Standby liquid control

The only human actions important in more than 50% of the BWR IPEs are manual depressurization, containment venting, initiation of standby liquid control (SLC), and system alignment for decay heat removal. In PWRs, only switch over to recirculation, feed-and-blecd, and the actions associated with depressurization and cooldown are important in more than 50% of the... 

This system is backed-up by a Standby Liquid Control System (SLCS) that injects sodium pentaborate into the moderator using a positive displacement pump (shown as a piston pump). Steam that originates in the core of a BWR, unlike the primary coolant in a PWR, exits the containment. The closing of the MSIVs isolates the radioactivity from the environment but when this is done, normal heat removal is not possible. The Residual Heat Removal (RHR) system... 

Render reactor lubcrilical Reactor protection system Render reactor subcritical Reactor protection system Standby liquid control sy.stein... 

Dquid poison injection systetn ( CCS for PWRs or improved standby liquid control syslem for BWRs). 

The RPV, together with its internals, provides guidance and support for the fine-motion control rod drives (FMCRDs). Certain of the reactor internals distribute sodium pentaborate solution delivered by the Standby Liquid Control (SLC) System when necessary to achieve core subcriticality via means other than insertion of control rods. 

The Standby Liquid Control System (SLCS) provides an alternate method of reactor shutdown from full power to cold subcritical by the injection of a neutron absorbing solution to theRPV. 

Standby liquid control system X Neutron absorbing fluid injection... 

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

Core Plate AP/Standby Liquid Control (SLC) Line... 

Core plate AP/standby liquid control (SLC) line... 

The core plate differential pressure (AP)/standby liquid control (SLC) line as shown in Figure 2-7 serves a dual function to provide a path for the injection of the liquid control solution (sodium pentaborate) to shut down the reactor from full power when reactivity control with control rods is not possible, and to sense the differential pressure across the core plate. This line enters the reactor vessel at a point below the core shroud as two concentric pipes (for BWR/6 a separate line in the bottom head). In the lower plenum, the two pipes separate. The inner pipe terminates near the lower core shroud with a perforated portion below the core plate. It is used to sense the pressure below the core plate during normal operation and to inject a liquid control solution if required. The outer pipe terminates immediately above the core plate and senses the pressure in the region outside the fuel assemblies. 

The core plate dP line instrumentation provides information on core flow performance for diagnostic purposes, and on core spray piping break. The ABWR design has only the core and internal pump differential pressure lines. The standby liquid control solution injection is served by the high pressure core flooder sparger. The core delta P lines, with an open top end, penetrate and terminate immediately above and below the core plate to sense the pressure during normal operation. The internal pump delta P lines terminate inside and outside the core shroud and sense the pressure across the pump during normal operation. 

The Siemens BWR uses the core plate differential pressure line only for measurement purposes, whereas a separate standby liquid control line for safe shut down is injecting concentrated boron solution from a storage tank via the feedwater lines into the reactor pressure vessel for neutron absorption. 

Standby Liquid Control BWRVIP-27-A BWRVIP-03 BWRVIP-53 BWRVIP-62/-79... 

Figure 14.11 The mixed spectrum supercritical water-cooled reactor safety system. ICS, isolation cooling system GDCS, gravity-driven cooling system ACC, accumulators ADS, automatic depressurization system PCCS, passive cote cooling system SLCS, standby liquid control system. 

Gravity driven cooling system (GDCS) system (ADS) Standby liquid control system (SLCS)... 

Reactivity Control Reactor Protection System Standby Liquid Control System... 

The standby liquid-control pumps could have been made available by performing a manual valve alignment, actuating two valves, and manually restoring power to the pumps. 

High-Pressure Systems High-Pressure cooiant injection Reactor core-isoiation cooling Reactor feedwater pumps Control-rod drive Standby liquid control... 

Each boiling water reactor must have a standby liquid control system (SLCS) with a minimum flow capacity and boron content equivalent in control capacity to 86 gallons per minute of 13 weight percent sodium pentaborate solution. The SLCS and its injection location must be designed to perform its function in a reliable manner. The SLCS initiation must be automatic and must be designed to perform its function in a reliable manner for plants granted... 

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