Coolant injection system

Elapsed Time in Thousands of Reactor Years Fig. 2.7-1 ERMA simulation of a low pressure coolant injection system. The absence of oscillations in the convergence is evidence of voter statistics Reprinted with permission of EPRI. USA... 

An example of a multipurpose system is a reactor s low pressure coolant injection system which uses one out of four (1/4) pumps for a small LOCA, and three-out-of-four pumps for a large LOCA (3/4). The top event for the small LOCA might be "none of four LPCI pump u1... 

ERMA simulation of a low pressure coolant injection system. 59... 

Oberjohn, W. J., and R. H. Wilson, 1966, The Effect of Non-uniform Axial Flux Shape on the Critical Heat Flux, ASME Paper 66-WA/HT-60, Winter Annual Meeting, ASME, New York. (5) Ogasawara, H. et al., 1973, Cooling Mechanism ofthe Low Pressure Coolant-Injection System of BWR and Other Studies on the Loss-of-Coolant-Accident Phenomena, ANS Topical Meeting Water Reactor Safety, p. 351, Salt Lake City, UT. (4)... 

Core make-up keep core flooding High pressure coolant injection system (2) Low pressure coolant injection system (2) Accumulator tank (2) High pressure coolant injection system (2) Low pressure coolant injection system (2) Rehieling tank (1) Core makeup water tank (2) Automatic depressurization system (2) Accumulator tank (2j Containment vessel water (Water-filled containment vessel) (1)... 

Long term coolant Low pressure coolant injection system (2) Re-circulation coolant system (1) Static residual heat removal system (2) (Natural circulates) Emergency decay heat removal system (3) (Natural circulates)... 

At low power ratings additional savings may result from the elimination of some components or systems through design simplification (e.g. primary coolant pumps and emergency coolant injection system). The cost savings associated with the use of advanced construction and fabrication techniques for modem large reactras would also ai ly to small reactors. 

Loss of (SG) feedwater operational redundancy in normal feedwater pumps, four train aux. FW supply system (HP coolant inj. system), pressure relief system permitting depressurization and operation of low pressure emergency coolant injection system reduce initiating frequency... 

Coolant inventory Water losses are made up by coolant injection systems active Water is drawn from condensation pool, pool water can be replenished from outside. 

There is a passive system for providing make up water in the event of a LOCA, the Emergency Coolant Injection System (ECIS). This uses steam injectors to pump water from the containment tanks into the RPV. The steam is taken from the top of the pressuriser. There is two times redundancy. This system can be combined with a bleed system to provide a second route for decay heat removal. Fig. 7.5.2. gives a schematic diagram of the safety systems and the nonsafety grade heat removal systems. 

Emergency Coolant Injection System (ECIS). Passive Yes 2 steam injectors take steam from pressuriser and water from containment tanks... 

Emergency Coolant Injection System (EClS) X 2 hydroaccumulators, 4 x 50 m capacity... 

No emergency coolant injection system is needed in case of primary circuit rupture. Under conditions of rupture in any place or of any size, cooling of the reactor core and the primary heat exchangers is ensured by placing the reactor tank in a leak-tight cavity (thus performing the function of redundant casing). 

In Siemens BWRs, both, high and low pressure coolant injection systems feed water from the pressure suppression pool into the reactor pressure vessel either via the feedwater line or via separate nozzles directly connected to the feedwater spargers. 

Decay heat could be removed by the steam generators or by installing independent systems cooled by the air. Because of the lower system pressure, an emergency core cooling system such as a coolant injection system required in LWRs is not required. Furthermore, in the case of air cooling systems, because of the sodium features, several experimental and prototype reactors succeeded in demonstrating the full natural circulation capability of decay heat removal. 

All reactors have redundant means of performing these functions. Table 2.2.3 presents examples of the systems that would perform these functions for a typical BWR and a typical PWR. In many cases, there is redundancy within individual systems. Often, in BWRs, a single coolant injection system, in combination... 

Coolant Inventory Control and Core Heat Removal High Pressure Coolant Injection System Reactor Core Isolation Cooling System Low Pressure Coolant Injection System Low Pressure Core Spray System Control Rod Drive Cooling System Condensate System High Pressure Service Water System... 

The cable spreading room below the control room is significant but not dominant in the fire analysis. The scenario of interest is a fire-induced transient coupled with fire-related failures of the control power for the high-pressure coolant injection system, the reactor core isolation cooling system, the automatic depressurization system, and the control rod drive hydraulic system. The analysis gave credit to the automatic CO2 fire-suppression system in this area. 

Results from MELCOR (Version 1.8.0) calculations of three accident sequences in a W-PWR 900 Mwe three loop plant are presented. The scenarios considered include an AB sequence and two V type events a rupture of the Low Pressure Coolant Injection System in the auxiliary building, and the rupture of ten steam generator tubes in all cases without the intervention of the active emergency core cooling systems. Emphasis is put on the release and transport of core materials. It has been found that deposition of vapors from the most volatile species is high within the core structures. Later in the accident, revaporization induced by decay heat takes place, at times in coincidence with the production of steam due to core slumping, what may change the nature and composition of source terms. 

The V-sequence refers to a Loss of Coolant Accident (LOCA) through the Low Pressure Coolant Injection System (LPIS), which in this type of nuclear power plants has a common part with the Residual Heat Removal System (RHRS). The suction pipe of the RHRS connects two of the three hot legs in the primary circuit with the RHRS pumps placed into the Auxiliary Building. It has been assumed that three isolation valves fail in one of these pipelines (two of them are motorized valves) a break near the RHR pump has been postulated as a result of the over-pressurization generated in the pipe. 

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