Reactor core isolation cooling system

RCIC - Reactor Core Isolation Cooling System... 

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 reactor core-isolation cooling system (RCICS) could have been made available by installing a special short piece of pipe that was stored nearby. 

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. 

The Reactor Core Isolation Cooling System cools the core in the event that the main steam condenser and the main feedwater system are not available. This process can be initiated automatically by an emergency actuation signal, or can be... 

Fig. 7.5 Reactor Core Isolation Cooling System (US Nuclear Regulatory Commission, n.d.b)...

In BWRs, the auxiliary feedwater system is usually termed the reactor core isolation cooling system. This system is used to maintain the water level in the reactor vessel in the event of a loss of feedwater in hot shutdown conditions (in such an event residual heat is removed from the reactor core by means of the release of steam through safety relief valves to a suppression pool). Another function of this system is to supply the necessary inventory of reactor coolant in the event of a small loss of coolant during normal operation. 

The reactor core isolation cooling system should be designed ... 

Standby liquid control (SBLC) system Reactor core isolation cooling (RQC) system RHR system... 

A potential problem in the Reactor Core Isolation Cooling (RCIC) system circuitry of a particular BWR was identified. Within this particular RCIC control system, because of the design of the RCIC steam leak detection circuit, it is possible for a sneak circuit to occur and cause an unintended, nonrecoverable isolation of the RCIC pump in conjunction with a station blackout. There are at least three subtle design aspects which lead to the occurrence of this failure mode (1) the RCIC system contains an isolation circuit, (2) the isolation circuitry is deenergized given a loss of offsite power (i.e., the circuitry is not fed by a nonintemiptible, battery-backed vital AC power supply), and (3) the isolation circuit contains a seal-in circuit. 

Control room fires are of considerable significance in the fire analysis of this plant. Fires in the control room were divided into two scenarios, one for fires initiating in the reactor core isolation cooling (RCIC) system cabinet and one for all others. Credit was given for automatic cycling of the RCIC system unless the fire initiated within its control panel. Because of the cabinet configuration within the control... 

H. Sato (JAEA) presented a paper discussing detection methods and system behaviour assessments for a tube rupture of the intermediate heat exchanger (IHX) for a sulphur-iodine based nuclear hydrogen plant. A rupture could be detected by monitoring the secondary helium gas supply using a control system that monitors the differential pressure between the primary and secondary helium gas supply. Isolation valves would be used to reduce the helium flow between the primary and secondary cooling systems. The study showed that the maximum temperature of the reactor core does not exceed its initial value and that system behaviour did not exceed acceptance criteria. 

The engineered safety features actuation system is a limit protection system. When a serious accident occurs in the plant, it actuates the corresponding engineered safety systems to provide emergency cooling for the reactor core so as to ensure containment integrity and to prevent radioactive contamination. The actuation system consists of five parts safety injection actuation, steam line isolation actuation, feedwater line isolation actuation, containment spray actuation, containment isolation actuation system. 

The Emergency Core Cooling System uses high pressure gas to inject ordinary water into the fuel channels, followed by pumped recirculation and cooling of water within the reactor building. The containment system includes the reactor building and the containment isolation system. 

The passive safety systems of the AFPR include passive containment cooling system reactor isolation condenser, core flood tanks and suppression chamber tanks. 

Reactor coolant system boundary isolation failure could result in coolant blowdown and overpressurization of the low pressure piping. This can lead to a loss of coolant accident and containment bypass that, if combined with failures in the emergency core cooling systems, would result in a core-melt accident with significant off-site radiation releases. 

The diverse actuation system is provided to automatically actuate selected systems such as the passive residual heat removal, the core make-up tank, the passive containment cooling system, reactor trip, and containment isolation. In addition, the system provides alarms and information to the main control room for manual actuation of these systems. 

Licensing. Very little work has been done to develop a regulatory framework for the AHTR. The NRC review of the conceptual design of S-PRISM (February 1994) provides the initial basis for the regulatory consideration of a pool-type reactor. The use of the same fuel as the fuel used in gas-cooled reactors implies that many of the licensing interactions associated with gas-cooled reactors are directly applicable. However, the licensing issues with fuel performance are less because of (1) use of a low-pressure system, (2) a coolant that dissolves fission products, and (3) an indirect power cycle that further isolates the reactor core from the environment. 

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