Standards 279, 308 and 603. In addition to normal offsite power sources, physically and electrically independent and redundant emergency power supply systems are provided to power safety-related components. See Chapter 8 for further information. 

Emergent power supply system (battencs, diesel gmierators) Total loss of heat sink ... 

The electrical power supply system in a PHWR station is divided mainly into two sub-systems. They are Class IV, system and on-site emergency power supply, system (section 5.9.2.2.3),... 

D. EMERGENCY POWER SUPPLY SYSTEM [rather backup power supply]... 

The boric acid and demineralized water control system is necessary to adjust the boron concentration in the reactor coolant system. To increase boron concentration in the coolant, boric acid solution is injected through the volume control system to reduce boron concentration, an adequate volume of coolant is replaced by demineralized water. This system (as well as the other systems discussed here) is a purely operational system and is not required for control of a design basis accident the extra borating system fulfils the necessary safety functions. However, to guarantee continued supply to the volume control system during emergency power operation, the pumps and motor-operated valves of the system are connected to the emergency power supply system. 

A reduction in cost for emergency power supply systems is achieved, since emergency cooldown of the reactor module is performed only by passive systems, relying on self-controlled natural circulation of air to which decay heat is removed through the reactor vessel. 

The effects of flooding on a nuclear power plant site may have a major bearing on the safety of the plant and may lead to a postulated initiating event (PIE) that is to be included in the plant safety analysis. The presence of water in many areas of the plant may be a common cause of failure for safety related systems, such as the emergency power supply systems or the electric switchyard, with the associated possibility of losing the external connection to the electrical power grid, the decay heat removal system and other vital systems. Details are provided in Ref [6]. 

AC/DC supply system Incorporated into Emergency power supply systems ... 

Auxiliary motor its purpose is to serve as a standby to enable the kiln to continue rotating (at reduced speed) in the event of a power supply failure or fault in the main motor. If the cement works has an emergency power supply system, the auxiliary motor may be a three-phase AC machine, otherwise an internal combustion engine - diesel or petrol (gasoline) - designed for quick starting will be provided. 

Automatic sequential paralleling system (ASPS) An emergency power supply system that operates multiple engine-generator sets in parallel. It allows the first set to reach acceptable... 

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