Community Research and Development Information Service - CORDIS


Fast-Acting Boron Injection System (FABIS)

Project ID: FIKS-CT-2001-00195
Funded under: FP5-EAECTP C


The objective of the FABIS project was to show that a fast shutdown of the reactor is feasible in the existing and future BWRs with a fast-acting boron injection system (FABIS). FABIS is needed since there is a risk in the existing BWRs that the nuclear fission process can't be stopped by the active fine motion control rod drives or by the passive scram system if there is a common cause failure in the control rod drive system. To reduce this risk, a diverse fastacting boron injection system (FABIS) is proposed which injects sodium pentaborate into the Reactor Pressure Vessel (RPV). See Figure 1 for the principle flow diagram of the system.
FABIS takes boron from a large tank where it is heated to 250 °C. Heating ensures the densities of the boron solution and water in RPV is the same. With a second set of heaters, the upper 20 % of the water are heated to 331-335 °C (130-140 bar). About 10% of the boron tank is filled with saturated steam. After activation of FABIS, steam expands and more steam is produced from saturated boron solution due to the pressure reduction. The boron solution flows through pipes inside RPV up to the upper side of the lower core plate. There the boron solution flows through smaller pipes adjacent to the lower core plate into the core bypass through about 100 small nozzles. This guarantees a homogeneous distribution of boron in RPV.

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